Genetic background strongly influences the severity of glomerulosclerosis in mice

The ICGN mouse strain is a glomerulosclerosis (GS) model that shows characteristic proteinuria, podocyte morphological abnormalities and increased extracellular matrix accumulation in the glomeruli, which are the final common pathology associated with a variety of kidney diseases leading to end-stage renal failure. Previously, we performed a quantitative trait locus (QTL) analysis to identify the causative genes for GS in ICGN mice and found the deletion mutation of the tensin2 (Tns2) gene that creates both a premature stop codon and dramatically decreases mRNA expression levels within the region of the major QTL (this mutation was designated Tns2(nep)). The severity of GS varies considerably in humans and other animals, indicating the influence of several genes controlling the disease phenotype. In this study, to identify the modifier/resistant gene(s) for GS, we produced congenic strains carrying the Tns2(nep) mutation on the C57BL/6J (B6) genetic background and analyzed GS severity. Interestingly, the B6 congenic mice exhibited milder phenotypes than the ICGN strain mice. The results suggest that B6 mice have a modifier(s) of GS resistance. Therefore, identification of the modifier loci in B6 mice will provide important new information regarding gene interactions controlling GS.