@article {502, title = { and Mutations Implicate RAB5 Regulation in Nephrotic Syndrome.}, journal = {J Am Soc Nephrol}, volume = {29}, year = {2018}, month = {2018 Aug}, pages = {2123-2138}, 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 functional significance of two genes and the mutations therein that we discovered through this sequencing and conducted complementary studies in podocyte-like nephrocytes.

RESULTS: We identified conserved, homozygous missense mutations of in two families with early-onset NS and a homozygous missense mutation of 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 or 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 mutations reduced nephrin-GAPVD1 binding affinity. In , silencing impaired endocytosis and caused mistrafficking of the nephrin ortholog.

CONCLUSIONS: Mutations in and probably in are novel monogenic causes of NS. The discovery of these genes implicates RAB5 regulation in the pathogenesis of human NS.

}, issn = {1533-3450}, doi = {10.1681/ASN.2017121312}, author = {Hermle, Tobias and Schneider, Ronen and Schapiro, David and Braun, Daniela A and van der Ven, Amelie T and Warejko, Jillian K and Daga, Ankana and Widmeier, Eugen and Nakayama, Makiko and Jobst-Schwan, Tilman and Majmundar, Amar J and Ashraf, Shazia and Rao, Jia and Finn, Laura S and Tasic, Velibor and Hernandez, Joel D and Bagga, Arvind and Jalalah, Sawsan M and El Desoky, Sherif and Kari, Jameela A and Laricchia, Kristen M and Lek, Monkol and Rehm, Heidi L and MacArthur, Daniel G and Mane, Shrikant and Lifton, Richard P and Shril, Shirlee and Hildebrandt, Friedhelm} } @article {611, title = {Mutations in WDR4 as a new cause of Galloway-Mowat syndrome.}, journal = {Am J Med Genet A}, volume = {176}, year = {2018}, month = {2018 Nov}, pages = {2460-2465}, abstract = {

Galloway-Mowat syndrome (GAMOS) is a phenotypically heterogeneous disorder characterized by neurodevelopmental defects combined with renal-glomerular disease, manifesting with proteinuria. To identify additional monogenic disease causes, we here performed whole exome sequencing (WES), linkage analysis, and homozygosity mapping in three affected siblings of an Indian family with GAMOS. Applying established criteria for variant filtering, we identify a novel homozygous splice site mutation in the gene WDR4 as the likely disease-causing mutation in this family. In line with previous reports, we observe growth deficiency, microcephaly, developmental delay, and intellectual disability as phenotypic features resulting from WDR4 mutations. However, the newly identified allele additionally gives rise to proteinuria and nephrotic syndrome, a phenotype that was never reported in patients with WDR4 mutations. Our data thus expand the phenotypic spectrum of WDR4 mutations by demonstrating that, depending on the specific mutated allele, a renal phenotype may be present. This finding suggests that GAMOS may occupy a phenotypic spectrum with other microcephalic diseases. Furthermore, WDR4 is an additional example of a gene that encodes a tRNA modifying enzyme and gives rise to GAMOS, if mutated. Our findings thereby support the recent observation that, like neurons, podocytes of the renal glomerulus are particularly vulnerable to cellular defects resulting from altered tRNA modifications.

}, issn = {1552-4833}, doi = {10.1002/ajmg.a.40489}, author = {Braun, Daniela A and Shril, Shirlee and Sinha, Aditi and Schneider, Ronen and Tan, Weizhen and Ashraf, Shazia and Hermle, Tobias and Jobst-Schwan, Tilman and Widmeier, Eugen and Majmundar, Amar J and Daga, Ankana and Warejko, Jillian K and Nakayama, Makiko and Schapiro, David and Chen, Jing and Airik, Merlin and Rao, Jia and Schmidt, Johanna Magdalena and Hoogstraten, Charlotte A and Hugo, Hannah and Meena, Jitendra and Lek, Monkol and Laricchia, Kristen M and Bagga, Arvind and Hildebrandt, Friedhelm} } @article {457, title = {Advillin acts upstream of phospholipase C ϵ1 in steroid-resistant nephrotic syndrome.}, journal = {J Clin Invest}, volume = {127}, year = {2017}, month = {2017 12 01}, pages = {4257-4269}, abstract = {

Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of chronic kidney disease. Here, we identified recessive mutations in the gene encoding the actin-binding protein advillin (AVIL) in 3 unrelated families with SRNS. While all AVIL mutations resulted in a marked loss of its actin-bundling ability, truncation of AVIL also disrupted colocalization with F-actin, thereby leading to impaired actin binding and severing. Additionally, AVIL colocalized and interacted with the phospholipase enzyme PLCE1 and with the ARP2/3 actin-modulating complex. Knockdown of AVIL in human podocytes reduced actin stress fibers at the cell periphery, prevented recruitment of PLCE1 to the ARP3-rich lamellipodia, blocked EGF-induced generation of diacylglycerol (DAG) by PLCE1, and attenuated the podocyte migration rate (PMR). These effects were reversed by overexpression of WT AVIL but not by overexpression of any of the 3 patient-derived AVIL mutants. The PMR was increased by overexpression of WT Avil or PLCE1, or by EGF stimulation; however, this increased PMR was ameliorated by inhibition of the ARP2/3 complex, indicating that ARP-dependent lamellipodia formation occurs downstream of AVIL and PLCE1 function. Together, these results delineate a comprehensive pathogenic axis of SRNS that integrates loss of AVIL function with alterations in the action of PLCE1, an established SRNS protein.

}, keywords = {Actin-Related Protein 2-3 Complex, Cell Movement, Diglycerides, Female, Humans, Male, Microfilament Proteins, Mutation, Nephrotic Syndrome, Phosphoinositide Phospholipase C, Podocytes, Pseudopodia}, issn = {1558-8238}, doi = {10.1172/JCI94138}, author = {Rao, Jia and Ashraf, Shazia and Tan, Weizhen and van der Ven, Amelie T and Gee, Heon Yung and Braun, Daniela A and Feh{\'e}r, Krisztina and George, Sudeep P and Esmaeilniakooshkghazi, Amin and Choi, Won-Il and Jobst-Schwan, Tilman and Schneider, Ronen and Schmidt, Johanna Magdalena and Widmeier, Eugen and Warejko, Jillian K and Hermle, Tobias and Schapiro, David and Lovric, Svjetlana and Shril, Shirlee and Daga, Ankana and Nayir, Ahmet and Shenoy, Mohan and Tse, Yincent and Bald, Martin and Helmchen, Udo and Mir, Sevgi and Berdeli, Afig and Kari, Jameela A and El Desoky, Sherif and Soliman, Neveen A and Bagga, Arvind and Mane, Shrikant and Jairajpuri, Mohamad A and Lifton, Richard P and Khurana, Seema and Martins, Jose C and Hildebrandt, Friedhelm} }