51
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Sun T, Song Y, Dai J, Mao D, Ma M, Ni JQ, Liang X, Pastor-Pareja JC. Spectraplakin Shot Maintains Perinuclear Microtubule Organization in Drosophila Polyploid Cells. Dev Cell 2019; 49:731-747.e7. [DOI: 10.1016/j.devcel.2019.03.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 02/05/2019] [Accepted: 03/26/2019] [Indexed: 02/06/2023]
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52
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Dlugos CP, Picciotto C, Lepa C, Krakow M, Stöber A, Eddy ML, Weide T, Jeibmann A, P Krahn M, Van Marck V, Klingauf J, Ricker A, Wedlich-Söldner R, Pavenstädt H, Klämbt C, George B. Nephrin Signaling Results in Integrin β1 Activation. J Am Soc Nephrol 2019; 30:1006-1019. [PMID: 31097607 DOI: 10.1681/asn.2018040362] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 03/18/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Patients with certain mutations in the gene encoding the slit diaphragm protein Nephrin fail to develop functional slit diaphragms and display severe proteinuria. Many adult-onset glomerulopathies also feature alterations in Nephrin expression and function. Nephrin signals from the podocyte slit diaphragm to the Actin cytoskeleton by recruiting proteins that can interact with C3G, a guanine nucleotide exchange factor of the small GTPase Rap1. Because Rap activity affects formation of focal adhesions, we hypothesized that Nephrin transmits signals to the Integrin receptor complex, which mediates podocyte adhesion to the extracellular matrix. METHODS To investigate Nephrin's role in transmitting signals to the Integrin receptor complex, we conducted genetic studies in Drosophila nephrocytes and validated findings from Drosophila in a cultured human podocyte model. RESULTS Drosophila nephrocytes form a slit diaphragm-like filtration barrier and express the Nephrin ortholog Sticks and stones (Sns). A genetic screen identified c3g as necessary for nephrocyte function. In vivo, nephrocyte-specific gene silencing of sns or c3g compromised nephrocyte filtration and caused nephrocyte diaphragm defects. Nephrocytes with impaired Sns or C3G expression displayed an altered localization of Integrin and the Integrin-associated protein Talin. Furthermore, gene silencing of c3g partly rescued nephrocyte diaphragm defects of an sns overexpression phenotype, pointing to genetic interaction of sns and c3g in nephrocytes. We also found that activated Nephrin recruited phosphorylated C3G and resulted in activation of Integrin β1 in cultured podocytes. CONCLUSIONS Our findings suggest that Nephrin can mediate a signaling pathway that results in activation of Integrin β1 at focal adhesions, which may affect podocyte attachment to the extracellular matrix.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Christian Klämbt
- Neurobiology, Westfälische-Wilhelms University Münster, Münster, Germany
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Kawasaki Y, Matsumoto A, Miyaki T, Kinoshita M, Kakuta S, Sakai T, Ichimura K. Three-dimensional architecture of pericardial nephrocytes in Drosophila melanogaster revealed by FIB/SEM tomography. Cell Tissue Res 2019; 378:289-300. [PMID: 31089884 DOI: 10.1007/s00441-019-03037-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 04/15/2019] [Indexed: 01/07/2023]
Abstract
Nephrocytes are similar in structure to podocytes and play a role in the isolation of toxic substances from hemolymph in insects. Drosophila melanogaster nephrocytes have recently been used to study podocyte function and disease. However, the three-dimensional ultrastructure of nephrocytes is not clearly understood because their surrounding basement membrane makes it difficult to observe using conventional scanning electron microscopy. We reconstructed the three-dimensional ultrastructure of Drosophila pericardial nephrocytes using serial focused-ion beam/scanning electron microscopy (FIB/SEM) images. The basal surfaces were occupied by foot processes and slit-like spaces between them. The slit-like spaces corresponded to the podocyte filtration slits and were formed by longitudinal infolding/invagination of the basal plasma membrane. The basal surface between the slit-like spaces became the foot processes, which ran almost linearly, and had a "washboard-like" appearance. Both ends of the foot processes were usually anastomosed to neighboring foot processes and thus free ends were rarely observed. We demonstrated that FIB/SEM is a powerful tool to better understand the three-dimensional architecture of nephrocytes.
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Affiliation(s)
- Yuto Kawasaki
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Akira Matsumoto
- Department of Biology, Juntendo University School of Medicine, Inzai, Chiba, Japan
| | - Takayuki Miyaki
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Mui Kinoshita
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Soichiro Kakuta
- Laboratory of Morphology and Image Analysis, Center for Biomedical Research Resources, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Tatsuo Sakai
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan. .,Laboratory of Morphology and Image Analysis, Center for Biomedical Research Resources, Juntendo University Graduate School of Medicine, Tokyo, Japan.
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54
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Odenthal J, Brinkkoetter PT. Drosophila melanogaster and its nephrocytes: A versatile model for glomerular research. Methods Cell Biol 2019; 154:217-240. [PMID: 31493819 DOI: 10.1016/bs.mcb.2019.03.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Glomerular disorders are a predominant cause of chronic kidney diseases and end-stage renal failure. Especially podocytes, epithelial cells which represent the outermost part of the filtration barrier, are affected by disease and experience a gradual loss of function. Despite recent advances in identifying potential pathways underlying podocyte injury, treatment remains challenging. It is therefore desirable to employ suitable model organisms in order to study glomerular disease and elucidate affected pathways. Due to its diverse ways of genetic manipulation and high genomic conservation, Drosophila melanogaster is a powerful model organism for biomedical research. The fly was recently used to assess podocytopathies by exploiting the nephrocyte system. Nephrocytes are spherical cells within the body cavity of the fly responsible for detoxification and clearance of unwanted substances. More importantly, they share many characteristics with mammalian podocytes. Here, we summarize how to use Drosophila as a model organism for podocyte research. We discuss examples of techniques that can be used to genetically manipulate nephrocytes and provide protocols for nephrocyte isolation and for morphological as well as functional analysis.
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Affiliation(s)
- Johanna Odenthal
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Paul Thomas Brinkkoetter
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
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55
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Zhao F, Zhu JY, Richman A, Fu Y, Huang W, Chen N, Pan X, Yi C, Ding X, Wang S, Wang P, Nie X, Huang J, Yang Y, Yu Z, Han Z. Mutations in NUP160 Are Implicated in Steroid-Resistant Nephrotic Syndrome. J Am Soc Nephrol 2019; 30:840-853. [PMID: 30910934 DOI: 10.1681/asn.2018080786] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 02/02/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Studies have identified mutations in >50 genes that can lead to monogenic steroid-resistant nephrotic syndrome (SRNS). The NUP160 gene, which encodes one of the protein components of the nuclear pore complex nucleoporin 160 kD (Nup160), is expressed in both human and mouse kidney cells. Knockdown of NUP160 impairs mouse podocytes in cell culture. Recently, siblings with SRNS and proteinuria in a nonconsanguineous family were found to carry compound-heterozygous mutations in NUP160. METHODS We identified NUP160 mutations by whole-exome and Sanger sequencing of genomic DNA from a young girl with familial SRNS and FSGS who did not carry mutations in other genes known to be associated with SRNS. We performed in vivo functional validation studies on the NUP160 mutations using a Drosophila model. RESULTS We identified two compound-heterozygous NUP160 mutations, NUP160R1173× and NUP160E803K . We showed that silencing of Drosophila NUP160 specifically in nephrocytes (fly renal cells) led to functional abnormalities, reduced cell size and nuclear volume, and disorganized nuclear membrane structure. These defects were completely rescued by expression of the wild-type human NUP160 gene in nephrocytes. By contrast, expression of the NUP160 mutant allele NUP160R1173× completely failed to rescue nephrocyte phenotypes, and mutant allele NUP160E803K rescued only nuclear pore complex and nuclear lamin localization defects. CONCLUSIONS Mutations in NUP160 are implicated in SRNS. Our findings indicate that NUP160 should be included in the SRNS diagnostic gene panel to identify additional patients with SRNS and homozygous or compound-heterozygous NUP160 mutations and further strengthen the evidence that NUP160 mutations can cause SRNS.
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Affiliation(s)
- Feng Zhao
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China.,Center for Genetic Medicine Research, Children's National Health System, Washington, DC.,Department of Pediatrics, Affiliated Dongfang Hospital, Xiamen University, Fujian, People's Republic of China.,Department of Pediatrics, Fuzhou Clinical Medical College, Fujian Medical University, Fujian, People's Republic of China
| | - Jun-Yi Zhu
- Center for Genetic Medicine Research, Children's National Health System, Washington, DC
| | - Adam Richman
- Center for Genetic Medicine Research, Children's National Health System, Washington, DC
| | - Yulong Fu
- Center for Genetic Medicine Research, Children's National Health System, Washington, DC
| | - Wen Huang
- Center for Genetic Medicine Research, Children's National Health System, Washington, DC
| | - Nan Chen
- Department of Nephrology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China; and
| | - Xiaoxia Pan
- Department of Nephrology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China; and
| | - Cuili Yi
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China
| | - Xiaohua Ding
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China
| | - Si Wang
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China
| | - Ping Wang
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China
| | - Xiaojing Nie
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China.,Department of Pediatrics, Affiliated Dongfang Hospital, Xiamen University, Fujian, People's Republic of China.,Department of Pediatrics, Fuzhou Clinical Medical College, Fujian Medical University, Fujian, People's Republic of China
| | - Jun Huang
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China.,Department of Pediatrics, Affiliated Dongfang Hospital, Xiamen University, Fujian, People's Republic of China.,Department of Pediatrics, Fuzhou Clinical Medical College, Fujian Medical University, Fujian, People's Republic of China
| | - Yonghui Yang
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China.,Department of Pediatrics, Affiliated Dongfang Hospital, Xiamen University, Fujian, People's Republic of China.,Department of Pediatrics, Fuzhou Clinical Medical College, Fujian Medical University, Fujian, People's Republic of China
| | - Zihua Yu
- Department of Pediatrics, Fuzhou Dongfang Hospital, Fujian, People's Republic of China; .,Department of Pediatrics, Affiliated Dongfang Hospital, Xiamen University, Fujian, People's Republic of China.,Department of Pediatrics, Fuzhou Clinical Medical College, Fujian Medical University, Fujian, People's Republic of China
| | - Zhe Han
- Center for Genetic Medicine Research, Children's National Health System, Washington, DC; .,Department of Genomics and Precision Medicine, The George Washington University School of Medicine and Health Sciences, Washington, DC
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56
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Ben-Zvi DS, Volk T. Escort cell encapsulation of Drosophila germline cells is maintained by irre cell recognition module proteins. Biol Open 2019; 8:bio039842. [PMID: 30837217 PMCID: PMC6451344 DOI: 10.1242/bio.039842] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 02/06/2019] [Indexed: 12/17/2022] Open
Abstract
Differentiation of germline stem cells (GSCs) in the Drosophila ovary is induced by somatic escort cells (ECs), which extend membrane protrusions encapsulating the germline cells (GCs). Germline encapsulation requires activated epidermal growth factor receptor (Egfr) signaling within the ECs, following secretion of its ligands from the GCs. We show that the conserved family of irre cell recognition module (IRM) proteins is essential for GC encapsulation by ECs, with a requirement for roughest (rst) and kin of irre (kirre) in the germline and for sticks and stones (sns) and hibris (hbs) in ECs. In the absence of IRM components in their respective cell types, EC extensions are reduced concomitantly with a decrease in Egfr signaling in these cells. Reintroducing either activated Egfr in the ECs, or overexpressing its ligand Spitz (Spi) from the germline, rescued the requirement for IRM proteins in both cell types. These experiments introduce novel essential components, the IRM proteins, into the process of inductive interactions between GCs and ECs, and imply that IRM-mediated activity is required upstream of the Egfr signaling.
