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Kosanović M, Milutinović B, Kutzner TJ, Mouloud Y, Bozic M. Clinical Prospect of Mesenchymal Stromal/Stem Cell-Derived Extracellular Vesicles in Kidney Disease: Challenges and the Way Forward. Pharmaceutics 2023; 15:1911. [PMID: 37514097 PMCID: PMC10384614 DOI: 10.3390/pharmaceutics15071911] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 06/23/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023] Open
Abstract
Kidney disease is a growing public health problem worldwide, including both acute and chronic forms. Existing therapies for kidney disease target various pathogenic mechanisms; however, these therapies only slow down the progression of the disease rather than offering a cure. One of the potential and emerging approaches for the treatment of kidney disease is mesenchymal stromal/stem cell (MSC) therapy, shown to have beneficial effects in preclinical studies. In addition, extracellular vesicles (EVs) released by MSCs became a potent cell-free therapy option in various preclinical models of kidney disease due to their regenerative, anti-inflammatory, and immunomodulatory properties. However, there are scarce clinical data available regarding the use of MSC-EVs in kidney pathologies. This review article provides an outline of the renoprotective effects of MSC-EVs in different preclinical models of kidney disease. It offers a comprehensive analysis of possible mechanisms of action of MSC-EVs with an emphasis on kidney disease. Finally, on the journey toward the implementation of MSC-EVs into clinical practice, we highlight the need to establish standardized methods for the characterization of an EV-based product and investigate the adequate dosing, safety, and efficacy of MSC-EVs application, as well as the development of suitable potency assays.
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Affiliation(s)
- Maja Kosanović
- Institute for the Application of Nuclear Energy (INEP), University of Belgrade, 11 000 Belgrade, Serbia
| | - Bojana Milutinović
- Department of Neurosurgery, MD Anderson Cancer Center, University of Texas, Houston, TX 770302, USA
| | - Tanja J Kutzner
- Institute for Transfusion Medicine, University Hospital Essen, University of Duisburg-Essen, 45355 Essen, North Rhine-Westhpalia, Germany
| | - Yanis Mouloud
- Institute for Transfusion Medicine, University Hospital Essen, University of Duisburg-Essen, 45355 Essen, North Rhine-Westhpalia, Germany
| | - Milica Bozic
- Institute for Transfusion Medicine, University Hospital Essen, University of Duisburg-Essen, 45355 Essen, North Rhine-Westhpalia, Germany
- Vascular and Renal Translational Research Group, Biomedical Research Institute of Lleida Dr. Pifarré Foundation (IRBLLEIDA), 25196 Lleida, Spain
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2
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Kosanović M, Milutinovic B, Glamočlija S, Morlans IM, Ortiz A, Bozic M. Extracellular Vesicles and Acute Kidney Injury: Potential Therapeutic Avenue for Renal Repair and Regeneration. Int J Mol Sci 2022; 23:ijms23073792. [PMID: 35409151 PMCID: PMC8998560 DOI: 10.3390/ijms23073792] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/27/2022] [Accepted: 03/28/2022] [Indexed: 12/10/2022] Open
Abstract
Acute kidney injury (AKI) is a sudden decline of renal function and represents a global clinical problem due to an elevated morbidity and mortality. Despite many efforts, currently there are no treatments to halt this devastating condition. Extracellular vesicles (EVs) are nanoparticles secreted by various cell types in both physiological and pathological conditions. EVs can arise from distinct parts of the kidney and can mediate intercellular communication between various cell types along the nephron. Besides their potential as diagnostic tools, EVs have been proposed as powerful new tools for regenerative medicine and have been broadly studied as therapeutic mediators in different models of experimental AKI. In this review, we present an overview of the basic features and biological relevance of EVs, with an emphasis on their functional role in cell-to-cell communication in the kidney. We explore versatile roles of EVs in crucial pathophysiological mechanisms contributing to AKI and give a detailed description of the renoprotective effects of EVs from different origins in AKI. Finally, we explain known mechanisms of action of EVs in AKI and provide an outlook on the potential clinical translation of EVs in the setting of AKI.
