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Rodriguez PQ, Unnersjö-Jess D, Zambrano SS, Guo J, Möller-Hackbarth K, Blom H, Jahnukainen T, Ebarasi L, Patrakka J. Inactivation of mediator complex protein 22 in podocytes results in intracellular vacuole formation, podocyte loss and premature death. Sci Rep 2020; 10:20037. [PMID: 33208756 PMCID: PMC7676236 DOI: 10.1038/s41598-020-76870-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 10/26/2020] [Indexed: 11/23/2022] Open
Abstract
Podocytes are critical for the maintenance of kidney ultrafiltration barrier and play a key role in the progression of glomerular diseases. Although mediator complex proteins have been shown to be important for many physiological and pathological processes, their role in kidney tissue has not been studied. In this study, we identified a mediator complex protein 22 (Med22) as a renal podocyte cell-enriched molecule. Podocyte-specific Med22 knockout mouse showed that Med22 was not needed for normal podocyte maturation. However, it was critical for the maintenance of podocyte health as the mice developed progressive glomerular disease and died due to renal failure. Detailed morphological analyses showed that Med22-deficiency in podocytes resulted in intracellular vacuole formation followed by podocyte loss. Moreover, Med22-deficiency in younger mice promoted the progression of glomerular disease, suggesting Med22-mediated processes may have a role in the development of glomerulopathies. This study shows for the first time that mediator complex has a critical role in kidney physiology.
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Affiliation(s)
- Patricia Q Rodriguez
- Integrated Cardio Metabolic Center, Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - David Unnersjö-Jess
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Solna, Sweden
| | - Sonia S Zambrano
- Integrated Cardio Metabolic Center, Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Jing Guo
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore, Singapore
| | - Katja Möller-Hackbarth
- Integrated Cardio Metabolic Center, Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Hans Blom
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Solna, Sweden
| | - Timo Jahnukainen
- Department of Pediatric Nephrology and Transplantation, New Children's Hospital, Helsinki University Hospital, University of Helsinki, Helsinki, Finland
| | - Lwaki Ebarasi
- Integrated Cardio Metabolic Center, Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Jaakko Patrakka
- Integrated Cardio Metabolic Center, Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
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Zambrano S, Möller-Hackbarth K, Li X, Rodriguez PQ, Charrin E, Schwarz A, Nyström J, Wernerson AÖ, Lal M, Patrakka J. GPRC5b Modulates Inflammatory Response in Glomerular Diseases via NF- κB Pathway. J Am Soc Nephrol 2019; 30:1573-1586. [PMID: 31285284 DOI: 10.1681/asn.2019010089] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/09/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Inflammatory processes play an important role in the pathogenesis of glomerulopathies. Finding novel ways to suppress glomerular inflammation may offer a new way to stop disease progression. However, the molecular mechanisms that initiate and drive inflammation in the glomerulus are still poorly understood. METHODS We performed large-scale gene expression profiling of glomerulus-associated G protein-coupled receptors (GPCRs) to identify new potential therapeutic targets for glomerulopathies. The expression of Gprc5b in disease was analyzed using quantitative PCR and immunofluorescence, and by analyzing published microarray data sets. In vivo studies were carried out in a podocyte-specific Gprc5b knockout mouse line. Mechanistic studies were performed in cultured human podocytes. RESULTS We identified an orphan GPCR, Gprc5b, as a novel gene highly enriched in podocytes that was significantly upregulated in common human glomerulopathies, including diabetic nephropathy, IgA nephropathy, and lupus nephritis. Similar upregulation of Gprc5b was detected in LPS-induced nephropathy in mice. Studies in podocyte-specific Gprc5b knockout mice showed that Gprc5b was not essential for normal development of the glomerular filtration barrier. However, knockout mice were partially protected from LPS-induced proteinuria and recruitment of inflammatory cells. Mechanistically, RNA sequencing in Gprc5b knockouts mice and experiments in cultured human podocytes showed that Gpr5cb regulated inflammatory response in podocytes via NF-κB signaling. CONCLUSIONS GPRC5b is a novel podocyte-specific receptor that regulates inflammatory response in the glomerulus by modulating the NF-κB signaling pathway. Upregulation of Gprc5b in human glomerulopathies suggests that it may play a role in their pathogenesis.