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Affiliation(s)
- Doreen S Ben-Zvi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Talila Volk
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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57
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Pei J, Kinch LN, Grishin NV. FlyXCDB—A Resource for Drosophila Cell Surface and Secreted Proteins and Their Extracellular Domains. J Mol Biol 2018; 430:3353-3411. [DOI: 10.1016/j.jmb.2018.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/31/2018] [Accepted: 06/02/2018] [Indexed: 02/06/2023]
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58
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Hermle T, Schneider R, Schapiro D, Braun DA, van der Ven AT, Warejko JK, Daga A, Widmeier E, Nakayama M, Jobst-Schwan T, Majmundar AJ, Ashraf S, Rao J, Finn LS, Tasic V, Hernandez JD, Bagga A, Jalalah SM, El Desoky S, Kari JA, Laricchia KM, Lek M, Rehm HL, MacArthur DG, Mane S, Lifton RP, Shril S, Hildebrandt F. GAPVD1 and ANKFY1 Mutations Implicate RAB5 Regulation in Nephrotic Syndrome. J Am Soc Nephrol 2018; 29:2123-2138. [PMID: 29959197 PMCID: PMC6065084 DOI: 10.1681/asn.2017121312] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/24/2018] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of CKD. The discovery of monogenic causes of SRNS has revealed specific pathogenetic pathways, but these monogenic causes do not explain all cases of SRNS. METHODS To identify novel monogenic causes of SRNS, we screened 665 patients by whole-exome sequencing. We then evaluated the in vitro functional significance of two genes and the mutations therein that we discovered through this sequencing and conducted complementary studies in podocyte-like Drosophila nephrocytes. RESULTS We identified conserved, homozygous missense mutations of GAPVD1 in two families with early-onset NS and a homozygous missense mutation of ANKFY1 in two siblings with SRNS. GAPVD1 and ANKFY1 interact with the endosomal regulator RAB5. Coimmunoprecipitation assays indicated interaction between GAPVD1 and ANKFY1 proteins, which also colocalized when expressed in HEK293T cells. Silencing either protein diminished the podocyte migration rate. Compared with wild-type GAPVD1 and ANKFY1, the mutated proteins produced upon ectopic expression of GAPVD1 or ANKFY1 bearing the patient-derived mutations exhibited altered binding affinity for active RAB5 and reduced ability to rescue the knockout-induced defect in podocyte migration. Coimmunoprecipitation assays further demonstrated a physical interaction between nephrin and GAPVD1, and immunofluorescence revealed partial colocalization of these proteins in rat glomeruli. The patient-derived GAPVD1 mutations reduced nephrin-GAPVD1 binding affinity. In Drosophila, silencing Gapvd1 impaired endocytosis and caused mistrafficking of the nephrin ortholog. CONCLUSIONS Mutations in GAPVD1 and probably in ANKFY1 are novel monogenic causes of NS. The discovery of these genes implicates RAB5 regulation in the pathogenesis of human NS.
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Affiliation(s)
- Tobias Hermle
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
- Renal Division, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ronen Schneider
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - David Schapiro
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Daniela A Braun
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amelie T van der Ven
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Jillian K Warejko
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ankana Daga
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Eugen Widmeier
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Makiko Nakayama
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Tilman Jobst-Schwan
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amar J Majmundar
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Shazia Ashraf
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Jia Rao
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Laura S Finn
- Department of Pathology, Seattle Children's Hospital, University of Washington, Seattle, Washington
| | - Velibor Tasic
- Department of Pediatric Nephrology, Medical Faculty Skopje, University Children's Hospital, Skopje, Macedonia
| | - Joel D Hernandez
- Department of Pediatric Nephrology, Providence Sacred Heart Medical Center and Children's Hospital, Spokane, Washington
| | - Arvind Bagga
- Division of Nephrology, All India Institute of Medical Sciences, New Delhi, India
| | | | - Sherif El Desoky
- Pediatric Nephrology Center of Excellence and Pediatric Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Jameela A Kari
- Pediatric Nephrology Center of Excellence and Pediatric Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Kristen M Laricchia
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Monkol Lek
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Heidi L Rehm
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Daniel G MacArthur
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut; and
| | - Richard P Lifton
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut; and
- Laboratory of Human Genetics and Genomics, The Rockefeller University, New York, New York
| | - Shirlee Shril
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Friedhelm Hildebrandt
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
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Schütte-Nütgen K, Edeling M, Mendl G, Krahn MP, Edemir B, Weide T, Kremerskothen J, Michgehl U, Pavenstädt H. Getting a Notch closer to renal dysfunction: activated Notch suppresses expression of the adaptor protein Disabled-2 in tubular epithelial cells. FASEB J 2018; 33:821-832. [PMID: 30052485 DOI: 10.1096/fj.201800392rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Reactivation of Notch signaling in kidneys of animal models and patients with chronic kidney disease (CKD) has been shown to contribute to epithelial injury and fibrosis development. Here, we investigated the mechanisms of Notch-induced injury in renal epithelial cells. We performed genome-wide transcriptome analysis to identify Notch target genes using an in vitro system of cultured tubular epithelial cells expressing the intracellular domain of Notch1. One of the top downregulated genes was Disabled-2 ( Dab2). With the use of Drosophila nephrocytes as a model system, we found that Dab (the Drosophila homolog of Dab2) knockdown resulted in a significant filtration defect, indicating that loss of Dab2 plays a functional role in kidney disease development. We showed that Dab2 expression in cultured tubular epithelial cells is involved in endocytic regulation and that it also protects cells from TGF-β-induced epithelial-to-mesenchymal transition. In vivo correlation studies indicated its additional role in renal ischemia-induced injury. Together, these data suggest that Dab2 plays a versatile role in the kidney and may impact on acute and CKDs.-Schütte-Nütgen, K., Edeling, M., Mendl, G., Krahn, M. P., Edemir, B., Weide, T., Kremerskothen, J., Michgehl, U., Pavenstädt, H. Getting a Notch closer to renal dysfunction: activated Notch suppresses expression of the adaptor protein Disabled-2 in tubular epithelial cells.
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Affiliation(s)
| | - Maria Edeling
- Internal Medicine D, University Hospital Muenster, Muenster, Germany; and
| | - Gudrun Mendl
- Internal Medicine D, University Hospital Muenster, Muenster, Germany; and
| | - Michael P Krahn
- Internal Medicine D, University Hospital Muenster, Muenster, Germany; and
| | - Bayram Edemir
- Internal Medicine D, University Hospital Muenster, Muenster, Germany; and.,Department of Hematology and Oncology, Internal Medicine IV, University Hospital Halle (Saale), Halle (Saale), Germany
| | - Thomas Weide
- Internal Medicine D, University Hospital Muenster, Muenster, Germany; and
| | | | - Ulf Michgehl
- Internal Medicine D, University Hospital Muenster, Muenster, Germany; and
| | - Hermann Pavenstädt
- Internal Medicine D, University Hospital Muenster, Muenster, Germany; and
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60
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Drosophila pericardial nephrocyte ultrastructure changes during ageing. Mech Ageing Dev 2018; 173:9-20. [DOI: 10.1016/j.mad.2018.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 04/17/2018] [Accepted: 04/23/2018] [Indexed: 10/17/2022]
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61
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Hochapfel F, Denk L, Maaßen C, Zaytseva Y, Rachel R, Witzgall R, Krahn MP. Electron microscopy of
Drosophila
garland cell nephrocytes: Optimal preparation, immunostaining and STEM tomography. J Cell Biochem 2018; 119:8011-8021. [DOI: 10.1002/jcb.26702] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/23/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Florian Hochapfel
- Molecular and Cellular AnatomyUniversity of RegensburgRegensburgGermany
- Medizinische Klinik und Poliklinik DUniversitätsklinikum MünsterMünsterGermany
| | - Lucia Denk
- Molecular and Cellular AnatomyUniversity of RegensburgRegensburgGermany
| | - Christine Maaßen
- Molecular and Cellular AnatomyUniversity of RegensburgRegensburgGermany
| | - Yulia Zaytseva
- Molecular and Cellular AnatomyUniversity of RegensburgRegensburgGermany
| | - Reinhard Rachel
- Molecular and Cellular AnatomyUniversity of RegensburgRegensburgGermany
| | - Ralph Witzgall
- Molecular and Cellular AnatomyUniversity of RegensburgRegensburgGermany
| | - Michael P. Krahn
- Molecular and Cellular AnatomyUniversity of RegensburgRegensburgGermany
- Medizinische Klinik und Poliklinik DUniversitätsklinikum MünsterMünsterGermany
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Modeling Renal Disease "On the Fly". BIOMED RESEARCH INTERNATIONAL 2018; 2018:5697436. [PMID: 29955604 PMCID: PMC6000847 DOI: 10.1155/2018/5697436] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 04/17/2018] [Indexed: 12/22/2022]
Abstract
Detoxification is a fundamental function for all living organisms that need to excrete catabolites and toxins to maintain homeostasis. Kidneys are major organs of detoxification that maintain water and electrolyte balance to preserve physiological functions of vertebrates. In insects, the renal function is carried out by Malpighian tubules and nephrocytes. Due to differences in their circulation, the renal systems of mammalians and insects differ in their functional modalities, yet carry out similar biochemical and physiological functions and share extensive genetic and molecular similarities. Evolutionary conservation can be leveraged to model specific aspects of the complex mammalian kidney function in the genetic powerhouse Drosophila melanogaster to study how genes interact in diseased states. Here, we compare the human and Drosophila renal systems and present selected fly disease models.
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Gonçalves S, Patat J, Guida MC, Lachaussée N, Arrondel C, Helmstädter M, Boyer O, Gribouval O, Gubler MC, Mollet G, Rio M, Charbit M, Bole-Feysot C, Nitschke P, Huber TB, Wheeler PG, Haynes D, Juusola J, Billette de Villemeur T, Nava C, Afenjar A, Keren B, Bodmer R, Antignac C, Simons M. A homozygous KAT2B variant modulates the clinical phenotype of ADD3 deficiency in humans and flies. PLoS Genet 2018; 14:e1007386. [PMID: 29768408 PMCID: PMC5973622 DOI: 10.1371/journal.pgen.1007386] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 05/29/2018] [Accepted: 04/30/2018] [Indexed: 12/25/2022] Open
Abstract
Recent evidence suggests that the presence of more than one pathogenic mutation in a single patient is more common than previously anticipated. One of the challenges hereby is to dissect the contribution of each gene mutation, for which animal models such as Drosophila can provide a valuable aid. Here, we identified three families with mutations in ADD3, encoding for adducin-γ, with intellectual disability, microcephaly, cataracts and skeletal defects. In one of the families with additional cardiomyopathy and steroid-resistant nephrotic syndrome (SRNS), we found a homozygous variant in KAT2B, encoding the lysine acetyltransferase 2B, with impact on KAT2B protein levels in patient fibroblasts, suggesting that this second mutation might contribute to the increased disease spectrum. In order to define the contribution of ADD3 and KAT2B mutations for the patient phenotype, we performed functional experiments in the Drosophila model. We found that both mutations were unable to fully rescue the viability of the respective null mutants of the Drosophila homologs, hts and Gcn5, suggesting that they are indeed pathogenic in flies. While the KAT2B/Gcn5 mutation additionally showed a significantly reduced ability to rescue morphological and functional defects of cardiomyocytes and nephrocytes (podocyte-like cells), this was not the case for the ADD3 mutant rescue. Yet, the simultaneous knockdown of KAT2B and ADD3 synergistically impaired kidney and heart function in flies as well as the adhesion and migration capacity of cultured human podocytes, indicating that mutations in both genes may be required for the full clinical manifestation. Altogether, our studies describe the expansion of the phenotypic spectrum in ADD3 deficiency associated with a homozygous likely pathogenic KAT2B variant and thereby identify KAT2B as a susceptibility gene for kidney and heart disease in ADD3-associated disorders.
