Abstract 025: Disruption of Shroom3 contributes to impaired glomerular podocyte function
SHROOM3 has been associated with chronic kidney disease by genome-wide association studies (GWAS), yet its role in renal function and diseases was completely unknown. Here, we leveraged the integrated physiological genomic approach in rat models and zebrafish to dissect the renal function of SHROOM3 and its contribution to renal impairments. Congenic mapping and sequence analysis in rats suggested Shroom3 was a strong positional candidate gene. Transferring a 14.50-21.40 Mbp region of the BN (Brown Norway) chromosome 14 containing the Shroom3 gene onto the FHH (Fawn-Hooded Hypertensive) background significantly lowered the level of albuminuria (31.07±3.98 vs 51.92±5.69 mg/day; P=0.001), glomerular permeability to albumin (0.48±0.02 vs 0.59±0.02; P<0.001), and glomerular sclerosis (0.72±0.03 vs 1.82±0.05; P<0.001). The FHH Shroom3 allele contains 13 amino acid variants compared to BN rat. In vivo injection of the wild-type BN Shroom3 mRNA, but not the FHH Shroom3, rescued the glomerular leakage induced by endogenous knockdown of shroom3 in zebrafish, suggesting that the FHH Shroom3 allele is defective and likely contributes to glomerular impairments seen in the FHH rat. Functional screening of the 13 FHH Shroom3 variants identified a mutation, which decreased Shroom3 binding affinity to actins (5.85±2.69 vs 52.28±16.18; P<0.05) and consequently, impaired glomerular permeability. These results demonstrate that Shroom3-mediated interaction with actin is a crucial mechanism underlying the control of glomerular filtration barrier. Furthermore, we showed that podocyte-specific shroom3 disruption in zebrafish caused glomerular impairments and podocyte effacement, indicated by reduced foot process number (2.85±0.07 vs 4.2±0.35; P<0.001) and increased foot process size (319.85±19.42 vs 164.39±8.24 nm; P<0.001). Taken together, these experiments provide the first direct demonstration that Shroom3 is functionally involved in renal pathophysiology by the control of glomerular podocyte function.
Author Disclosures: N. Yeo: None. C. O'Meara: None. K. Veth: None. R. Tomar: None. M. Flister: None. I. Drummond: None. J. Lazar: None. B. Link: None. H. Jacob: None.
- © 2014 by American Heart Association, Inc.