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Faivre A, Bugarski M, Rinaldi A, Sakhi IB, Verissimo T, Legouis D, Rutkowski JM, Correia S, Kaminska M, Dalga D, Malpetti D, Cippa PE, de Seigneux S, Hall AM. Spatiotemporal Landscape of Kidney Tubular Responses to Glomerular Proteinuria. J Am Soc Nephrol 2024; 35:854-869. [PMID: 38652545 PMCID: PMC11230716 DOI: 10.1681/asn.0000000000000357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Abstract
Key Points
Glomerular proteinuria induces large-scale changes in gene expression along the nephron.Increased protein uptake in the proximal tubule results in axial remodeling and injury.Increased protein delivery to the distal tubule causes dedifferentiation of the epithelium.
Background
Large increases in glomerular protein filtration induce major changes in body homeostasis and are associated with a higher risk of kidney functional decline and cardiovascular disease. We investigated how elevated protein exposure modifies the landscape of tubular function along the entire nephron, to understand the cellular changes that mediate these important clinical phenomena.
Methods
We conducted single-nucleus RNA sequencing, functional intravital imaging, and antibody staining to spatially map transport processes along the mouse kidney tubule. We then delineated how these were altered in a transgenic mouse model of inducible glomerular proteinuria (POD-ATTAC) at 7 and 28 days.
Results
Glomerular proteinuria activated large-scale and pleiotropic changes in gene expression in all major nephron sections. Extension of protein uptake from early (S1) to later (S2) parts of the proximal tubule initially triggered dramatic expansion of a hybrid S1/2 population, followed by injury and failed repair, with the cumulative effect of loss of canonical S2 functions. Proteinuria also induced acute injury in S3. Meanwhile, overflow of luminal proteins to the distal tubule caused transcriptional convergence between specialized regions and generalized dedifferentiation.
Conclusions
Proteinuria modulated cell signaling in tubular epithelia and caused distinct patterns of remodeling and injury in a segment-specific manner.
Podcast
This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/JASN/2024_05_01_ASN0000000000000357.mp3
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Affiliation(s)
- Anna Faivre
- Department of Medicine and Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Milica Bugarski
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Anna Rinaldi
- Laboratories for Translational Research, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
- Division of Nephrology, Department of Medicine, Ente Ospedaliero Cantonale, Lugano, Switzerland
| | - Imene B Sakhi
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Thomas Verissimo
- Department of Medicine and Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - David Legouis
- Department of Medicine and Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- Division of Intensive Care, Department of Acute Medicine, University Hospital of Geneva, Geneva, Switzerland
| | | | - Sara Correia
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Monika Kaminska
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Delal Dalga
- Department of Medicine and Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Daniele Malpetti
- Istituto Dalle Molle di Studi sull'Intelligenza Artificiale (IDSIA), USI/SUPSI, Lugano, Switzerland
| | - Pietro E Cippa
- Laboratories for Translational Research, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
- Division of Nephrology, Department of Medicine, Ente Ospedaliero Cantonale, Lugano, Switzerland
| | - Sophie de Seigneux
- Department of Medicine and Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- Department of Medicine, Service of Nephrology, Geneva University Hospitals, Geneva, Switzerland
| | - Andrew M Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
- Department of Nephrology, University Hospital Zurich, Zurich, Switzerland
- Zurich Kidney Center, Zurich, Switzerland
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Das F, Ghosh-Choudhury N, Kasinath BS, Sharma K, Choudhury GG. High glucose-induced downregulation of PTEN-Long is sufficient for proximal tubular cell injury in diabetic kidney disease. Exp Cell Res 2024; 440:114116. [PMID: 38830568 DOI: 10.1016/j.yexcr.2024.114116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 04/24/2024] [Accepted: 05/31/2024] [Indexed: 06/05/2024]
Abstract
During the progression of diabetic kidney disease, proximal tubular epithelial cells respond to high glucose to induce hypertrophy and matrix expansion leading to renal fibrosis. Recently, a non-canonical PTEN has been shown to be translated from an upstream initiation codon CUG (leucine) to produce a longer protein called PTEN-Long (PTEN-L). Interestingly, the extended sequence present in PTEN-L contains cell secretion/penetration signal. Role of this non-canonical PTEN-L in diabetic renal tubular injury is not known. We show that high glucose decreases expression of PTEN-L. As a mechanism of its function, we find that reduced PTEN-L activates Akt-2, which phosphorylates and inactivate tuberin and PRAS40, resulting in activation of mTORC1 in tubular cells. Antibacterial agent acriflavine and antiviral agent ATA regulate translation from CUG codon. Acriflavine and ATA, respectively, decreased and increased expression of PTEN-L to altering Akt-2 and mTORC1 activation in the absence of change in expression of canonical PTEN. Consequently, acriflavine and ATA modulated high glucose-induced tubular cell hypertrophy and lamininγ1 expression. Importantly, expression of PTEN-L inhibited high glucose-stimulated Akt/mTORC1 activity to abrogate these processes. Since PTEN-L contains secretion/penetration signals, addition of conditioned medium containing PTEN-L blocked Akt-2/mTORC1 activity. Notably, in renal cortex of diabetic mice, we found reduced PTEN-L concomitant with Akt-2/mTORC1 activation, leading to renal hypertrophy and lamininγ1 expression. These results present first evidence for involvement of PTEN-L in diabetic kidney disease.
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Affiliation(s)
- Falguni Das
- VA Research, South Texas Veterans Health Care System, San Antonio, TX, USA; Department of Medicine, TX, USA
| | | | | | - Kumar Sharma
- VA Research, South Texas Veterans Health Care System, San Antonio, TX, USA; Department of Medicine, TX, USA
| | - Goutam Ghosh Choudhury
- VA Research, South Texas Veterans Health Care System, San Antonio, TX, USA; Department of Medicine, TX, USA; Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, TX, USA.
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Demko J, Saha B, Takagi E, Mannis A, Weber R, Pearce D. Coordinated Regulation of Renal Glucose Reabsorption and Gluconeogenesis by mTORC2 and Potassium. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.22.600201. [PMID: 38979219 PMCID: PMC11230149 DOI: 10.1101/2024.06.22.600201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Background The kidney proximal tubule is uniquely responsible for reabsorption of filtered glucose and gluconeogenesis (GNG). Insulin stimulates glucose transport and suppresses GNG in the proximal tubule, however, the signaling mechanisms and coordinated regulation of these processes remain poorly understood. The kinase complex mTORC2 is critical for regulation of growth, metabolism, solute transport, and electrolyte homeostasis in response to a wide array of inputs. Here we examined its role in the regulation of renal glucose reabsorption and GNG. Methods Rictor, an essential component of mTORC2, was knocked out using the Pax8-LC1 system to generate inducible tubule specific Rictor knockout (TRKO) mice. These animals were subjected to fasting, refeeding, and variation in dietary K + . Metabolic parameters including glucose homeostasis and renal function were assessed in balance cages. Kidneys and livers were also harvested for molecular analysis of gluconeogenic enzymes, mTORC2-regulated targets, and plasma membrane glucose transporters. Results On a normal chow diet, TRKO mice had marked glycosuria despite indistinguishable blood glucose relative to WT controls. Kidney plasma membrane showed lower SGLT2 and SGLT1 in the fed state, supporting reduced renal glucose reabsorption. Additional metabolic testing provided evidence for renal insulin resistance with elevated fasting insulin, impaired pyruvate tolerance, elevated hemoglobin A1c, and increased renal gluconeogenic enzymes in the fasted and fed states. These effects were correlated with reduced downstream phosphorylation of Akt and the transcription factor FOXO4, identifying a novel role of FOXO4 in the kidney. Interestingly, high dietary K + prevented glycosuria and excessive GNG in TRKO mice, despite persistent reduction in mTORC2 substrate phosphorylation. Conclusion Renal tubule mTORC2 is critical for coordinated regulation of sodium-glucose cotransport by SGLT2 and SGLT1 as well as renal GNG. Dietary K + promotes glucose reabsorption and suppresses GNG independently of insulin signaling and mTORC2, potentially providing an alternative signaling mechanism in states of insulin resistance. SIGNIFICANCE STATEMENT The kidney contributes to regulation of blood glucose through reabsorption of filtered glucose and gluconeogenesis. This study shows that mTORC2 and dietary potassium coordinate the regulation of sodium-glucose cotransport and glucose production in the kidney via independent mechanisms. New insights into the regulation of these processes in the kidney offer promising implications for diabetes mellitus management and treatment.
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Zhang Y, Bock F, Ferdaus M, Arroyo JP, L Rose K, Patel P, Denton JS, Delpire E, Weinstein AM, Zhang MZ, Harris RC, Terker AS. Low potassium activation of proximal mTOR/AKT signaling is mediated by Kir4.2. Nat Commun 2024; 15:5144. [PMID: 38886379 PMCID: PMC11183202 DOI: 10.1038/s41467-024-49562-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 06/07/2024] [Indexed: 06/20/2024] Open
Abstract
The renal epithelium is sensitive to changes in blood potassium (K+). We identify the basolateral K+ channel, Kir4.2, as a mediator of the proximal tubule response to K+ deficiency. Mice lacking Kir4.2 have a compensated baseline phenotype whereby they increase their distal transport burden to maintain homeostasis. Upon dietary K+ depletion, knockout animals decompensate as evidenced by increased urinary K+ excretion and development of a proximal renal tubular acidosis. Potassium wasting is not proximal in origin but is caused by higher ENaC activity and depends upon increased distal sodium delivery. Three-dimensional imaging reveals Kir4.2 knockouts fail to undergo proximal tubule expansion, while the distal convoluted tubule response is exaggerated. AKT signaling mediates the dietary K+ response, which is blunted in Kir4.2 knockouts. Lastly, we demonstrate in isolated tubules that AKT phosphorylation in response to low K+ depends upon mTORC2 activation by secondary changes in Cl- transport. Data support a proximal role for cell Cl- which, as it does along the distal nephron, responds to K+ changes to activate kinase signaling.
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Affiliation(s)
- Yahua Zhang
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
| | - Fabian Bock
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
| | - Mohammed Ferdaus
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Juan Pablo Arroyo
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
| | - Kristie L Rose
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Purvi Patel
- Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jerod S Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weil Medical College, New York, NY, USA
| | - Ming-Zhi Zhang
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
| | - Raymond C Harris
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Andrew S Terker
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA.
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Albalawy WN, Youm EB, Shipman KE, Trull KJ, Baty CJ, Long KR, Rbaibi Y, Wang XP, Fagunloye OG, White KA, Jurczak MJ, Kashlan OB, Weisz OA. SGLT2-independent effects of canagliflozin on NHE3 and mitochondrial complex I activity inhibit proximal tubule fluid transport and albumin uptake. Am J Physiol Renal Physiol 2024; 326:F1041-F1053. [PMID: 38660713 DOI: 10.1152/ajprenal.00005.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 04/03/2024] [Accepted: 04/18/2024] [Indexed: 04/26/2024] Open
Abstract
Beyond glycemic control, SGLT2 inhibitors (SGLT2is) have protective effects on cardiorenal function. Renoprotection has been suggested to involve inhibition of NHE3 leading to reduced ATP-dependent tubular workload and mitochondrial oxygen consumption. NHE3 activity is also important for regulation of endosomal pH, but the effects of SGLT2i on endocytosis are unknown. We used a highly differentiated cell culture model of proximal tubule (PT) cells to determine the direct effects of SGLT2i on Na+-dependent fluid transport and endocytic uptake in this nephron segment. Strikingly, canagliflozin but not empagliflozin reduced fluid transport across cell monolayers and dramatically inhibited endocytic uptake of albumin. These effects were independent of glucose and occurred at clinically relevant concentrations of drug. Canagliflozin acutely inhibited surface NHE3 activity, consistent with a direct effect, but did not affect endosomal pH or NHE3 phosphorylation. In addition, canagliflozin rapidly and selectively inhibited mitochondrial complex I activity. Inhibition of mitochondrial complex I by metformin recapitulated the effects of canagliflozin on endocytosis and fluid transport, whereas modulation of downstream effectors AMPK and mTOR did not. Mice given a single dose of canagliflozin excreted twice as much urine over 24 h compared with empagliflozin-treated mice despite similar water intake. We conclude that canagliflozin selectively suppresses Na+-dependent fluid transport and albumin uptake in PT cells via direct inhibition of NHE3 and of mitochondrial function upstream of the AMPK/mTOR axis. These additional targets of canagliflozin contribute significantly to reduced PT Na+-dependent fluid transport in vivo.NEW & NOTEWORTHY Reduced NHE3-mediated Na+ transport has been suggested to underlie the cardiorenal protection provided by SGLT2 inhibitors. We found that canagliflozin, but not empagliflozin, reduced NHE3-dependent fluid transport and endocytic uptake in cultured proximal tubule cells. These effects were independent of SGLT2 activity and resulted from inhibition of mitochondrial complex I and NHE3. Studies in mice are consistent with greater effects of canagliflozin versus empagliflozin on fluid transport. Our data suggest that these selective effects of canagliflozin contribute to reduced Na+-dependent transport in proximal tubule cells.
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Affiliation(s)
- Wafaa N Albalawy
- Department of Human Genetics, Pitt Public Health, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Elynna B Youm
- Department of Human Genetics, Pitt Public Health, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Katherine E Shipman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Keelan J Trull
- Department of Chemistry and Biochemistry, University of Notre Dame, South Bend, Indiana, United States
| | - Catherine J Baty
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Kimberly R Long
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Youssef Rbaibi
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Xue-Ping Wang
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Olayemi G Fagunloye
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Katharine A White
- Department of Chemistry and Biochemistry, University of Notre Dame, South Bend, Indiana, United States
| | - Michael J Jurczak
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Ossama B Kashlan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Ora A Weisz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
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Christer S, Simons M. Lysosomal cystine accumulation activates mTOR signaling in cystinosis: are mTOR inhibitors the cure? Kidney Int 2024; 105:656-658. [PMID: 38519228 DOI: 10.1016/j.kint.2023.11.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/01/2023] [Indexed: 03/24/2024]
Affiliation(s)
- Salómon Christer
- Nephrogenetics Unit, Institute of Human Genetics, University Hospital Heidelberg, Heidelberg, Germany
| | - Matias Simons
- Nephrogenetics Unit, Institute of Human Genetics, University Hospital Heidelberg, Heidelberg, Germany.