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Affiliation(s)
- Sara Gonçalves
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Laboratory of Epithelial Biology and Disease, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Julie Patat
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Maria Clara Guida
- Development, Aging and Regeneration Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, United States of America
| | - Noelle Lachaussée
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Christelle Arrondel
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Martin Helmstädter
- Department of Medicine IV, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Olivia Boyer
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
- Department of Pediatric Nephrology, Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Hôpital Necker-Enfants Malades, Assistance Publique—Hôpitaux de Paris (AP-HP), Paris, France
| | - Olivier Gribouval
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Marie-Claire Gubler
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Geraldine Mollet
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Marlène Rio
- Department of Genetics, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Marina Charbit
- Department of Pediatric Nephrology, Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Hôpital Necker-Enfants Malades, Assistance Publique—Hôpitaux de Paris (AP-HP), Paris, France
| | | | - Patrick Nitschke
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Tobias B. Huber
- Department of Medicine IV, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- BIOSS Center for Biological Signalling Studies and Center for Systems Biology (ZBSA), Albert-Ludwigs-University, Freiburg, Germany
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Patricia G. Wheeler
- Division of Genetics, Arnold Palmer Hospital for Children, Orlando Health, Orlando, FL, United States of America
| | - Devon Haynes
- Division of Genetics, Arnold Palmer Hospital for Children, Orlando Health, Orlando, FL, United States of America
| | - Jane Juusola
- GeneDx, Inc, Gaithersburg, MD, United States of America
| | - Thierry Billette de Villemeur
- Sorbonne Université, UPMC, GRC ConCer-LD and AP-HP, Hôpital Trousseau, Service de Neuropédiatrie—Pathologie du développement, Paris, France
- Centre de référence des déficits intellectuels de causes rares, Inserm U 1141, Paris, France
| | - Caroline Nava
- Sorbonne Universités, UPMC Univ Paris 06, Inserm U1127, CNRS UMR 7225, Institut du Cerveau et de la Moèlle Épinière (ICM), Paris, France
- AP-HP, GH Pitié-Salpêtrière, Department of Genetics, Unit of Developmental Genomics, Paris, France
| | - Alexandra Afenjar
- AP-HP, Hôpital Trousseau, Centre de référence des malformations et maladies congénitales du cervelet, Département de génétique et embryologie médicale, Paris, France
| | - Boris Keren
- AP-HP, GH Pitié-Salpêtrière, Department of Genetics, Unit of Developmental Genomics, Paris, France
| | - Rolf Bodmer
- Development, Aging and Regeneration Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, United States of America
| | - Corinne Antignac
- Laboratory of Hereditary Kidney Diseases, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
- Department of Genetics, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
- * E-mail: (CA); (MS)
| | - Matias Simons
- Laboratory of Epithelial Biology and Disease, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1163, Imagine Institute, Paris, France
- Université Paris Descartes—Sorbonne Paris Cité, Imagine Institute, Paris, France
- * E-mail: (CA); (MS)
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Muraleedharan S, Sam A, Skaer H, Inamdar MS. Networks that link cytoskeletal regulators and diaphragm proteins underpin filtration function in Drosophila nephrocytes. Exp Cell Res 2018; 364:234-242. [PMID: 29458174 PMCID: PMC5883325 DOI: 10.1016/j.yexcr.2018.02.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 02/06/2018] [Accepted: 02/15/2018] [Indexed: 11/25/2022]
Abstract
Insect nephrocytes provide a valuable model for kidney disease, as they are structurally and functionally homologous to mammalian kidney podocytes. They possess an exceptional macromolecular assembly, the nephrocyte diaphragm (ND), which serves as a filtration barrier and helps maintain tissue homeostasis by filtering out wastes and toxic products. However, the elements that maintain nephrocyte architecture and the ND are not understood. We show that Drosophila nephrocytes have a unique cytoplasmic cluster of F-actin, which is maintained by the microtubule cytoskeleton and Rho-GTPases. A balance of Rac1 and Cdc42 activity as well as proper microtubule organization and endoplasmic reticulum structure, are required to position the actin cluster. Further, ND proteins Sns and Duf also localize to this cluster and regulate organization of the actin and microtubule cytoskeleton. Perturbation of any of these inter-dependent components impairs nephrocyte ultrafiltration. Thus cytoskeletal components, Rho-GTPases and ND proteins work in concert to maintain the specialized nephrocyte architecture and function. Drosophila nephrocytes have a unique cytoplasmic cluster of F-actin. Microtubules, Rho-GTPases and endoplasmic reticulum position the actin cluster. Nephrocyte diaphragm proteins localize to and regulate actin cluster organization. Perturbation of any of these inter-dependent components impairs ultrafiltration.
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Affiliation(s)
- Simi Muraleedharan
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Aksah Sam
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Helen Skaer
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Maneesha S Inamdar
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India; Institute for Stem Cell Biology and Regenerative Medicine, GKVK, Bellary Road, Bangalore 560065, India.
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65
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Hochapfel F, Denk L, Mendl G, Schulze U, Maaßen C, Zaytseva Y, Pavenstädt H, Weide T, Rachel R, Witzgall R, Krahn MP. Distinct functions of Crumbs regulating slit diaphragms and endocytosis in Drosophila nephrocytes. Cell Mol Life Sci 2017; 74:4573-4586. [PMID: 28717874 PMCID: PMC11107785 DOI: 10.1007/s00018-017-2593-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 06/26/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
Abstract
Mammalian podocytes, the key determinants of the kidney's filtration barrier, differentiate from columnar epithelial cells and several key determinants of apical-basal polarity in the conventional epithelia have been shown to regulate podocyte morphogenesis and function. However, little is known about the role of Crumbs, a conserved polarity regulator in many epithelia, for slit-diaphragm formation and podocyte function. In this study, we used Drosophila nephrocytes as model system for mammalian podocytes and identified a conserved function of Crumbs proteins for cellular morphogenesis, nephrocyte diaphragm assembly/maintenance, and endocytosis. Nephrocyte-specific knock-down of Crumbs results in disturbed nephrocyte diaphragm assembly/maintenance and decreased endocytosis, which can be rescued by Drosophila Crumbs as well as human Crumbs2 and Crumbs3, which were both expressed in human podocytes. In contrast to the extracellular domain, which facilitates nephrocyte diaphragm assembly/maintenance, the intracellular FERM-interaction motif of Crumbs is essential for regulating endocytosis. Moreover, Moesin, which binds to the FERM-binding domain of Crumbs, is essential for efficient endocytosis. Thus, we describe here a new mechanism of nephrocyte development and function, which is likely to be conserved in mammalian podocytes.
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Affiliation(s)
- Florian Hochapfel
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Lucia Denk
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Gudrun Mendl
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Ulf Schulze
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Christine Maaßen
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Yulia Zaytseva
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Hermann Pavenstädt
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Thomas Weide
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Reinhard Rachel
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Ralph Witzgall
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Michael P Krahn
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany.
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany.
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66
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Fu Y, Zhu JY, Richman A, Zhao Z, Zhang F, Ray PE, Han Z. A Drosophila model system to assess the function of human monogenic podocyte mutations that cause nephrotic syndrome. Hum Mol Genet 2017; 26:768-780. [PMID: 28164240 DOI: 10.1093/hmg/ddw428] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 12/16/2016] [Indexed: 12/15/2022] Open
Abstract
Many genetic mutations have been identified as monogenic causes of nephrotic syndrome (NS), but important knowledge gaps exist in the roles of these genes in kidney cell biology and renal diseases. More animal models are needed to assess the functions of these genes in vivo, and to determine how they cause NS in a timely manner. Drosophila nephrocytes and human podocytes share striking similarities, but to what degree these known NS genes play conserved roles in nephrocytes remains unknown. Here we systematically studied 40 genes associated with NS, including 7 that have not previously been analysed for renal function in an animal model. We found that 85% of these genes are required for nephrocyte functions, suggesting that a majority of human genes known to be associated with NS play conserved roles in renal function from flies to humans. To investigate functional conservation in more detail, we focused on Cindr, the fly homolog of the human NS gene CD2AP. Silencing Cindr in nephrocytes led to dramatic nephrocyte functional impairment and shortened life span, as well as collapse of nephrocyte lacunar channels and effacement of nephrocyte slit diaphragms. These phenotypes could be rescued by expression of a wild-type human CD2AP gene, but not a mutant allele derived from a patient with CD2AP-associated NS. We conclude that the Drosophila nephrocyte can be used to elucidate clinically relevant molecular mechanisms underlying the pathogenesis of most monogenic forms of NS, and to efficiently generate personalized in vivo models of genetic renal diseases bearing patient-specific mutations.
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Affiliation(s)
- Yulong Fu
- Center for Cancer and Immunology Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA
| | - Jun-Yi Zhu
- Center for Cancer and Immunology Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA
| | - Adam Richman
- Center for Cancer and Immunology Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA
| | - Zhanzheng Zhao
- Department of Nephrology, First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China
| | - Fujian Zhang
- Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, People's Republic of China
| | - Patricio E Ray
- Center for Genetic Medicine Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA.,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Zhe Han
- Center for Cancer and Immunology Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA.,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
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67
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Hermle T, Braun DA, Helmstädter M, Huber TB, Hildebrandt F. Modeling Monogenic Human Nephrotic Syndrome in the Drosophila Garland Cell Nephrocyte. J Am Soc Nephrol 2017; 28:1521-1533. [PMID: 27932481 PMCID: PMC5407722 DOI: 10.1681/asn.2016050517] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 11/05/2016] [Indexed: 11/03/2022] Open
Abstract
Steroid-resistant nephrotic syndrome is characterized by podocyte dysfunction. Drosophila garland cell nephrocytes are podocyte-like cells and thus provide a potential in vivo model in which to study the pathogenesis of nephrotic syndrome. However, relevant pathomechanisms of nephrotic syndrome have not been studied in nephrocytes. Here, we discovered that two Drosophila slit diaphragm proteins, orthologs of the human genes encoding nephrin and nephrin-like protein 1, colocalize within a fingerprint-like staining pattern that correlates with ultrastructural morphology. Using RNAi and conditional CRISPR/Cas9 in nephrocytes, we found this pattern depends on the expression of both orthologs. Tracer endocytosis by nephrocytes required Cubilin and reflected size selectivity analogous to that of glomerular function. Using RNAi and tracer endocytosis as a functional read-out, we screened Drosophila orthologs of human monogenic causes of nephrotic syndrome and observed conservation of the central pathogenetic alterations. We focused on the coenzyme Q10 (CoQ10) biosynthesis gene Coq2, the silencing of which disrupted slit diaphragm morphology. Restoration of CoQ10 synthesis by vanillic acid partially rescued the phenotypic and functional alterations induced by Coq2-RNAi. Notably, Coq2 colocalized with mitochondria, and Coq2 silencing increased the formation of reactive oxygen species (ROS). Silencing of ND75, a subunit of the mitochondrial respiratory chain that controls ROS formation independently of CoQ10, phenocopied the effect of Coq2-RNAi. Moreover, the ROS scavenger glutathione partially rescued the effects of Coq2-RNAi. In conclusion, Drosophila garland cell nephrocytes provide a model with which to study the pathogenesis of nephrotic syndrome, and ROS formation may be a pathomechanism of COQ2-nephropathy.
