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Delaney M, Zhao Y, van de Leemput J, Lee H, Han Z. Actin Cytoskeleton and Integrin Components Are Interdependent for Slit Diaphragm Maintenance in Drosophila Nephrocytes. Cells 2024; 13:1350. [PMID: 39195240 DOI: 10.3390/cells13161350] [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: 07/19/2024] [Revised: 08/08/2024] [Accepted: 08/11/2024] [Indexed: 08/29/2024] Open
Abstract
In nephrotic syndrome, the podocyte filtration structures are damaged in a process called foot process effacement. This is mediated by the actin cytoskeleton; however, which actins are involved and how they interact with other filtration components, like the basement membrane, remains poorly understood. Here, we used the well-established Drosophila pericardial nephrocyte-the equivalent of podocytes in flies-knockdown models (RNAi) to study the interplay of the actin cytoskeleton (Act5C, Act57B, Act42A, and Act87E), alpha- and beta-integrin (basement membrane), and the slit diaphragm (Sns and Pyd). Knockdown of an actin gene led to variations of formation of actin stress fibers, the internalization of Sns, and a disrupted slit diaphragm cortical pattern. Notably, deficiency of Act5C, which resulted in complete absence of nephrocytes, could be partially mitigated by overexpressing Act42A or Act87E, suggesting at least partial functional redundancy. Integrin localized near the actin cytoskeleton as well as slit diaphragm components, but when the nephrocyte cytoskeleton or slit diaphragm was disrupted, this switched to colocalization, both at the surface and internalized in aggregates. Altogether, the data show that the interdependence of the slit diaphragm, actin cytoskeleton, and integrins is key to the structure and function of the Drosophila nephrocyte.
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Affiliation(s)
- Megan Delaney
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
| | - Yunpo Zhao
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
| | - Joyce van de Leemput
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
| | - Hangnoh Lee
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
| | - Zhe Han
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD 21201, USA
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Leroy C, Lang K, Spitz D, Milosavljevic J, Heinkele H, Kayser S, Helmstädter M, Walz G, Ulbrich MH, Hermle T. Linking Basement Membrane and Slit Diaphragm in Drosophila Nephrocytes. J Am Soc Nephrol 2024:00001751-990000000-00329. [PMID: 38776165 DOI: 10.1681/asn.0000000000000400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 05/17/2024] [Indexed: 05/24/2024] Open
Abstract
Key Points
Drosophila nephrocytes feature a special basement membrane that may serve to model joint function of the glomerular filtration barrier.Silencing of Drosophila laminin and collagen IV genes reduced the density of slit diaphragms in nephrocytes, showing a direct effect of the matrix.Matrix receptor silencing phenocopied basement membrane disruption, indicating that the matrix guides slit diaphragm position through matrix receptors.
Background
The glomerular basement membrane and the slit diaphragm are essential parts of the filtration barrier. How these layers collaborate remains unclear. The podocyte-like nephrocytes in Drosophila harbor both a slit diaphragm and a basement membrane, serving as a model to address this critical question.
Methods
Basement membrane components and matrix receptors were silenced using RNA interference in nephrocytes. Slit diaphragms were analyzed using immunofluorescence, followed by automated quantification. Tracer endocytosis was applied for functional readouts.
Results
Immunofluorescence indicated a significant reduction in slit diaphragm density upon loss of laminin and collagen IV components. This was accompanied by reduced expression of fly nephrin and shallower membrane invaginations. Tracer studies revealed that the basement membrane defines properties of the nephrocyte filtration barrier. Acute enzymatic disruption of the basement membrane via collagenase rapidly caused slit diaphragm mislocalization and disintegration, which was independent of cell death. Loss of matrix-interacting receptors, particularly integrins mys and mew, phenocopied basement membrane disruption. Integrins and nephrin colocalized at the slit diaphragm in nephrocytes in a mutually dependent manner, interacting genetically. Human integrin α3 interacted physically with nephrin.
Conclusions
The glomerular basement membrane model in Drosophila nephrocytes reveals that matrix receptor–mediated cues ensure correct positioning of the slit diaphragm and the overall filtration barrier architecture.
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Grants
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 â€" SFB 1453 Deutsche Forschungsgemeinschaft
- HE 7456/6-1 Deutsche Forschungsgemeinschaft
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 - SFB 1453 Deutsche Forschungsgemeinschaft
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 - SFB 1453 Deutsche Forschungsgemeinschaft
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 - SFB 1453 Deutsche Forschungsgemeinschaft
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 - SFB 1453 Deutsche Forschungsgemeinschaft
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Affiliation(s)
- Claire Leroy
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
| | - Konrad Lang
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
| | - Dominik Spitz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
| | - Julian Milosavljevic
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
| | - Helena Heinkele
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
| | - Séverine Kayser
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
- EMcore, Renal Division, Department of Medicine, University Hospital Freiburg, University Faculty of Medicine, Freiburg, Germany
| | - Martin Helmstädter
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
- EMcore, Renal Division, Department of Medicine, University Hospital Freiburg, University Faculty of Medicine, Freiburg, Germany
| | - Gerd Walz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
- CIBSS - Centre for Integrative Biological Signalling Studies, Freiburg, Germany
| | - Maximilian H Ulbrich
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Tobias Hermle
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
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3
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Cara-Fuentes G, Verma R, Venkatareddy M, Bauer C, Piani F, Aksoy ST, Vazzalwar N, Garcia GE, Banks M, Ordoñez FA, de Lucas-Collantes C, Bjornstad P, González Rodríguez JD, Johnson RJ, Garg P. β1-Integrin blockade prevents podocyte injury in experimental models of minimal change disease. Nefrologia 2024; 44:90-99. [PMID: 37150673 DOI: 10.1016/j.nefroe.2023.04.003] [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: 08/03/2022] [Accepted: 11/10/2022] [Indexed: 05/09/2023] Open
Abstract
INTRODUCTION Activation of the focal adhesion kinase (FAK) in podocytes is involved in the pathogenesis of minimal change disease (MCD), but the pathway leading to its activation in this disease is unknown. Here, we tested whether podocyte β1 integrin is the upstream modulator of FAK activation and podocyte injury in experimental models of MCD-like injury. METHODS We used lipopolysaccharide (LPS) and MCD sera to induce MCD-like changes in vivo and in cultured human podocytes, respectively. We performed functional studies using specific β1 integrin inhibitors in vivo and in vitro, and integrated histological analysis, western blotting, and immunofluorescence to assess for morphological and molecular changes in podocytes. By ELISA, we measured serum LPS levels in 35 children with MCD or presumed MCD (idiopathic nephrotic syndrome [INS]) and in 18 healthy controls. RESULTS LPS-injected mice showed morphological (foot process effacement, and normal appearing glomeruli on light microscopy) and molecular features (synaptopodin loss, nephrin mislocalization, FAK phosphorylation) characteristic of human MCD. Administration of a β1 integrin inhibitor to mice abrogated FAK phosphorylation, and ameliorated proteinuria and podocyte injury following LPS. Children with MCD/INS in relapse had higher serum LPS levels than controls. In cultured human podocytes, β1 integrin blockade prevented cytoskeletal rearrangements following exposure to MCD sera in relapse. CONCLUSIONS Podocyte β1 integrin activation is an upstream mediator of FAK phosphorylation and podocyte injury in models of MCD-like injury.
