There was a significant reduction in the FRET signal obtained from analysis of murine TRPC6 FRET constructs with homologous amino-terminal mutations (M131T, G108S) that had been identified in human patients with inherited focal segmental glomerulosclerosis, a condition that can lead to end-stage renal disease.
Human genetics point to three additional TRP channels as plausible therapeutic targets: TRPC6 in FSGS, PKD2 in polycystic kidney disease, and TRPM6 in familial hypomagnesemia with secondary hypocalcemia (HSH).
Rare genetic forms of FSGS can be caused by mutations in TRPC6, which encodes a Ca<sup>2+</sup>-permeable cationic channel expressed in mesangial cells and podocytes; and NPHS2, which encodes podocin, a TRPC6-binding protein expressed in podocyte slit diaphragm domains.
Transient receptor potential cation channel-6 (TRPC6) is one of the proteins that plays a key role causing focal segmental glomerulosclerosis (FSGS) associated with the steroid-resistant nephritic syndrome (SRNS).
One of the key proteins responsible for calcium flux in the podocytes is transient receptor potential cation channel, subfamily C, member 6 (TRPC6); a gain-of-function mutation in TRPC6 has been associated with the onset of the familial forms of focal segmental glomerulosclerosis (FSGS).
Mutations in canonical transient receptor potential channel 6 (TRPC6) have been identified as responsible for the development of focal segmental glomerulosclerosis, a proteinuric disease with steroid resistance and poor prognosis.
Together, these data suggest a dual and context dependent role of TRPC6 in podocytes where acute activation protects from complement-mediated damage, but chronic overactivation leads to focal segmental glomerulosclerosis.
Genomic DNA was extracted from peripheral blood cells, and Sanger sequencing was performed for all exons and exon-intron boundaries of TRPC6 and ACTN4 in the probands of all FSGS pedigrees enrolled in this study.
The Ca(2+)-permeable, nonselective cation channel TRPC6 is gated via phospholipase C-activating receptors and has recently been implicated in hypoxia-induced pulmonary vasoconstriction (HPV), idiopathic pulmonary hypertension and focal segmental glomerulosclerosis (FSGS).
The latest advance in familial focal segmental glomerulosclerosis (FSGS) has been the discovery of a mutant form of canonical transient receptor potential channel 6 (TRPC6) leading to FSGS through unclear mechanisms.
These results delineate the mechanism of TRPC6 activation regulated by tyrosine phosphorylation, and imply the cell type-specific regulation, which correlates the FSGS mutations with deregulated TRPC6 channel activity.