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Affiliation(s)
- Tobias Hermle
- Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
| | - Daniela A Braun
- Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Martin Helmstädter
- Renal Division, University Medical Center Freiburg, Freiburg, Germany, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
| | - Tobias B Huber
- Renal Division, University Medical Center Freiburg, Freiburg, Germany, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
- BIOSS Center for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Friedhelm Hildebrandt
- Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
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68
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Helmstädter M, Simons M. Using Drosophila nephrocytes in genetic kidney disease. Cell Tissue Res 2017; 369:119-126. [PMID: 28401308 DOI: 10.1007/s00441-017-2606-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/05/2017] [Indexed: 01/01/2023]
Abstract
Renal diseases are a growing health burden, and innovative models to study their pathomechanisms are greatly needed. Here, we highlight how the fruit fly Drosophila melanogaster can be used to model kidney diseases. We focus on the nephrocyte that has recently been shown to exhibit podocyte and proximal tubular cell features. These cells can be manipulated with precise genetic tools to dissect filtration and reabsorption mechanisms. Thus, they represent a novel and easy-to-use alternative in experimental nephrology.
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Affiliation(s)
- Martin Helmstädter
- Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, 79106, Freiburg, Germany
| | - Matias Simons
- Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, 75015, Paris, France. .,Institut Imagine, 24 Boulevard du Montparnasse, Paris, France.
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69
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Fu Y, Zhu JY, Zhang F, Richman A, Zhao Z, Han Z. Comprehensive functional analysis of Rab GTPases in Drosophila nephrocytes. Cell Tissue Res 2017; 368:615-627. [PMID: 28180992 DOI: 10.1007/s00441-017-2575-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 12/15/2016] [Indexed: 12/20/2022]
Abstract
The Drosophila nephrocyte is a critical component of the fly renal system and bears structural and functional homology to podocytes and proximal tubule cells of the mammalian kidney. Investigations of nephrocyte cell biological processes are fundamental to understanding the insect renal system. Nephrocytes are highly active in endocytosis and vesicle trafficking. Rab GTPases regulate endocytosis and trafficking but specific functions of nephrocyte Rabs remain undefined. We analyzed Rab GTPase expression and function in Drosophila nephrocytes and found that 11 out of 27 Drosophila Rabs were required for normal activity. Rabs 1, 5, 7, 11 and 35 were most important. Gene silencing of the nephrocyte-specific Rab5 eliminated all intracellular vesicles and the specialized plasma membrane structures essential for nephrocyte function. Rab7 silencing dramatically increased clear vacuoles and reduced lysosomes. Rab11 silencing increased lysosomes and reduced clear vacuoles. Our results suggest that Rab5 mediates endocytosis that is essential for the maintenance of functionally critical nephrocyte plasma membrane structures and that Rabs 7 and 11 mediate alternative downstream vesicle trafficking pathways leading to protein degradation and membrane recycling, respectively. Elucidating molecular pathways underlying nephrocyte function has the potential to yield important insights into human kidney cell physiology and mechanisms of cell injury that lead to disease. The Drosophila nephrocyte is emerging as a useful in vivo model system for molecular target identification and initial testing of therapeutic approaches in humans.
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Affiliation(s)
- Yulong Fu
- Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Jun-Yi Zhu
- Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Fujian Zhang
- Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Adam Richman
- Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Zhanzheng Zhao
- Department of Nephrology, First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China
| | - Zhe Han
- Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA.
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70
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Lovric S, Goncalves S, Gee HY, Oskouian B, Srinivas H, Choi WI, Shril S, Ashraf S, Tan W, Rao J, Airik M, Schapiro D, Braun DA, Sadowski CE, Widmeier E, Jobst-Schwan T, Schmidt JM, Girik V, Capitani G, Suh JH, Lachaussée N, Arrondel C, Patat J, Gribouval O, Furlano M, Boyer O, Schmitt A, Vuiblet V, Hashmi S, Wilcken R, Bernier FP, Innes AM, Parboosingh JS, Lamont RE, Midgley JP, Wright N, Majewski J, Zenker M, Schaefer F, Kuss N, Greil J, Giese T, Schwarz K, Catheline V, Schanze D, Franke I, Sznajer Y, Truant AS, Adams B, Désir J, Biemann R, Pei Y, Ars E, Lloberas N, Madrid A, Dharnidharka VR, Connolly AM, Willing MC, Cooper MA, Lifton RP, Simons M, Riezman H, Antignac C, Saba JD, Hildebrandt F. Mutations in sphingosine-1-phosphate lyase cause nephrosis with ichthyosis and adrenal insufficiency. J Clin Invest 2017; 127:912-928. [PMID: 28165339 DOI: 10.1172/jci89626] [Citation(s) in RCA: 132] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 12/12/2016] [Indexed: 12/24/2022] Open
Abstract
Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in SGPL1, which encodes sphingosine-1-phosphate (S1P) lyase. All mutations resulted in reduced or absent SGPL1 protein and/or enzyme activity. Overexpression of cDNA representing SGPL1 mutations resulted in subcellular mislocalization of SGPL1. Furthermore, expression of WT human SGPL1 rescued growth of SGPL1-deficient dpl1Δ yeast strains, whereas expression of disease-associated variants did not. Immunofluorescence revealed SGPL1 expression in mouse podocytes and mesangial cells. Knockdown of Sgpl1 in rat mesangial cells inhibited cell migration, which was partially rescued by VPC23109, an S1P receptor antagonist. In Drosophila, Sply mutants, which lack SGPL1, displayed a phenotype reminiscent of nephrotic syndrome in nephrocytes. WT Sply, but not the disease-associated variants, rescued this phenotype. Together, these results indicate that SGPL1 mutations cause a syndromic form of SRNS.
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71
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Weide T, Vollenbröker B, Schulze U, Djuric I, Edeling M, Bonse J, Hochapfel F, Panichkina O, Wennmann DO, George B, Kim S, Daniel C, Seggewiß J, Amann K, Kriz W, Krahn MP, Pavenstädt H. Pals1 Haploinsufficiency Results in Proteinuria and Cyst Formation. J Am Soc Nephrol 2017; 28:2093-2107. [PMID: 28154200 DOI: 10.1681/asn.2016040474] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 01/03/2017] [Indexed: 12/30/2022] Open
Abstract
The nephron is the basic physiologic subunit of the mammalian kidney and is made up of several apicobasally polarized epithelial cell types. The process of apicobasal polarization in animal cells is controlled by the evolutionarily conserved Crumbs (CRB), Partitioning-defective, and Scribble protein complexes. Here, we investigated the role of protein associated with LIN-7 1 (Pals1, also known as Mpp5), a core component of the apical membrane-determining CRB complex in the nephron. Pals1 interacting proteins, including Crb3 and Wwtr1/Taz, have been linked to renal cyst formation in mice before. Immunohistologic analysis revealed Pals1 expression in renal tubular cells and podocytes of human kidneys. Mice lacking one Pals1 allele (functionally haploid for Pals1) in nephrons developed a fully penetrant phenotype, characterized by cyst formation and severe defects in renal barrier function, which led to death within 6-8 weeks. In Drosophila nephrocytes, deficiency of the Pals1 ortholog caused alterations in slit-diaphragm-like structures. Additional studies in epithelial cell culture models revealed that Pals1 functions as a dose-dependent upstream regulator of the crosstalk between Hippo- and TGF-β-mediated signaling. Furthermore, Pals1 haploinsufficiency in mouse kidneys associated with the upregulation of Hippo pathway target genes and marker genes of TGF-β signaling, including biomarkers of renal diseases. These findings support a link between apical polarity proteins and renal diseases, especially renal cyst diseases. Further investigation of the Pals1-linked networks is required to decipher the mechanisms underlying the pathogenesis of these diseases.
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Affiliation(s)
- Thomas Weide
- Internal Medicine D, University Hospital of Münster, Münster, Germany;
| | | | - Ulf Schulze
- Internal Medicine D, University Hospital of Münster, Münster, Germany
| | - Ivona Djuric
- Internal Medicine D, University Hospital of Münster, Münster, Germany
| | - Maria Edeling
- Internal Medicine D, University Hospital of Münster, Münster, Germany
| | - Jakob Bonse
- Internal Medicine D, University Hospital of Münster, Münster, Germany
| | - Florian Hochapfel
- Institute for Molecular and Cellular Anatomy, University of Regensburg, Regensburg, Germany
| | - Olga Panichkina
- Institute for Molecular and Cellular Anatomy, University of Regensburg, Regensburg, Germany
| | | | - Britta George
- Internal Medicine D, University Hospital of Münster, Münster, Germany
| | - Seonhee Kim
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Christoph Daniel
- Nephropathology Department, Institute of Pathology, Erlangen-Nürnberg University, Erlangen, Germany
| | - Jochen Seggewiß
- Interdisciplinary Center for Clinical Research, University of Münster, Munster, Germany; and
| | - Kerstin Amann
- Nephropathology Department, Institute of Pathology, Erlangen-Nürnberg University, Erlangen, Germany
| | - Wilhelm Kriz
- Department of Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Michael P Krahn
- Institute for Molecular and Cellular Anatomy, University of Regensburg, Regensburg, Germany
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72
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Helmstädter M, Huber TB, Hermle T. Using the Drosophila Nephrocyte to Model Podocyte Function and Disease. Front Pediatr 2017; 5:262. [PMID: 29270398 PMCID: PMC5725439 DOI: 10.3389/fped.2017.00262] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 11/24/2017] [Indexed: 12/19/2022] Open
Abstract
Glomerular disorders are a major cause of end-stage renal disease and effective therapies are often lacking. Nephrocytes are considered to be part of the Drosophila excretory system and form slit diaphragms across cellular membrane invaginations. Nehphrocytes have been shown to share functional, morphological, and molecular features with podocytes, which form the glomerular filter in vertebrates. Here, we report the progress and the evolving tool-set of this model system. Combining a functional, accessible slit diaphragm with the power of the genetic tool-kit in Drosophila, the nephrocyte has the potential to greatly advance our understanding of the glomerular filtration barrier in health and disease.
