TRPC1 and diabetic kidney disease: TRPC1 and the nuclear receptor, hepatic nuclear factor 4 alpha (HNF4 alpha), have been proposed as possibly involved in diabetic nephropathy (Niehof and Borlak, 2008), because TRPC1 expression was found to be reduced in this condition, in 12-week-old, and in 26-week-old diabetic db/db mice.