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Koehler S, Huber TB. Insights into human kidney function from the study of Drosophila. Pediatr Nephrol 2023; 38:3875-3887. [PMID: 37171583 PMCID: PMC10584755 DOI: 10.1007/s00467-023-05996-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 04/13/2023] [Accepted: 04/18/2023] [Indexed: 05/13/2023]
Abstract
Biological and biomedical research using Drosophila melanogaster as a model organism has gained recognition through several Nobel prizes within the last 100 years. Drosophila exhibits several advantages when compared to other in vivo models such as mice and rats, as its life cycle is very short, animal maintenance is easy and inexpensive and a huge variety of transgenic strains and tools are publicly available. Moreover, more than 70% of human disease-causing genes are highly conserved in the fruit fly. Here, we explain the use of Drosophila in nephrology research and describe two kidney tissues, Malpighian tubules and the nephrocytes. The latter are the homologous cells to mammalian glomerular podocytes and helped to provide insights into a variety of signaling pathways due to the high morphological similarities and the conserved molecular make-up between nephrocytes and podocytes. In recent years, nephrocytes have also been used to study inter-organ communication as links between nephrocytes and the heart, the immune system and the muscles have been described. In addition, other tissues such as the eye and the reproductive system can be used to study the functional role of proteins being part of the kidney filtration barrier.
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Affiliation(s)
- Sybille Koehler
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
- Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Tobias B Huber
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Mao X, Xu DQ, Yue SJ, Fu RJ, Zhang S, Tang YP. Potential Medicinal Value of Rhein for Diabetic Kidney Disease. Chin J Integr Med 2023; 29:951-960. [PMID: 36607584 DOI: 10.1007/s11655-022-3591-y] [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] [Accepted: 10/12/2022] [Indexed: 01/07/2023]
Abstract
Diabetic kidney disease (DKD) is the primary cause of mortality among diabetic patients. With the increasing prevalence of diabetes, it has become a major concern around the world. The therapeutic effect of clinical use of drugs is far from expected, and therapy choices to slow the progression of DKD remain restricted. Therefore, research on new drugs and treatments for DKD has been a hot topic in the medical field. It has been found that rhein has the potential to target the pathogenesis of DKD and has a wide range of pharmacological effects on DKD, such as anti-nephritis, decreasing blood glucose, controlling blood lipids and renal protection. In recent years, the medical value of rhein in the treatment of diabetes, DKD and renal disease has gradually attracted worldwide attention, especially its potential in the treatment of DKD. Currently, DKD can only be treated with medications from a single symptom and are accompanied by adverse effects, while rhein improves DKD with a multi-pathway and multi-target approach. Therefore, this paper reviews the therapeutic effects of rhein on DKD, and proposes solutions to the limitations of rhein itself, in order to provide valuable references for the clinical application of rhein in DKD and the development of new drugs.
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Affiliation(s)
- Xi Mao
- Key Laboratory of Shaanxi Administration of Traditional Chinese Medicine for TCM Compatibility, Shaanxi University of Chinese Medicine, Xi'an, 712046, China
| | - Ding-Qiao Xu
- Key Laboratory of Shaanxi Administration of Traditional Chinese Medicine for TCM Compatibility, Shaanxi University of Chinese Medicine, Xi'an, 712046, China
| | - Shi-Jun Yue
- Key Laboratory of Shaanxi Administration of Traditional Chinese Medicine for TCM Compatibility, Shaanxi University of Chinese Medicine, Xi'an, 712046, China
| | - Rui-Jia Fu
- Key Laboratory of Shaanxi Administration of Traditional Chinese Medicine for TCM Compatibility, Shaanxi University of Chinese Medicine, Xi'an, 712046, China
| | - Sai Zhang
- Key Laboratory of Shaanxi Administration of Traditional Chinese Medicine for TCM Compatibility, Shaanxi University of Chinese Medicine, Xi'an, 712046, China
| | - Yu-Ping Tang
- Key Laboratory of Shaanxi Administration of Traditional Chinese Medicine for TCM Compatibility, Shaanxi University of Chinese Medicine, Xi'an, 712046, China.
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Chhuon C, Herrera-Marcos LV, Zhang SY, Charrière-Bertrand C, Jung V, Lipecka J, Savas B, Nasser N, Pawlak A, Boulmerka H, Audard V, Sahali D, Guerrera IC, Ollero M. Proteomics of Plasma and Plasma-Treated Podocytes: Application to Focal and Segmental Glomerulosclerosis. Int J Mol Sci 2023; 24:12124. [PMID: 37569500 PMCID: PMC10418338 DOI: 10.3390/ijms241512124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/21/2023] [Accepted: 07/26/2023] [Indexed: 08/13/2023] Open
Abstract
Focal and segmental glomerulosclerosis (FSGS) is a severe form of idiopathic nephrotic syndrome (INS), a glomerulopathy of presumably immune origin that is attributed to extrarenal pathogenic circulating factors. The recurrence of FSGS (rFSGS) after transplant occurs in 30% to 50% of cases. The direct analysis of patient plasma proteome has scarcely been addressed to date, mainly due to the methodological difficulties associated with plasma complexity and dynamic range. In this study, first, we compared different methods of plasma preparation, second, we compared the plasma proteomes of rFSGS and controls using two preparation methods, and third, we analyzed the early proximal signaling events in podocytes subjected to patient plasma, through a combination of phosphoproteomics and lipid-raft proteomics (raftomics). By combining immunodepletion and high pH fractionation, we performed a differential proteomic analysis of soluble plasma proteins and of extracellular vesicles (EV) obtained from healthy controls, non-INS patient controls, and rFSGS patients (n = 4). In both the soluble- and the EV-protein sets from the rFSGS patients, we found a statistically significant increase in a cluster of proteins involved in neutrophil degranulation. A group of lipid-binding proteins, generally associated with lipoproteins, was found to be decreased in the soluble set from the rFSGS patients. In addition, three amino acid transporters involved in mTORC1 activation were found to be significantly increased in the EV from the rFSGS. Next, we incubated human podocytes for 30 min with 10% plasma from both groups of patients. The phosphoproteomics and raftomics of the podocytes revealed profound differences in the proteins involved in the mTOR pathway, in autophagy, and in cytoskeleton organization. We analyzed the correlation between the abundance of plasma and plasma-regulated podocyte proteins. The observed changes highlight some of the mechanisms involved in FSGS recurrence and could be used as specific early markers of circulating-factor activity in podocytes.
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Affiliation(s)
- Cerina Chhuon
- Proteomic Platform Necker, Université Paris Cité Structure Fédérative de Recherche SFR Necker US24, 75015 Paris, France; (C.C.); (V.J.); (J.L.)