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Affiliation(s)
- Martin Helmstädter
- Renal Division, University Medical Center Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Tobias B Huber
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tobias Hermle
- Renal Division, University Medical Center Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
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73
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Schejter ED. Myoblast fusion: Experimental systems and cellular mechanisms. Semin Cell Dev Biol 2016; 60:112-120. [DOI: 10.1016/j.semcdb.2016.07.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/11/2016] [Accepted: 07/12/2016] [Indexed: 12/18/2022]
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74
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Kruzel-Davila E, Shemer R, Ofir A, Bavli-Kertselli I, Darlyuk-Saadon I, Oren-Giladi P, Wasser WG, Magen D, Zaknoun E, Schuldiner M, Salzberg A, Kornitzer D, Marelja Z, Simons M, Skorecki K. APOL1-Mediated Cell Injury Involves Disruption of Conserved Trafficking Processes. J Am Soc Nephrol 2016; 28:1117-1130. [PMID: 27864431 DOI: 10.1681/asn.2016050546] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 10/05/2016] [Indexed: 01/08/2023] Open
Abstract
APOL1 harbors C-terminal sequence variants (G1 and G2), which account for much of the increased risk for kidney disease in sub-Saharan African ancestry populations. Expression of the risk variants has also been shown to cause injury to podocytes and other cell types, but the underlying mechanisms are not understood. We used Drosophila melanogaster and Saccharomyces cerevisiae to help clarify these mechanisms. Ubiquitous expression of the human APOL1 G1 and G2 disease risk alleles caused near-complete lethality in D. melanogaster, with no effect of the G0 nonrisk APOL1 allele, corresponding to the pattern of human disease risk. We also observed a congruent pattern of cellular damage with tissue-specific expression of APOL1. In particular, expression of APOL1 risk variants in D. melanogaster nephrocytes caused cell-autonomous accumulation of the endocytic tracer atrial natriuretic factor-red fluorescent protein at early stages and nephrocyte loss at later stages. We also observed differential toxicity of the APOL1 risk variants compared with the APOL1 nonrisk variants in S. cerevisiae, including impairment of vacuole acidification. Yeast strains defective in endosomal trafficking or organelle acidification but not those defective in autophagy displayed augmented APOL1 toxicity with all isoforms. This pattern of differential injury by the APOL1 risk alleles compared with the nonrisk alleles across evolutionarily divergent species is consistent with an impairment of conserved core intracellular endosomal trafficking processes. This finding should facilitate the identification of cell injury pathways and corresponding therapeutic targets of interest in these amenable experimental platforms.
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Affiliation(s)
- Etty Kruzel-Davila
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Departments of
| | | | - Ayala Ofir
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Departments of
| | - Ira Bavli-Kertselli
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Departments of
| | | | - Pazit Oren-Giladi
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Departments of
| | - Walter G Wasser
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Departments of.,Department of Nephrology, Mayanei HaYeshua Medical Center, Bnei Brak, Israel
| | - Daniella Magen
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Departments of.,Genetics and Developmental Biology and
| | | | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel; and
| | | | - Daniel Kornitzer
- Microbiology and Inflammation, Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Zvonimir Marelja
- Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, Paris, France
| | - Matias Simons
- Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, Paris, France
| | - Karl Skorecki
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Departments of .,Genetics and Developmental Biology and
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75
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Fu Y, Zhu JY, Richman A, Zhang Y, Xie X, Das JR, Li J, Ray PE, Han Z. APOL1-G1 in Nephrocytes Induces Hypertrophy and Accelerates Cell Death. J Am Soc Nephrol 2016; 28:1106-1116. [PMID: 27864430 DOI: 10.1681/asn.2016050550] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 10/09/2016] [Indexed: 01/17/2023] Open
Abstract
People of African ancestry carrying certain APOL1 mutant alleles are at elevated risk of developing renal diseases. However, the mechanisms underlying APOL1-associated renal diseases are unknown. Because the APOL1 gene is unique to humans and some primates, new animal models are needed to understand the function of APOL1 in vivo We generated transgenic Drosophila fly lines expressing the human APOL1 wild type allele (G0) or the predominant APOL1 risk allele (G1) in different tissues. Ubiquitous expression of APOL1 G0 or G1 in Drosophila induced lethal phenotypes, and G1 was more toxic than was G0. Selective expression of the APOL1 G0 or G1 transgene in nephrocytes, fly cells homologous to mammalian podocytes, induced increased endocytic activity and accumulation of hemolymph proteins, dextran particles, and silver nitrate. As transgenic flies with either allele aged, nephrocyte function declined, cell size increased, and nephrocytes died prematurely. Compared with G0-expressing cells, however, G1-expressing cells showed more dramatic phenotypes, resembling those observed in cultured mammalian podocytes overexpressing APOL1-G1. Expressing the G0 or G1 APOL1 transgene in nephrocytes also impaired the acidification of organelles. We conclude that expression of an APOL1 transgene initially enhances nephrocyte function, causing hypertrophy and subsequent cell death. This new Drosophila model uncovers a novel mechanism by which upregulated expression of APOL1-G1 could precipitate renal disease in humans. Furthermore, this model may facilitate the identification of APOL1-interacting molecules that could serve as new drug targets to treat APOL1-associated renal diseases.
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Affiliation(s)
- Yulong Fu
- Center for Cancer and Immunology Research, Washington, DC
| | - Jun-Yi Zhu
- Center for Cancer and Immunology Research, Washington, DC
| | - Adam Richman
- Center for Cancer and Immunology Research, Washington, DC
| | - Yi Zhang
- Center for Cancer and Immunology Research, Washington, DC.,Center for Genetic Medicine Research, Washington, DC
| | - Xuefang Xie
- Center for Genetic Medicine Research, Washington, DC
| | - Jharna R Das
- Center for Genetic Medicine Research, Washington, DC.,Division of Nephrology, Children's National Health Systems, Washington, DC; and.,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Jinliang Li
- Center for Genetic Medicine Research, Washington, DC.,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Patricio E Ray
- Center for Genetic Medicine Research, Washington, DC.,Division of Nephrology, Children's National Health Systems, Washington, DC; and.,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Zhe Han
- Center for Cancer and Immunology Research, Washington, DC; .,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC
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76
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Ettensohn CA, Dey D. KirrelL, a member of the Ig-domain superfamily of adhesion proteins, is essential for fusion of primary mesenchyme cells in the sea urchin embryo. Dev Biol 2016; 421:258-270. [PMID: 27866905 DOI: 10.1016/j.ydbio.2016.11.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 11/01/2016] [Accepted: 11/01/2016] [Indexed: 11/25/2022]
Abstract
In the sea urchin embryo, primary mesenchyme cells (PMCs) adhere to one another and fuse via filopodia, forming cable-like structures within which skeletal rods are deposited. Although this process was first described more than a century ago, molecules that participate in PMC adhesion and fusion have not been identified. Here we show that KirrelL, a PMC-specific, Ig domain-containing transmembrane protein, is essential for PMC fusion, probably by mediating filopodial adhesions that are a pre-requisite for subsequent membrane fusion. We show that KirrelL is not required for PMC specification, migration, or for direct filopodial contacts between PMCs. In the absence of KirrelL, however, filopodial contacts do not result in fusion. kirrelL is a member of a family of closely related, intronless genes that likely arose through an echinoid-specific gene expansion, possibly via retrotransposition. Our findings are significant in that they establish a direct linkage between the transcriptional network deployed in the PMC lineage and an effector molecule required for a critically important PMC morphogenetic process. In addition, our results point to a conserved role for Ig domain-containing adhesion proteins in facilitating cell fusion in both muscle and non-muscle cell lineages during animal development.
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Affiliation(s)
- Charles A Ettensohn
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, United States.
| | - Debleena Dey
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, United States
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77
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Lőrincz P, Lakatos Z, Varga Á, Maruzs T, Simon-Vecsei Z, Darula Z, Benkő P, Csordás G, Lippai M, Andó I, Hegedűs K, Medzihradszky KF, Takáts S, Juhász G. MiniCORVET is a Vps8-containing early endosomal tether in Drosophila. eLife 2016; 5. [PMID: 27253064 PMCID: PMC4935465 DOI: 10.7554/elife.14226] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 06/01/2016] [Indexed: 01/06/2023] Open
Abstract
Yeast studies identified two heterohexameric tethering complexes, which consist of 4 shared (Vps11, Vps16, Vps18 and Vps33) and 2 specific subunits: Vps3 and Vps8 (CORVET) versus Vps39 and Vps41 (HOPS). CORVET is an early and HOPS is a late endosomal tether. The function of HOPS is well known in animal cells, while CORVET is poorly characterized. Here we show that Drosophila Vps8 is highly expressed in hemocytes and nephrocytes, and localizes to early endosomes despite the lack of a clear Vps3 homolog. We find that Vps8 forms a complex and acts together with Vps16A, Dor/Vps18 and Car/Vps33A, and loss of any of these proteins leads to fragmentation of endosomes. Surprisingly, Vps11 deletion causes enlargement of endosomes, similar to loss of the HOPS-specific subunits Vps39 and Lt/Vps41. We thus identify a 4 subunit-containing miniCORVET complex as an unconventional early endosomal tether in Drosophila. DOI:http://dx.doi.org/10.7554/eLife.14226.001
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Affiliation(s)
- Péter Lőrincz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Zsolt Lakatos
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Ágnes Varga
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Tamás Maruzs
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsófia Simon-Vecsei
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsuzsanna Darula
- Laboratory of Proteomics Research, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Péter Benkő
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Gábor Csordás
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Mónika Lippai
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - István Andó
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Krisztina Hegedűs
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Katalin F Medzihradszky
- Laboratory of Proteomics Research, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Szabolcs Takáts
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary.,Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
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78
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On the Morphology of the Drosophila Heart. J Cardiovasc Dev Dis 2016; 3:jcdd3020015. [PMID: 29367564 PMCID: PMC5715677 DOI: 10.3390/jcdd3020015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/03/2016] [Accepted: 03/29/2016] [Indexed: 11/17/2022] Open
Abstract
The circulatory system of Drosophilamelanogaster represents an easily amenable genetic model whose analysis at different levels, i.e., from single molecules up to functional anatomy, has provided new insights into general aspects of cardiogenesis, heart physiology and cardiac aging, to name a few examples. In recent years, the Drosophila heart has also attracted the attention of researchers in the field of biomedicine. This development is mainly due to the fact that several genes causing human heart disease are also present in Drosophila, where they play the same or similar roles in heart development, maintenance or physiology as their respective counterparts in humans. This review will attempt to briefly introduce the anatomy of the Drosophila circulatory system and then focus on the different cell types and non-cellular tissue that constitute the heart.
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79
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Kuckwa J, Fritzen K, Buttgereit D, Rothenbusch-Fender S, Renkawitz-Pohl R. A new level of plasticity: Drosophila smooth-like testes muscles compensate failure of myoblast fusion. Development 2015; 143:329-38. [PMID: 26657767 PMCID: PMC4725342 DOI: 10.1242/dev.126730] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 11/28/2015] [Indexed: 12/26/2022]
Abstract
The testis of Drosophila resembles an individual testis tubule of mammals. Both are surrounded by a sheath of smooth muscles, which in Drosophila are multinuclear and originate from a pool of myoblasts that are set aside in the embryo and accumulate on the genital disc later in development. These muscle stem cells start to differentiate early during metamorphosis and give rise to all muscles of the inner male reproductive system. Shortly before the genital disc and the developing testes connect, multinuclear nascent myotubes appear on the anterior tips of the seminal vesicles. Here, we show that adhesion molecules are distinctly localized on the seminal vesicles; founder cell (FC)-like myoblasts express Dumbfounded (Duf) and Roughest (Rst), and fusion-competent myoblast (FCM)-like cells mainly express Sticks and stones (Sns). The smooth but multinuclear myotubes of the testes arose by myoblast fusion. RNAi-mediated attenuation of Sns or both Duf and Rst severely reduced the number of nuclei in the testes muscles. Duf and Rst probably act independently in this context. Despite reduced fusion in all of these RNAi-treated animals, myotubes migrated onto the testes, testes were shaped and coiled, muscle filaments were arranged as in the wild type and spermatogenesis proceeded normally. Hence, the testes muscles compensate for fusion defects so that the myofibres encircling the adult testes are indistinguishable from those of the wild type and male fertility is guaranteed. Summary:Drosophila testes muscles arise from stem cells and can compensate for fusion defects to safeguard fertility; this plasticity may compensate for the observed lack of satellite cells in Drosophila.