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Chrysopoulou M, Rinschen MM. Metabolic Rewiring and Communication: An Integrative View of Kidney Proximal Tubule Function. Annu Rev Physiol 2024; 86:405-427. [PMID: 38012048 DOI: 10.1146/annurev-physiol-042222-024724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The kidney proximal tubule is a key organ for human metabolism. The kidney responds to stress with altered metabolite transformation and perturbed metabolic pathways, an ultimate cause for kidney disease. Here, we review the proximal tubule's metabolic function through an integrative view of transport, metabolism, and function, and embed it in the context of metabolome-wide data-driven research. Function (filtration, transport, secretion, and reabsorption), metabolite transformation, and metabolite signaling determine kidney metabolic rewiring in disease. Energy metabolism and substrates for key metabolic pathways are orchestrated by metabolite sensors. Given the importance of renal function for the inner milieu, we also review metabolic communication routes with other organs. Exciting research opportunities exist to understand metabolic perturbation of kidney and proximal tubule function, for example, in hypertension-associated kidney disease. We argue that, based on the integrative view outlined here, kidney diseases without genetic cause should be approached scientifically as metabolic diseases.
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Affiliation(s)
| | - Markus M Rinschen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark;
- III. Department of Medicine and Hamburg Center for Kidney Health, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
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8
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Yamahara K, Yasuda-Yamahara M, Kuwagata S, Chin-Kanasaki M, Kume S. Ketone Body Metabolism in Diabetic Kidney Disease. KIDNEY360 2024; 5:320-326. [PMID: 38227425 PMCID: PMC10914200 DOI: 10.34067/kid.0000000000000359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 01/10/2024] [Indexed: 01/17/2024]
Abstract
Ketone bodies have a negative image because of ketoacidosis, one of the acute and serious complications in diabetes. The negative image persists despite the fact that ketone bodies are physiologically produced in the liver and serve as an indispensable energy source in extrahepatic organs, particularly during long-term fasting. However, accumulating experimental evidence suggests that ketone bodies exert various health benefits. Particularly in the field of aging research, there is growing interest in the potential organoprotective effects of ketone bodies. In addition, ketone bodies have a potential role in preventing kidney diseases, including diabetic kidney disease (DKD), a diabetic complication caused by prolonged hyperglycemia that leads to a decline in kidney function. Ketone bodies may help alleviate the renal burden from hyperglycemia by being used as an alternative energy source in patients with diabetes. Furthermore, ketone body production may reduce inflammation and delay the progression of several kidney diseases in addition to DKD. Although there is still insufficient research on the use of ketone bodies as a treatment and their effects, their renoprotective effects are being gradually proven. This review outlines the ketone body-mediated renoprotective effects in DKD and other kidney diseases.
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Affiliation(s)
- Kosuke Yamahara
- Department of Medicine, Shiga University of Medical Science, Otsu, Japan
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Rega LR, Janssens V, Graversen JH, Moestrup SK, Cairoli S, Goffredo BM, Nevo N, Courtoy GE, Jouret F, Antignac C, Emma F, Pierreux CE, Courtoy PJ. Dietary supplementation of cystinotic mice by lysine inhibits the megalin pathway and decreases kidney cystine content. Sci Rep 2023; 13:17276. [PMID: 37828038 PMCID: PMC10570359 DOI: 10.1038/s41598-023-43105-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 09/20/2023] [Indexed: 10/14/2023] Open
Abstract
Megalin/LRP2 is a major receptor supporting apical endocytosis in kidney proximal tubular cells. We have previously reported that kidney-specific perinatal ablation of the megalin gene in cystinotic mice, a model of nephropathic cystinosis, essentially blocks renal cystine accumulation and partially preserves kidney tissue integrity. Here, we examined whether inhibition of the megalin pathway in adult cystinotic mice by dietary supplementation (5x-fold vs control regular diet) with the dibasic amino-acids (dAAs), lysine or arginine, both of which are used to treat patients with other rare metabolic disorders, could also decrease renal cystine accumulation and protect cystinotic kidneys. Using surface plasmon resonance, we first showed that both dAAs compete for protein ligand binding to immobilized megalin in a concentration-dependent manner, with identical inhibition curves by L- and D-stereoisomers. In cystinotic mice, 2-month diets with 5x-L-lysine and 5x-L-arginine were overall well tolerated, while 5x-D-lysine induced strong polyuria but no weight loss. All diets induced a marked increase of dAA urinary excretion, most prominent under 5x-D-lysine, without sign of kidney insufficiency. Renal cystine accumulation was slowed down approx. twofold by L-dAAs, and totally suppressed by D-lysine. We conclude that prolonged dietary manipulation of the megalin pathway in kidneys is feasible, tolerable and can be effective in vivo.
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Affiliation(s)
- L R Rega
- Nephrology Research Unit, Translational Pediatrics and Clinical Genetics Research Area, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - V Janssens
- Cell Biology Unit, de Duve Institute and Louvain University Medical School, Brussels, Belgium
| | - J H Graversen
- Department of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - S K Moestrup
- Department of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - S Cairoli
- Division of Metabolic Diseases and Drug Biology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - B M Goffredo
- Division of Metabolic Diseases and Drug Biology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - N Nevo
- Laboratoire des Maladies Rénales Héréditaires, Inserm UMR 1163, Institut Imagine, Université Paris Cité, Paris, France
| | - G E Courtoy
- Imaging Platform (2IP), Institut de Recherche Expérimentale et Clinique, Louvain University Medical School, Brussels, Belgium
| | - F Jouret
- Groupe Interdisciplinaire de Génoprotéomique Appliquée (GIGA), Cardiovascular Sciences, University of Liège, Liège, Belgium
| | - C Antignac
- Laboratoire des Maladies Rénales Héréditaires, Inserm UMR 1163, Institut Imagine, Université Paris Cité, Paris, France
| | - F Emma
- Nephrology Research Unit, Translational Pediatrics and Clinical Genetics Research Area, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - C E Pierreux
- Cell Biology Unit, de Duve Institute and Louvain University Medical School, Brussels, Belgium.
| | - P J Courtoy
- Cell Biology Unit, de Duve Institute and Louvain University Medical School, Brussels, Belgium.
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10
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Packer M. Fetal Reprogramming of Nutrient Surplus Signaling, O-GlcNAcylation, and the Evolution of CKD. J Am Soc Nephrol 2023; 34:1480-1491. [PMID: 37340541 PMCID: PMC10482065 DOI: 10.1681/asn.0000000000000177] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/07/2023] [Indexed: 06/22/2023] Open
Abstract
ABSTRACT Fetal kidney development is characterized by increased uptake of glucose, ATP production by glycolysis, and upregulation of mammalian target of rapamycin (mTOR) and hypoxia-inducible factor-1 alpha (HIF-1 α ), which (acting in concert) promote nephrogenesis in a hypoxic low-tubular-workload environment. By contrast, the healthy adult kidney is characterized by upregulation of sirtuin-1 and adenosine monophosphate-activated protein kinase, which enhances ATP production through fatty acid oxidation to fulfill the needs of a normoxic high-tubular-workload environment. During stress or injury, the kidney reverts to a fetal signaling program, which is adaptive in the short term, but is deleterious if sustained for prolonged periods when both oxygen tension and tubular workload are heightened. Prolonged increases in glucose uptake in glomerular and proximal tubular cells lead to enhanced flux through the hexosamine biosynthesis pathway; its end product-uridine diphosphate N -acetylglucosamine-drives the rapid and reversible O-GlcNAcylation of thousands of intracellular proteins, typically those that are not membrane-bound or secreted. Both O-GlcNAcylation and phosphorylation act at serine/threonine residues, but whereas phosphorylation is regulated by hundreds of specific kinases and phosphatases, O-GlcNAcylation is regulated only by O-GlcNAc transferase and O-GlcNAcase, which adds or removes N-acetylglucosamine, respectively, from target proteins. Diabetic and nondiabetic CKD is characterized by fetal reprogramming (with upregulation of mTOR and HIF-1 α ) and increased O-GlcNAcylation, both experimentally and clinically. Augmentation of O-GlcNAcylation in the adult kidney enhances oxidative stress, cell cycle entry, apoptosis, and activation of proinflammatory and profibrotic pathways, and it inhibits megalin-mediated albumin endocytosis in glomerular mesangial and proximal tubular cells-effects that can be aggravated and attenuated by augmentation and muting of O-GlcNAcylation, respectively. In addition, drugs with known nephroprotective effects-angiotensin receptor blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors-are accompanied by diminished O-GlcNAcylation in the kidney, although the role of such suppression in mediating their benefits has not been explored. The available evidence supports further work on the role of uridine diphosphate N -acetylglucosamine as a critical nutrient surplus sensor (acting in concert with upregulated mTOR and HIF-1 α signaling) in the development of diabetic and nondiabetic CKD.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute , Dallas , Texas and Imperial College , London , United Kingdom
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11
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Berquez M, Chen Z, Festa BP, Krohn P, Keller SA, Parolo S, Korzinkin M, Gaponova A, Laczko E, Domenici E, Devuyst O, Luciani A. Lysosomal cystine export regulates mTORC1 signaling to guide kidney epithelial cell fate specialization. Nat Commun 2023; 14:3994. [PMID: 37452023 PMCID: PMC10349091 DOI: 10.1038/s41467-023-39261-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 06/06/2023] [Indexed: 07/18/2023] Open
Abstract
Differentiation is critical for cell fate decisions, but the signals involved remain unclear. The kidney proximal tubule (PT) cells reabsorb disulphide-rich proteins through endocytosis, generating cystine via lysosomal proteolysis. Here we report that defective cystine mobilization from lysosomes through cystinosin (CTNS), which is mutated in cystinosis, diverts PT cells towards growth and proliferation, disrupting their functions. Mechanistically, cystine storage stimulates Ragulator-Rag GTPase-dependent recruitment of mechanistic target of rapamycin complex 1 (mTORC1) and its constitutive activation. Re-introduction of CTNS restores nutrient-dependent regulation of mTORC1 in knockout cells, whereas cell-permeant analogues of L-cystine, accumulating within lysosomes, render wild-type cells resistant to nutrient withdrawal. Therapeutic mTORC1 inhibition corrects lysosome and differentiation downstream of cystine storage, and phenotypes in preclinical models of cystinosis. Thus, cystine serves as a lysosomal signal that tailors mTORC1 and metabolism to direct epithelial cell fate decisions. These results identify mechanisms and therapeutic targets for dysregulated homeostasis in cystinosis.
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Affiliation(s)
- Marine Berquez
- Institute of Physiology, University of Zurich, 8057, Zurich, Switzerland
| | - Zhiyong Chen
- Institute of Physiology, University of Zurich, 8057, Zurich, Switzerland
| | | | - Patrick Krohn
- Institute of Physiology, University of Zurich, 8057, Zurich, Switzerland
| | | | - Silvia Parolo
- Fondazione The Microsoft Research University of Trento-Centre for Computational and Systems Biology (COSBI), 38068, Rovereto, Italy
| | - Mikhail Korzinkin
- Insilico Medicine Hong Kong Ltd., Hong Kong Science and Technology Park, Hong Kong, Hong Kong SAR, China
| | - Anna Gaponova
- Insilico Medicine Hong Kong Ltd., Hong Kong Science and Technology Park, Hong Kong, Hong Kong SAR, China
| | - Endre Laczko
- Functional Genomics Center Zurich, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Enrico Domenici
- Fondazione The Microsoft Research University of Trento-Centre for Computational and Systems Biology (COSBI), 38068, Rovereto, Italy
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, 38123, Trento, Italy
| | - Olivier Devuyst
- Institute of Physiology, University of Zurich, 8057, Zurich, Switzerland.
- Institute for Rare Diseases, UCLouvain Medical School, 1200, Brussels, Belgium.
| | - Alessandro Luciani
- Institute of Physiology, University of Zurich, 8057, Zurich, Switzerland.
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12
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Peres RAS, Peruchetti DB, Silva-Aguiar RP, Teixeira DE, Gomes CP, Takiya CM, Pinheiro AAS, Caruso-Neves C. Rapamycin treatment induces tubular proteinuria: role of megalin-mediated protein reabsorption. Front Pharmacol 2023; 14:1194816. [PMID: 37484026 PMCID: PMC10359992 DOI: 10.3389/fphar.2023.1194816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 06/27/2023] [Indexed: 07/25/2023] Open
Abstract
Introduction: Rapamycin is an immunosuppressor that acts by inhibiting the serine/threonine kinase mechanistic target of rapamycin complex 1. Therapeutic use of rapamycin is limited by its adverse effects. Proteinuria is an important marker of kidney damage and a risk factor for kidney diseases progression and has been reported in patients and animal models treated with rapamycin. However, the mechanism underlying proteinuria induced by rapamycin is still an open matter. In this work, we investigated the effects of rapamycin on parameters of renal function and structure and on protein handling by proximal tubule epithelial cells (PTECs). Methods: Healthy BALB/c mice were treated with 1.5 mg/kg rapamycin by oral gavage for 1, 3, or 7 days. At the end of each treatment, the animals were kept in metabolic cages and renal function and structural parameters were analyzed. LLC-PK1 cell line was used as a model of PTECs to test specific effect of rapamycin. Results: Rapamycin treatment did not change parameters of glomerular structure and function. Conversely, there was a transient increase in 24-h proteinuria, urinary protein to creatinine ratio (UPCr), and albuminuria in the groups treated with rapamycin. In accordance with these findings, rapamycin treatment decreased albumin-fluorescein isothiocyanate uptake in the renal cortex. This effect was associated with reduced brush border expression and impaired subcellular distribution of megalin in PTECs. The effect of rapamycin seems to be specific for albumin endocytosis machinery because it did not modify renal sodium handling or (Na++K+)ATPase activity in BALB/c mice and in the LLC-PK1 cell line. A positive Pearson correlation was found between megalin expression and albumin uptake while an inverse correlation was shown between albumin uptake and UPCr or 24-h proteinuria. Despite its effect on albumin handling in PTECs, rapamycin treatment did not induce tubular injury measured by interstitial space and collagen deposition. Conclusion: These findings suggest that proteinuria induced by rapamycin could have a tubular rather than a glomerular origin. This effect involves a specific change in protein endocytosis machinery. Our results open new perspectives on understanding the undesired effect of proteinuria generated by rapamycin.