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Affiliation(s)
- Sonia Zambrano
- Karolinska Insitutet/AstraZeneca Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Katja Möller-Hackbarth
- Karolinska Insitutet/AstraZeneca Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Xidan Li
- Karolinska Insitutet/AstraZeneca Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Patricia Q Rodriguez
- Karolinska Insitutet/AstraZeneca Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Emmanuelle Charrin
- Karolinska Insitutet/AstraZeneca Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Angelina Schwarz
- Karolinska Insitutet/AstraZeneca Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Jenny Nyström
- Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Annika Östman Wernerson
- Division of Renal Medicine, Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden; and
| | - Mark Lal
- Division of Bioscience, Department of Cardiovascular, Renal and Metabolic Diseases, Innovative Medicines Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Jaakko Patrakka
- Karolinska Insitutet/AstraZeneca Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden;
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Zambrano S, Rodriguez PQ, Guo J, Möller-Hackbarth K, Schwarz A, Patrakka J. FYVE domain-containing protein ZFYVE28 regulates EGFR-signaling in podocytes but is not critical for the function of filtration barrier in mice. Sci Rep 2018; 8:4712. [PMID: 29549365 PMCID: PMC5856817 DOI: 10.1038/s41598-018-23104-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 03/06/2018] [Indexed: 12/27/2022] Open
Abstract
The kidney ultrafiltration barrier is formed of endothelial cells, the glomerular basement membrane and podocytes. Podocytes have a central role in normal physiology and disease pathogenesis of the glomerulus. Signaling through epidermal growth factor receptor (EGFR) in podocytes mediates development of many glomerular disease processes. In this work, we have identified zinc finger FYVE-type containing 28 (ZFYVE28) as a novel highly podocyte-enriched gene. We localize ZFYVE28 in podocyte foot processes in adult kidney. During glomerulogenesis, Zfyve28 is first expressed at the early capillary loop glomerulus. In cultured podocytes, we show that overexpression of ZFYVE28 promotes EGF-signaling, possibly by up-regulating EGFR expression and by modulating its localization. To study the role of ZFYVE28 in vivo, we generated both conventional and podocyte-specific knockout mouse lines. Kidneys developed normally in ZFYVE28-deficient mice. In adult mice, the absence of ZFYVE28 did not affect the maintenance of the filtration barrier. Moreover, ZFYVE28-deficiency did not affect the outcome of glomerular damage induced by injection of nephrotoxic serum. Taken together, we have identified Zfyve28 as a new molecular component of podocyte foot processes and show that it mediates EGF-signaling in podocytes. However, ZFYVE28 is not essential for the development or maintenance of the glomerulus filtration barrier.
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Affiliation(s)
- Sonia Zambrano
- KI/AZ Integrated CardioMetabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Patricia Q Rodriguez
- KI/AZ Integrated CardioMetabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Jing Guo
- KI/AZ Integrated CardioMetabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Katja Möller-Hackbarth
- KI/AZ Integrated CardioMetabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Angelina Schwarz
- KI/AZ Integrated CardioMetabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Jaakko Patrakka
- KI/AZ Integrated CardioMetabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden.
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Rodriguez PQ, Oddsson A, Ebarasi L, He B, Hultenby K, Wernerson A, Betsholtz C, Tryggvason K, Patrakka J. Knockdown of Tmem234 in zebrafish results in proteinuria. Am J Physiol Renal Physiol 2015; 309:F955-66. [PMID: 26377798 DOI: 10.1152/ajprenal.00525.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 09/10/2015] [Indexed: 12/15/2022] Open
Abstract
Podocytes are highly specialized epithelial cells located at the outer aspects of the glomerular capillary tuft and critical components of the kidney filtration barrier. To maintain their unique features, podocytes express a number of proteins that are only sparsely found elsewhere in the body. In this study, we have identified four (Tmem234, Znf185, Lrrc49, and Slfn5) new highly podocyte-enriched proteins. The proteins are strongly expressed by podocytes, while other parts of the kidney show only weak or no expression. Tmem234, Slfn5, and Lrrc49 are located in foot processes, whereas Znf185 is found in both foot and major processes. Expressional studies in developing kidneys show that these proteins are first expressed at the capillary stage glomerulus, the same stage when the formation of major and foot processes begins. We identified zebrafish orthologs for Tmem234 and Znf185 genes and knocked down their expression using morpholino technology. Studies in zebrafish larvae indicate that Tmem234 is essential for the organization and functional integrity of the pronephric glomerulus filtration barrier, as inactivation of Tmem234 expression results in foot process effacement and proteinuria. In summary, we have identified four novel highly podocyte-enriched proteins and show that one of them, Tmem234, is essential for the normal filtration barrier in the zebrafish pronephric glomerulus. Identification of new molecular components of the kidney filtration barrier opens up possibilities to study their role in glomerulus biology and diseases.
