Focal segmental glomerulosclerosis (FSGS), a common cause of kidney failure, is the result of pathogenic changes that alter the functional integrity of the glomerular filtration barrier (GFB). The study of familial FSGS cases points to a central role of the podocyte in its pathogenesis. Our long term goals are to understand the molecular pathogenesis of FSGS by identifying pathways that are critical for the maintenance of the functional integrity of the GFB and identify novel therapeutic targets for FSGS. The overall objective of this application is to study the mechanisms by which mutations in an F-actin binding cell cycle gene, ANLN, cause FSGS. Our approach is feasible because we recently identified a mutation in F-actin binding domain of ANLN, R431C, as a cause of familial FSGS. We showed that anillin is upregulated in kidney biopsies of humans and mice with collapsing FSGS. Podocyte cell lines expressing the R431C mutation demonstrate defective binding to CD2AP a key podocyte protein, activation of AKT and aberrant cell motility. Also, knockdown of anillin in zebrafish embryos disrupts the GFB. Our overarching hypothesis is that mutations in the F-actin binding domain of anillin affect F-actin cytoskeleton polymerization and lead to aberrant podocyte proliferation, apoptosis and migration;disruption of podocyte homeostasis then disrupts normal GFB function and leads to the pathogenesis of FSGS. We will explore this hypothesis through the following specific aims: 1) Determine the mechanisms by which podocyte homeostasis is disrupted by ANLN R431C by characterizing a) the signaling cascades activated by the R431C mutation b) determine the functional effect of the R431C mutation on apoptosis, cell proliferation and cell migration, and c) the effect of pharmacologic inhibitors of the PI3K/AKT coupled signaling pathways on the phenotype induced by the mutation. 2) Determine the functional effect of the R431C mutation on the GFB of zebrafish embryos using an in vivo complementation assay to determine allele pathogenicity of R431C ANLN mutation and assess pharmacologic rescue using glomerular filtration as a physiologically relevant readout. 3) Analyze mutations of the ANLN gene in a cohort of patients with FSGS by sequencing the exons of ANLN in FSGS patients and comparing the disease phenotype in subjects with and without mutations. Innovation: This proposal represents the first study designed to define the mechanisms by which anillin variants cause FSGS. Significance: Unraveling the mechanisms by which mutations in ANLN cause FSGS may identify pathways that are important for maintaining the functional integrity of the podocyte cytoskeleton. Furthermore, by probing the role of anillin in cell proliferation, apoptosis, and motility, we will provide insight into the mechanisms of podocyte renewal in health and disease. Our genetic and mechanistic approaches will advance our understanding of the molecular pathogenesis of podocyte phenotype changes in FSGS and lead to identification of novel therapeutic targets and less toxic pharmacologic approaches.
This application describes an innovative approach to address the public health problem of FSGS and other glomerular diseases through the understanding of disease mechanisms, an approach that has the potential to lead to identification of specific therapeutic targets for FSGS and other proteinuric kidney diseases.
|Adeyemo, Adebowale; Esezobor, Christopher; Solarin, Adaobi et al. (2018) HLA-DQA1 and APOL1 as Risk Loci for Childhood-Onset Steroid-Sensitive and Steroid-Resistant Nephrotic Syndrome. Am J Kidney Dis 71:399-406|
|Bensimhon, Adam R; Williams, Anna E; Gbadegesin, Rasheed A (2018) Treatment of steroid-resistant nephrotic syndrome in the genomic era. Pediatr Nephrol :|
|Hall, Gentzon; Lane, Brandon M; Khan, Kamal et al. (2018) The Human FSGS-Causing ANLN R431C Mutation Induces Dysregulated PI3K/AKT/mTOR/Rac1 Signaling in Podocytes. J Am Soc Nephrol 29:2110-2122|
|Pelletier, Jonathan H; Kumar, Karan R; Engen, Rachel et al. (2018) Recurrence of nephrotic syndrome following kidney transplantation is associated with initial native kidney biopsy findings. Pediatr Nephrol 33:1773-1780|
|Hall, Gentzon; Lane, Brandon; Chryst-Ladd, Megan et al. (2017) Dysregulation of WTI (-KTS) is Associated with the Kidney-Specific Effects of the LMX1B R246Q Mutation. Sci Rep 7:39933|
|Hall, Gentzon; Routh, Jonathan C; Gbadegesin, Rasheed A (2017) Urinary Anomalies in 22q11.2 Deletion (DiGeorge syndrome): From Copy Number Variations to Single-Gene Determinants of Phenotype. Am J Kidney Dis 70:8-10|
|Karp, Alana M; Gbadegesin, Rasheed A (2017) Genetics of childhood steroid-sensitive nephrotic syndrome. Pediatr Nephrol 32:1481-1488|
|Rheault, Michelle N; Gbadegesin, Rasheed A (2016) The Genetics of Nephrotic Syndrome. J Pediatr Genet 5:15-24|
|Hall, Gentzon; Gbadegesin, Rasheed A (2015) Translating genetic findings in hereditary nephrotic syndrome: the missing loops. Am J Physiol Renal Physiol 309:F24-8|
|Phelan, Paul J; Hall, Gentzon; Wigfall, Delbert et al. (2015) Variability in phenotype induced by the podocin variant R229Q plus a single pathogenic mutation. Clin Kidney J 8:538-42|
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