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Affiliation(s)
- Rodrigo A. S. Peres
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Diogo B. Peruchetti
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Rodrigo P. Silva-Aguiar
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Douglas E. Teixeira
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Carlos P. Gomes
- Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- School of Medicine and Surgery, Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Christina M. Takiya
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ana Acacia S. Pinheiro
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Rio de Janeiro Innovation Network in Nanosystems for Health-NanoSAÚDE/FAPERJ, Rio de Janeiro, Brazil
| | - Celso Caruso-Neves
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Rio de Janeiro Innovation Network in Nanosystems for Health-NanoSAÚDE/FAPERJ, Rio de Janeiro, Brazil
- National Institute of Science and Technology for Regenerative Medicine, Rio de Janeiro, Brazil
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13
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Rinschen MM, Harder JL, Carter-Timofte ME, Zanon Rodriguez L, Mirabelli C, Demir F, Kurmasheva N, Ramakrishnan SK, Kunke M, Tan Y, Billing A, Dahlke E, Larionov AA, Bechtel-Walz W, Aukschun U, Grabbe M, Nielsen R, Christensen EI, Kretzler M, Huber TB, Wobus CE, Olagnier D, Siuzdak G, Grahammer F, Theilig F. VPS34-dependent control of apical membrane function of proximal tubule cells and nutrient recovery by the kidney. Sci Signal 2022; 15:eabo7940. [PMID: 36445937 PMCID: PMC10350314 DOI: 10.1126/scisignal.abo7940] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The lipid kinase VPS34 orchestrates autophagy, endocytosis, and metabolism and is implicated in cancer and metabolic disease. The proximal tubule in the kidney is a key metabolic organ that controls reabsorption of nutrients such as fatty acids, amino acids, sugars, and proteins. Here, by combining metabolomics, proteomics, and phosphoproteomics analyses with functional and superresolution imaging assays of mice with an inducible deficiency in proximal tubular cells, we revealed that VPS34 controlled the metabolome of the proximal tubule. In addition to inhibiting pinocytosis and autophagy, VPS34 depletion induced membrane exocytosis and reduced the abundance of the retromer complex necessary for proper membrane recycling and lipid retention, leading to a loss of fuel and biomass. Integration of omics data into a kidney cell metabolomic model demonstrated that VPS34 deficiency increased β-oxidation, reduced gluconeogenesis, and enhanced the use of glutamine for energy consumption. Furthermore, the omics datasets revealed that VPS34 depletion triggered an antiviral response that included a decrease in the abundance of apically localized virus receptors such as ACE2. VPS34 inhibition abrogated SARS-CoV-2 infection in human kidney organoids and cultured proximal tubule cells in a glutamine-dependent manner. Thus, our results demonstrate that VPS34 adjusts endocytosis, nutrient transport, autophagy, and antiviral responses in proximal tubule cells in the kidney.
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Affiliation(s)
- Markus M Rinschen
- Scripps Center for Metabolomics, Scripps Research, La Jolla, CA 92037, USA
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
- Department II of Internal Medicine and Center for Molecular Medicine, University of Cologne, 50937 Cologne, Germany
- Aarhus Institute for Advanced Studies, Aarhus University, 8000 Aarhus, Denmark
| | - Jennifer L Harder
- Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | | | | - Carmen Mirabelli
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Fatih Demir
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | | | | | - Madlen Kunke
- Department of Anatomy, Christian-Albrechts-University Kiel, 24118 Kiel, Germany
| | - Yifan Tan
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - Anja Billing
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - Eileen Dahlke
- Department of Anatomy, Christian-Albrechts-University Kiel, 24118 Kiel, Germany
| | - Alexey A Larionov
- Department of Medicine, University of Fribourg, 1700 Fribourg, Switzerland
| | - Wibke Bechtel-Walz
- IV Department of Medicine and Faculty of Medicine, University Medical Center Freiburg, 79110 Freiburg, Germany
| | - Ute Aukschun
- IV Department of Medicine and Faculty of Medicine, University Medical Center Freiburg, 79110 Freiburg, Germany
| | - Marlen Grabbe
- IV Department of Medicine and Faculty of Medicine, University Medical Center Freiburg, 79110 Freiburg, Germany
| | - Rikke Nielsen
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | | | - Matthias Kretzler
- Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Tobias B Huber
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Christiane E Wobus
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - David Olagnier
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - Gary Siuzdak
- Scripps Center for Metabolomics, Scripps Research, La Jolla, CA 92037, USA
| | - Florian Grahammer
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Franziska Theilig
- Department of Anatomy, Christian-Albrechts-University Kiel, 24118 Kiel, Germany
- Department of Medicine, University of Fribourg, 1700 Fribourg, Switzerland
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14
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Dachy A, Decuypere JP, Vennekens R, Jouret F, Mekahli D. Is autosomal dominant polycystic kidney disease an early sweet disease? Pediatr Nephrol 2022; 37:1945-1955. [PMID: 34988697 DOI: 10.1007/s00467-021-05406-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 10/19/2022]
Abstract
The clinical course of autosomal dominant polycystic kidney disease (ADPKD) starts in childhood. Evidence of the beneficial impact of early nephron-protective strategies and lifestyle modifications on ADPKD prognosis is accumulating. Recent studies have described the association of overweight and obesity with rapid disease progression in adults with ADPKD. Moreover, defective glucose metabolism and metabolic reprogramming have been reported in distinct ADPKD models highlighting these pathways as potential therapeutic targets in ADPKD. Several "metabolic" approaches are currently under evaluation in adults, including ketogenic diet, food restriction, and metformin therapy. No data are available on the impact of these approaches in childhood thus far. Yet, according to World Health Organization (WHO), we are currently facing a childhood obesity crisis with an increased prevalence of overweight/obesity in the pediatric population associated with a cardio-metabolic risk profile. The present review summarizes the knowledge about the role of glucose metabolism in the pathophysiology of ADPKD and underscores the possible harm of overweight and obesity in ADPKD especially in terms of long-term cardiovascular outcomes and renal prognosis.
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Affiliation(s)
- Angélique Dachy
- PKD Research Group, GPURE, Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Department of Pediatrics, ULiège Academic Hospital, Liège, Belgium.,Laboratory of Translational Research in Nephrology (LTRN), GIGA Cardiovascular Sciences, ULiège, Liège, Belgium
| | - Jean-Paul Decuypere
- PKD Research Group, GPURE, Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Rudi Vennekens
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, VIB Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
| | - François Jouret
- Laboratory of Translational Research in Nephrology (LTRN), GIGA Cardiovascular Sciences, ULiège, Liège, Belgium.,Division of Nephrology, Department of Internal Medicine, ULiège Academic Hospital, Liège, Belgium
| | - Djalila Mekahli
- PKD Research Group, GPURE, Department of Development and Regeneration, KU Leuven, Leuven, Belgium. .,Department of Pediatric Nephrology, University Hospitals Leuven, Herestraat 49, B-3000, Leuven, Belgium.
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15
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Metabolic mechanisms of acute proximal tubular injury. Pflugers Arch 2022; 474:813-827. [PMID: 35567641 PMCID: PMC9338906 DOI: 10.1007/s00424-022-02701-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/12/2022] [Accepted: 05/02/2022] [Indexed: 12/11/2022]
Abstract
Damage to the proximal tubule (PT) is the most frequent cause of acute kidney injury (AKI) in humans. Diagnostic and treatment options for AKI are currently limited, and a deeper understanding of pathogenic mechanisms at a cellular level is required to rectify this situation. Metabolism in the PT is complex and closely coupled to solute transport function. Recent studies have shown that major changes in PT metabolism occur during AKI and have highlighted some potential targets for intervention. However, translating these insights into effective new therapies still represents a substantial challenge. In this article, in addition to providing a brief overview of the current state of the field, we will highlight three emerging areas that we feel are worthy of greater attention. First, we will discuss the role of axial heterogeneity in cellular function along the PT in determining baseline susceptibility to different metabolic hits. Second, we will emphasize that elucidating insult specific pathogenic mechanisms will likely be critical in devising more personalized treatments for AKI. Finally, we will argue that uncovering links between tubular metabolism and whole-body homeostasis will identify new strategies to try to reduce the considerable morbidity and mortality associated with AKI. These concepts will be illustrated by examples of recent studies emanating from the authors' laboratories and performed under the auspices of the Swiss National Competence Center for Kidney Research (NCCR Kidney.ch).
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16
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Ilatovskaya DV, Levchenko V, Winsor K, Blass GR, Spires DR, Sarsenova E, Polina I, Zietara A, Paterson M, Kriegel AJ, Staruschenko A. Effects of elevation of ANP and its deficiency on cardiorenal function. JCI Insight 2022; 7:148682. [PMID: 35380994 PMCID: PMC9090260 DOI: 10.1172/jci.insight.148682] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/30/2022] [Indexed: 11/17/2022] Open
Abstract
Atrial natriuretic peptide (ANP), encoded by Nppa, is a vasodilatory hormone that promotes salt excretion. Genome-wide association studies identified Nppa as a causative factor of blood pressure development, and in humans, ANP levels were suggested as an indicator of salt sensitivity. This study aimed to provide insights into the effects of ANP on cardiorenal function in salt-sensitive hypertension. To address this question, hypertension was induced in SSNPPA-/- (knockout of Nppa in the Dahl Salt-Sensitive (SS) rat background) or SSWT (wild type Dahl SS) rats by a high salt diet challenge (HS, 4% NaCl for 21 days). Chronic infusion of ANP in SSWT rats attenuated the increase in blood pressure and cardiorenal damage. Overall, SSNPPA-/- strain demonstrated higher blood pressure and intensified cardiac fibrosis (with no changes in ejection fraction) compared to SSWT rats. Furthermore, SSNPPA-/- rats exhibited kidney hypertrophy and higher glomerular injury scores, reduced diuresis, and lower sodium and chloride excretion than SSWT when fed a HS diet. Additionally, the activity of epithelial Na+ channel (ENaC) was found to be increased in the collecting ducts of the SSNPPA-/- rats. Taken together, these data show promise for the therapeutic benefits of ANP and ANP-increasing drugs for treating salt-sensitive hypertension.
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Affiliation(s)
- Daria V Ilatovskaya
- Department of Physiology, Medical College of Georgia, Augusta, United States of America
| | - Vladislav Levchenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, United States of America
| | - Kristen Winsor
- Department of Physiology, Medical College of Wisconsin, Milwaukee, United States of America
| | - Gregory R Blass
- Department of Physiology, Medical College of Wisconsin, Milwaukee, United States of America
| | - Denisha R Spires
- Department of Physiology, Medical College of Georgia, Augusta, United States of America
| | - Elizaveta Sarsenova
- Department of Medicine, Medical University of South Carolina, Charleston, United States of America
| | - Iuliia Polina
- Department of Medicine, Medical University of South Carolina, Charleston, United States of America
| | - Adrian Zietara
- Department of Physiology, Medical College of Wisconsin, Milwaukee, United States of America
| | - Mark Paterson
- Department of Physiology, Medical College of Wisconsin, Milwaukee, United States of America
| | - Alison J Kriegel
- Department of Physiology, Medical College of Wisconsin, Milwaukee, United States of America
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17
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Molitoris BA, Sandoval RM, Yadav SPS, Wagner MC. Albumin Uptake and Processing by the Proximal Tubule: Physiologic, Pathologic and Therapeutic Implications. Physiol Rev 2022; 102:1625-1667. [PMID: 35378997 PMCID: PMC9255719 DOI: 10.1152/physrev.00014.2021] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
For nearly 50 years the proximal tubule (PT) has been known to reabsorb, process, and either catabolize or transcytose albumin from the glomerular filtrate. Innovative techniques and approaches have provided insights into these processes. Several genetic diseases, nonselective PT cell defects, chronic kidney disease (CKD), and acute PT injury lead to significant albuminuria, reaching nephrotic range. Albumin is also known to stimulate PT injury cascades. Thus, the mechanisms of albumin reabsorption, catabolism, and transcytosis are being reexamined with the use of techniques that allow for novel molecular and cellular discoveries. Megalin, a scavenger receptor, cubilin, amnionless, and Dab2 form a nonselective multireceptor complex that mediates albumin binding and uptake and directs proteins for lysosomal degradation after endocytosis. Albumin transcytosis is mediated by a pH-dependent binding affinity to the neonatal Fc receptor (FcRn) in the endosomal compartments. This reclamation pathway rescues albumin from urinary losses and cellular catabolism, extending its serum half-life. Albumin that has been altered by oxidation, glycation, or carbamylation or because of other bound ligands that do not bind to FcRn traffics to the lysosome. This molecular sorting mechanism reclaims physiological albumin and eliminates potentially toxic albumin. The clinical importance of PT albumin metabolism has also increased as albumin is now being used to bind therapeutic agents to extend their half-life and minimize filtration and kidney injury. The purpose of this review is to update and integrate evolving information regarding the reabsorption and processing of albumin by proximal tubule cells including discussion of genetic disorders and therapeutic considerations.
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Affiliation(s)
- Bruce A. Molitoris
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Dept.of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Ruben M. Sandoval
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Shiv Pratap S. Yadav
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Mark C. Wagner
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
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18
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Hinden L, Ahmad M, Hamad S, Nemirovski A, Szanda G, Glasmacher S, Kogot-Levin A, Abramovitch R, Thorens B, Gertsch J, Leibowitz G, Tam J. Opposite physiological and pathological mTORC1-mediated roles of the CB1 receptor in regulating renal tubular function. Nat Commun 2022; 13:1783. [PMID: 35379807 PMCID: PMC8980033 DOI: 10.1038/s41467-022-29124-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/25/2022] [Indexed: 12/13/2022] Open
Abstract
Activation of the cannabinoid-1 receptor (CB1R) and the mammalian target of rapamycin complex 1 (mTORC1) in the renal proximal tubular cells (RPTCs) contributes to the development of diabetic kidney disease (DKD). However, the CB1R/mTORC1 signaling axis in the kidney has not been described yet. We show here that hyperglycemia-induced endocannabinoid/CB1R stimulation increased mTORC1 activity, enhancing the transcription of the facilitative glucose transporter 2 (GLUT2) and leading to the development of DKD in mice; this effect was ameliorated by specific RPTCs ablation of GLUT2. Conversely, CB1R maintained the normal activity of mTORC1 by preventing the cellular excess of amino acids during normoglycemia. Our findings highlight a novel molecular mechanism by which the activation of mTORC1 in RPTCs is tightly controlled by CB1R, either by enhancing the reabsorption of glucose and inducing kidney dysfunction in diabetes or by preventing amino acid uptake and maintaining normal kidney function in healthy conditions. Renal proximal tubules modulate whole-body homeostasis by sensing various nutrients. Here the authors describe the existence and importance of a unique CB1/mTORC1/GLUT2 signaling axis in regulating nutrient homeostasis in healthy and diseased kidney.
