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Abstract: TH-PO059

Protective Effect of TRPC6 Knockout in Chronic PAN Nephrosis in Sprague-Dawley Rats

Session Information

Category: Glomerular

  • 1002 Glomerular: Basic/Experimental Pathology

Authors

  • Dryer, Stuart E., University of Houston, Houston, Texas, United States
  • Kim, Eunyoung, University of Houston, Houston, Texas, United States
Background

Mutations in TRPC6 channels give rise to rare forms of focal and segmental glomerulosclerosis (FSGS). A possible role of wild-type TRPC6 channels in the progression of acquired forms of FSGS is not firmly established, and it is important to examine this in multiple species. Here we examined the role of TRPC6 channels in chronic puromycin aminonucleoside (PAN) nephrosis in Sprague-Dawley rats. Chronic PAN nephrosis is one of the most extensively studied models of secondary FSGS. A major advantage of this model is that experimental animals get a severe glomerular disease.

Methods

A global constitutive TRPC6-/- rat was generated on the Sprague-Dawley background using CRISPR/Cas9 technology. Experiments were carried out using TRPC6+/+ and TRPC6-/- littermates. Rats were given two i.p. injections of PAN at 30 day intervals. Renal phenotypes were characterized by standard histological, ultastructural, and biochemical methods. All experiments were approved by the University of Houston IACUC.

Results

Nephrotic range albuminuria was present 9-10 days after the first PAN injection and there was no difference in 24-hour urine albumin excretion in TRPC6+/+ and TRPC6-/- rats at that time. In marked contrast to the acute phase, at 30 and 60 days after the initial PAN injection, TRPC6-/- rats had biologically and statistically significantly reduced urine albumin excretion, reduced serum cholesterol and triglycerides, and improved BUN compared to TRPC6+/+ littermates. Glomerulosclerosis was severe during chronic PAN nephrosis in TRPC6+/+ rats, but was markedly reduced in TRPC6-/- littermates. TRPC6 knockout rats also had less severe tubulointerstitial fibrosis, and reduced foot process effacement and glomerular basement thickening compared to TRPC6+/+ controls. TRPC6-/- rats also had reduced infiltration of monocytes or macrophages into glomeruli, and reduced expression of α-smooth muscle actin in renal cortex compared to TRPC6+/+ littermates. Basal TRPC3 abundance in renal cortex was increased in TRPC6-/- rats compared to TRPC6+/+ controls. However TRPC3 did not increase further in chronic PAN nephrosis. None of the manipulations in this study affected TRPC5 channels.

Conclusion

TRPC3/6 family channels may represent useful therapeutic targets for acquired forms of FSGS.

Funding

  • NIDDK Support