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
| | - Luis Vicente Herrera-Marcos
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
| | - Shao-Yu Zhang
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
| | - Cécile Charrière-Bertrand
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
| | - Vincent Jung
- Proteomic Platform Necker, Université Paris Cité Structure Fédérative de Recherche SFR Necker US24, 75015 Paris, France; (C.C.); (V.J.); (J.L.)
| | - Joanna Lipecka
- Proteomic Platform Necker, Université Paris Cité Structure Fédérative de Recherche SFR Necker US24, 75015 Paris, France; (C.C.); (V.J.); (J.L.)
| | - Berkan Savas
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
| | - Nour Nasser
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
| | - André Pawlak
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
| | - Hocine Boulmerka
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
| | - Vincent Audard
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
- AP-HP, Hôpitaux Universitaires Henri Mondor, Service de Néphrologie, F-94010 Creteil, France
| | - Dil Sahali
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
- AP-HP, Hôpitaux Universitaires Henri Mondor, Service de Néphrologie, F-94010 Creteil, France
| | - Ida Chiara Guerrera
- Proteomic Platform Necker, Université Paris Cité Structure Fédérative de Recherche SFR Necker US24, 75015 Paris, France; (C.C.); (V.J.); (J.L.)
| | - Mario Ollero
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (L.V.H.-M.); (S.-Y.Z.); (C.C.-B.); (B.S.); (N.N.); (A.P.); (H.B.); (V.A.); (D.S.)
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7
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Vöing K, Michgehl U, Mertens ND, Picciotto C, Maywald ML, Goretzko J, Waimann S, Gilhaus K, Rogg M, Schell C, Klingauf J, Tsytsyura Y, Hansen U, van Marck V, Edinger AL, Vollenbröker B, Rescher U, Braun DA, George B, Weide T, Pavenstädt H. Disruption of the Rab7-Dependent Final Common Pathway of Endosomal and Autophagic Processing Results in a Severe Podocytopathy. J Am Soc Nephrol 2023; 34:1191-1206. [PMID: 37022133 PMCID: PMC10356157 DOI: 10.1681/asn.0000000000000126] [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: 10/26/2022] [Accepted: 03/03/2023] [Indexed: 04/07/2023] Open
Abstract
SIGNIFICANCE STATEMENT Endocytosis, recycling, and degradation of proteins are essential functions of mammalian cells, especially for terminally differentiated cells with limited regeneration rates and complex morphology, such as podocytes. To improve our understanding on how disturbances of these trafficking pathways are linked to podocyte depletion and slit diaphragm (SD) injury, the authors explored the role of the small GTPase Rab7, which is linked to endosomal, lysosomal, and autophagic pathways, using as model systems mice and Drosophila with podocyte-specific or nephrocyte-specific loss of Rab7, and a human podocyte cell line depleted for Rab7. Their findings point to maturation and fusion events during endolysosomal and autophagic maturation as key processes for podocyte homeostasis and function and identify altered lysosomal pH values as a putative novel mechanism for podocytopathies. BACKGROUND Endocytosis, recycling, and degradation of proteins are essential functions of mammalian cells, especially for terminally differentiated cells with limited regeneration rates, such as podocytes. How disturbances within these trafficking pathways may act as factors in proteinuric glomerular diseases is poorly understood. METHODS To explore how disturbances in trafficking pathways may act as factors in proteinuric glomerular diseases, we focused on Rab7, a highly conserved GTPase that controls the homeostasis of late endolysosomal and autophagic processes. We generated mouse and Drosophila in vivo models lacking Rab7 exclusively in podocytes or nephrocytes, and performed histologic and ultrastructural analyses. To further investigate Rab7 function on lysosomal and autophagic structures, we used immortalized human cell lines depleted for Rab7. RESULTS Depletion of Rab7 in mice, Drosophila , and immortalized human cell lines resulted in an accumulation of diverse vesicular structures resembling multivesicular bodies, autophagosomes, and autoendolysosomes. Mice lacking Rab7 developed a severe and lethal renal phenotype with early-onset proteinuria and global or focal segmental glomerulosclerosis, accompanied by an altered distribution of slit diaphragm proteins. Remarkably, structures resembling multivesicular bodies began forming within 2 weeks after birth, prior to the glomerular injuries. In Drosophila nephrocytes, Rab7 knockdown resulted in the accumulation of vesicles and reduced slit diaphragms. In vitro , Rab7 knockout led to similar enlarged vesicles and altered lysosomal pH values, accompanied by an accumulation of lysosomal marker proteins. CONCLUSIONS Disruption within the final common pathway of endocytic and autophagic processes may be a novel and insufficiently understood mechanism regulating podocyte health and disease.
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Affiliation(s)
- Kristin Vöing
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Ulf Michgehl
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Nils David Mertens
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Cara Picciotto
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Mee-Ling Maywald
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Jonas Goretzko
- Research Group Regulatory Mechanisms of Inflammation, Institute of Medical Biochemistry, Centre for Molecular Biology of Inflammation, University of Muenster, Muenster, Germany
| | - Sofie Waimann
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Kevin Gilhaus
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Manuel Rogg
- Institute of Surgical Pathology, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany
| | - Christoph Schell
- Institute of Surgical Pathology, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, University of Muenster, Muenster, Germany
| | - Yaroslav Tsytsyura
- Institute of Medical Physics and Biophysics, University of Muenster, Muenster, Germany
| | - Uwe Hansen
- Institute for Musculoskeletal Medicine (IMM), University of Muenster, Muenster, Germany
| | - Veerle van Marck
- Department of Pathology, University Hospital Muenster Muenster, Germany
| | - Aimee L. Edinger
- Department of Developmental & Cell Biology, University of California, Irvine, California
| | - Beate Vollenbröker
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Ursula Rescher
- Research Group Regulatory Mechanisms of Inflammation, Institute of Medical Biochemistry, Centre for Molecular Biology of Inflammation, University of Muenster, Muenster, Germany
| | - Daniela Anne Braun
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Britta George
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Thomas Weide
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
| | - Hermann Pavenstädt
- Department of Internal Medicine and Nephrology, University Hospital of Münster, Medical Clinic D, Munster, Germany
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8
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Gilhaus K, Cepok C, Kamm D, Surmann B, Nedvetsky PI, Emich J, Sundukova A, Saatkamp K, Nüsse H, Klingauf J, Wennmann DO, George B, Krahn MP, Pavenstädt HJ, Vollenbröker BA. Activation of Hippo Pathway Damages Slit Diaphragm by Deprivation of Ajuba Proteins. J Am Soc Nephrol 2023; 34:1039-1055. [PMID: 36930055 PMCID: PMC10278832 DOI: 10.1681/asn.0000000000000107] [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: 07/22/2022] [Accepted: 02/06/2023] [Indexed: 03/18/2023] Open
Abstract
SIGNIFICANCE STATEMENT Nuclear exclusion of the cotranscription factor YAP, which is a consequence of activation of the Hippo signaling pathway, leads to FSGS and podocyte apoptosis. Ajuba proteins play an important role in the glomerular filtration barrier by keeping the Hippo pathway inactive. In nephrocytes from Drosophila melanogaster , a well-established model system for podocyte research, Ajuba proteins ensure slit diaphragm (SD) formation and function. Hippo pathway activation leads to mislocalization of Ajuba proteins, decreased SD formation, rearrangement of the actin cytoskeleton, and increased SD permeability. Targeting the kinases of the Hippo pathway with specific inhibitors in the glomerulus could, therefore, be a promising strategy for therapy of FSGS. BACKGROUND The highly conserved Hippo pathway, which regulates organ growth and cell proliferation by inhibiting transcriptional cofactors YAP/TAZ, plays a special role in podocytes, where activation of the pathway leads to apoptosis. The Ajuba family proteins (Ajuba, LIM domain-containing protein 1 (LIMD1) and Wilms tumor protein 1-interacting protein [WTIP]) can bind and inactivate large tumor suppressor kinases 1 and 2, (LATS1/2) two of the Hippo pathway key kinases. WTIP, furthermore, connects the slit diaphragm (SD), the specialized cell-cell junction between podocytes, with the actin cytoskeleton. METHODS We used garland cell nephrocytes of Drosophila melanogaster to monitor the role of Ajuba proteins in Hippo pathway regulation and structural integrity of the SD. Microscopy and functional assays analyzed the interplay between Ajuba proteins and LATS2 regarding expression, localization, interaction, and effects on the functionality of the SD. RESULTS In nephrocytes, the Ajuba homolog Djub recruited Warts (LATS2 homolog) to the SD. Knockdown of Djub activated the Hippo pathway. Reciprocally, Hippo activation reduced the Djub level. Both Djub knockdown and Hippo activation led to morphological changes in the SD, rearrangement of the cortical actin cytoskeleton, and increased SD permeability. Knockdown of Warts or overexpression of constitutively active Yki prevented these effects. In podocytes, Hippo pathway activation or knockdown of YAP also decreased the level of Ajuba proteins. CONCLUSIONS Ajuba proteins regulate the structure and function of the SD in nephrocytes, connecting the SD protein complex to the actin cytoskeleton and maintaining the Hippo pathway in an inactive state. Hippo pathway activation directly influencing Djub expression suggests a self-amplifying feedback mechanism.