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19
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Ono Y, Matsuzawa K, Ikenouchi J. mTORC2 suppresses cell death induced by hypo-osmotic stress by promoting sphingomyelin transport. J Cell Biol 2022; 221:213090. [PMID: 35319770 PMCID: PMC8952684 DOI: 10.1083/jcb.202106160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 12/28/2021] [Accepted: 01/24/2022] [Indexed: 11/22/2022] Open
Abstract
Epithelial cells are constantly exposed to osmotic stress. The influx of water molecules into the cell in a hypo-osmotic environment increases plasma membrane tension as it rapidly expands. Therefore, the plasma membrane must be supplied with membrane lipids since expansion beyond its elastic limit will cause the cell to rupture. However, the molecular mechanism to maintain a constant plasma membrane tension is not known. In this study, we found that the apical membrane selectively expands when epithelial cells are exposed to hypo-osmotic stress. This requires the activation of mTORC2, which enhances the transport of secretory vesicles containing sphingomyelin, the major lipid of the apical membrane. We further show that the mTORC2–Rab35 axis plays an essential role in the defense against hypotonic stress by promoting the degradation of the actin cortex through the up-regulation of PI(4,5)P2 metabolism, which facilitates the apical tethering of sphingomyelin-loaded vesicles to relieve plasma membrane tension.
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Affiliation(s)
- Yumiko Ono
- Department of Biology, Faculty of Sciences, Kyushu University, Nishi-ku, Fukuoka, Japan
| | - Kenji Matsuzawa
- Department of Biology, Faculty of Sciences, Kyushu University, Nishi-ku, Fukuoka, Japan
| | - Junichi Ikenouchi
- Department of Biology, Faculty of Sciences, Kyushu University, Nishi-ku, Fukuoka, Japan
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20
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Laouari D, Vergnaud P, Hirose T, Zaidan M, Rabant M, Nguyen C, Burtin M, Legendre C, Codogno P, Friedlander G, Anglicheau D, Terzi F. The sexual dimorphism of kidney growth in mice and humans. Kidney Int 2022; 102:78-95. [PMID: 35337891 DOI: 10.1016/j.kint.2022.02.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 02/02/2022] [Accepted: 02/16/2022] [Indexed: 10/18/2022]
Abstract
Kidney mass and function are sexually determined, but the cellular events and the molecular mechanisms involved in this dimorphism are poorly characterized. By combining female and male mice with castration/replacement experiments, we showed that male mice exhibited kidney overgrowth from five weeks of age. This effect was organ specific, since liver and heart weight were comparable between males and females, regardless of age. Consistently, the androgen receptor was found to be expressed in the kidneys of males, but not in the liver. In growing mice, androgens led to kidney overgrowth by first inducing a burst of cell proliferation and then an increase of cell size. Remarkably, androgens were also required to maintain cell size in adults. In fact, orchiectomy resulted in smaller kidneys in a matter of few weeks. These changes paralleled the changes of the expression of ornithine decarboxylase and cyclin D1, two known mediators of kidney growth, whereas, unexpectedly, mTORC1 and Hippo pathways did not seem to be involved. Androgens also enhanced kidney autophagy, very likely by increasing transcription factor EB nuclear translocation. Functionally, the increase of tubular mass resulted in increased sodium/phosphate transport. These findings were relevant to humans. Remarkably, by studying living gender-paired kidney donors-recipients, we showed that tubular cell size increased three months after transplantation in men as compared to women, regardless of the donor gender. Thus, our results identify novel signaling pathways that may be involved in androgen-induced kidney growth and homeostasis, and suggest that androgens determine kidney size after transplantation.
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Affiliation(s)
- Denise Laouari
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Paul Vergnaud
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service de Néphrologie Pédiatrique-Hémodialyse-Transplantation, AP-HP, Hôpital Necker, Paris, France
| | - Takuo Hirose
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Mohamad Zaidan
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service de Néphrologie-Transplantation, AP-HP, Hôpital Bicêtre, Le Kremlin-Bicêtre, France
| | - Marion Rabant
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service d'Anatomo-Pathologie, AP-HP, Hôpital Necker, Paris, France
| | - Clément Nguyen
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Martine Burtin
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Christophe Legendre
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service de Néphrologie-Transplantation, AP-HP, Hôpital Necker, Paris, France
| | - Patrice Codogno
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Gerard Friedlander
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Dany Anglicheau
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service de Néphrologie-Transplantation, AP-HP, Hôpital Necker, Paris, France
| | - Fabiola Terzi
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France.
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Kozyraki R, Verroust P, Cases O. Cubilin, the intrinsic factor-vitamin B12 receptor. VITAMINS AND HORMONES 2022; 119:65-119. [PMID: 35337634 DOI: 10.1016/bs.vh.2022.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cubilin (CUBN), the intrinsic factor-vitamin B12 receptor is a large endocytic protein involved in various physiological functions: vitamin B12 uptake in the gut; reabsorption of albumin and maturation of vitamin D in the kidney; nutrient delivery during embryonic development. Cubilin is an atypical receptor, peripherally associated to the plasma membrane. The transmembrane proteins amnionless (AMN) and Lrp2/Megalin are the currently known molecular partners contributing to plasma membrane transport and internalization of Cubilin. The role of Cubilin/Amn complex in the handling of vitamin B12 in health and disease has extensively been studied and so is the role of the Cubilin-Lrp2 tandem in renal pathophysiology. Accumulating evidence strongly supports a role of Cubilin in some developmental defects including impaired closure of the neural tube. Are these defects primarily caused by the dysfunction of a specific Cubilin ligand or are they secondary to impaired vitamin B12 or protein uptake? We will present the established Cubilin functions, discuss the developmental data and provide an overview of the emerging implications of Cubilin in the field of cardiovascular disease and cancer pathogenesis.
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Affiliation(s)
- Renata Kozyraki
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France.
| | - Pierre Verroust
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France
| | - Olivier Cases
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France
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22
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Wang T, Woodman P, Humphrey SJ, Petersen J. Environmental control of Pub1 (NEDD4 family E3 ligase) in Schizosaccharomyces pombe is regulated by TORC2 and Gsk3. Life Sci Alliance 2022; 5:5/5/e202101082. [PMID: 35121625 PMCID: PMC8817228 DOI: 10.26508/lsa.202101082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/24/2022] Open
Abstract
The NEDD4 family E3 ligase Pub1 is regulated by the nutrient environment, TORC2, and Gsk3 signalling pathway to control the level of amino acid transporters on the plasma membrane and thus nutrient uptake. Cells respond to changing nutrient environments by adjusting the abundance of surface nutrient transporters and receptors. This can be achieved by modulating ubiquitin-dependent endocytosis, which in part is regulated by the NEDD4 family of E3 ligases. Here we report novel regulation of Pub1, a fission yeast Schizosaccharomyces pombe member of the NEDD4-family of E3 ligases. We show that nitrogen stress inhibits Pub1 function, thereby increasing the abundance of the amino acid transporter Aat1 at the plasma membrane and enhancing sensitivity to the toxic arginine analogue canavanine. We show that TOR complex 2 (TORC2) signalling negatively regulates Pub1, thus TORC2 mutants under nutrient stress have decreased Aat1 at the plasma membrane and are resistant to canavanine. Inhibition of TORC2 signalling increases Pub1 phosphorylation, and this is dependent on Gsk3 activity. Addition of the Tor inhibitor Torin1 increases phosphorylation of Pub1 at serine 199 (S199) by 2.5-fold, and Pub1 protein levels in S199A phospho-ablated mutants are reduced. S199 is conserved in NEDD4 and is located immediately upstream of a WW domain required for protein interaction. Together, we describe how the major TORC2 nutrient-sensing signalling network regulates environmental control of Pub1 to modulate the abundance of nutrient transporters.
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Affiliation(s)
- Tingting Wang
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, Australia
| | - Philip Woodman
- School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Sean J Humphrey
- Charles Perkins Centre, School of Life and Environmental Sciences, The University of Sydney, Camperdown, Australia
| | - Janni Petersen
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, Australia
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23
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Khbouz B, Rowart P, Poma L, Dahlke E, Bottner M, Stokes M, Bolen G, Rahmouni S, Theilig F, Jouret F. The genetic deletion of the Dual Specificity Phosphatase 3 (DUSP3) attenuates kidney damage and inflammation following ischaemia/reperfusion injury in mouse. Acta Physiol (Oxf) 2022; 234:e13735. [PMID: 34704357 DOI: 10.1111/apha.13735] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 12/16/2022]
Abstract
AIM Dual Specificity Phosphatase 3 (DUSP3) regulates the innate immune response, with a putative role in angiogenesis. Modulating inflammation and perfusion contributes to renal conditioning against ischaemia/reperfusion (I/R). We postulate that the functional loss of DUSP3 is associated with kidney resistance to I/R. METHODS Ten C57BL/6 male WT and Dusp3-/- mice underwent right nephrectomy and left renal I/R (30 min/48 hours). Renal injury was assessed based on serum levels of urea (BUN) and Jablonski score. The expression of CD31 and VEGF vascular markers was quantified by RT-qPCR and immuno-staining. Renal resistivity index (RRI) was measured in vivo by Doppler ultrasound. Comparative phosphoproteomics was conducted using IMAC enrichment of phosphopeptides. Inflammatory markers were quantified at both mRNA and protein levels in ischaemic vs non-ischaemic kidneys in WT vs Dusp3-/- . RESULTS At baseline, we located DUSP3 in renal glomeruli and endothelial cells. CD31-positive vascular network was significantly larger in Dusp3-/- kidneys compared to WT, with a lower RRI in Dusp3-/- mice. Following I/R, BUN and Jablonski score were significantly lower in Dusp3-/- vs WT mice. Phosphoproteomics highlighted a down-regulation of inflammatory pathways and up-regulation of phospho-sites involved in cell metabolism and VEGF-related angiogenesis in Dusp3-/- vs WT ischaemic kidneys. Dusp3-/- ischaemic kidneys showed decreased mRNA levels of CD11b, TNF-α, KIM-1, IL-6, IL-1β and caspase-3 compared to controls. The numbers of PCNA-, F4-80- and CD11b-positive cells were reduced in Dusp3-/- vs WT kidneys post-I/R. CONCLUSION Genetic inactivation of Dusp3 is associated with kidney conditioning against I/R, possibly due to attenuated inflammation and improved perfusion.
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Affiliation(s)
- Badr Khbouz
- Groupe Interdisciplinaire de Génoprotéomique Appliquée (GIGA) Cardiovascular Sciences University of Liège (ULiège) Liège Belgium
| | - Pascal Rowart
- Groupe Interdisciplinaire de Génoprotéomique Appliquée (GIGA) Cardiovascular Sciences University of Liège (ULiège) Liège Belgium
- Department of Pharmacology and Chemical Biology School of Medicine University of Pittsburgh Pittsburgh Pennsylvania USA
| | - Laurence Poma
- Groupe Interdisciplinaire de Génoprotéomique Appliquée (GIGA) Cardiovascular Sciences University of Liège (ULiège) Liège Belgium
| | - Eileen Dahlke
- Institute of Anatomy Christian Albrechts‐University Kiel Germany
| | - Martina Bottner
- Institute of Anatomy Christian Albrechts‐University Kiel Germany
| | - Matthew Stokes
- Cell Signaling Technology, Inc. Danvers Massachusetts USA
| | - Géraldine Bolen
- Department of Clinical Sciences Fundamental and Applied Research for Animals & Health (FARAH) Veterinary Faculty University of Liège (ULiège) Liège Belgium
| | - Souad Rahmouni
- Groupe Interdisciplinaire de Génoprotéomique Appliquée (GIGA) Medical Genomics University of Liège (ULiège) Liège Belgium
| | - Franziska Theilig
- Institute of Anatomy Christian Albrechts‐University Kiel Germany
- Institute of Anatomy Department of Medicine University of Fribourg Fribourg Switzerland
| | - François Jouret
- Groupe Interdisciplinaire de Génoprotéomique Appliquée (GIGA) Cardiovascular Sciences University of Liège (ULiège) Liège Belgium
- Division of Nephrology CHU of Liège University of Liège (CHU ULiège) Liège Belgium
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24
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Defective Cystinosin, Aberrant Autophagy−Endolysosome Pathways, and Storage Disease: Towards Assembling the Puzzle. Cells 2022; 11:cells11030326. [PMID: 35159136 PMCID: PMC8834619 DOI: 10.3390/cells11030326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/03/2022] [Accepted: 01/11/2022] [Indexed: 02/05/2023] Open
Abstract
Epithelial cells that form the kidney proximal tubule (PT) rely on an intertwined ecosystem of vesicular membrane trafficking pathways to ensure the reabsorption of essential nutrients—a key requisite for homeostasis. The endolysosome stands at the crossroads of this sophisticated network, internalizing molecules through endocytosis, sorting receptors and nutrient transporters, maintaining cellular quality control via autophagy, and toggling the balance between PT differentiation and cell proliferation. Dysregulation of such endolysosome-guided trafficking pathways might thus lead to a generalized dysfunction of PT cells, often causing chronic kidney disease and life-threatening complications. In this review, we highlight the biological functions of endolysosome-residing proteins from the perspectives of understanding—and potentially reversing—the pathophysiology of rare inherited diseases affecting the kidney PT. Using cystinosis as a paradigm of endolysosome disease causing PT dysfunction, we discuss how the endolysosome governs the homeostasis of specialized epithelial cells. This review also provides a critical analysis of the molecular mechanisms through which defects in autophagy pathways can contribute to PT dysfunction, and proposes potential interventions for affected tissues. These insights might ultimately accelerate the discovery and development of new therapeutics, not only for cystinosis, but also for other currently intractable endolysosome-related diseases, eventually transforming our ability to regulate homeostasis and health.
