Mutations in TRPV4 cause Charcot-Marie-Tooth disease type 2C

Abstract

Charcot-Marie-Tooth disease type 2C (CMT2C) is an autosomal dominant neuropathy characterized by limb, diaphragm, and laryngeal muscle weakness. Two unrelated families with CMT2C showed significant linkage to chromosome 12q24.11. All genes in this region were sequenced and heterozygous missense mutations were identified in the TRPV4 gene at positions c.805C>T and c.806G>A, causing the amino acid substitutions R269C and R269H. TRPV4 is a well known member of the TRP superfamily of cation channels. In TRPV4-transfected cells, the CMT2C mutations caused marked cellular toxicity and increased constitutive and activated channel currents. Mutations in TRPV4 were previously associated with skeletal dysplasias. Our findings indicate that TRPV4 mutations can also cause a degenerative disorder of peripheral nerves. The CMT2C mutations lie in a distinct region of the TRPV4 ankyrin repeats, suggesting that this striking phenotypic variability may be due to differential effects on regulatory protein-protein interactions.

TRPV4 channel activity is modulated by direct interaction of the ankyrin domain to PI(4,5)P2

“…3). The protein structure of the ARD IP 3 complex is nearly identical to the present and reported ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/ncomms5994 chicken TRPV4 ARD structures without a ligand 9 (Fig. 2d), indicating that IP 3 binding does not affect the overall structure of ARD.…”

“…2d). The conformational change in finger 2 is observed upon ATP binding to the human TRPV4 ARD 9 (Fig. 2d).…”

“…2d), indicating that IP 3 binding does not affect the overall structure of ARD. On the other hand, the finger 3 conformation differs from those of the chicken TRPV4 ARD in complex with phosphate ion and the human TRPV4 ARD without a ligand 9,23 (Fig. 2d).…”

“…To identify the PI(4,5)P 2 -binding site, we prepared crystals of the chicken TRPV4 ARD and exposed them to a solution containing IP 3 , the head-group of PI(4,5)P 2 . The crystal structure of the chicken TRPV4 ARD (residues 133-382, corresponding to human residues 147-396) in complex with IP 3 was determined at 1.9 Å resolution by the molecular replacement method, using the reported chicken TRPV4 ARD structure (PDB ID: 3JXI 9 ) as the search model (Fig. 2a-c, Supplementary Fig.…”

“…The mutations in TRPV4 are the most recently identified CMT subtype, in terms of genetic locus 1,2 . Previous studies have suggested that the gain-of-function mutations of TRPV4 in these diseases, which exhibit increased basal and maximum Ca 2 þ channel activities, are clustered within the TRPV4 ARD and affect arginine residues, especially at the R232C, R269C/H, R315W, R316C/H positions [7][8][9][10] . The increased Ca 2 þ influx and subsequent Ca 2 þ overload associated with these mutations are thought to be the cause of cell death, and have been proposed as a mechanism for peripheral axonal degeneration in TRPV4-dependent neuropathies 9,10 .…”