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Affiliation(s)
- Patricia Q Rodriguez
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Asmundur Oddsson
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Lwaki Ebarasi
- KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Bing He
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Kjell Hultenby
- Clinical Research Center, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Annika Wernerson
- Division of Renal Medicine, Department of Clinical Science, Intervention, and Technology, Stockholm, Sweden; and
| | - Christer Betsholtz
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; and
| | - Karl Tryggvason
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School, Singapore
| | - Jaakko Patrakka
- KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden;
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Perisic L, Rodriguez PQ, Hultenby K, Sun Y, Lal M, Betsholtz C, Uhlén M, Wernerson A, Hedin U, Pikkarainen T, Tryggvason K, Patrakka J. Correction: Schip1 Is a Novel Podocyte Foot Process Protein that Mediates Actin Cytoskeleton Rearrangements and Forms a Complex with Nherf2 and Ezrin. PLoS One 2015; 10:e0126079. [PMID: 25965062 PMCID: PMC4428695 DOI: 10.1371/journal.pone.0126079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Perisic L, Rodriguez PQ, Hultenby K, Sun Y, Lal M, Betsholtz C, Uhlén M, Wernerson A, Hedin U, Pikkarainen T, Tryggvason K, Patrakka J. Schip1 is a novel podocyte foot process protein that mediates actin cytoskeleton rearrangements and forms a complex with Nherf2 and ezrin. PLoS One 2015; 10:e0122067. [PMID: 25807495 PMCID: PMC4373682 DOI: 10.1371/journal.pone.0122067] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 02/18/2015] [Indexed: 01/28/2023] Open
Abstract
Background Podocyte foot process effacement accompanied by actin cytoskeleton rearrangements is a cardinal feature of many progressive human proteinuric diseases. Results By microarray profiling of mouse glomerulus, SCHIP1 emerged as one of the most highly enriched transcripts. We detected Schip1 protein in the kidney glomerulus, specifically in podocytes foot processes. Functionally, Schip1 inactivation in zebrafish by morpholino knock-down results in foot process disorganization and podocyte loss leading to proteinuria. In cultured podocytes Schip1 localizes to cortical actin-rich regions of lamellipodia, where it forms a complex with Nherf2 and ezrin, proteins known to participate in actin remodeling stimulated by PDGFβ signaling. Mechanistically, overexpression of Schip1 in vitro causes accumulation of cortical F-actin with dissolution of transversal stress fibers and promotes cell migration in response to PDGF-BB stimulation. Upon actin disassembly by latrunculin A treatment, Schip1 remains associated with the residual F-actin-containing structures, suggesting a functional connection with actin cytoskeleton possibly via its interaction partners. A similar assay with cytochalasin D points to stabilization of cortical actin cytoskeleton in Schip1 overexpressing cells by attenuation of actin depolymerisation. Conclusions Schip1 is a novel glomerular protein predominantly expressed in podocytes, necessary for the zebrafish pronephros development and function. Schip1 associates with the cortical actin cytoskeleton network and modulates its dynamics in response to PDGF signaling via interaction with the Nherf2/ezrin complex. Its implication in proteinuric diseases remains to be further investigated.
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Affiliation(s)
- Ljubica Perisic
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- Division of Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Patricia Q. Rodriguez
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Kjell Hultenby
- Clinical Research Center, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - Ying Sun
- Vascular Biology Division, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Mark Lal
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Christer Betsholtz
- Vascular Biology Division, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Mathias Uhlén
- Department of Biotechnology, Royal Institute of Technology, Stockholm, Sweden
| | - Annika Wernerson
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden
| | - Ulf Hedin
- Division of Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Timo Pikkarainen
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Karl Tryggvason
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Jaakko Patrakka
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- * E-mail:
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Xiao Z, Rodriguez PQ, He L, Betsholtz C, Tryggvason K, Patrakka J. Wtip- and gadd45a-interacting protein dendrin is not crucial for the development or maintenance of the glomerular filtration barrier. PLoS One 2013; 8:e83133. [PMID: 24376653 PMCID: PMC3869763 DOI: 10.1371/journal.pone.0083133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 10/31/2013] [Indexed: 11/18/2022] Open
Abstract
Glomerular podocyte cells are critical for the function of the renal ultrafiltration barrier. Especially, the highly specialized cell–cell junction of podocytes, the slit diaphragm, has a central role in the filtration barrier. This is highlighted by the fact that mutations in molecular components of the slit diaphragm, including nephrin and Cd2-associated protein (Cd2ap), result in proteinuric diseases in man. Dendrin is a poorly characterized cytosolic component of the slit diaphragm in where it interacts with nephrin and Cd2ap. Dendrin is highly specific for the podocyte slit diaphragm, suggesting that it has a dedicated role in the glomerular filtration barrier. In this study, we have generated a dendrin knockout mouse line and explored the molecular interactions of dendrin. Dendrin-deficient mice were viable, fertile, and had a normal life span. Morphologically, the glomerulogenesis proceeded normally and adult dendrin-deficient mice showed normal glomerular histology. No significant proteinuria was observed. Following glomerular injury, lack of dendrin did not affect the severity of the damage or the recovery process. Yeast two-hybrid screen and co-immunoprecipitation experiments showed that dendrin binds to Wt1-interacting protein (Wtip) and growth arrest and DNA-damage-inducible 45 alpha (Gadd45a). Wtip and Gadd45a mediate gene transcription in the nucleus, suggesting that dendrin may have similar functions in podocytes. In line with this, we observed the relocation of dendrin to nucleus in adriamycin nephropathy model. Our results indicate that dendrin is dispensable for the function of the normal glomerular filtration barrier and that dendrin interacts with Wtip and Gadd45a.