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Affiliation(s)
- Jessica Kuckwa
- Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany
| | - Katharina Fritzen
- Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany
| | - Detlev Buttgereit
- Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany
| | - Silke Rothenbusch-Fender
- Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany
| | - Renate Renkawitz-Pohl
- Philipps-Universität Marburg, Fachbereich Biologie, Entwicklungsbiologie, Karl-von-Frisch Strasse 8, Marburg 35043, Germany
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80
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Ichimura K, Sakai T. Evolutionary morphology of podocytes and primary urine-producing apparatus. Anat Sci Int 2015; 92:161-172. [PMID: 26627098 PMCID: PMC5315740 DOI: 10.1007/s12565-015-0317-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/14/2015] [Indexed: 01/27/2023]
Abstract
Excretory organs were acquired in the early phase of metazoan evolution, and they play a crucial role in the maintenance of homeostasis of body fluids. In general, these organs consist of two functional components, the primary-urine producing apparatus and the modulating tubule. This basic organization of the excretory organs is conserved among most metazoans. Herein, we present an overview of the morphological evolution of the primary urine-producing apparatus in metazoans and describe the acquisition of the renal glomerulus—a specialized primary urine-producing apparatus—in vertebrates. We also describe the advancement of the glomerular structure and function in higher vertebrates.
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Affiliation(s)
- Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
| | - Tatsuo Sakai
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
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81
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On the Ultrastructure and Function of Rhogocytes from the Pond Snail Lymnaea stagnalis. PLoS One 2015; 10:e0141195. [PMID: 26488403 PMCID: PMC4619347 DOI: 10.1371/journal.pone.0141195] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 10/06/2015] [Indexed: 11/19/2022] Open
Abstract
Rhogocytes, also termed "pore cells", occur as solitary or clustered cells in the connective tissue of gastropod molluscs. Rhogocytes possess an enveloping lamina of extracellular matrix and enigmatic extracellular lacunae bridged by cytoplasmic bars that form 20 nm diaphragmatic slits likely to act as a molecular sieve. Recent papers highlight the embryogenesis and ultrastructure of these cells, and their role in heavy metal detoxification. Rhogocytes are the site of hemocyanin or hemoglobin biosynthesis in gastropods. Based on electron microscopy, we recently proposed a possible pathway of hemoglobin exocytosis through the slit apparatus, and provided molecular evidence of a common phylogenetic origin of molluscan rhogocytes, insect nephrocytes and vertebrate podocytes. However, the previously proposed secretion mode of the respiratory proteins into the hemolymph is still rather hypothetical, and the possible role of rhogocytes in detoxification requires additional data. Although our previous study on rhogocytes of the red-blooded (hemoglobin-containing) freshwater snail Biomphalaria glabrata provided much new information, a disadvantage was that the hemoglobin molecules were not unequivocally defined in the electron microscope. This made it difficult to trace the exocytosis pathway of this protein. Therefore, we have now performed a similar study on the rhogocytes of the blue-blooded (hemocyanin-containing) freshwater snail Lymnaea stagnalis. The intracellular hemocyanin could be identified in the electron microscope, either as individual molecules or as pseudo-crystalline arrays. Based on 3D-electron microscopy, and supplemented by in situ hybridization, immunocytochemistry and stress response experiments, we provide here additional details on the structure and hemocyanin biosynthesis of rhogocytes, and on their response in animals under cadmium and starvation stress. Moreover, we present an advanced model on the release of synthesized hemocyanin molecules through the slit apparatus into the hemolymph, and the uptake of much smaller particles such as cadmium ions from the hemolymph through the slit apparatus into the cytoplasm.
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82
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Ivy JR, Drechsler M, Catterson JH, Bodmer R, Ocorr K, Paululat A, Hartley PS. Klf15 Is Critical for the Development and Differentiation of Drosophila Nephrocytes. PLoS One 2015; 10:e0134620. [PMID: 26301956 PMCID: PMC4547745 DOI: 10.1371/journal.pone.0134620] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 07/11/2015] [Indexed: 12/20/2022] Open
Abstract
Insect nephrocytes are highly endocytic scavenger cells that represent the only invertebrate model for the study of human kidney podocytes. Despite their importance, nephrocyte development is largely uncharacterised. This work tested whether the insect ortholog of mammalian Kidney Krüppel-Like Factor (Klf15), a transcription factor required for mammalian podocyte differentiation, was required for insect nephrocyte development. It was found that expression of Drosophila Klf15 (dKlf15, previously known as Bteb2) was restricted to the only two nephrocyte populations in Drosophila, the garland cells and pericardial nephrocytes. Loss of dKlf15 function led to attrition of both nephrocyte populations and sensitised larvae to the xenotoxin silver nitrate. Although pericardial nephrocytes in dKlf15 loss of function mutants were specified during embryogenesis, they failed to express the slit diaphragm gene sticks and stones and did not form slit diaphragms. Conditional silencing of dKlf15 in adults led to reduced surface expression of the endocytic receptor Amnionless and loss of in vivo scavenger function. Over-expression of dKlf15 increased nephrocyte numbers and rescued age-dependent decline in nephrocyte function. The data place dKlf15 upstream of sns and Amnionless in a nephrocyte-restricted differentiation pathway and suggest dKlf15 expression is both necessary and sufficient to sustain nephrocyte differentiation. These findings explain the physiological relevance of dKlf15 in Drosophila and imply that the role of KLF15 in human podocytes is evolutionarily conserved.
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Affiliation(s)
- Jessica R. Ivy
- University of Edinburgh / British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, 47 Little France Crescent, Edinburgh, EH16 4TJ, United Kingdom
| | - Maik Drechsler
- Department of Zoology & Developmental Biology, University of Osnabrück, Barbarastr. 11, D-49069 Osnabrück, Germany
| | - James H. Catterson
- University of Edinburgh / British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, 47 Little France Crescent, Edinburgh, EH16 4TJ, United Kingdom
| | - Rolf Bodmer
- Neuroscience and Aging Research Center, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, United States of America
| | - Karen Ocorr
- Neuroscience and Aging Research Center, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, United States of America
| | - Achim Paululat
- Department of Zoology & Developmental Biology, University of Osnabrück, Barbarastr. 11, D-49069 Osnabrück, Germany
| | - Paul S. Hartley
- Department of Life and Environmental Science, University of Bournemouth, Talbot Campus, Poole, Dorset BH12 5BB, United Kingdom
- * E-mail:
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83
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Na J, Sweetwyne MT, Park ASD, Susztak K, Cagan RL. Diet-Induced Podocyte Dysfunction in Drosophila and Mammals. Cell Rep 2015; 12:636-47. [PMID: 26190114 DOI: 10.1016/j.celrep.2015.06.056] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 05/15/2015] [Accepted: 06/17/2015] [Indexed: 01/15/2023] Open
Abstract
Diabetic nephropathy is a major cause of end-stage kidney disease. Characterized by progressive microvascular disease, most efforts have focused on injury to the glomerular endothelium. Recent work has suggested a role for the podocyte, a highly specialized component of the glomerular filtration barrier. Here, we demonstrate that the Drosophila nephrocyte, a cell analogous to the mammalian podocyte, displays defects that phenocopy aspects of diabetic nephropathy in animals fed chronic high dietary sucrose. Through functional studies, we identify an OGT-Polycomb-Knot-Sns pathway that links dietary sucrose to loss of the Nephrin ortholog Sns. Reducing OGT through genetic or drug means is sufficient to rescue loss of Sns, leading to overall extension of lifespan. We demonstrate upregulation of the Knot ortholog EBF2 in glomeruli of human diabetic nephropathy patients and a mouse ob/ob diabetes model. Furthermore, we demonstrate rescue of Nephrin expression and cell viability in ebf2(-/-) primary podocytes cultured in high glucose.
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Affiliation(s)
- Jianbo Na
- Department of Developmental and Regenerative Biology and School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029-1020, USA
| | - Mariya T Sweetwyne
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, 405B Clinical Research Building, Philadelphia, PA 19104-4539, USA
| | - Ae Seo Deok Park
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, 405B Clinical Research Building, Philadelphia, PA 19104-4539, USA
| | - Katalin Susztak
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, 405B Clinical Research Building, Philadelphia, PA 19104-4539, USA
| | - Ross L Cagan
- Department of Developmental and Regenerative Biology and School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029-1020, USA.
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84
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Thi-Kim Vu H, Rink JC, McKinney SA, McClain M, Lakshmanaperumal N, Alexander R, Sánchez Alvarado A. Stem cells and fluid flow drive cyst formation in an invertebrate excretory organ. eLife 2015; 4:e07405. [PMID: 26057828 PMCID: PMC4500094 DOI: 10.7554/elife.07405] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 06/09/2015] [Indexed: 12/29/2022] Open
Abstract
Cystic kidney diseases (CKDs) affect millions of people worldwide. The defining pathological features are fluid-filled cysts developing from nephric tubules due to defective flow sensing, cell proliferation and differentiation. The underlying molecular mechanisms, however, remain poorly understood, and the derived excretory systems of established invertebrate models (Caenorhabditis elegans and Drosophila melanogaster) are unsuitable to model CKDs. Systematic structure/function comparisons revealed that the combination of ultrafiltration and flow-associated filtrate modification that is central to CKD etiology is remarkably conserved between the planarian excretory system and the vertebrate nephron. Consistently, both RNA-mediated genetic interference (RNAi) of planarian orthologues of human CKD genes and inhibition of tubule flow led to tubular cystogenesis that share many features with vertebrate CKDs, suggesting deep mechanistic conservation. Our results demonstrate a common evolutionary origin of animal excretory systems and establish planarians as a novel and experimentally accessible invertebrate model for the study of human kidney pathologies.
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Affiliation(s)
- Hanh Thi-Kim Vu
- Stowers Institute for Medical Research, Kansas City, United States
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, United States
| | - Jochen C Rink
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Sean A McKinney
- Stowers Institute for Medical Research, Kansas City, United States
| | - Melainia McClain
- Stowers Institute for Medical Research, Kansas City, United States
| | | | | | - Alejandro Sánchez Alvarado
- Stowers Institute for Medical Research, Kansas City, United States
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, United States
- Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States
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85
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Gee HY, Zhang F, Ashraf S, Kohl S, Sadowski CE, Vega-Warner V, Zhou W, Lovric S, Fang H, Nettleton M, Zhu JY, Hoefele J, Weber LT, Podracka L, Boor A, Fehrenbach H, Innis JW, Washburn J, Levy S, Lifton RP, Otto EA, Han Z, Hildebrandt F. KANK deficiency leads to podocyte dysfunction and nephrotic syndrome. J Clin Invest 2015; 125:2375-84. [PMID: 25961457 DOI: 10.1172/jci79504] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 04/16/2015] [Indexed: 01/28/2023] Open
Abstract
Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of progressive renal function decline and affects millions of people. In a recent study, 30% of SRNS cases evaluated were the result of monogenic mutations in 1 of 27 different genes. Here, using homozygosity mapping and whole-exome sequencing, we identified recessive mutations in kidney ankyrin repeat-containing protein 1 (KANK1), KANK2, and KANK4 in individuals with nephrotic syndrome. In an independent functional genetic screen of Drosophila cardiac nephrocytes, which are equivalents of mammalian podocytes, we determined that the Drosophila KANK homolog (dKank) is essential for nephrocyte function. RNAi-mediated knockdown of dKank in nephrocytes disrupted slit diaphragm filtration structures and lacuna channel structures. In rats, KANK1, KANK2, and KANK4 all localized to podocytes in glomeruli, and KANK1 partially colocalized with synaptopodin. Knockdown of kank2 in zebrafish recapitulated a nephrotic syndrome phenotype, resulting in proteinuria and podocyte foot process effacement. In rat glomeruli and cultured human podocytes, KANK2 interacted with ARHGDIA, a known regulator of RHO GTPases in podocytes that is dysfunctional in some types of nephrotic syndrome. Knockdown of KANK2 in cultured podocytes increased active GTP-bound RHOA and decreased migration. Together, these data suggest that KANK family genes play evolutionarily conserved roles in podocyte function, likely through regulating RHO GTPase signaling.