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Affiliation(s)
- Maja Kosanović
- Institute for the Application of Nuclear Energy, INEP, University of Belgrade, 11080 Belgrade, Serbia; (M.K.); (S.G.)
| | - Bojana Milutinovic
- Department of Neurosurgery, MD Anderson Cancer Center, University of Texas, Houston, TX 77030, USA;
| | - Sofija Glamočlija
- Institute for the Application of Nuclear Energy, INEP, University of Belgrade, 11080 Belgrade, Serbia; (M.K.); (S.G.)
| | - Ingrid Mena Morlans
- Vascular and Renal Translational Research Group, Biomedical Research Institute of Lleida Dr. Pifarré Foundation (IRBLleida), 25196 Lleida, Spain;
| | - Alberto Ortiz
- Department of Nephrology and Hypertension, IIS-Fundación Jiménez Díaz, Universidad Autónoma Madrid, 28040 Madrid, Spain;
| | - Milica Bozic
- Vascular and Renal Translational Research Group, Biomedical Research Institute of Lleida Dr. Pifarré Foundation (IRBLleida), 25196 Lleida, Spain;
- Correspondence:
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Caus M, Eritja À, Bozic M. Role of microRNAs in Obesity-Related Kidney Disease. Int J Mol Sci 2021; 22:ijms222111416. [PMID: 34768854 PMCID: PMC8583993 DOI: 10.3390/ijms222111416] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 12/14/2022] Open
Abstract
Obesity is a major global health problem and is associated with a significant risk of renal function decline. Obesity-related nephropathy, as one of the complications of obesity, is characterized by a structural and functional damage of the kidney and represents one of the important contributors to the morbidity and mortality worldwide. Despite increasing data linking hyperlipidemia and lipotoxicity to kidney injury, the apprehension of molecular mechanisms leading to a development of kidney damage is scarce. MicroRNAs (miRNAs) are endogenously produced small noncoding RNA molecules with an important function in post-transcriptional regulation of gene expression. miRNAs have been demonstrated to be important regulators of a vast array of physiological and pathological processes in many organs, kidney being one of them. In this review, we present an overview of miRNAs, focusing on their functional role in the pathogenesis of obesity-associated renal pathologies. We explain novel findings regarding miRNA-mediated signaling in obesity-related nephropathies and highlight advantages and future perspectives of the therapeutic application of miRNAs in renal diseases.
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Martins JR, Haenni D, Bugarski M, Figurek A, Hall AM. Quantitative intravital Ca2+ imaging maps single cell behavior to kidney tubular structure. Am J Physiol Renal Physiol 2020; 319:F245-F255. [DOI: 10.1152/ajprenal.00052.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Ca2+ is an important second messenger that translates extracellular stimuli into intracellular responses. Although there has been significant progress in understanding Ca2+ dynamics in organs such as the brain, the nature of Ca2+ signals in the kidney is still poorly understood. Here, we show that by using a genetically expressed highly sensitive reporter (GCaMP6s), it is possible to perform imaging of Ca2+ signals at high resolution in the mouse kidney in vivo. Moreover, by applying machine learning-based automated analysis using a Ca2+-independent signal, quantitative data can be extracted in an unbiased manner. By projecting the resulting data onto the structure of the kidney, we show that different tubular segments display highly distinct spatiotemporal patterns of Ca2+ signals. Furthermore, we provide evidence that Ca2+ activity in the proximal tubule decreases with increasing distance from the glomerulus. Finally, we demonstrate that substantial changes in intracellular Ca2+ can be detected in proximal tubules in a cisplatin model of acute kidney injury, which can be linked to alterations in cell structure and transport function. In summary, we describe a powerful new tool to investigate how single cell behavior is integrated with whole organ structure and function and how it is altered in disease states relevant to humans.