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25
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Silva-Aguiar RP, Peruchetti DB, Florentino LS, Takiya CM, Marzolo MP, Dias WB, Pinheiro AAS, Caruso-Neves C. Albumin Expands Albumin Reabsorption Capacity in Proximal Tubule Epithelial Cells through a Positive Feedback Loop between AKT and Megalin. Int J Mol Sci 2022; 23:ijms23020848. [PMID: 35055044 PMCID: PMC8776186 DOI: 10.3390/ijms23020848] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/05/2022] [Accepted: 01/11/2022] [Indexed: 12/20/2022] Open
Abstract
Renal proximal tubule cells (PTECs) act as urine gatekeepers, constantly and efficiently avoiding urinary protein waste through receptor-mediated endocytosis. Despite its importance, little is known about how this process is modulated in physiologic conditions. Data suggest that the phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) pathway regulates PTEC protein reabsorption. Here, we worked on the hypothesis that the physiologic albumin concentration and PI3K/AKT pathway form a positive feedback loop to expand endocytic capacity. Using LLC-PK1 cells, a model of PTECs, we showed that the PI3K/AKT pathway is required for megalin recycling and surface expression, affecting albumin uptake. Inhibition of this pathway stalls megalin at EEA1+ endosomes. Physiologic albumin concentration (0.01 mg/mL) activated AKT; this depends on megalin-mediated albumin endocytosis and requires previous activation of PI3K/mTORC2. This effect is correlated to the increase in albumin endocytosis, a phenomenon that we refer to as “albumin-induced albumin endocytosis”. Mice treated with L-lysine present decreased albumin endocytosis leading to proteinuria and albuminuria associated with inhibition of AKT activity. Renal cortex explants obtained from control mice treated with MK-2206 decreased albumin uptake and promoted megalin internalization. Our data highlight the mechanism behind the capacity of PTECs to adapt albumin reabsorption to physiologic fluctuations in its filtration, avoiding urinary excretion.
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Affiliation(s)
- Rodrigo P. Silva-Aguiar
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (R.P.S.-A.); (D.B.P.); (L.S.F.); (C.M.T.); (W.B.D.); (A.A.S.P.)
| | - Diogo B. Peruchetti
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (R.P.S.-A.); (D.B.P.); (L.S.F.); (C.M.T.); (W.B.D.); (A.A.S.P.)
| | - Lucas S. Florentino
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (R.P.S.-A.); (D.B.P.); (L.S.F.); (C.M.T.); (W.B.D.); (A.A.S.P.)
| | - Christina M. Takiya
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (R.P.S.-A.); (D.B.P.); (L.S.F.); (C.M.T.); (W.B.D.); (A.A.S.P.)
| | - María-Paz Marzolo
- Departamento de Biología Celular y Molecular, Pontificia Universidad Católica de Chile, Santiago 8330163, Chile;
| | - Wagner B. Dias
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (R.P.S.-A.); (D.B.P.); (L.S.F.); (C.M.T.); (W.B.D.); (A.A.S.P.)
| | - Ana Acacia S. Pinheiro
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (R.P.S.-A.); (D.B.P.); (L.S.F.); (C.M.T.); (W.B.D.); (A.A.S.P.)
- Redes de Pesquisa em Nanotecnologia para Saúde, NanoSaúde/FAPERJ, Rio de Janeiro 21040-900, Brazil
| | - Celso Caruso-Neves
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (R.P.S.-A.); (D.B.P.); (L.S.F.); (C.M.T.); (W.B.D.); (A.A.S.P.)
- Redes de Pesquisa em Nanotecnologia para Saúde, NanoSaúde/FAPERJ, Rio de Janeiro 21040-900, Brazil
- Instituto Nacional de Ciência e Tecnologia em Medicina Regenerativa, INCT-Regenera, Rio de Janeiro 21941-902, Brazil
- Correspondence: ; Tel.: +55-21-3938-6582
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26
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Wang Z, Yu J, Hao D, Liu X, Wang X. Transcriptomic signatures responding to PKM2 activator TEPP-46 in the hyperglycemic human renal proximal epithelial tubular cells. Front Endocrinol (Lausanne) 2022; 13:965379. [PMID: 36120453 PMCID: PMC9471676 DOI: 10.3389/fendo.2022.965379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 08/01/2022] [Indexed: 11/22/2022] Open
Abstract
Pyruvate kinase M2 (PKM2), as the terminal and last rate-limiting enzyme of the glycolytic pathway, is an ideal enzyme for regulating metabolic phenotype. PKM2 tetramer activation has shown a protective role against diabetic kidney disease (DKD). However, the molecular mechanisms involved in diabetic tubular have not been investigated so far. In this study, we performed transcriptome gene expression profiling in human renal proximal tubular epithelial cell line (HK-2 cells) treated with 25 mM high D-glucose (HG) for 7 days before the addition of 10 μM TEPP-46, an activator of PKM2 tetramerization, for a further 1 day in the presence of HG. Afterwards, we analyzed the differentially expressed (DE) genes and investigated gene relationships based on weighted gene co-expression network analysis. The results showed that 2,902 DE genes were identified (adjusted P-value ≤ 0.05), where 2,509 DE genes (86.46%) were co-expressed in the key module. Four extremely downregulated DE genes (HSPA8, HSPA2, HSPA1B, and ARRB1) and three extremely upregulated DE genes (GADD45A, IGFBP3, and SIAH1) enriched in the downregulated endocytosis (hsa04144) and upregulated p53 signaling pathway (hsa04115), respectively, were validated by qRT-PCR experiments. The qRT-PCR results showed that the relative expression levels of HSPA8 [adjusted P-value = 4.45 × 10-34 and log2(FC) = -1.12], HSPA2 [adjusted P-value = 6.09 × 10-14 and log2(FC) = -1.27], HSPA1B [adjusted P-value = 1.14 × 10-11 and log2(FC) = -1.02], and ARRB1 [adjusted P-value = 2.60 × 10-5 and log2(FC) = -1.13] were significantly different (P-value < 0.05) from the case group to the control group. Furthermore, the interactions and predicted microRNAs of the key genes (HSPA8, HSPA2, HSPA1B, and ARRB1) were visualized in networks. This study identified the key candidate transcriptomic biomarkers and biological pathways in hyperglycemic HK-2 cells responding to the PKM2 activator TEPP-46 that can highlight a possibility of PKM2 tetramerization reshaping the interplay among endocytic trafficking through the versatile networks of Hsp70s and rewiring the crosstalk between EGFR signal transduction circuits and metabolic stress to promote resilience, which will be valuable for further research on PKM2 in DKD.
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Affiliation(s)
- Zhimin Wang
- Division of Endocrinology and Metabolic Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Jiating Yu
- Division of Pediatric Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Dan Hao
- Shijiazhuang Zhongnongtongchuang (ZNTC) Biotechnology Co., Ltd., Shijiazhuang, China
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Xin Liu
- Division of Clinical Laboratory, Key Clinical Laboratory of Henan Province, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- *Correspondence: Xin Liu, ; Xiao Wang,
| | - Xiao Wang
- Konge Larsen ApS, Kongens Lyngby, Denmark
- College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, China
- *Correspondence: Xin Liu, ; Xiao Wang,
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27
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Culver SA, Akhtar S, Rountree-Jablin C, Keller SR, Cathro HP, Gildea JJ, Siragy HM. Knockout of Nephron ATP6AP2 Impairs Proximal Tubule Function and Prevents High-Fat Diet-Induced Obesity in Male Mice. Endocrinology 2021; 162:bqab200. [PMID: 34534267 PMCID: PMC8489432 DOI: 10.1210/endocr/bqab200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Indexed: 12/24/2022]
Abstract
ATP6AP2 expression is increased in the nephron during high-fat diet (HFD) and its knockout (ATP6AP2 KO) reduces body weight (WT) in mice. We evaluated the contribution of ATP6AP2 to urinary glucose (UG) and albumin (Ualb) handling during HFD. We hypothesized that nephron ATP6AP2 KO increases UG and Ualb and minimizes HFD-induced obesity. Eight-week-old male C57BL/6J mice with inducible nephron-specific ATP6AP2 KO and noninduced controls were fed either normal diet (ND, 12% kcal fat) or HFD (45% kcal fat) for 6 months. ATP6AP2 KO mice on ND had 20% (P < 0.01) lower WT compared with controls. HFD-fed mice had 41% (P < 0.05) greater WT than ND-fed control mice. In contrast, ATP6AP2 KO abrogated the increase in WT induced by HFD by 40% (P < 0.05). Mice on HFD had less caloric intake compared with ND controls (P < 0.01). There were no significant differences in metabolic rate between all groups. UG and Ualb was significantly increased in ATP6AP2 KO mice on both ND and HFD. ATP6AP2 KO showed greater levels of proximal tubule apoptosis and histologic evidence of proximal tubule injury. In conclusion, our results demonstrate that nephron-specific ATP6AP2 KO is associated with glucosuria and albuminuria, most likely secondary to renal proximal tubule injury and/or dysfunction. Urinary loss of nutrients may have contributed to the reduced WT of knockout mice on ND and lack of WT gain in response to HFD. Future investigation should elucidate the mechanisms by which loss of renal ATP6AP2 causes proximal tubule injury and dysfunction.
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Affiliation(s)
- Silas A Culver
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Safia Akhtar
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Callie Rountree-Jablin
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Susanna R Keller
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Helen P Cathro
- Department of Pathology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - John J Gildea
- Department of Pathology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Helmy M Siragy
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
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28
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Grahammer F, Huber TB, Artunc F. Role of mTOR Signaling for Tubular Function and Disease. Physiology (Bethesda) 2021; 36:350-358. [PMID: 34514872 DOI: 10.1152/physiol.00021.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) forms two distinct intracellular multiprotein complexes that control a multitude of intracellular processes linked to metabolism, proliferation, actin cytoskeleton, and survival. Recent studies have identified the importance of these complexes for transport regulation of ions and nutrients along the entire nephron. First reports could link altered activity of these complexes to certain disease entities, i.e. diabetic nephropathy, acute kidney injury or hyperkalemia.
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Affiliation(s)
- Florian Grahammer
- Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tobias B Huber
- Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ferruh Artunc
- Department of Internal Medicine, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University Tübingen, Tübingen, Germany.,German Center for Diabetes Research, University Tübingen, Tübingen, Germany
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29
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Schlingmann KP, Jouret F, Shen K, Nigam A, Arjona FJ, Dafinger C, Houillier P, Jones DP, Kleinerüschkamp F, Oh J, Godefroid N, Eltan M, Güran T, Burtey S, Parotte MC, König J, Braun A, Bos C, Ibars Serra M, Rehmann H, Zwartkruis FJ, Renkema KY, Klingel K, Schulze-Bahr E, Schermer B, Bergmann C, Altmüller J, Thiele H, Beck BB, Dahan K, Sabatini D, Liebau MC, Vargas-Poussou R, Knoers NV, Konrad M, de Baaij JH. mTOR-Activating Mutations in RRAGD Are Causative for Kidney Tubulopathy and Cardiomyopathy. J Am Soc Nephrol 2021; 32:2885-2899. [PMID: 34607910 PMCID: PMC8806087 DOI: 10.1681/asn.2021030333] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 07/07/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Over the last decade, advances in genetic techniques have resulted in the identification of rare hereditary disorders of renal magnesium and salt handling. Nevertheless, approximately 20% of all patients with tubulopathy lack a genetic diagnosis. METHODS We performed whole-exome and -genome sequencing of a patient cohort with a novel, inherited, salt-losing tubulopathy; hypomagnesemia; and dilated cardiomyopathy. We also conducted subsequent in vitro functional analyses of identified variants of RRAGD, a gene that encodes a small Rag guanosine triphosphatase (GTPase). RESULTS In eight children from unrelated families with a tubulopathy characterized by hypomagnesemia, hypokalemia, salt wasting, and nephrocalcinosis, we identified heterozygous missense variants in RRAGD that mostly occurred de novo. Six of these patients also had dilated cardiomyopathy and three underwent heart transplantation. We identified a heterozygous variant in RRAGD that segregated with the phenotype in eight members of a large family with similar kidney manifestations. The GTPase RagD, encoded by RRAGD, plays a role in mediating amino acid signaling to the mechanistic target of rapamycin complex 1 (mTORC1). RagD expression along the mammalian nephron included the thick ascending limb and the distal convoluted tubule. The identified RRAGD variants were shown to induce a constitutive activation of mTOR signaling in vitro. CONCLUSIONS Our findings establish a novel disease, which we call autosomal dominant kidney hypomagnesemia (ADKH-RRAGD), that combines an electrolyte-losing tubulopathy and dilated cardiomyopathy. The condition is caused by variants in the RRAGD gene, which encodes Rag GTPase D; these variants lead to an activation of mTOR signaling, suggesting a critical role of Rag GTPase D for renal electrolyte handling and cardiac function.