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Affiliation(s)
- Kevin Gilhaus
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Claudia Cepok
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - David Kamm
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Beate Surmann
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Pavel I. Nedvetsky
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Jana Emich
- Institute of Reproductive Genetics, University Hospital of Münster, Münster, Germany
| | - Alina Sundukova
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Katharina Saatkamp
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Harald Nüsse
- Institute of Medical Physics and Biophysics, Westfälische-Wilhelms University Münster, Münster, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, Westfälische-Wilhelms University Münster, Münster, Germany
| | - Dirk O. Wennmann
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Britta George
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Michael P. Krahn
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | | | - Beate A. Vollenbröker
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
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9
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Perez-Vale KZ, Yow KD, Gurley NJ, Greene M, Peifer M. Rap1 regulates apical contractility to allow embryonic morphogenesis without tissue disruption and acts in part via Canoe-independent mechanisms. Mol Biol Cell 2022; 34:ar7. [PMID: 36287827 PMCID: PMC9816648 DOI: 10.1091/mbc.e22-05-0176] [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] [Indexed: 02/03/2023] Open
Abstract
Embryonic morphogenesis is powered by dramatic changes in cell shape and arrangement driven by the cytoskeleton and its connections to adherens junctions. This requires robust linkage allowing morphogenesis without disrupting tissue integrity. The small GTPase Rap1 is a key regulator of cell adhesion, controlling both cadherin-mediated and integrin-mediated processes. We have defined multiple roles in morphogenesis for one Rap1 effector, Canoe/Afadin, which ensures robust junction-cytoskeletal linkage. We now ask what mechanisms regulate Canoe and other junction-cytoskeletal linkers during Drosophila morphogenesis, defining roles for Rap1 and one of its guanine nucleotide exchange factor (GEF) regulators, Dizzy. Rap1 uses Canoe as one effector, regulating junctional planar polarity. However, Rap1 has additional roles in junctional protein localization and balanced apical constriction-in its absence, Bazooka/Par3 localization is fragmented, and cells next to mitotic cells apically constrict and invaginate, disrupting epidermal integrity. In contrast, the GEF Dizzy has phenotypes similar to but slightly less severe than Canoe loss, suggesting that this GEF regulates Rap1 action via Canoe. Taken together, these data reveal that Rap1 is a crucial regulator of morphogenesis, likely acting in parallel via Canoe and other effectors, and that different Rap1 GEFs regulate distinct functions of Rap1.
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Affiliation(s)
- Kia Z. Perez-Vale
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kristi D. Yow
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Noah J. Gurley
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Melissa Greene
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Mark Peifer
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280,*Address correspondence to: Mark Peifer ()
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10
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Glycosphingolipid GM3 prevents albuminuria and podocytopathy induced by anti-nephrin antibody. Sci Rep 2022; 12:16058. [PMID: 36163359 PMCID: PMC9513075 DOI: 10.1038/s41598-022-20265-w] [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: 05/23/2022] [Accepted: 09/12/2022] [Indexed: 11/18/2022] Open
Abstract
Podocytopathy, which is characterized by injury to podocytes, frequently causes proteinuria or nephrotic syndrome. There is currently a paucity of effective therapeutic drugs to treat proteinuric kidney disease. Recent research suggests the possibility that glycosphingolipid GM3 maintains podocyte function by acting on various molecules including nephrin, but its mechanism of action remains unknown. Here, various analyses were performed to examine the potential relationship between GM3 and nephrin, and the function of GM3 in podocytes using podocytopathy mice, GM3 synthase gene knockout mice, and nephrin injury cells. Reduced amounts of GM3 and nephrin were observed in podocytopathy mice. Intriguingly, this reduction of GM3 and nephrin, as well as albuminuria, were inhibited by administration of valproic acid. However, when the same experiment was performed using GM3 synthase gene knockout mice, valproic acid administration did not inhibit albuminuria. Equivalent results were obtained in model cells. These findings indicate that GM3 acts with nephrin in a collaborative manner in the cell membrane. Taken together, elevated levels of GM3 stabilize nephrin, which is a key molecule of the slit diaphragm, by enhancing the environment of the cell membrane and preventing albuminuria. This study provides novel insight into new drug discovery, which may offer a new therapy for kidney disease with albuminuria.
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11
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Lausecker F, Koehler S, Fresquet M, Naylor RW, Tian P, Wanner N, Braun F, Butt L, Huber TB, Lennon R. Integrating basic science with translational research: the 13th International Podocyte Conference 2021. Kidney Int 2022; 102:708-719. [PMID: 35964799 PMCID: PMC9386279 DOI: 10.1016/j.kint.2022.07.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/20/2022] [Accepted: 07/26/2022] [Indexed: 11/30/2022]
Abstract
The 13th International Podocyte Conference was held in Manchester, UK, and online from July 28 to 30, 2021. Originally planned for 2020, this biannual meeting was postponed by a year because of the coronavirus disease 2019 (COVID-19) pandemic and proceeded as an innovative hybrid meeting. In addition to in-person attendance, online registration was offered, and this attracted 490 conference registrations in total. As a Podocyte Conference first, a day for early-career researchers was introduced. This premeeting included talks from graduate students and postdoctoral researchers. It gave early career researchers the opportunity to ask a panel, comprising academic leaders and journal editors, about career pathways and the future for podocyte research. The main meeting over 3 days included a keynote talk and 4 focused sessions each day incorporating invited talks, followed by selected abstract presentations, and an open panel discussion. The conference concluded with a Patient Day, which brought together patients, clinicians, researchers, and industry representatives. The Patient Day was an interactive and diverse day. As well as updates on improving diagnosis and potential new therapies, the Patient Day included a PodoArt competition, exercise and cooking classes with practical nutrition advice, and inspirational stories from patients and family members. This review summarizes the exciting science presented during the 13th International Podocyte Conference and demonstrates the resilience of researchers during a global pandemic.