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86
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Li Y, Zheng R, Wang R, Lu X, Zhu C, Lin HY, Wang H, Yu X, Fu J. Involvement of nephrin in human placental trophoblast syncytialization. Reproduction 2015; 149:339-46. [DOI: 10.1530/rep-14-0424] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The placenta has numerous functions, such as transporting oxygen and nutrients and building the immune tolerance of the fetus. Cell fusion is an essential process for placental development and maturation. In human placental development, mononucleated cytotrophoblast (CTB) cells can fuse to form a multinucleated syncytiotrophoblast (STB), which is the outermost layer of the placenta. Nephrin is a transmembrane protein that belongs to the Ig superfamily. Previous studies have shown that nephrin contributes to the fusion of myoblasts into myotubes in zebrafish and mice, presenting a functional conservation with its Drosophila ortholog sticks and stones. However, whether nephrin is involved in trophoblast syncytialization remains unclear. In this study, we report that nephrin was localized predominantly in the CTB cells and STB of human placenta villi from first trimester to term pregnancy. Using a spontaneous fusion model of primary CTB cells, the expression of nephrin was found to be increased during trophoblast cell fusion. Moreover, the spontaneous syncytialization and the expression of syncytin 2, connexin 43, and human chorionic gonadotropin beta were significantly inhibited by nephrin-specific siRNAs. The above results demonstrate that nephrin plays an important role in trophoblast syncytialization.
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87
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Abstract
Many of the major discoveries in the fields of genetics and developmental biology have been made using the fruit fly, Drosophila melanogaster. With regard to heart development, the conserved network of core cardiac transcription factors that underlies cardiogenesis has been studied in great detail in the fly, and the importance of several signaling pathways that regulate heart morphogenesis, such as Slit/Robo, was first shown in the fly model. Recent technological advances have led to a large increase in the genomic data available from patients with congenital heart disease (CHD). This has highlighted a number of candidate genes and gene networks that are potentially involved in CHD. To validate genes and genetic interactions among candidate CHD-causing alleles and to better understand heart formation in general are major tasks. The specific limitations of the various cardiac model systems currently employed (mammalian and fish models) provide a niche for the fly model, despite its evolutionary distance to vertebrates and humans. Here, we review recent advances made using the Drosophila embryo that identify factors relevant for heart formation. These underline how this model organism still is invaluable for a better understanding of CHD.
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88
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Andreenkova OV, Karpova EK, Menshanov PN, Rauschenbach IY. Knockdown of InR gene in ventral nephrocytes promotes resistance to toxic stress in Drosophila melanogaster females. RUSS J GENET+ 2015. [DOI: 10.1134/s1022795415020027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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89
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Nakamura T, Takagi S, Matsumoto M, Tashiro F, Sakai T, Ichimura K. Expression of Nephrin Homologue in the Freshwater Planarian, Dugesia japonica. Acta Histochem Cytochem 2014; 47:303-10. [PMID: 25859064 PMCID: PMC4387267 DOI: 10.1267/ahc.14044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 11/04/2014] [Indexed: 12/20/2022] Open
Abstract
Excretory organs contain epithelial cells that form a filtration membrane specialized for ultrafiltration to produce primary urine. In vertebrates, the filtration membrane is made up of slit diaphragm (SD) formed by glomerular podocytes. Basal metazoans such as flatworms are also known have filtration epithelial cells, called flame cells, which exhibit SD-like structures. The molecular components of podocyte SD have been studied in detail, while those of the SD-like structures in basal metazoans including flatworms remain to be clarified. To determine whether the SD-like structures in flatworms have molecular components common to the SD in vertebrate podocytes, we examined the expression of gene homologue for mammalian nephrin, which encodes an essential transmembrane protein that participates in the formation of the SD, in a species of flatworms, planarian (Dugesia japonica). Flame cells were distributed throughout the entire body of the planarian, but the nephrin-expressing cells identified by in situ hybridization were mainly detected at body periphery excluding head region. The distribution pattern of nephrin-expressing cells was similar to that of proliferating cell nuclear antigen-expressing neoblasts, which are pluripotent stem cells characteristic to planarians. These findings indicated that the SD-like structures can be formed without the Nephrin protein in planarian flame cells.
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Affiliation(s)
- Tomomi Nakamura
- Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science
- Department of Anatomy and Life Structure, Juntendo University School of Medicine
| | - Sota Takagi
- Department of Biological Sciences and Informatics, Keio University
| | - Midori Matsumoto
- Department of Biological Sciences and Informatics, Keio University
| | - Fumio Tashiro
- Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science
| | - Tatsuo Sakai
- Department of Anatomy and Life Structure, Juntendo University School of Medicine
| | - Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University School of Medicine
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90
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Haralalka S, Shelton C, Cartwright HN, Guo F, Trimble R, Kumar RP, Abmayr SM. Live imaging provides new insights on dynamic F-actin filopodia and differential endocytosis during myoblast fusion in Drosophila. PLoS One 2014; 9:e114126. [PMID: 25474591 PMCID: PMC4256407 DOI: 10.1371/journal.pone.0114126] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 10/28/2014] [Indexed: 11/29/2022] Open
Abstract
The process of myogenesis includes the recognition, adhesion, and fusion of committed myoblasts into multinucleate syncytia. In the larval body wall muscles of Drosophila, this elaborate process is initiated by Founder Cells and Fusion-Competent Myoblasts (FCMs), and cell adhesion molecules Kin-of-IrreC (Kirre) and Sticks-and-stones (Sns) on their respective surfaces. The FCMs appear to provide the driving force for fusion, via the assembly of protrusions associated with branched F-actin and the WASp, SCAR and Arp2/3 pathways. In the present study, we utilize the dorsal pharyngeal musculature that forms in the Drosophila embryo as a model to explore myoblast fusion and visualize the fusion process in live embryos. These muscles rely on the same cell types and genes as the body wall muscles, but are amenable to live imaging since they do not undergo extensive morphogenetic movement during formation. Time-lapse imaging with F-actin and membrane markers revealed dynamic FCM-associated actin-enriched protrusions that rapidly extend and retract into the myotube from different sites within the actin focus. Ultrastructural analysis of this actin-enriched area showed that they have two morphologically distinct structures: wider invasions and/or narrow filopodia that contain long linear filaments. Consistent with this, formin Diaphanous (Dia) and branched actin nucleator, Arp3, are found decorating the filopodia or enriched at the actin focus, respectively, indicating that linear actin is present along with branched actin at sites of fusion in the FCM. Gain-of-function Dia and loss-of-function Arp3 both lead to fusion defects, a decrease of F-actin foci and prominent filopodia from the FCMs. We also observed differential endocytosis of cell surface components at sites of fusion, with actin reorganizing factors, WASp and SCAR, and Kirre remaining on the myotube surface and Sns preferentially taken up with other membrane proteins into early endosomes and lysosomes in the myotube.
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Affiliation(s)
- Shruti Haralalka
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Claude Shelton
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Heather N. Cartwright
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Fengli Guo
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Rhonda Trimble
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Ram P. Kumar
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Susan M. Abmayr
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, Kansas, 66160, United States of America
- * E-mail:
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91
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Montgomery SL, Vorojeikina D, Huang W, Mackay TFC, Anholt RRH, Rand MD. Genome-wide association analysis of tolerance to methylmercury toxicity in Drosophila implicates myogenic and neuromuscular developmental pathways. PLoS One 2014; 9:e110375. [PMID: 25360876 PMCID: PMC4215868 DOI: 10.1371/journal.pone.0110375] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 09/11/2014] [Indexed: 11/30/2022] Open
Abstract
Methylmercury (MeHg) is a persistent environmental toxin present in seafood that can compromise the developing nervous system in humans. The effects of MeHg toxicity varies among individuals, despite similar levels of exposure, indicating that genetic differences contribute to MeHg susceptibility. To examine how genetic variation impacts MeHg tolerance, we assessed developmental tolerance to MeHg using the sequenced, inbred lines of the Drosophila melanogaster Genetic Reference Panel (DGRP). We found significant genetic variation in the effects of MeHg on development, measured by eclosion rate, giving a broad sense heritability of 0.86. To investigate the influence of dietary factors, we measured MeHg toxicity with caffeine supplementation in the DGRP lines. We found that caffeine counteracts the deleterious effects of MeHg in the majority of lines, and there is significant genetic variance in the magnitude of this effect, with a broad sense heritability of 0.80. We performed genome-wide association (GWA) analysis for both traits, and identified candidate genes that fall into several gene ontology categories, with enrichment for genes involved in muscle and neuromuscular development. Overexpression of glutamate-cysteine ligase, a MeHg protective enzyme, in a muscle-specific manner leads to a robust rescue of eclosion of flies reared on MeHg food. Conversely, mutations in kirre, a pivotal myogenic gene identified in our GWA analyses, modulate tolerance to MeHg during development in accordance with kirre expression levels. Finally, we observe disruptions of indirect flight muscle morphogenesis in MeHg-exposed pupae. Since the pathways for muscle development are evolutionarily conserved, it is likely that the effects of MeHg observed in Drosophila can be generalized across phyla, implicating muscle as an additional hitherto unrecognized target for MeHg toxicity. Furthermore, our observations that caffeine can ameliorate the toxic effects of MeHg show that nutritional factors and dietary manipulations may offer protection against the deleterious effects of MeHg exposure.
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Affiliation(s)
- Sara L. Montgomery
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Daria Vorojeikina
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Wen Huang
- Department of Biological Sciences, Genetics Program, and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Trudy F. C. Mackay
- Department of Biological Sciences, Genetics Program, and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Robert R. H. Anholt
- Department of Biological Sciences, Genetics Program, and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Matthew D. Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
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92
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Affiliation(s)
- Fujian Zhang
- Department of Nephrology, Chinese PLA General Hospital, State Key Laboratory of Kidney Diseases, National Clinical Research Center of Kidney Diseases, 28 Fuxing Road, Beijing 100853, China
| | - Xiangmei Chen
- Department of Nephrology, Chinese PLA General Hospital, State Key Laboratory of Kidney Diseases, National Clinical Research Center of Kidney Diseases, 28 Fuxing Road, Beijing 100853, China
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93
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Zhang F, Chen X. The Drosophila nephrocyte has a glomerular filtration system. Nat Rev Nephrol 2014. [DOI: 10.1038/nrneph.2014.290-c1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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94
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Abstract
The description of the Rst protein by Karl-Friedrich Fischbach and colleagues was a milestone in the discovery of the irre cell recognition module (IRM). IRM proteins represent a family of immunoglobulin superfamily cell adhesion proteins that orchestrate intercellular adhesion and signaling events necessary for the development of various tissues. This review briefly summarizes the fundamental role of IRM proteins for neuronal wiring and filtration in organisms spanning the evolutionary distance from Drosophila (nephrocyte diaphragm) to humans (slit diaphragm).