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Affiliation(s)
| | - Dominik Haenni
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
| | - Milica Bugarski
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Andreja Figurek
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Andrew M. Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
- Department of Nephrology, University Hospital Zurich, Zurich, Switzerland
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Enhanced remedial effects for vitamin D3 and calcium co-supplementation against pre-existing lead nephrotoxicity in mice: The roles of renal calcium homeostatic molecules. Biochim Biophys Acta Mol Basis Dis 2019; 1865:512-524. [DOI: 10.1016/j.bbadis.2018.11.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 11/09/2018] [Accepted: 11/24/2018] [Indexed: 12/31/2022]
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Jiang K, Tang H, Mishra PK, Macura SI, Lerman LO. A rapid T 1 mapping method for assessment of murine kidney viability using dynamic manganese-enhanced magnetic resonance imaging. Magn Reson Med 2018; 80:190-199. [PMID: 29193339 PMCID: PMC5876081 DOI: 10.1002/mrm.27025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 10/09/2017] [Accepted: 11/01/2017] [Indexed: 12/22/2022]
Abstract
PURPOSE Dynamic manganese-enhanced MRI (MEMRI) allows assessment of tissue viability by tracing manganese uptake. We aimed to develop a rapid T1 mapping method for dynamic MEMRI to facilitate assessments of murine kidney viability. METHODS A multi-slice saturation recovery fast spin echo (MSRFSE) was developed, validated, and subsequently applied in dynamic MEMRI at 16.4T on ischemic mouse kidneys after 4 weeks of unilateral renal artery stenosis (RAS). Baseline T1 values and post-contrast R1 (1/T1 ) changes were measured in cortex (CO), outer (OSOM), inner (ISOM) strips of outer medulla, and inner medulla (IM). RESULTS Validation studies showed strong agreement between MSRFSE and an established saturation recovery Look-Locker method. Baseline T1 (s) increased in the stenotic kidney CO (2.10 [1.95-2.56] vs. 1.88 [1.81-2.00], P = 0.0317) and OSOM (2.17 [2.05-2.33] vs. 1.96 [1.87-2.00], P = 0.0075) but remained unchanged in ISOM and IM. This method allowed a temporal resolution of 1.43 min in dynamic MEMRI. Mn2+ uptake and retention decreased in stenotic kidneys, particularly in the OSOM (ΔR1 : 0.48 [0.38-0.56] vs. 0.64 [0.61-0.69] s-1 , P < 0.0001). CONCLUSION Dynamic MEMRI by MSRFSE detected decreased cellular viability and discerned the regional responses to RAS. This technique may provide a valuable tool for noninvasive evaluation of renal viability. Magn Reson Med 80:190-199, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Kai Jiang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Hui Tang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Prassana K. Mishra
- Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Slobodan I. Macura
- Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Lilach O. Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
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Tang L, Zheng S, Ren H, He D, Zeng C, Wang WE. Activation of angiotensin II type 1 receptors increases D 4 dopamine receptor expression in rat renal proximal tubule cells. Hypertens Res 2017; 40:652-657. [PMID: 28230199 DOI: 10.1038/hr.2017.13] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 12/27/2016] [Accepted: 12/28/2016] [Indexed: 12/22/2022]
Abstract
Both the dopaminergic and renin-angiotensin systems play important roles in the regulation of blood pressure. Our previous study showed that the stimulation of dopaminergic D4 receptors reduced angiotensin II type 1 (AT1) receptor expression in renal proximal tubule (RPT) cells. In this study, we tested whether AT1 receptors, in return, would regulate D4 receptor expression and function in RPT cells. Expression of the D4 receptor from Wistar-Kyoto (WKY) or spontaneously hypertensive rats (SHRs) RPT cells and renal cortex tissues were determined by western blot, and Na+-K+ ATPase activity was determined using an enzyme assay. Urine volume and urine sodium of WKY rats and SHRs treated with or without D4 receptor stimulation were measured. Thus, activation of AT1 receptors with angiotensin II (Ang II) increased D4 receptor protein expression in RPT cells, and this increase was blocked by nicardipine, a calcium influx blocker. The D4 receptor agonist PD168077 inhibited Na+-K+ ATPase activity in WKY RPT cells but not in SHR RPT cells. Ang II pre-treatment promoted D4 receptor-mediated inhibition of Na+-K+ ATPase in RPT cells in WKY rats but not in SHRs. Meanwhile, Ang II pre-treatment augmented the natriuretic effect of PD168077 in WKY rats but not in SHRs. In conclusion, AT1 stimulation can regulate the expression and natriuretic function of dopaminergic D4 receptors in RPT cells and might be involved in the pathogenesis of essential hypertension.