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Affiliation(s)
- Zhijie Xiao
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Patricia Q. Rodriguez
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Liqun He
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- Department of Immunology, Genetic and Pathology, Uppsala University, Uppsala, Sweden
| | - Christer Betsholtz
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- Department of Immunology, Genetic and Pathology, Uppsala University, Uppsala, Sweden
| | - Karl Tryggvason
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- Cardiovascular and Metabolic Disorders Program, Duke-NUS, Singapore
| | - Jaakko Patrakka
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
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Rodriguez PQ, Lohkamp B, Celsi G, Mache CJ, Auer-Grumbach M, Wernerson A, Hamajima N, Tryggvason K, Patrakka J. Novel INF2 mutation p. L77P in a family with glomerulopathy and Charcot-Marie-Tooth neuropathy. Pediatr Nephrol 2013; 28:339-43. [PMID: 22961558 DOI: 10.1007/s00467-012-2299-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 07/23/2012] [Accepted: 07/24/2012] [Indexed: 11/29/2022]
Abstract
BACKGROUND Mutations in inverted formin, FH2, and WH2 domain containing (INF2) are common causes of dominant focal segmental glomerulosclerosis. INF2 encodes a member of the diaphanous-related formin family, which regulates actin and microtubule cytoskeletons. Charcot-Marie-Tooth neuropathy (CMT) is a group of inherited disorders affecting peripheral neurons. Many reports have shown that glomerulopathy can associate with CMT. However, it has been unclear whether these two processes in the same individual represent one disorder or if they are two separate diseases. CASE DIAGNOSIS/TREATMENT Recently, INF2 mutations were identified in 12 of 16 patients with CMT-associated glomerulopathy, suggesting that these mutations are a common cause of the dual phenotype. In this study, we report two cases of CMT-associated glomerulopathy that both showed INF2 mutations. A novel INF2 mutation, p. L77P, was identified in a family in which the dual phenotype was inherited in a dominant fashion. The pathogenic effect of p. L77P was proposed using a structural homology model. In addition, we identified a patient with a sporadic CMT-associated glomerulopathy carrying a known INF2 mutation: p. L128P. CONCLUSIONS Our study confirms the link between INF2 mutations and CMT-associated glomerulopathy and widens the spectrum of pathogenic mutations.
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Affiliation(s)
- Patricia Q Rodriguez
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden
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Sistani L, Rodriguez PQ, Hultenby K, Uhlen M, Betsholtz C, Jalanko H, Tryggvason K, Wernerson A, Patrakka J. Neuronal proteins are novel components of podocyte major processes and their expression in glomerular crescents supports their role in crescent formation. Kidney Int 2012; 83:63-71. [PMID: 22913984 DOI: 10.1038/ki.2012.321] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The podocyte has a central role in the glomerular filtration barrier typified by a sophisticated morphology of highly organized primary (major) and secondary (foot) processes. The molecular makeup of foot processes is well characterized, but that of major processes is poorly known. Previously, we profiled the glomerular transcriptome through large-scale sequencing and microarray profiling. Unexpectedly, the survey found expression of three neuronal proteins (Huntingtin interacting protein 1 (Hip1), neurofascin (Nfasc), and olfactomedin-like 2a (Olfml2a)), all enriched in the glomerulus. These proteins were expressed exclusively by podocytes, wherein they localized to major processes as verified by RT-PCR, western blotting, immunofluorescence, and immunoelectron microscopy. During podocyte development, these proteins colocalized with vimentin, confirming their association with major processes. Using immunohistochemistry, we found coexpression of Hip1 and Olfml2a along with the recognized podocyte markers synaptopodin and Pdlim2 in glomerular crescents of human kidneys, indicating the presence of podocytes in these lesions. Thus, three neuronal proteins are highly expressed in podocyte major process. Using these new markers we found that podocytes contribute to the formation of glomerular crescents.
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Affiliation(s)
- Laleh Sistani
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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