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Affiliation(s)
- Karl P. Schlingmann
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - François Jouret
- Division of Nephrology, Department of Internal Medicine, University of Liège Hospital, Liège, Belgium,Interdisciplinary Group of Applied Genoproteomics, Cardiovascular Sciences, University of Liège, Liège, Belgium
| | - Kuang Shen
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts,Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts,Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts,Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Anukrati Nigam
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Francisco J. Arjona
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Claudia Dafinger
- Department of Pediatrics and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Pascal Houillier
- Cordeliers Research Center, Centre National de la Recherche Scientifique (CNRS), ERL8228, Institut National de la Santé et de la Recherche Médicale (INSERM), Sorbonne University, University of Paris, Paris, France,Department of Physiology, Assistance Publique-Hôpitaux de Paris (AP-HP), European Hospital Georges Pompidou, Paris, France,Reference Center for Hereditary Renal Diseases in Children and Adults (MARHEA), Paris, France
| | - Deborah P. Jones
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Felix Kleinerüschkamp
- Department of Pediatric Cardiology, University Children’s Hospital, Münster, Germany
| | - Jun Oh
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Nathalie Godefroid
- Division of Pediatric Nephrology, Saint-Luc University Clinics, Catholic University of Louvain, Brussels, Belgium
| | - Mehmet Eltan
- Department of Pediatric Endocrinology and Diabetes, School of Medicine, Marmara University, Istanbul, Turkey
| | - Tülay Güran
- Department of Pediatric Endocrinology and Diabetes, School of Medicine, Marmara University, Istanbul, Turkey
| | - Stéphane Burtey
- Center for Nephrology and Renal Transplantation, Assistance Publique-Hôpitaux de Marseille, Aix-Marseille University, Marseille, France
| | - Marie-Christine Parotte
- Division of Nephrology-Dialysis, Department of Internal Medicine, CHR Verviers East Belgium, Verviers, Belgium
| | - Jens König
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Alina Braun
- Department of Pediatrics and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Caro Bos
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maria Ibars Serra
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Holger Rehmann
- Department of Molecular Cancer Research, Center for Molecular Medicine, Oncode Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Fried J.T. Zwartkruis
- Department of Molecular Cancer Research, Center for Molecular Medicine, Oncode Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Kirsten Y. Renkema
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Karin Klingel
- Cardiopathology, Institute for Pathology and Neuropathology, University Hospital Tübingen, Tübingen, Germany
| | - Eric Schulze-Bahr
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Bernhard Schermer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,CECAD, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Carsten Bergmann
- Limbach Genetics, Medizinische Genetik Mainz, Mainz, Germany,Division of Nephrology, Department of Medicine, University Hospital Freiburg, Breisgau, Germany
| | - Janine Altmüller
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Holger Thiele
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Bodo B. Beck
- Institute of Human Genetics, University Hospital Cologne and University of Cologne, Faculty of Medicine, Cologne, Germany,Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine, University Hospital Cologne, Cologne, Germany,Center for Rare Diseases, Medical Faculty, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Karin Dahan
- Center of Human Genetics, Gosselies, Belgium,Division of Nephrology, Saint-Luc University Clinics, Catholic University of Louvain, Brussels, Belgium
| | - David Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts,Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts,Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Max C. Liebau
- Department of Pediatrics and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,Center for Rare Diseases, Medical Faculty, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Rosa Vargas-Poussou
- Department of Genetics, AP-HP, European Hospital Georges Pompidou, Paris, France
| | - Nine V.A.M. Knoers
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Martin Konrad
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Jeroen H.F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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30
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Giannaki M, Ludwig C, Heermann S, Roussa E. Regulation of electrogenic Na + /HCO 3 - cotransporter 1 (NBCe1) function and its dependence on m-TOR mediated phosphorylation of Ser 245. J Cell Physiol 2021; 237:1372-1388. [PMID: 34642952 DOI: 10.1002/jcp.30601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 09/09/2021] [Accepted: 10/01/2021] [Indexed: 11/09/2022]
Abstract
Astrocytes are pivotal responders to alterations of extracellular pH, primarily by regulation of their principal acid-base transporter, the membrane-bound electrogenic Na+ /bicarbonate cotransporter 1 (NBCe1). Here, we describe amammalian target of rapamycin (mTOR)-dependent and NBCe1-mediated astroglial response to extracellular acidosis. Using primary mouse cortical astrocytes, we investigated the effect of long-term extracellular metabolic acidosis on regulation of NBCe1 and elucidated the underlying molecular mechanisms by immunoblotting, biotinylation of surface proteins, intracellular H+ recording using the H+ -sensitive dye 2',7'-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein, and phosphoproteomic analysis. The results showed significant increase of NBCe1-mediated recovery of intracellular pH from acidification in WT astrocytes, but not in cortical astrocytes from NBCe1-deficient mice. Acidosis-induced upregulation of NBCe1 activity was prevented following inhibition of mTOR signaling by rapamycin. Yet, during acidosis or following exposure of astrocytes to rapamycin, surface protein abundance of NBCe1 remained -unchanged. Mutational analysis in HeLa cells suggested that NBCe1 activity was dependent on phosphorylation state of Ser245 , a residue conserved in all NBCe1 variants. Moreover, phosphorylation state of Ser245 is regulated by mTOR and is inversely correlated with NBCe1 transport activity. Our results identify pSer245 as a novel regulator of NBCe1 functional expression. We propose that context-dependent and mTOR-mediated multisite phosphorylation of serine residues of NBCe1 is likely to be a potent mechanism contributing to the response of astrocytes to acid/base challenges during pathophysiological conditions.
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Affiliation(s)
- Marina Giannaki
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Medical Faculty, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Christina Ludwig
- Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), Technical University of Munich (TUM), Freising, Germany
| | - Stephan Heermann
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Medical Faculty, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Eleni Roussa
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Medical Faculty, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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31
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Colombero C, Remy D, Antoine‐Bally S, Macé A, Monteiro P, ElKhatib N, Fournier M, Dahmani A, Montaudon E, Montagnac G, Marangoni E, Chavrier P. mTOR Repression in Response to Amino Acid Starvation Promotes ECM Degradation Through MT1-MMP Endocytosis Arrest. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2101614. [PMID: 34250755 PMCID: PMC8425857 DOI: 10.1002/advs.202101614] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/07/2021] [Indexed: 05/02/2023]
Abstract
Under conditions of starvation, normal and tumor epithelial cells can rewire their metabolism toward the consumption of extracellular proteins, including extracellular matrix-derived components as nutrient sources. The mechanism of pericellular matrix degradation by starved cells has been largely overlooked. Here it is shown that matrix degradation by breast and pancreatic tumor cells and patient-derived xenograft explants increases by one order of magnitude upon amino acid and growth factor deprivation. In addition, it is found that collagenolysis requires the invadopodia components, TKS5, and the transmembrane metalloproteinase, MT1-MMP, which are key to the tumor invasion program. Increased collagenolysis is controlled by mTOR repression upon nutrient depletion or pharmacological inhibition by rapamycin. The results reveal that starvation hampers clathrin-mediated endocytosis, resulting in MT1-MMP accumulation in arrested clathrin-coated pits. The study uncovers a new mechanism whereby mTOR repression in starved cells leads to the repurposing of abundant plasma membrane clathrin-coated pits into robust ECM-degradative assemblies.
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Affiliation(s)
| | - David Remy
- Institut CuriePSL Research UniversityCNRS UMR 144Paris75005France
| | | | - Anne‐Sophie Macé
- Institut CuriePSL Research UniversityCNRS UMR 144Paris75005France
- Cell and Tissue Imaging Facility (PICT‐IBiSA)Institut CuriePSL Research UniversityParis75005France
| | - Pedro Monteiro
- Institut CuriePSL Research UniversityCNRS UMR 144Paris75005France
| | - Nadia ElKhatib
- Gustave Roussy InstituteUniversité Paris‐SaclayINSERM U1279Villejuif94805France
| | - Margot Fournier
- Institut CuriePSL Research UniversityCNRS UMR 144Paris75005France
| | - Ahmed Dahmani
- Translational Research DepartmentInstitut CuriePSL Research UniversityParis75005France
| | - Elodie Montaudon
- Translational Research DepartmentInstitut CuriePSL Research UniversityParis75005France
| | - Guillaume Montagnac
- Gustave Roussy InstituteUniversité Paris‐SaclayINSERM U1279Villejuif94805France
| | - Elisabetta Marangoni
- Translational Research DepartmentInstitut CuriePSL Research UniversityParis75005France
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32
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Madhivanan K, Ramadesikan S, Hsieh WC, Aguilar MC, Hanna CB, Bacallao RL, Aguilar RC. Lowe syndrome patient cells display mTOR- and RhoGTPase-dependent phenotypes alleviated by rapamycin and statins. Hum Mol Genet 2021; 29:1700-1715. [PMID: 32391547 DOI: 10.1093/hmg/ddaa086] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/20/2020] [Accepted: 05/04/2020] [Indexed: 12/25/2022] Open
Abstract
Lowe syndrome (LS) is an X-linked developmental disease characterized by cognitive deficiencies, bilateral congenital cataracts and renal dysfunction. Unfortunately, this disease leads to the early death of affected children often due to kidney failure. Although this condition was first described in the early 1950s and the affected gene (OCRL1) was identified in the early 1990s, its pathophysiological mechanism is not fully understood and there is no LS-specific cure available to patients. Here we report two important signaling pathways affected in LS patient cells. While RhoGTPase signaling abnormalities led to adhesion and spreading defects as compared to normal controls, PI3K/mTOR hyperactivation interfered with primary cilia assembly (scenario also observed in other ciliopathies with compromised kidney function). Importantly, we identified two FDA-approved drugs able to ameliorate these phenotypes. Specifically, statins mitigated adhesion and spreading abnormalities while rapamycin facilitated ciliogenesis in LS patient cells. However, no single drug was able to alleviate both phenotypes. Based on these and other observations, we speculate that Ocrl1 has dual, independent functions supporting proper RhoGTPase and PI3K/mTOR signaling. Therefore, this study suggest that Ocrl1-deficiency leads to signaling defects likely to require combinatorial drug treatment to suppress patient phenotypes and symptoms.
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Affiliation(s)
- Kayalvizhi Madhivanan
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Swetha Ramadesikan
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Wen-Chieh Hsieh
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Mariana C Aguilar
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Claudia B Hanna
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
| | - Robert L Bacallao
- Division of Nephrology, Indiana University School of Medicine, 340 W 10th St #6200, Indianapolis, IN 46202, USA
| | - R Claudio Aguilar
- Department of Biological Sciences, Purdue University, Hansen Life Sciences Building, Room 321, 201 S. University street, West Lafayette, IN 47907, USA
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33
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High glucose-stimulated enhancer of zeste homolog-2 (EZH2) forces suppression of deptor to cause glomerular mesangial cell pathology. Cell Signal 2021; 86:110072. [PMID: 34224844 DOI: 10.1016/j.cellsig.2021.110072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/23/2021] [Accepted: 06/29/2021] [Indexed: 11/24/2022]
Abstract
Function of mTORC1 and mTORC2 has emerged as a driver of mesangial cell pathologies in diabetic nephropathy. The mechanism of mTOR activation is poorly understood in this disease. Deptor is a constitutive subunit and a negative regulator of both mTOR complexes. Mechanistic investigation in mesangial cells revealed that high glucose decreased the expression of deptor concomitant with increased mTORC1 and mTORC2 activities, induction of hypertrophy and, expression of fibronectin and PAI-1. shRNAs against deptor mimicked these pathologic outcomes of high glucose. Conversely, overexpression of deptor significantly inhibited all effects of high glucose. To determine the mechanism of deptor suppression, we found that high glucose significantly increased the expression of EZH2, resulting in lysine-27 tri-methylation of histone H3 (H3K27Me3). Employing approaches including pharmacological inhibition, shRNA-mediated downregulation and overexpression of EZH2, we found that EZH2 regulates high glucose-induced deptor suppression along with activation of mTOR, mesangial cell hypertrophy and fibronectin/PAI-1 expression. Moreover, expression of hyperactive mTORC1 reversed shEZH2-mediated inhibition of hypertrophy and expression of fibronectin and PAI-1 by high glucose. Finally, in renal cortex of diabetic mice, we found that enhanced expression of EZH2 is associated with decreased deptor levels and increased mTOR activity and, expression of fibronectin and PAI-1. Together, our findings provide a novel mechanism for mTOR activation via EZH2 to induce mesangial cell hypertrophy and matrix expansion during early progression of diabetic nephropathy. These results suggest a strategy for leveraging the intrinsic effect of deptor to suppress mTOR activity via reducing EZH2 as a novel therapy for diabetic nephropathy.
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34
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Spires DR, Palygin O, Levchenko V, Isaeva E, Klemens CA, Khedr S, Nikolaienko O, Kriegel A, Cheng X, Yeo JY, Joe B, Staruschenko A. Sexual dimorphism in the progression of type 2 diabetic kidney disease in T2DN rats. Physiol Genomics 2021; 53:223-234. [PMID: 33870721 PMCID: PMC8285576 DOI: 10.1152/physiolgenomics.00009.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/05/2021] [Accepted: 04/14/2021] [Indexed: 12/14/2022] Open
Abstract
Diabetic kidney disease (DKD) is a common complication of diabetes, which frequently leads to end-stage renal failure and increases cardiovascular disease risk. Hyperglycemia promotes renal pathologies such as glomerulosclerosis, tubular hypertrophy, microalbuminuria, and a decline in glomerular filtration rate. Importantly, recent clinical data have demonstrated distinct sexual dimorphism in the pathogenesis of DKD in people with diabetes, which impacts both severity- and age-related risk factors. This study aimed to define sexual dimorphism and renal function in a nonobese type 2 diabetes model with the spontaneous development of advanced diabetic nephropathy (T2DN rats). T2DN rats at 12- and over 48-wk old were used to define disease progression and kidney injury development. We found impaired glucose tolerance and glomerular hyperfiltration in T2DN rats to compare with nondiabetic Wistar control. The T2DN rat displays a significant sexual dimorphism in insulin resistance, plasma cholesterol, renal and glomerular injury, urinary nephrin shedding, and albumin handling. Our results indicate that both male and female T2DN rats developed nonobese type 2 DKD phenotype, where the females had significant protection from the development of severe forms of DKD. Our findings provide further evidence for the T2DN rat strain's effectiveness for studying the multiple facets of DKD.