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Affiliation(s)
- Luxun Tang
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Institute of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Cardiovascular Clinical Research Center, Daping Hospital, Third Military Medical University, Chongqing, PR China
| | - Shuo Zheng
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Institute of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Cardiovascular Clinical Research Center, Daping Hospital, Third Military Medical University, Chongqing, PR China
| | - Hongmei Ren
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Institute of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Cardiovascular Clinical Research Center, Daping Hospital, Third Military Medical University, Chongqing, PR China
| | - Duofen He
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Institute of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Cardiovascular Clinical Research Center, Daping Hospital, Third Military Medical University, Chongqing, PR China
| | - Chunyu Zeng
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Institute of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Cardiovascular Clinical Research Center, Daping Hospital, Third Military Medical University, Chongqing, PR China
| | - Wei Eric Wang
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Institute of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, PR China.,Chongqing Cardiovascular Clinical Research Center, Daping Hospital, Third Military Medical University, Chongqing, PR China
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8
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Husi H, Human C. Molecular determinants of acute kidney injury. J Inj Violence Res 2016; 7:75-86. [PMID: 26104320 PMCID: PMC4522318 DOI: 10.5249/jivr.v7i2.615] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 07/10/2014] [Indexed: 12/18/2022] Open
Abstract
Background: Acute kidney injury (AKI) is a condition that leads to a rapid deterioration of renal function associated with impairment to maintain electrolyte and acid balance, and, if left untreated, ultimately irreversible kidney damage and renal necrosis. There are a number of causes that can trigger AKI, ranging from underlying conditions as well as trauma and surgery. Specifically, the global rise in surgical procedures led to a substantial increase of AKI incidence rates, which in turn impacts on mortality rates, quality of life and economic costs to the healthcare system. However, no effective therapy for AKI exists. Current approaches, such as pharmacological intervention, help in alleviating symptoms in slowing down the progression, but do not prevent or reverse AKI-induced organ damage. Methods: An in-depth understanding of the molecular machinery involved in and modulated by AKI induction and progression is necessary to specifically pharmacologically target key molecules. A major hurdle to devise a successful strategy is the multifactorial and complex nature of the disorder itself, whereby the activation of a number of seemingly independent molecular pathways in the kidney leads to apoptotic and necrotic events. Results: The renin-angiotensin-aldosterone-system (RAAS) axis appears to be a common element, leading to downstream events such as triggers of immune responses via the NFB pathway. Other pathways intricately linked with AKI-induction and progression are the tumor necrosis factor alpha (TNF α) and transforming growth factor beta (TGF β) signaling cascades, as well as a number of other modulators. Surprisingly, it has been shown that the involvement of the glutamatergic axis, believed to be mainly a component of the neurological system, is also a major contributor. Conclusions: Here we address the current understanding of the molecular pathways evoked in AKI, their interplay, and the potential to pharmacologically intervene in the effective prevention and/or progression of AKI.
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Affiliation(s)
- Holger Husi
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK.
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9
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Di Mise A, Tamma G, Ranieri M, Svelto M, Heuvel BVD, Levtchenko EN, Valenti G. Conditionally immortalized human proximal tubular epithelial cells isolated from the urine of a healthy subject express functional calcium-sensing receptor. Am J Physiol Renal Physiol 2015; 308:F1200-6. [PMID: 25656364 DOI: 10.1152/ajprenal.00352.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 02/03/2015] [Indexed: 02/08/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor, which plays an essential role in regulating Ca(2+) homeostasis. Here we show that conditionally immortalized proximal tubular epithelial cell line (ciPTEC) obtained by immortalizing and subcloning cells exfoliated in the urine of a healthy subject expresses functional endogenous CaSR. Immunolocalization studies of polarized ciPTEC revealed the apical localization of the receptor. By Western blotting of ciPTEC lysates, both monomeric and dimeric forms of CaSR at 130 and ∼250 kDa, respectively, were detected. Functional studies indicated that both external calcium and the positive CaSR allosteric modulator, NPS-R568, induced a significant increase in cytosolic calcium, proving a high sensitivity of the endogenous receptor to its agonists. Calcium depletion from the endoplasmic reticulum using cyclopiazonic acid abolished the increase in cytosolic calcium elicited by NPS-R568, confirming calcium exit from intracellular stores. Activation of CaSR by NPS-R significantly reduced the increase in cAMP elicited by forskolin (FK), a direct activator of adenylate cyclase, further confirming the functional expression of the receptor in this cell line. CaSR expressed in ciPTEC was found to interact with Gq as a downstream effector, which in turn can cause release of calcium from intracellular stores via phospholipase C activation. We conclude that human proximal tubular ciPTEC express functional CaSR and respond to its activation with a release of calcium from intracellular stores. These cell lines represent a valuable tool for research into the disorder associated with gain or loss of function of the CaSR by producing cell lines from patients.
