@article {989, title = {Rho-GTPase Activating Protein myosin MYO9A identified as a novel candidate gene for monogenic focal segmental glomerulosclerosis.}, journal = {Kidney Int}, volume = {99}, year = {2021}, month = {2021 05}, pages = {1102-1117}, abstract = {

Focal segmental glomerulosclerosis (FSGS) is a podocytopathy leading to kidney failure, whose molecular cause frequently remains unresolved. Here, we describe a rare MYO9A loss of function nonsense heterozygous mutation (p.Arg701) as a possible contributor to disease in a sibling pair with familial FSGS/proteinuria. MYO9A variants of uncertain significance were identified by whole exome sequencing in a cohort of 94 biopsy proven patients with FSGS. MYO9A is an unconventional myosin with a Rho-GAP domain that controls epithelial cell junction assembly, crosslinks and bundles actin and deactivates the small GTPase protein encoded by the RHOA gene. RhoA activity is associated with cytoskeleton regulation of actin stress fiber formation and actomyosin contractility. Myo9A was detected in mouse and human podocytes in~vitro and in~vivo. Knockin mice carrying the p.Arg701MYO9A (Myo9A) generated by gene editing developed proteinuria, podocyte effacement and FSGS. Kidneys and podocytes from Myo9A mutant mice revealed Myo9A haploinsufficiency, increased RhoA activity, decreased Myo9A-actin-calmodulin interaction, impaired podocyte attachment and migration. Our results indicate that Myo9A is a novel component of the podocyte cytoskeletal apparatus that regulates RhoA activity and podocyte function. Thus, Myo9A knock-in mice recapitulate the proband FSGS phenotype, demonstrate that p.R701X Myo9A is an FSGS-causing mutation in mice and suggest that heterozygous loss-of-function MYO9A mutations may cause a novel form of human autosomal dominant FSGS. Hence, identification of MYO9A pathogenic variants in additional individuals with familial or sporadic FSGS is needed to ascertain the gene contribution to disease.

}, issn = {1523-1755}, doi = {10.1016/j.kint.2020.12.022}, author = {Li, Qi and Gulati, Ashima and Lemaire, Mathieu and Nottoli, Timothy and Bale, Allen and Tufro, Alda} } @article {647, title = {Inherited glomerular diseases in the gilded age of genomic advancements.}, journal = {Pediatr Nephrol}, volume = {35}, year = {2020}, month = {2020 06}, pages = {959-968}, abstract = {

The synchronized advent of high-throughput next-generation sequencing technology and knowledge of the human genome has rendered exponential contributions to our understanding of the pathophysiology of glomerular kidney diseases. A genetic diagnosis can now be made or confirmed in about two-thirds of the suspected inherited glomerular diseases. Next-generation sequencing is adept at identifying single nucleotide variations and small insertions or deletions that constitute majority of the disease-causing mutations. Description of the complete mutation spectrum in syndromic glomerulopathies may require the use of both sequencing and cytogenetic methods to detect large structural DNA variation in addition to single nucleotide changes. The enthusiastic application of genetic and genomic knowledge to inherited glomerular diseases has uncovered anticipated and unforeseen challenges mainly related to the biological interpretation of variants of uncertain significance and the limited benefit on clinical management for the individual patient when a diagnosis is obtained. To attain the ultimate goal of transforming clinical decision-making based on accurate genetic diagnosis using genomic information, these challenges need to be addressed. Till then, the glory of genomic medicine stands the test of time in this gilded age of genomic advancements.

}, keywords = {Adolescent, Age Factors, Branchio-Oto-Renal Syndrome, Child, Female, High-Throughput Nucleotide Sequencing, Humans, Infant, Kidney Failure, Chronic, Male, Middle Aged, Mutation, Pedigree, Polymorphism, Single Nucleotide, Renal Insufficiency, Chronic, Whole Exome Sequencing}, issn = {1432-198X}, doi = {10.1007/s00467-019-04266-y}, author = {Gulati, Ashima and Dahl, Neera and Tufro, Alda} } @article {402, title = {Isolated polycystic liver disease genes define effectors of polycystin-1 function.}, journal = {J Clin Invest}, volume = {127}, year = {2017}, month = {2017 May 01}, pages = {1772-1785}, abstract = {

Dominantly inherited isolated polycystic liver disease (PCLD) consists of liver cysts that are radiologically and pathologically identical to those seen in autosomal dominant polycystic kidney disease, but without clinically relevant kidney cysts. The causative genes are known for fewer than 40\% of PCLD index cases. Here, we have used whole exome sequencing in a discovery cohort of 102 unrelated patients who were excluded for mutations in the 2 most common PCLD genes, PRKCSH and SEC63, to identify heterozygous loss-of-function mutations in 3 additional genes, ALG8, GANAB, and SEC61B. Similarly to PRKCSH and SEC63, these genes encode proteins that are integral to the protein biogenesis pathway in the endoplasmic reticulum. We inactivated these candidate genes in cell line models to show that loss of function of each results in defective maturation and trafficking of polycystin-1, the central determinant of cyst pathogenesis. Despite acting in a common pathway, each PCLD gene product demonstrated distinct effects on polycystin-1 biogenesis. We also found enrichment on a genome-wide basis of heterozygous mutations in the autosomal recessive polycystic kidney disease gene PKHD1, indicating that adult PKHD1 carriers can present with clinical PCLD. These findings define genetic and biochemical modulators of polycystin-1 function and provide a more complete definition of the spectrum of dominant human polycystic diseases.

}, keywords = {Adult, Animals, Cell Line, Transformed, Cysts, Endoplasmic Reticulum, Female, Genome-Wide Association Study, Glucosidases, Glucosyltransferases, Heterozygote, Humans, Intracellular Signaling Peptides and Proteins, Liver Diseases, Male, Membrane Proteins, Mice, Mutation, SEC Translocation Channels, TRPP Cation Channels}, issn = {1558-8238}, doi = {10.1172/JCI90129}, author = {Besse, Whitney and Dong, Ke and Choi, Jungmin and Punia, Sohan and Fedeles, Sorin V and Choi, Murim and Gallagher, Anna-Rachel and Huang, Emily B and Gulati, Ashima and Knight, James and Mane, Shrikant and Tahvanainen, Esa and Tahvanainen, Pia and Sanna-Cherchi, Simone and Lifton, Richard P and Watnick, Terry and Pei, York P and Torres, Vicente E and Somlo, Stefan} }