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Affiliation(s)
- Denisha R Spires
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Vladislav Levchenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Elena Isaeva
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Christine A Klemens
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Sherif Khedr
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Department of Physiology, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Oksana Nikolaienko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Alison Kriegel
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Xi Cheng
- Department of Physiology and Pharmacology, University of Toledo, Ohio
| | - Ji-Youn Yeo
- Department of Physiology and Pharmacology, University of Toledo, Ohio
| | - Bina Joe
- Department of Physiology and Pharmacology, University of Toledo, Ohio
| | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
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35
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Proximal Tubule mTORC1 Is a Central Player in the Pathophysiology of Diabetic Nephropathy and Its Correction by SGLT2 Inhibitors. Cell Rep 2021; 32:107954. [PMID: 32726619 PMCID: PMC7397516 DOI: 10.1016/j.celrep.2020.107954] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 06/18/2020] [Accepted: 07/01/2020] [Indexed: 02/06/2023] Open
Abstract
Diabetic kidney disease (DKD) increases the risk for mortality and is the leading cause of end-stage renal disease. Treatment with sodium-glucose cotransporter 2 inhibitors (SGLT2i) attenuates the progression of DKD, especially in patients with advanced kidney disease. Herein, we show that in diabetes, mTORC1 activity is increased in renal proximal tubule cells (RPTCs) along with enhanced tubule-interstitial fibrosis; this is prevented by SGLT2i. Constitutive activation of mTORC1 in RPTCs induces renal fibrosis and failure and abolishes the renal-protective effects of SGLT2i in diabetes. On the contrary, partial inhibition of mTORC1 in RPTCs prevents fibrosis and the decline in renal function. Stimulation of mTORC1 in RPTCs turns on a pro-fibrotic program in the renal cortex, whereas its inhibition in diabetes reverses the alterations in gene expression. We suggest that RPTC mTORC1 is a critical node that mediates kidney dysfunction in diabetes and the protective effects of SGLT2i by regulating fibrogenesis. In diabetes, mTORC1 activity is increased in renal proximal tubule cells (RPTCs) Diabetes and SGLT2i regulate mTORC1 by modulating nutrient transport to RPTCs Inhibition of mTORC1 in RPTCs prevents fibrosis and the decline in renal function RPTC mTORC1 mediates renal fibrosis in diabetes and the beneficial effects of SGLT2i
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36
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Lv Z, Yue Z, Shao Y, Li C, Zhao X, Guo M. mTORC2/Rictor is essential for coelomocyte endocytosis in Apostichopus japonicus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 118:104000. [PMID: 33444645 DOI: 10.1016/j.dci.2021.104000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Endocytosis plays an important role in the immune defence systems of invertebrates through the interaction between the mechanical target of rapamycin complex 2 (mTORC2) and the AGC kinase family. Rictor is the most important unique subunit protein of mTORC2 and is thought to regulate almost all functions of mTORC2, including endocytosis. In the present study, a novel invertebrate Rictor homologue was identified from Apostichopus japonicus (designated as AjRictor) via the rapid amplification of cDNA ends (RACE). Spatial expression analysis indicated that AjRictor is ubiquitously expressed in all the examined tissues and has the highest transcript level in coelomocytes. Vibrio splendidus challenge in vivo and lipopolysaccharide (LPS) exposure in vitro could remarkably up-regulate the messenger RNA (mRNA) expression of AjRictor compared with the control group. AjRictor knockdown by 0.49- and 0.69-fold resulted in the significant decrease in endocytosis rate by 0.53- (P < 0.01) and 0.59-fold (P < 0.01) in vivo and in vitro compared with the control group, respectively. Similarly, the treatment of coelomocytes with rapamycin for 24 h and the destruction of the assembly of mTORC2 markedly decreased the endocytosis rate of the coelomocytes by 35.92% (P < 0.05). We detected the expression levels of endocytosis-related molecular markers after AjRictor knockdown and rapamycin treatment to further study the molecular mechanism between mTORC2 and endocytosis. Our results showed that AGC kinase family members (PKCα and Pan1) and the phosphorylation level of AktS473 were remarkably decreased after reducing mTORC2 activity; thus, mTORC2/Rictor plays a key role in the immune regulation of endocytosis in coelomocytes. Our current study indicates that mTORC2/Rictor is involved in the coelomocyte endocytosis of sea cucumber and plays an essential regulation role in defending pathogen invasion.
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Affiliation(s)
- Zhimeng Lv
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Zongxu Yue
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Yina Shao
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China.
| | - Chenghua Li
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China.
| | - Xuelin Zhao
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
| | - Ming Guo
- School of Marine Sciences, Ningbo University, Ningbo, 315211, PR China
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37
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Basso PJ, Andrade-Oliveira V, Câmara NOS. Targeting immune cell metabolism in kidney diseases. Nat Rev Nephrol 2021; 17:465-480. [PMID: 33828286 DOI: 10.1038/s41581-021-00413-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2021] [Indexed: 02/06/2023]
Abstract
Insights into the relationship between immunometabolism and inflammation have enabled the targeting of several immunity-mediated inflammatory processes that underlie infectious diseases and cancer or drive transplant rejection, but this field remains largely unexplored in kidney diseases. The kidneys comprise heterogeneous cell populations, contain distinct microenvironments such as areas of hypoxia and hypersalinity, and are responsible for a functional triad of filtration, reabsorption and secretion. These distinctive features create myriad potential metabolic therapeutic targets in the kidney. Immune cells have crucial roles in the maintenance of kidney homeostasis and in the response to kidney injury, and their function is intricately connected to their metabolic properties. Changes in nutrient availability and biomolecules, such as cytokines, growth factors and hormones, initiate cellular signalling events that involve energy-sensing molecules and other metabolism-related proteins to coordinate immune cell differentiation, activation and function. Disruption of homeostasis promptly triggers the metabolic reorganization of kidney immune and non-immune cells, which can promote inflammation and tissue damage. The metabolic differences between kidney and immune cells offer an opportunity to specifically target immunometabolism in the kidney.
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Affiliation(s)
- Paulo José Basso
- Laboratory of Immunobiology of Transplantation, Department of Immunology, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | | | - Niels Olsen Saraiva Câmara
- Laboratory of Immunobiology of Transplantation, Department of Immunology, Universidade de São Paulo, São Paulo, São Paulo, Brazil. .,Laboratory of Clinical and Experimental Immunology, Division of Nephrology, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil.
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38
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Wang S, Lin CW, Carleton AE, Cortez CL, Johnson C, Taniguchi LE, Sekulovski N, Townshend RF, Basrur V, Nesvizhskii AI, Zou P, Fu J, Gumucio DL, Duncan MC, Taniguchi K. Spatially resolved cell polarity proteomics of a human epiblast model. SCIENCE ADVANCES 2021; 7:7/17/eabd8407. [PMID: 33893097 PMCID: PMC8064645 DOI: 10.1126/sciadv.abd8407] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 03/05/2021] [Indexed: 05/08/2023]
Abstract
Critical early steps in human embryonic development include polarization of the inner cell mass, followed by formation of an expanded lumen that will become the epiblast cavity. Recently described three-dimensional (3D) human pluripotent stem cell-derived cyst (hPSC-cyst) structures can replicate these processes. To gain mechanistic insights into the poorly understood machinery involved in epiblast cavity formation, we interrogated the proteomes of apical and basolateral membrane territories in 3D human hPSC-cysts. APEX2-based proximity bioinylation, followed by quantitative mass spectrometry, revealed a variety of proteins without previous annotation to specific membrane subdomains. Functional experiments validated the requirement for several apically enriched proteins in cyst morphogenesis. In particular, we found a key role for the AP-1 clathrin adaptor complex in expanding the apical membrane domains during lumen establishment. These findings highlight the robust power of this proximity labeling approach for discovering novel regulators of epithelial morphogenesis in 3D stem cell-based models.
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Affiliation(s)
- Sicong Wang
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Chien-Wei Lin
- Division of Biostatistics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Amber E Carleton
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Chari L Cortez
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Craig Johnson
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Linnea E Taniguchi
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Nikola Sekulovski
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ryan F Townshend
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Venkatesha Basrur
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Alexey I Nesvizhskii
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Peng Zou
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Jianping Fu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Deborah L Gumucio
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Mara C Duncan
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Kenichiro Taniguchi
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Hinden L, Kogot-Levin A, Tam J, Leibowitz G. Pathogenesis of diabesity-induced kidney disease: role of kidney nutrient sensing. FEBS J 2021; 289:901-921. [PMID: 33630415 DOI: 10.1111/febs.15790] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/09/2021] [Accepted: 02/24/2021] [Indexed: 12/11/2022]
Abstract
Diabetes kidney disease (DKD) is a major healthcare problem associated with increased risk for developing end-stage kidney disease and high mortality. It is widely accepted that DKD is primarily a glomerular disease. Recent findings however suggest that kidney proximal tubule cells (KPTCs) may play a central role in the pathophysiology of DKD. In diabetes and obesity, KPTCs are exposed to nutrient overload, including glucose, free-fatty acids and amino acids, which dysregulate nutrient and energy sensing by mechanistic target of rapamycin complex 1 and AMP-activated protein kinase, with subsequent induction of tubular injury, inflammation, and fibrosis. Pharmacological treatments that modulate nutrient sensing and signaling in KPTCs, including cannabinoid-1 receptor antagonists and sodium glucose transporter 2 inhibitors, exert robust kidney protective effects. Shedding light on how nutrients are sensed and metabolized in KPTCs and in other kidney domains, and on their effects on signal transduction pathways that mediate kidney injury, is important for understanding the pathophysiology of DKD and for the development of novel therapeutic approaches in DKD and probably also in other forms of kidney disease.
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Affiliation(s)
- Liad Hinden
- Obesity and Metabolism Laboratory, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Israel
| | - Aviram Kogot-Levin
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Joseph Tam
- Obesity and Metabolism Laboratory, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Israel
| | - Gil Leibowitz
- Diabetes Unit and Endocrine Service, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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Roles of mTOR in Diabetic Kidney Disease. Antioxidants (Basel) 2021; 10:antiox10020321. [PMID: 33671526 PMCID: PMC7926630 DOI: 10.3390/antiox10020321] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/13/2021] [Accepted: 02/18/2021] [Indexed: 02/06/2023] Open
Abstract
Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease and the number of patients affected is increasing worldwide. Thus, there is a need to establish a new treatment for DKD to improve the renal prognosis of diabetic patients. Recently, it has shown that intracellular metabolic abnormalities are involved in the pathogenesis of DKD. In particular, the activity of mechanistic target of rapamycin complex 1 (mTORC1), a nutrient-sensing signaling molecule, is hyperactivated in various organs of diabetic patients, which suggests the involvement of excessive mTORC1 activation in the pathogenesis of diabetes. In DKD, hyperactivated mTORC1 may be involved in the pathogenesis of podocyte damage, which causes proteinuria, and tubular cell injury that decreases renal function. Therefore, elucidating the role of mTORC1 in DKD and developing new therapeutic agents that suppress mTORC1 hyperactivity may shed new light on DKD treatments in the future.
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Moore MN, Sforzini S, Viarengo A, Barranger A, Aminot Y, Readman JW, Khlobystov AN, Arlt VM, Banni M, Jha AN. Antagonistic cytoprotective effects of C 60 fullerene nanoparticles in simultaneous exposure to benzo[a]pyrene in a molluscan animal model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142355. [PMID: 33022458 DOI: 10.1016/j.scitotenv.2020.142355] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/10/2020] [Accepted: 09/11/2020] [Indexed: 06/11/2023]
Abstract
The hypothesis that C60 fullerene nanoparticles (C60) exert an antagonistic interactive effect on the toxicity of benzo[a]pyrene (BaP) has been supported by this investigation. Mussels were exposed to BaP (5, 50 & 100μg/L) and C60 (C60-1mg/L) separately and in combination. Both BaP and C60 were shown to co-localize in the secondary lysosomes of the hepatopancreatic digestive cells in the digestive gland where they reduced lysosomal membrane stability (LMS) or increased membrane permeability, while BaP also induced increased lysosomal lipid and lipofuscin, indicative of oxidative cell injury and autophagic dysfunction. Combinations of BaP and C60 showed antagonistic effects for lysosomal stability, mTORC1 (mechanistic target of rapamycin complex 1) inhibition and intralysosomal lipid (5 & 50μg/L BaP). The biomarker data (i.e., LMS, lysosomal lipidosis and lipofuscin accumulation; lysosomal/cell volume and dephosphorylation of mTORC1) were further analysed using multivariate statistics. Principal component and cluster analysis clearly indicated that BaP on its own was more injurious than in combination with C60. Use of a network model that integrated the biomarker data for the cell pathophysiological processes, indicated that there were significant antagonistic interactions in network complexity (% connectance) at all BaP concentrations for the combined treatments. Loss of lysosomal membrane stability probably causes the release of intralysosomal iron and hydrolases into the cytosol, where iron can generate harmful reactive oxygen species (ROS). It was inferred that this adverse oxidative reaction induced by BaP was ameliorated in the combination treatments by the ROS scavenging property of intralysosomal C60, thus limiting the injury to the lysosomal membrane; and reducing the oxidative damage in the cytosol and to the nuclear DNA. The ROS scavenging by C60, in combination with enhanced autophagic turnover of damaged cell constituents, appeared to have a cytoprotective effect against the toxic reaction to BaP in the combined treatments.
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Affiliation(s)
- Michael N Moore
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK; European Centre for Environment & Human Health (ECEHH), University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital, Cornwall TR1 3LJ, UK; Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3HD, UK.
| | - Susanna Sforzini
- Institute for the Study of Anthropic Impacts and Sustainability in Marine Environment - IAS, National Research Council - CNR, Via de Marini, 6, 16149 Genova, GE, Italy
| | - Aldo Viarengo
- Institute for the Study of Anthropic Impacts and Sustainability in Marine Environment - IAS, National Research Council - CNR, Via de Marini, 6, 16149 Genova, GE, Italy
| | - Audrey Barranger
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK
| | - Yann Aminot
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK
| | - James W Readman
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK; Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3HD, UK
| | - Andrei N Khlobystov
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK; Nanoscale and Microscale Research Centre, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, King's College London, MRC-PHE Centre for Environmental & Health, London SE1 9NH, UK; Toxicology Department, GAB Consulting GmbH, 69126 Heidelberg, Germany
| | - Mohamed Banni
- Laboratory of Biochemistry and Environmental Toxicology, ISA, Chott-Mariem, Sousse, Tunisia
| | - Awadhesh N Jha
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK
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Festa BP, Berquez M, Nieri D, Luciani A. Endolysosomal Disorders Affecting the Proximal Tubule of the Kidney: New Mechanistic Insights and Therapeutics. Rev Physiol Biochem Pharmacol 2021; 185:233-257. [PMID: 33649992 DOI: 10.1007/112_2020_57] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Epithelial cells that line the proximal tubule of the kidney rely on an intertwined ecosystem of vesicular membrane trafficking pathways to ensure the reabsorption of essential nutrients. To function effectively and to achieve homeostasis, these specialized cells require the sorting and recycling of a wide array of cell surface proteins within the endolysosomal network, including signaling receptors, nutrient transporters, ion channels, and polarity markers. The dysregulation of the endolysosomal system can lead to a generalized proximal tubule dysfunction, ultimately causing severe metabolic complications and kidney disease.In this chapter, we highlight the biological functions of the genes that code endolysosomal proteins from the perspective of understanding - and potentially reversing - the pathophysiology of endolysosomal disorders affecting the proximal tubule of the kidney. These insights might ultimately lead to potential treatments for currently intractable diseases and transform our ability to regulate kidney homeostasis and health.
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Affiliation(s)
- Beatrice Paola Festa
- Institute of Physiology, Mechanisms of Inherited Kidney Disorders Group, University of Zurich, Zurich, Switzerland
| | - Marine Berquez
- Institute of Physiology, Mechanisms of Inherited Kidney Disorders Group, University of Zurich, Zurich, Switzerland
| | - Daniela Nieri
- Institute of Physiology, Mechanisms of Inherited Kidney Disorders Group, University of Zurich, Zurich, Switzerland
| | - Alessandro Luciani
- Institute of Physiology, Mechanisms of Inherited Kidney Disorders Group, University of Zurich, Zurich, Switzerland.