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Affiliation(s)
- Annarita Di Mise
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Marianna Ranieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Maria Svelto
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy; Center of Excellence in Comparative Genomics(CEGBA), Bari, Italy
| | - Bert van den Heuvel
- Department of Pediatric Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; and
| | - Elena N Levtchenko
- Department of Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy; Center of Excellence in Comparative Genomics(CEGBA), Bari, Italy;
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Zhang X, Howell GM, Guo L, Collage RD, Loughran PA, Zuckerbraun BS, Rosengart MR. CaMKIV-dependent preservation of mTOR expression is required for autophagy during lipopolysaccharide-induced inflammation and acute kidney injury. THE JOURNAL OF IMMUNOLOGY 2014; 193:2405-15. [PMID: 25070845 DOI: 10.4049/jimmunol.1302798] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Autophagy, an evolutionarily conserved homeostasis process regulating biomass quantity and quality, plays a critical role in the host response to sepsis. Recent studies show its calcium dependence, but the calcium-sensitive regulatory cascades have not been defined. In this study, we describe a novel mechanism in which calcium/calmodulin-dependent protein kinase IV (CaMKIV), through inhibitory serine phosphorylation of GSK-3β and inhibition of FBXW7 recruitment, prevents ubiquitin proteosomal degradation of mammalian target of rapamycin (mTOR) and thereby augments autophagy in both the macrophage and the kidney. Under the conditions of sepsis studied, mTOR expression and activity were requisite for autophagy, a paradigm countering the current perspective that prototypically, mTOR inhibition induces autophagy. CaMKIV-mTOR-dependent autophagy was fundamentally important for IL-6 production in vitro and in vivo. Similar mechanisms were operant in the kidney during endotoxemia and served a cytoprotective role in mitigating acute kidney injury. Thus, CaMKIV-mTOR-dependent autophagy is conserved in both immune and nonimmune/parenchymal cells and is fundamental for the respective functional and adaptive responses to septic insult.
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Affiliation(s)
- Xianghong Zhang
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Gina M Howell
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Lanping Guo
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Richard D Collage
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213
| | - Patricia A Loughran
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213; Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213; and
| | | | - Matthew R Rosengart
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213; Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15213
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11
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Hering-Smith KS, Mao W, Schiro FR, Coleman-Barnett J, Pajor AM, Hamm LL. Localization of the calcium-regulated citrate transport process in proximal tubule cells. Urolithiasis 2014; 42:209-19. [PMID: 24652587 DOI: 10.1007/s00240-014-0653-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 02/25/2014] [Indexed: 11/26/2022]
Abstract
Urinary citrate is an important inhibitor of calcium-stone formation. Most of the citrate reabsorption in the proximal tubule is thought to occur via a dicarboxylate transporter NaDC1 located in the apical membrane. OK cells, an established opossum kidney proximal tubule cell line, transport citrate but the characteristics change with extracellular calcium such that low calcium solutions stimulate total citrate transport as well as increase the apparent affinity for transport. The present studies address several fundamental properties of this novel process: the polarity of the transport process, the location of the calcium-sensitivity and whether NaDC1 is present in OK cells. OK cells grown on permeable supports exhibited apical >basolateral citrate transport. Apical transport of both citrate and succinate was sensitive to extracellular calcium whereas basolateral transport was not. Apical calcium, rather than basolateral, was the predominant determinant of changes in transport. Also 2,3-dimethylsuccinate, previously identified as an inhibitor of basolateral dicarboxylate transport, inhibited apical citrate uptake. Although the calcium-sensitive transport process in OK cells is functionally not typical NaDC1, NaDC1 is present in OK cells by Western blot and PCR. By immunolocalization studies, NaDC1 was predominantly located in discrete apical membrane or subapical areas. However, by biotinylation, apical NaDC1 decreases in the apical membrane with lowering calcium. In sum, OK cells express a calcium-sensitive/regulated dicarboxylate process at the apical membrane which responds to variations in apical calcium. Despite the functional differences of this process compared to NaDC1, NaDC1 is present in these cells, but predominantly in subapical vesicles.
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Affiliation(s)
- Kathleen S Hering-Smith
- Research Service, Southeastern Louisiana Veterans Health Care System (SLVHCS), New Orleans, LA, 70161, USA,
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