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Affiliation(s)
- Franziska Lausecker
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Sybille Koehler
- Biomedical Sciences, University of Edinburgh, Edinburgh, UK; III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maryline Fresquet
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Richard W Naylor
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Pinyuan Tian
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Nicola Wanner
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fabian Braun
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Linus Butt
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Tobias B Huber
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK; Department of Paediatric Nephrology, Royal Manchester Children's Hospital, Manchester University Hospitals National Health Service (NHS) Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.
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12
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Martin CE, Phippen NJ, Keyvani Chahi A, Tilak M, Banerjee SL, Lu P, New LA, Williamson CR, Platt MJ, Simpson JA, Krendel M, Bisson N, Gingras AC, Jones N. Complementary Nck1/2 Signaling in Podocytes Controls α Actinin-4-Mediated Actin Organization, Adhesion, and Basement Membrane Composition. J Am Soc Nephrol 2022; 33:1546-1567. [PMID: 35906089 PMCID: PMC9342632 DOI: 10.1681/asn.2021101343] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 04/26/2022] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Maintenance of the kidney filtration barrier requires coordinated interactions between podocytes and the underlying glomerular basement membrane (GBM). GBM ligands bind podocyte integrins, which triggers actin-based signaling events critical for adhesion. Nck1/2 adaptors have emerged as essential regulators of podocyte cytoskeletal dynamics. However, the precise signaling mechanisms mediated by Nck1/2 adaptors in podocytes remain to be fully elucidated. METHODS We generated podocytes deficient in Nck1 and Nck2 and used transcriptomic approaches to profile expression differences. Proteomic techniques identified specific binding partners for Nck1 and Nck2 in podocytes. We used cultured podocytes and mice deficient in Nck1 and/or Nck2, along with podocyte injury models, to comprehensively verify our findings. RESULTS Compound loss of Nck1/2 altered expression of genes involved in actin binding, cell adhesion, and extracellular matrix composition. Accordingly, Nck1/2-deficient podocytes showed defects in actin organization and cell adhesion in vitro, with podocyte detachment and altered GBM morphology present in vivo. We identified distinct interactomes for Nck1 and Nck2 and uncovered a mechanism by which Nck1 and Nck2 cooperate to regulate actin bundling at focal adhesions via α actinin-4. Furthermore, loss of Nck1 or Nck2 resulted in increased matrix deposition in vivo, with more prominent defects in Nck2-deficient mice, consistent with enhanced susceptibility to podocyte injury. CONCLUSION These findings reveal distinct, yet complementary, roles for Nck proteins in regulating podocyte adhesion, controlling GBM composition, and sustaining filtration barrier integrity.
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Affiliation(s)
- Claire E Martin
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.,Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Noah J Phippen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Ava Keyvani Chahi
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Manali Tilak
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Sara L Banerjee
- Division of Oncology, Centre de Recherche du Centre Hospitalier Universitaire de Quebec-Laval University, Quebec City, Quebec, Canada.,Centre de Recherche sur le Cancer de l'Université Laval, Quebec City, Quebec, Canada
| | - Peihua Lu
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Laura A New
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Casey R Williamson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Mathew J Platt
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, Ontario, Canada
| | - Jeremy A Simpson
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, Ontario, Canada
| | - Mira Krendel
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Nicolas Bisson
- Division of Oncology, Centre de Recherche du Centre Hospitalier Universitaire de Quebec-Laval University, Quebec City, Quebec, Canada.,Centre de Recherche sur le Cancer de l'Université Laval, Quebec City, Quebec, Canada.,PROTEO-Quebec Network for Research on Protein Function, Engineering, and Applications Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec City, Quebec, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Nina Jones
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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13
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Ye Q, Lan B, Liu H, Persson PB, Lai EY, Mao J. A critical role of the podocyte cytoskeleton in the pathogenesis of glomerular proteinuria and autoimmune podocytopathies. Acta Physiol (Oxf) 2022; 235:e13850. [PMID: 35716094 DOI: 10.1111/apha.13850] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/23/2022] [Accepted: 06/13/2022] [Indexed: 01/19/2023]
Abstract
Selective glomerular filtration relies on the membrane separating the glomerular arterioles from the Bowman space. As a major component of the glomerular filtration barrier, podocytes form foot processes by the actin cytoskeleton, which dynamically adjusts in response to environmental changes to maintain filtration barrier integrity. The slit diaphragms bridge the filtration slits between neighboring foot processes and act as signaling hubs interacting with the actin cytoskeleton. Focal adhesions relay signals to regulate actin dynamics while allowing podocyte adherence to the basement membrane. Mutations in actin regulatory and signaling proteins may disrupt the actin cytoskeleton, resulting in foot process retraction, effacement, and proteinuria. Large-scale gene expression profiling platforms, transgenic animal models, and other in vivo gene delivery methods now enhance our understanding of the interactions among podocyte focal adhesions, slit diaphragms, and actin dynamics. In addition, our team found that at least 66% of idiopathic nephrotic syndrome (INS) children have podocyte autoantibodies, which was defined as a new disease subgroup-, autoimmune podocytopathies. This review outlines the pathophysiological mechanisms of podocyte cytoskeleton protein interactions in proteinuria and glomerular podocytopathy.
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Affiliation(s)
- Qing Ye
- Department of Clinical Laboratory, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Bing Lan
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Huihui Liu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Pontus B Persson
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Translational Physiology, Berlin, Germany
| | - En Yin Lai
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Translational Physiology, Berlin, Germany.,Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
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14
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Kostovska I, Trajkovska KT, Topuzovska S, Cekovska S, Labudovic D, Kostovski O, Spasovski G. Nephrinuria and podocytopathies. Adv Clin Chem 2022; 108:1-36. [PMID: 35659057 DOI: 10.1016/bs.acc.2021.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The discovery of nephrin in 1998 has launched a new era in glomerular diseases research, emphasizing its crucial role in the structure and function of the glomerular filtration barrier. In the past 20 years, substantial advances have been made in understanding podocyte structure and function as well as the discovery of several podocyte-related proteins including nephrin. The glomerular filtration barrier is comprised of podocytes, the glomerular basement membrane and endothelial cells. Podocytes, with their specialized slit diaphragm, form the essential backbone of the glomerular filtration barrier. Nephrin is a crucial structural and functional feature of the slit diaphragm that prevents plasma protein, blood cell and macromolecule leakage into the urine. Podocyte damage results in nephrin release. Podocytopathies are kidney diseases in which podocyte damage drives proteinuria, i.e., nephrotic syndrome. Many kidney diseases involve podocytopathy including congenital nephrotic syndrome of Finnish type, diffuse mesangial sclerosis, minimal change disease, focal segmental glomerulosclerosis, collapsing glomerulonephropathy, diabetic nephropathy, lupus nephropathy, hypertensive nephropathy and preeclampsia. Recently, urinary nephrin measurement has become important in the early detection of podocytopathies. In this chapter, we elaborate the main structural and functional features of nephrin as a podocyte-specific protein, pathomechanisms of podocytopathies which result in nephrinuria, highlight the most commonly used methods for detecting urinary nephrin and investigate the diagnostic, prognostic and potential therapeutic relevance of urinary nephrin in primary and secondary proteinuric kidney diseases.