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95
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Kokkinopoulou M, Güler MA, Lieb B, Barbeck M, Ghanaati S, Markl J. 3D-ultrastructure, functions and stress responses of gastropod (Biomphalaria glabrata) rhogocytes. PLoS One 2014; 9:e101078. [PMID: 24971744 PMCID: PMC4074132 DOI: 10.1371/journal.pone.0101078] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 06/03/2014] [Indexed: 11/18/2022] Open
Abstract
Rhogocytes are pore cells scattered among the connective tissue of different body parts of gastropods and other molluscs, with great variation in their number, shape and size. They are enveloped by a lamina of extracellular matrix. Their most characteristic feature is the "slit apparatus", local invaginations of the plasma membrane bridged by cytoplasmic bars, forming slits of ca. 20 nm width. A slit diaphragm creates a molecular sieve with permeation holes of 20×20 nm. In blue-blooded gastropods, rhogocytes synthesize and secrete the respiratory protein hemocyanin, and it has been proposed-though not proven-that in the rare red-blooded snail species they might synthesize and secrete the hemoglobin. However, the cellular secretion pathway for respiratory proteins, and the functional role(s) of the enigmatic rhogocyte slit apparatus are still unclear. Additional functions for rhogocytes have been proposed, notably a role in protein uptake and degradation, and in heavy metal detoxification. Here we provide new structural and functional information on the rhogocytes of the red-blooded freshwater snail Biomphalaria glabrata. By in situ hybridization of mantle tissues, we prove that rhogocytes indeed synthesize hemoglobin. By electron tomography, the first three dimensional (3D) reconstructions of the slit apparatus are provided, showing detail of highly dense material in the cytoplasmic bars close to the slits. By immunogold labelling, we collected evidence that a major component of this material is actin. By genome databank mining, the complete sequence of a B. glabrata nephrin was obtained, and localized to the rhogocytes by immunofluorescence microscopy. The presence of both proteins fit the ultrastructure-based hypothesis that rhogocytes are related to mammalian podocytes and insect nephrocytes. Reactions of the rhogocytes to deprivation of food and cadmium toxification are also documented, and a possible secretion pathway of newly synthesized respiratory proteins through the slit apparatus is discussed.
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Affiliation(s)
| | | | - Bernhard Lieb
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - Mike Barbeck
- Institute of Pathology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Shahram Ghanaati
- Institute of Pathology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Jürgen Markl
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
- * E-mail:
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96
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ROS regulate cardiac function via a distinct paracrine mechanism. Cell Rep 2014; 7:35-44. [PMID: 24656823 PMCID: PMC4164050 DOI: 10.1016/j.celrep.2014.02.029] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/10/2014] [Accepted: 02/20/2014] [Indexed: 02/07/2023] Open
Abstract
Reactive oxygen species (ROS) can act cell autonomously and in a paracrine manner by diffusing into nearby cells. Here, we reveal a ROS-mediated paracrine signaling mechanism that does not require entry of ROS into target cells. We found that under physiological conditions, nonmyocytic pericardial cells (PCs) of the Drosophila heart contain elevated levels of ROS compared to the neighboring cardiomyocytes (CMs). We show that ROS in PCs act in a paracrine manner to regulate normal cardiac function, not by diffusing into the CMs to exert their function, but by eliciting a downstream D-MKK3-D-p38 MAPK signaling cascade in PCs that acts on the CMs to regulate their function. We find that ROS-D-p38 signaling in PCs during development is also important for establishing normal adult cardiac function. Our results provide evidence for a previously unrecognized role of ROS in mediating PC/CM interactions that significantly modulates heart function.
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97
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Lennon R, Randles MJ, Humphries MJ. The importance of podocyte adhesion for a healthy glomerulus. Front Endocrinol (Lausanne) 2014; 5:160. [PMID: 25352829 PMCID: PMC4196579 DOI: 10.3389/fendo.2014.00160] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/21/2014] [Indexed: 12/23/2022] Open
Abstract
Podocytes are specialized epithelial cells that cover the outer surfaces of glomerular capillaries. Unique cell junctions, known as slit diaphragms, which feature nephrin and Neph family proteins in addition to components of adherens, tight, and gap junctions, connect adjacent podocyte foot processes. Single gene disorders affecting the slit diaphragm result in nephrotic syndrome in humans, characterized by massive loss of protein across the capillary wall. In addition to specialized cell junctions, interconnecting podocytes also adhere to the glomerular basement membrane (GBM) of the capillary wall. The GBM is a dense network of secreted, extracellular matrix (ECM) components and contains tissue-restricted isoforms of collagen IV and laminin in addition to other structural proteins and ECM regulators such as proteases and growth factors. The specialized niche of the GBM provides a scaffold for endothelial cells and podocytes to support their unique functions and human genetic mutations in GBM components lead to renal failure, thus highlighting the importance of cell-matrix interactions in the glomerulus. Cells adhere to ECM via adhesion receptors, including integrins, syndecans, and dystroglycan and in particular the integrin heterodimer α3β1 is required to maintain barrier integrity. Therefore, the sophisticated function of glomerular filtration relies on podocyte adhesion both at cell junctions and at the interface with the ECM. In health, the podocyte coordinates signals from cell junctions and cell-matrix interactions, in response to environmental cues in order to regulate filtration and as our understanding of mechanisms that control cell adhesion in the glomerulus develops, then insight into the effects of disease will improve. The ultimate goal will be to develop targeted therapies to prevent or repair defects in the filtration barrier and to restore glomerular function.
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Affiliation(s)
- Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
- Department of Paediatric Nephrology, Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK
- *Correspondence: Rachel Lennon, Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Michael Smith Building, Manchester M13 9PT, UK e-mail:
| | - Michael J. Randles
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
| | - Martin J. Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
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98
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Laurin M, Dumouchel A, Fukui Y, Côté JF. The Rac-specific exchange factors Dock1 and Dock5 are dispensable for the establishment of the glomerular filtration barrier in vivo. Small GTPases 2013; 4:221-30. [PMID: 24365888 DOI: 10.4161/sgtp.27430] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Podocytes are specialized kidney cells that form the kidney filtration barrier through the connection of their foot processes. Nephrin and Neph family transmembrane molecules at the surface of podocytes interconnect to form a unique type of cell-cell junction, the slit diaphragm, which acts as a molecular sieve. The cytoplasmic tails of Nephrin and Neph mediate cytoskeletal rearrangement that contributes to the maintenance of the filtration barrier. Nephrin and Neph1 orthologs are essential to regulate cell-cell adhesion and Rac-dependent actin rearrangement during Drosophila myoblast fusion. We hypothesized here that molecules regulating myoblast fusion in Drosophila could contribute to signaling downstream of Nephrin and Neph1 in podocytes. We found that Nephrin engagement promoted recruitment of the Rac exchange factor Dock1 to the membrane. Furthermore, Nephrin overexpression led to lamellipodia formation that could be blocked by inhibiting Rac1 activity. We generated in vivo mouse models to investigate whether Dock1 and Dock5 contribute to the formation and maintenance of the kidney filtration barrier. Our results indicate that while Dock1 and Dock5 are expressed in podocytes, their functions are not essential for the development of the glomerular filtration barrier. Furthermore, mice lacking Dock1 were not protected from LPS-induced podocyte effacement. Our data suggest that Dock1 and Dock5 are not the important exchange factors regulating Rac activity during the establishment and maintenance of the glomerular barrier.
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Affiliation(s)
- Mélanie Laurin
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada; Département de Médecine (Programmes de Biologie Moléculaire); Université de Montréal; Montréal, QC, Canada
| | - Annie Dumouchel
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada
| | - Yoshinori Fukui
- Division of Immunogenetics; Department of Immunobiology and Neuroscience; Medical Institute of Bioregulation; Kyushu University; Fukuoda, Japan
| | - Jean-François Côté
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada; Département de Médecine (Programmes de Biologie Moléculaire); Université de Montréal; Montréal, QC, Canada; Département de Biochimie; Université de Montréal; Montréal, QC, Canada; Division of Experimental Medicine; McGill University; Montréal, QC, Canada
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Tutor AS, Prieto-Sánchez S, Ruiz-Gómez M. Src64B phosphorylates Dumbfounded and regulates slit diaphragm dynamics: Drosophila as a model to study nephropathies. Development 2013; 141:367-76. [PMID: 24335255 DOI: 10.1242/dev.099408] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Drosophila nephrocytes are functionally homologous to vertebrate kidney podocytes. Both share the presence of slit diaphragms that function as molecular filters during the process of blood and haemolymph ultrafiltration. The protein components of the slit diaphragm are likewise conserved between flies and humans, but the mechanisms that regulate slit diaphragm dynamics in response to injury or nutritional changes are still poorly characterised. Here, we show that Dumbfounded/Neph1, a key diaphragm constituent, is a target of the Src kinase Src64B. Loss of Src64B activity leads to a reduction in the number of diaphragms, and this effect is in part mediated by loss of Dumbfounded/Neph1 tyrosine phosphorylation. The phosphorylation of Duf by Src64B, in turn, regulates Duf association with the actin regulator Dock. We also find that diaphragm damage induced by administration of the drug puromycin aminonucleoside (PAN model) directly associates with Src64B hyperactivation, suggesting that diaphragm stability is controlled by Src-dependent phosphorylation of diaphragm components. Our findings indicate that the balance between diaphragm damage and repair is controlled by Src-dependent phosphorylation of diaphragm components, and point to Src family kinases as novel targets for the development of pharmacological therapies for the treatment of kidney diseases that affect the function of the glomerular filtration barrier.
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Affiliation(s)
- Antonio S Tutor
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, 28049, Madrid, Spain
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100
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Grahammer F, Schell C, Huber TB. The podocyte slit diaphragm--from a thin grey line to a complex signalling hub. Nat Rev Nephrol 2013; 9:587-98. [PMID: 23999399 DOI: 10.1038/nrneph.2013.169] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The architectural design of our kidneys is amazingly complex, and culminates in the 3D structure of the glomerular filter. During filtration, plasma passes through a sieve consisting of a fenestrated endothelium and a broad basement membrane before it reaches the most unique part, the slit diaphragm, a specialized type of intercellular junction that connects neighbouring podocyte foot processes. When podocytes become stressed, irrespective of the causative stimulus, they undergo foot process effacement and loss of slit diaphragms--two key steps leading to proteinuria. Thus, proteinuria is the unifying denominator of a broad spectrum of podocytopathies. With the rising prevalence of chronic kidney disease and the fact that glomerular diseases account for the majority of patients with end-stage renal disease, further investigation and elucidation of this unique structure is of paramount importance. This Review recounts how perception of the slit diaphragm has changed over time as a result of intense research, from its first anatomical description as a thin intercellular connection, to an appreciation of its role as a dynamic signalling hub. These observations led to the introduction of novel concepts in podocyte biology, which could pave the way to development of highly desired, specific therapeutic strategies for glomerular diseases.
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Affiliation(s)
- Florian Grahammer
- Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, Freiburg 79106, Germany
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