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Wang Y, Liu Z, Shu S, Cai J, Tang C, Dong Z. AMPK/mTOR Signaling in Autophagy Regulation During Cisplatin-Induced Acute Kidney Injury. Front Physiol 2020; 11:619730. [PMID: 33391038 PMCID: PMC7773913 DOI: 10.3389/fphys.2020.619730] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 11/27/2020] [Indexed: 12/12/2022] Open
Abstract
Autophagy is a conserved, multistep pathway that degrades and recycles dysfunctional organelles and macromolecules to maintain cellular homeostasis. Mammalian target of rapamycin (mTOR) and adenosine-monophosphate activated-protein kinase (AMPK) are major negative and positive regulators of autophagy, respectively. In cisplatin-induced acute kidney injury (AKI) or nephrotoxicity, autophagy is rapidly induced in renal tubular epithelial cells and acts as a cytoprotective mechanism for cell survival. Both mTOR and AMPK have been implicated in the regulation of autophagy in cisplatin-induced AKI. Targeting mTOR and/or AMPK may offer effective strategies for kidney protection during cisplatin-mediated chemotherapy.
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Affiliation(s)
- Ying Wang
- Department of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China
| | - Zhiwen Liu
- Department of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China
| | - Shaoqun Shu
- Department of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China
| | - Juan Cai
- Department of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China
| | - Chengyuan Tang
- Department of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China
| | - Zheng Dong
- Department of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China.,Department of Cellular Biology and Anatomy, Charlie Norwood Veterans Affair Medical Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
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Gyimesi G, Pujol-Giménez J, Kanai Y, Hediger MA. Sodium-coupled glucose transport, the SLC5 family, and therapeutically relevant inhibitors: from molecular discovery to clinical application. Pflugers Arch 2020; 472:1177-1206. [PMID: 32767111 PMCID: PMC7462921 DOI: 10.1007/s00424-020-02433-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 06/24/2020] [Accepted: 07/02/2020] [Indexed: 02/06/2023]
Abstract
Sodium glucose transporters (SGLTs) belong to the mammalian solute carrier family SLC5. This family includes 12 different members in human that mediate the transport of sugars, vitamins, amino acids, or smaller organic ions such as choline. The SLC5 family belongs to the sodium symporter family (SSS), which encompasses transporters from all kingdoms of life. It furthermore shares similarity to the structural fold of the APC (amino acid-polyamine-organocation) transporter family. Three decades after the first molecular identification of the intestinal Na+-glucose cotransporter SGLT1 by expression cloning, many new discoveries have evolved, from mechanistic analysis to molecular genetics, structural biology, drug discovery, and clinical applications. All of these advances have greatly influenced physiology and medicine. While SGLT1 is essential for fast absorption of glucose and galactose in the intestine, the expression of SGLT2 is largely confined to the early part of the kidney proximal tubules, where it reabsorbs the bulk part of filtered glucose. SGLT2 has been successfully exploited by the pharmaceutical industry to develop effective new drugs for the treatment of diabetic patients. These SGLT2 inhibitors, termed gliflozins, also exhibit favorable nephroprotective effects and likely also cardioprotective effects. In addition, given the recent finding that SGLT2 is also expressed in tumors of pancreas and prostate and in glioblastoma, this opens the door to potential new therapeutic strategies for cancer treatment by specifically targeting SGLT2. Likewise, further discoveries related to the functional association of other SGLTs of the SLC5 family to human pathologies will open the door to potential new therapeutic strategies. We furthermore hope that the herein summarized information about the physiological roles of SGLTs and the therapeutic benefits of the gliflozins will be useful for our readers to better understand the molecular basis of the beneficial effects of these inhibitors, also in the context of the tubuloglomerular feedback (TGF), and the renin-angiotensin system (RAS). The detailed mechanisms underlying the clinical benefits of SGLT2 inhibition by gliflozins still warrant further investigation that may serve as a basis for future drug development.
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Affiliation(s)
- Gergely Gyimesi
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland
| | - Jonai Pujol-Giménez
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland
| | - Yoshikatsu Kanai
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Matthias A Hediger
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland.
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Bissler JJ, Budde K, Sauter M, Franz DN, Zonnenberg BA, Frost MD, Belousova E, Berkowitz N, Ridolfi A, Christopher Kingswood J. Effect of everolimus on renal function in patients with tuberous sclerosis complex: evidence from EXIST-1 and EXIST-2. Nephrol Dial Transplant 2020; 34:1000-1008. [PMID: 30053159 PMCID: PMC6545468 DOI: 10.1093/ndt/gfy132] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Indexed: 02/06/2023] Open
Abstract
Background A reduction in renal angiomyolipoma volume observed with everolimus (EVE) treatment in patients with tuberous sclerosis complex (TSC) has been postulated to translate to clinical benefit by reducing the risk of renal hemorrhage and chronic renal failure. Methods The long-term effects of EVE on renal function (∼4 years of treatment) were examined in patients treated with EVE in the Phase 3 EXIST-1 and EXIST-2 studies. Patients in EXIST-1 had TSC and subependymal giant cell astrocytoma (SEGA), and patients in EXIST-2 had renal angiomyolipoma and a definite diagnosis of TSC or sporadic lymphangioleiomyomatosis. EVE was administered at 4.5 mg/m2/day, with adjustment to achieve target trough levels of 5–15 ng/mL in EXIST-1 and at 10 mg/day in EXIST-2. Estimated glomerular filtration rate (eGFR) and creatinine levels were assessed at baseline, at Weeks 2, 4, 6, 8, 12 and 18, then every 3 months thereafter. Proteinuria was graded according to National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. Results A total of 111 patients from EXIST-1 and 112 patients from EXIST-2 were included in this analysis. Respective mean ages at EVE initiation were 10.5 [standard deviation (SD) 6.45] and 33.2 (SD 10.29) years, and 3.6% and 37.5% of patients had undergone prior renal intervention. Mean baseline eGFR was 115 and 88 mL/min/1.73 m2 in EXIST-1 and EXIST-2, respectively. Overall, mean eGFR remained stable over time in both studies, with an decline in renal function mostly confined to some patients with severely compromised renal function before treatment. Patients with prior renal intervention exhibited low eGFR values throughout the study. The incidence of proteinuria increased after initiating treatment with EVE and was mostly Grade 1/2 in severity, with Grade 3 proteinuria reported in only two patients. Measurements of proteinuria were limited by the use of urine dipstick tests. Conclusions The use of EVE does not appear to be nephrotoxic in patients with SEGA or renal angiomyolipoma associated with TSC and may preserve renal function in most patients. ClinicalTrials.gov identifiers NCT00789828 and NCT00790400
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Affiliation(s)
- John J Bissler
- St. Jude Children's Research Hospital and Le Bonheur Children's Hospital, Memphis, TN, USA
| | | | - Matthias Sauter
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany
| | - David N Franz
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | | | | | - Elena Belousova
- Moscow Research and Clinical Institute of Pediatrics, Moscow, Russian Federation
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Verschuren EHJ, Castenmiller C, Peters DJM, Arjona FJ, Bindels RJM, Hoenderop JGJ. Sensing of tubular flow and renal electrolyte transport. Nat Rev Nephrol 2020; 16:337-351. [DOI: 10.1038/s41581-020-0259-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2020] [Indexed: 02/06/2023]
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Alqahtani FM, Arivett BA, Taylor ZE, Handy ST, Farone AL, Farone MB. Chemogenomic profiling to understand the antifungal action of a bioactive aurone compound. PLoS One 2019; 14:e0226068. [PMID: 31825988 PMCID: PMC6905557 DOI: 10.1371/journal.pone.0226068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 11/18/2019] [Indexed: 12/15/2022] Open
Abstract
Every year, more than 250,000 invasive candidiasis infections are reported with 50,000 deaths worldwide. The limited number of antifungal agents necessitates the need for alternative antifungals with potential novel targets. The 2-benzylidenebenzofuran-3-(2H)-ones have become an attractive scaffold for antifungal drug design. This study aimed to determine the antifungal activity of a synthetic aurone compound and characterize its mode of action. Using the broth microdilution method, aurone SH1009 exhibited inhibition against C. albicans, including resistant isolates, as well as C. glabrata, and C. tropicalis with IC50 values of 4-29 μM. Cytotoxicity assays using human THP-1, HepG2, and A549 human cell lines showed selective toxicity toward fungal cells. The mode of action for SH1009 was characterized using chemical-genetic interaction via haploinsufficiency (HIP) and homozygous (HOP) profiling of a uniquely barcoded Saccharomyces cerevisiae mutant collection. Approximately 5300 mutants were competitively treated with SH1009 followed by DNA extraction, amplification of unique barcodes, and quantification of each mutant using multiplexed next-generation sequencing. Barcode post-sequencing analysis revealed 238 sensitive and resistant mutants that significantly (FDR P values ≤ 0.05) responded to aurone SH1009. The enrichment analysis of KEGG pathways and gene ontology demonstrated the cell cycle pathway as the most significantly enriched pathway along with DNA replication, cell division, actin cytoskeleton organization, and endocytosis. Phenotypic studies of these significantly enriched responses were validated in C. albicans. Flow cytometric analysis of SH1009-treated C. albicans revealed a significant accumulation of cells in G1 phase, indicating cell cycle arrest. Fluorescence microscopy detected abnormally interrupted actin dynamics, resulting in enlarged, unbudded cells. RT-qPCR confirmed the effects of SH1009 in differentially expressed cell cycle, actin polymerization, and signal transduction genes. These findings indicate the target of SH1009 as a cell cycle-dependent organization of the actin cytoskeleton, suggesting a novel mode of action of the aurone compound as an antifungal inhibitor.
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Affiliation(s)
- Fatmah M. Alqahtani
- Department of Biology, Middle Tennessee State University, Murfreesboro, Tennessee, United States of America
| | - Brock A. Arivett
- Department of Biology, Middle Tennessee State University, Murfreesboro, Tennessee, United States of America
| | - Zachary E. Taylor
- Department of Chemistry, Middle Tennessee State University, Murfreesboro, Tennessee, United States of America
| | - Scott T. Handy
- Department of Chemistry, Middle Tennessee State University, Murfreesboro, Tennessee, United States of America
| | - Anthony L. Farone
- Department of Biology, Middle Tennessee State University, Murfreesboro, Tennessee, United States of America
| | - Mary B. Farone
- Department of Biology, Middle Tennessee State University, Murfreesboro, Tennessee, United States of America
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Polesel M, Hall AM. Axial differences in endocytosis along the kidney proximal tubule. Am J Physiol Renal Physiol 2019; 317:F1526-F1530. [DOI: 10.1152/ajprenal.00459.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The proximal tubule (PT) reabsorbs filtered proteins via receptor-mediated endocytosis to prevent energetically inefficient wasting in the urine. Recent intravital imaging studies have suggested that protein reabsorption occurs in early (S1) segments, which have a very high capacity. In contrast, uptake of fluid phase substrates also occurs in distal (S2) segments. In this article, we will review these findings and their implications for understanding integrated proximal tubular function, patterns of damage caused by endocytosed toxins, and the origins of proteinuria. We will also discuss whether compensatory downstream increases in protein uptake might occur in disease states, and the environmental factors that could drive these changes.
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Affiliation(s)
| | - Andrew M. Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
- Department of Nephrology, University Hospital Zurich, Zurich, Switzerland
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Rahmani S, Defferrari MS, Wakarchuk WW, Antonescu CN. Energetic adaptations: Metabolic control of endocytic membrane traffic. Traffic 2019; 20:912-931. [DOI: 10.1111/tra.12705] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 09/11/2019] [Accepted: 10/13/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Sadia Rahmani
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
| | | | - Warren W. Wakarchuk
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
| | - Costin N. Antonescu
- Department of Chemistry and BiologyRyerson University Toronto Ontario Canada
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital Toronto Ontario Canada
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50
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Margaria JP, Campa CC, De Santis MC, Hirsch E, Franco I. The PI3K/Akt/mTOR pathway in polycystic kidney disease: A complex interaction with polycystins and primary cilium. Cell Signal 2019; 66:109468. [PMID: 31715259 DOI: 10.1016/j.cellsig.2019.109468] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 11/08/2019] [Accepted: 11/08/2019] [Indexed: 12/19/2022]
Abstract
Over-activation of the PI3K/Akt/mTOR network is a well-known pathogenic event that leads to hyper-proliferation. Pharmacological targeting of this pathway has been developed for the treatment of multiple diseases, including cancer. In polycystic kidney disease (PKD), the mTOR cascade promotes cyst growth by boosting proliferation, size and metabolism of kidney tubule epithelial cells. Therefore, mTOR inhibition has been tested in pre-clinical and clinical studies, but only the former showed positive results. This review reports recent discoveries describing the activity and molecular mechanisms of mTOR activation in tubule epithelial cells and cyst formation and discusses the evidence of an upstream regulation of mTOR by the PI3K/Akt axis. In particular, the complex interconnections of the PI3K/Akt/mTOR network with the principal signaling routes involved in the suppression of cyst formation are dissected. These interactions include the antagonism and the reciprocal negative regulation between mTOR complex 1 and the proteins whose deletion causes Autosomal Dominant PKD, the polycystins. In addition, the emerging role of phopshoinositides, membrane components modulated by PI3K, will be presented in the context of primary cilium signaling, cell polarization and protection from cyst formation. Overall, studies demonstrate that the activity of various members of the PI3K/Akt/mTOR network goes beyond the classical transduction of mitogenic signals and can impact several aspects of kidney tubule homeostasis and morphogenesis. These properties might be useful to guide the establishment of more effective treatment protocols to be tested in clinical trials.
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Affiliation(s)
- Jean Piero Margaria
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino 10126, Italy
| | - Carlo Cosimo Campa
- Department of Biosystems Science and Engineering, ETH Zurich, 4058 Basel, Switzerland
| | - Maria Chiara De Santis
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino 10126, Italy
| | - Emilio Hirsch
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino 10126, Italy
| | - Irene Franco
- Department of Biosciences and Nutrition, Center for Innovative Medicine, Karolinska Institutet, 14157 Huddinge, Sweden.
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