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Affiliation(s)
- Irena Kostovska
- Department of Medical and Experimental Biochemistry, Faculty of Medicine, Ss. Cyril and Methodius University, Skopje, North Macedonia.
| | - Katerina Tosheska Trajkovska
- Department of Medical and Experimental Biochemistry, Faculty of Medicine, Ss. Cyril and Methodius University, Skopje, North Macedonia
| | - Sonja Topuzovska
- Department of Medical and Experimental Biochemistry, Faculty of Medicine, Ss. Cyril and Methodius University, Skopje, North Macedonia
| | - Svetlana Cekovska
- Department of Medical and Experimental Biochemistry, Faculty of Medicine, Ss. Cyril and Methodius University, Skopje, North Macedonia
| | - Danica Labudovic
- Department of Medical and Experimental Biochemistry, Faculty of Medicine, Ss. Cyril and Methodius University, Skopje, North Macedonia
| | - Ognen Kostovski
- University Clinic of Abdominal Surgery, Faculty of Medicine, Ss. Cyril and Methodius University, Skopje, North Macedonia
| | - Goce Spasovski
- University Clinic of Nephrology, Faculty of Medicine, Ss. Cyril and Methodius University, Skopje, North Macedonia
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15
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Maywald ML, Picciotto C, Lepa C, Bertgen L, Yousaf FS, Ricker A, Klingauf J, Krahn MP, Pavenstädt H, George B. Rap1 Activity Is Essential for Focal Adhesion and Slit Diaphragm Integrity. Front Cell Dev Biol 2022; 10:790365. [PMID: 35372328 PMCID: PMC8972170 DOI: 10.3389/fcell.2022.790365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 02/24/2022] [Indexed: 11/24/2022] Open
Abstract
Glomerular podocytes build, with their intercellular junctions, part of the kidney filter. The podocyte cell adhesion protein, nephrin, is essential for developing and maintaining slit diaphragms as functional loss in humans results in heavy proteinuria. Nephrin expression and function are also altered in many adult-onset glomerulopathies. Nephrin signals from the slit diaphragm to the actin cytoskeleton and integrin β1 at focal adhesions by recruiting Crk family proteins, which can interact with the Rap guanine nucleotide exchange factor 1 C3G. As Rap1 activity affects focal adhesion formation, we hypothesize that nephrin signals via Rap1 to integrin β. To address this issue, we combined Drosophila in vivo and mammalian cell culture experiments. We find that Rap1 is necessary for correct targeting of integrin β to focal adhesions in Drosophila nephrocytes, which also form slit diaphragm-like structures. In the fly, the Rap1 activity is important for signaling of the nephrin ortholog to integrin β, as well as for nephrin-dependent slit diaphragm integrity. We show by genetic interaction experiments that Rap1 functions downstream of nephrin signaling to integrin β and downstream of nephrin signaling necessary for slit diaphragm integrity. Similarly, in human podocyte culture, nephrin activation results in increased activation of Rap1. Thus, Rap1 is necessary for downstream signal transduction of nephrin to integrin β.
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Affiliation(s)
- Mee-Ling Maywald
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Cara Picciotto
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Carolin Lepa
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Luisa Bertgen
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | | | - Andrea Ricker
- Institute of Medical Physics and Biophysics, Westfälische Wilhelms-University Münster, Münster, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, Westfälische Wilhelms-University Münster, Münster, Germany
| | - Michael P. Krahn
- Medizinische Klinik D, Medical Cell Biology, University Hospital Münster, Münster, Germany
| | | | - Britta George
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
- *Correspondence: Britta George,
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16
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Zhao X, Chen H, Zhu Y, Liu Y, Gao L, Wang H, Ao Y. The selection and identification of compound housekeeping genes for quantitative real-time polymerase chain reaction analysis in rat fetal kidney. J Appl Toxicol 2021; 42:360-370. [PMID: 34374451 DOI: 10.1002/jat.4221] [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: 05/16/2021] [Revised: 06/12/2021] [Accepted: 07/05/2021] [Indexed: 11/06/2022]
Abstract
During quantitative real-time polymerase chain reaction (RT-qPCR) data analysis, the selection of optimal housekeeping gene is necessary to ensure the accuracy of results. It is noteworthy that housekeeping genes commonly used in adult studies may not be applicable for fetus. However, the stability analysis of housekeeping gene in fetal kidney has not been reported. This study intends to screen the applicable compound housekeeping genes in rat fetal kidney. In this study, eight housekeeping genes used in kidney studies based on literature reports (GAPDH, ACTB, 18S, HPRT, YWHAZ, HMBS, PPIA, and TBP) were selected as the research object. Their expression levels in the rat fetal kidney in physiological condition and the intrauterine growth retardation (IUGR) model induced by prenatal dexamethasone exposure (PDE) (0.2 mg/kg·day from gestation Days 9 to 20) was measured. Furthermore, these eight housekeeping genes were used to conduct relative quantitative analysis of nephrin expression in the fetal kidney in PDE-induced IUGR model, to compare the influence of choosing different housekeeping gene on data analysis of nephrin expression and to verify the reliability of selected compound housekeeping genes. In this study, stable housekeeping genes of fetal kidney tissues in PDE-induced IUGR model were identified: ACTB, GAPDH, TBP, and HMBS for males; ACTB, YWHAZ, and GAPDH for females. Besides, our results suggest that ACTB + GAPDH were the best compound housekeeping genes for normalization analysis in male fetal kidney studies, and ACTB + YWHAZ in females. This study will provide an experimental evidence basis for the selection of housekeeping genes in the RT-qPCR experiment in renal development toxicology-related models.
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Affiliation(s)
- Xiaoqi Zhao
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Haiyun Chen
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Yanan Zhu
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Yi Liu
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Lili Gao
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Hui Wang
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
| | - Ying Ao
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
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17
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Fibrosis, the Bad Actor in Cardiorenal Syndromes: Mechanisms Involved. Cells 2021; 10:cells10071824. [PMID: 34359993 PMCID: PMC8307805 DOI: 10.3390/cells10071824] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/08/2021] [Accepted: 07/13/2021] [Indexed: 02/06/2023] Open
Abstract
Cardiorenal syndrome is a term that defines the complex bidirectional nature of the interaction between cardiac and renal disease. It is well established that patients with kidney disease have higher incidence of cardiovascular comorbidities and that renal dysfunction is a significant threat to the prognosis of patients with cardiac disease. Fibrosis is a common characteristic of organ injury progression that has been proposed not only as a marker but also as an important driver of the pathophysiology of cardiorenal syndromes. Due to the relevance of fibrosis, its study might give insight into the mechanisms and targets that could potentially be modulated to prevent fibrosis development. The aim of this review was to summarize some of the pathophysiological pathways involved in the fibrotic damage seen in cardiorenal syndromes, such as inflammation, oxidative stress and endoplasmic reticulum stress, which are known to be triggers and mediators of fibrosis.
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Wang L, Wen P, van de Leemput J, Zhao Z, Han Z. Slit diaphragm maintenance requires dynamic clathrin-mediated endocytosis facilitated by AP-2, Lap, Aux and Hsc70-4 in nephrocytes. Cell Biosci 2021; 11:83. [PMID: 33975644 PMCID: PMC8111712 DOI: 10.1186/s13578-021-00595-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/29/2021] [Indexed: 11/10/2022] Open
Abstract
Background The Slit diaphragm (SD) is the key filtration structure in human glomerular kidney that is affected in many types of renal diseases. SD proteins are known to undergo endocytosis and recycling to maintain the integrity of the filtration structure. However, the key components of this pathway remain unclear. Methods Using the Drosophila nephrocyte as a genetic screen platform, we screened most genes involved in endocytosis and cell trafficking, and identified the key components of the cell trafficking pathway required for SD protein endocytosis and recycling. Results We discovered that the SD protein endocytosis and recycling pathway contains clathrin, dynamin, AP-2 complex, like-AP180 (Lap), auxilin and Hsc70-4 (the endocytosis part) followed by Rab11 and the exocyst complex (the recycling part). Disrupting any component in this pathway led to disrupted SD on the cell surface and intracellular accumulation of mislocalized SD proteins. We also showed the first in vivo evidence of trapped SD proteins in clathrin-coated pits at the plasma membrane when this pathway is disrupted. Conclusions All genes in this SD protein endocytosis and recycling pathway, as well as SD proteins themselves, are highly conserved from flies to humans. Thus, our results suggest that the SD proteins in human kidney undergo the same endocytosis and recycling pathway to maintain the filtration structure, and mutations in any genes in this pathway could lead to abnormal SD and renal diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-021-00595-4.
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Affiliation(s)
- Luyao Wang
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe Eastern Road, Zhengzhou, 450052, Henan, China.,Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD, 21201, USA.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Pei Wen
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD, 21201, USA.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Joyce van de Leemput
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD, 21201, USA.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Zhanzheng Zhao
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe Eastern Road, Zhengzhou, 450052, Henan, China.
| | - Zhe Han
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD, 21201, USA. .,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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19
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Möller-Kerutt A, Rodriguez-Gatica JE, Wacker K, Bhatia R, Siebrasse JP, Boon N, Van Marck V, Boor P, Kubitscheck U, Wijnholds J, Pavenstädt H, Weide T. Crumbs2 Is an Essential Slit Diaphragm Protein of the Renal Filtration Barrier. J Am Soc Nephrol 2021; 32:1053-1070. [PMID: 33687977 PMCID: PMC8259666 DOI: 10.1681/asn.2020040501] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 12/28/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Crumbs2 is expressed at embryonic stages as well as in the retina, brain, and glomerular podocytes. Recent studies identified CRB2 mutations as a novel cause of steroid-resistant nephrotic syndrome (SRNS). METHODS To study the function of Crb2 at the renal filtration barrier, mice lacking Crb2 exclusively in podocytes were generated. Gene expression and histologic studies as well as transmission and scanning electron microscopy were used to analyze these Crb2podKO knockout mice and their littermate controls. Furthermore, high-resolution expansion microscopy was used to investigate Crb2 distribution in murine glomeruli. For pull-down experiments, live cell imaging, and transcriptome analyses, cell lines were applied that inducibly express fluorescent protein-tagged CRB2 wild type and mutants. RESULTS Crb2podKO mice developed proteinuria directly after birth that preceded a prominent development of disordered and effaced foot processes, upregulation of renal injury and inflammatory markers, and glomerulosclerosis. Pull-down assays revealed an interaction of CRB2 with Nephrin, mediated by their extracellular domains. Expansion microscopy showed that in mice glomeruli, Crb2 and Nephrin are organized in adjacent clusters. SRNS-associated CRB2 protein variants and a mutant that lacks a putative conserved O-glycosylation site were not transported to the cell surface. Instead, mutants accumulated in the ER, showed altered glycosylation pattern, and triggered an ER stress response. CONCLUSIONS Crb2 is an essential component of the podocyte's slit diaphragm, interacting with Nephrin. Loss of slit diaphragm targeting and increasing ER stress are pivotal factors for onset and progression of CRB2-related SRNS.
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Affiliation(s)
- Annika Möller-Kerutt
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Juan E. Rodriguez-Gatica
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Karin Wacker
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Rohan Bhatia
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Jan-Peter Siebrasse
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Nanda Boon
- Leiden University Medical Center, Department of Ophthalmology, Leiden, The Netherlands
| | - Veerle Van Marck
- Gerhard-Domagk Institute of Pathology, University Hospital of Muenster, Muenster, Germany
| | - Peter Boor
- Institute of Pathology, Department of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany,The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Ulrich Kubitscheck
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Jan Wijnholds
- Leiden University Medical Center, Department of Ophthalmology, Leiden, The Netherlands
| | - Hermann Pavenstädt
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Thomas Weide
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
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20
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Lepa C, Hoppe S, Stöber A, Skryabin BV, Sievers LK, Heitplatz B, Ciarimboli G, Neugebauer U, Lindenmeyer MT, Cohen CD, Drexler HC, Boor P, Weide T, Pavenstädt H, George B. TrkC Is Essential for Nephron Function and Trans-Activates Igf1R Signaling. J Am Soc Nephrol 2021; 32:357-374. [PMID: 33380522 PMCID: PMC8054883 DOI: 10.1681/asn.2020040424] [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: 04/08/2020] [Accepted: 11/03/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Injury to kidney podocytes often results in chronic glomerular disease and consecutive nephron malfunction. For most glomerular diseases, targeted therapies are lacking. Thus, it is important to identify novel signaling pathways contributing to glomerular disease. Neurotrophic tyrosine kinase receptor 3 (TrkC) is expressed in podocytes and the protein transmits signals to the podocyte actin cytoskeleton. METHODS Nephron-specific TrkC knockout (TrkC-KO) and nephron-specific TrkC-overexpressing (TrkC-OE) mice were generated to dissect the role of TrkC in nephron development and maintenance. RESULTS Both TrkC-KO and TrkC-OE mice exhibited enlarged glomeruli, mesangial proliferation, basement membrane thickening, albuminuria, podocyte loss, and aspects of FSGS during aging. Igf1 receptor (Igf1R)-associated gene expression was dysregulated in TrkC-KO mouse glomeruli. Phosphoproteins associated with insulin, erb-b2 receptor tyrosine kinase (Erbb), and Toll-like receptor signaling were enriched in lysates of podocytes treated with the TrkC ligand neurotrophin-3 (Nt-3). Activation of TrkC by Nt-3 resulted in phosphorylation of the Igf1R on activating tyrosine residues in podocytes. Igf1R phosphorylation was increased in TrkC-OE mouse kidneys while it was decreased in TrkC-KO kidneys. Furthermore, TrkC expression was elevated in glomerular tissue of patients with diabetic kidney disease compared with control glomerular tissue. CONCLUSIONS Our results show that TrkC is essential for maintaining glomerular integrity. Furthermore, TrkC modulates Igf-related signaling in podocytes.
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Affiliation(s)
- Carolin Lepa
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Sascha Hoppe
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Antje Stöber
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Boris V. Skryabin
- Medical Faculty, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), Westfälische-Wilhelms-University, Münster, Germany
| | | | - Barbara Heitplatz
- Gerhard-Domagk Institute for Pathology, University Hospital Münster, Münster, Germany
| | | | - Ute Neugebauer
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Maja T. Lindenmeyer
- III. Medizinische Klinik und Poliklinik, University Hospital Hamburg-Eppendorf, Germany
| | - Clemens D. Cohen
- Klinik für Nieren-, Hochdruck- und Rheumaerkrankungen, München Klinik Harlaching, Germany
| | - Hannes C.A. Drexler
- Mass Spectrometry Unit, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Peter Boor
- Institute of Pathology and Department of Nephrology, University Hospital Aachen, Rheinisch-Westfälische Technische Hochschule Aachen, Aachen, Germany
| | - Thomas Weide
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | | | - Britta George
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
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21
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Bayraktar S, Nehrig J, Menis E, Karli K, Janning A, Struk T, Halbritter J, Michgehl U, Krahn MP, Schuberth CE, Pavenstädt H, Wedlich-Söldner R. A Deregulated Stress Response Underlies Distinct INF2-Associated Disease Profiles. J Am Soc Nephrol 2021; 31:1296-1313. [PMID: 32444357 DOI: 10.1681/asn.2019111174] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 03/20/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Monogenic diseases provide favorable opportunities to elucidate the molecular mechanisms of disease progression and improve medical diagnostics. However, the complex interplay between genetic and environmental factors in disease etiologies makes it difficult to discern the mechanistic links between different alleles of a single locus and their associated pathophysiologies. Inverted formin 2 (INF2), an actin regulator, mediates a stress response-calcium mediated actin reset, or CaAR-that reorganizes the actin cytoskeleton of mammalian cells in response to calcium influx. It has been linked to the podocytic kidney disease focal segemental glomerulosclerosis (FSGS), as well as to cases of the neurologic disorder Charcot-Marie-Tooth disease that are accompanied by nephropathy, mostly FSGS. METHODS We used a combination of quantitative live cell imaging and validation in primary patient cells and Drosophila nephrocytes to systematically characterize a large panel of >50 autosomal dominant INF2 mutants that have been reported to cause either FSGS alone or with Charcot-Marie-Tooth disease. RESULTS We found that INF2 mutations lead to deregulated activation of formin and a constitutive stress response in cultured cells, primary patient cells, and Drosophila nephrocytes. We were able to clearly distinguish between INF2 mutations that were linked exclusively to FSGS from those that caused a combination of FSGS and Charcot-Marie-Tooth disease. Furthermore, we were able to identify distinct subsets of INF2 variants that exhibit varying degrees of activation. CONCLUSIONS Our results suggest that CaAR can be used as a sensitive assay for INF2 function and for robust evaluation of diseased-linked variants of formin. More broadly, these findings indicate that cellular profiling of disease-associated mutations has potential to contribute substantially to sequence-based phenotype predictions.
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Affiliation(s)
- Samet Bayraktar
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany.,Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Julian Nehrig
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Ekaterina Menis
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Kevser Karli
- Medical Cell Biology, Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Annette Janning
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Thaddäus Struk
- Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Jan Halbritter
- Division of Nephrology, University of Leipzig, Leipzig, Germany
| | - Ulf Michgehl
- Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Michael P Krahn
- Medical Cell Biology, Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Christian E Schuberth
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | | | - Roland Wedlich-Söldner
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
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22
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Dehnen L, Janz M, Verma JK, Psathaki OE, Langemeyer L, Fröhlich F, Heinisch JJ, Meyer H, Ungermann C, Paululat A. A trimeric metazoan Rab7 GEF complex is crucial for endocytosis and scavenger function. J Cell Sci 2020; 133:jcs247080. [PMID: 32499409 DOI: 10.1242/jcs.247080] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/20/2020] [Indexed: 12/12/2022] Open
Abstract
Endosome biogenesis in eukaryotic cells is critical for nutrient uptake and plasma membrane integrity. Early endosomes initially contain Rab5, which is replaced by Rab7 on late endosomes prior to their fusion with lysosomes. Recruitment of Rab7 to endosomes requires the Mon1-Ccz1 guanine-nucleotide-exchange factor (GEF). Here, we show that full function of the Drosophila Mon1-Ccz1 complex requires a third stoichiometric subunit, termed Bulli (encoded by CG8270). Bulli localises to Rab7-positive endosomes, in agreement with its function in the GEF complex. Using Drosophila nephrocytes as a model system, we observe that absence of Bulli results in (i) reduced endocytosis, (ii) Rab5 accumulation within non-acidified enlarged endosomes, (iii) defective Rab7 localisation and (iv) impaired endosomal maturation. Moreover, longevity of animals lacking bulli is affected. Both the Mon1-Ccz1 dimer and a Bulli-containing trimer display Rab7 GEF activity. In summary, this suggests a key role for Bulli in the Rab5 to Rab7 transition during endosomal maturation rather than a direct influence on the GEF activity of Mon1-Ccz1.
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Affiliation(s)
- Lena Dehnen
- Department of Biology and Chemistry, Zoology and Developmental Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Maren Janz
- Department of Biology and Chemistry, Zoology and Developmental Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Jitender Kumar Verma
- Department of Biology and Chemistry, Biochemistry, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Olympia Ekaterini Psathaki
- Center of Cellular Nanoanalytics, Integrated Bioimaging Facility Osnabrück (iBiOs), University of Osnabrück, 49076 Osnabrück, Germany
| | - Lars Langemeyer
- Department of Biology and Chemistry, Biochemistry, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Florian Fröhlich
- Department of Biology and Chemistry, Molecular Membrane Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Jürgen J Heinisch
- Department of Biology and Chemistry, Genetics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Heiko Meyer
- Department of Biology and Chemistry, Zoology and Developmental Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology and Chemistry, Biochemistry, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Achim Paululat
- Department of Biology and Chemistry, Zoology and Developmental Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
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23
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Kawachi H, Fukusumi Y. New insight into podocyte slit diaphragm, a therapeutic target of proteinuria. Clin Exp Nephrol 2020; 24:193-204. [PMID: 32020343 PMCID: PMC7040068 DOI: 10.1007/s10157-020-01854-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 01/15/2020] [Indexed: 12/26/2022]
Abstract
Dysfunction of slit diaphragm, a cell–cell junction of glomerular podocytes, is involved in the development of proteinuria in several glomerular diseases. Slit diaphragm should be a target of a novel therapy for proteinuria. Nephrin, NEPH1, P-cadherin, FAT, and ephrin-B1 were reported to be extracellular components forming a molecular sieve of the slit diaphragm. Several cytoplasmic proteins such as ZO-1, podocin, CD2AP, MAGI proteins and Par-complex molecules were identified as scaffold proteins linking the slit diaphragm to the cytoskeleton. In this article, new insights into these molecules and the pathogenic roles of the dysfunction of these molecules were introduced. The slit diaphragm functions not only as a barrier but also as a signaling platform transfer the signal to the inside of the cell. For maintaining the slit diaphragm function properly, the phosphorylation level of nephrin is strictly regulated. The recent studies on the signaling pathway from nephrin, NEPH1, and ephrin-B1 were reviewed. Although the mechanism regulating the function of the slit diaphragm had remained unclear, recent studies revealed TRPC6 and angiotensin II-regulating mechanisms play a critical role in regulating the barrier function of the slit diaphragm. In this review, recent investigations on the regulation of the slit diaphragm function were reviewed, and a strategy for the establishment of a novel therapy for proteinuria was proposed.
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Affiliation(s)
- Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata, 951-8510, Japan.
| | - Yoshiyasu Fukusumi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata, 951-8510, Japan
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