title: Mutations in TRPV4 cause an inherited arthropathy of hands and feet.
abstract: Familial digital arthropathy-brachydactyly (FDAB) is a dominantly inherited condition that is characterized by aggressive osteoarthropathy of the fingers and toes and consequent shortening of the middle and distal phalanges. Here we show in three unrelated families that FDAB is caused by mutations encoding p.Gly270Val, p.Arg271Pro and p.Phe273Leu substitutions in the intracellular ankyrin-repeat domain of the cation channel TRPV4. Functional testing of mutant TRPV4 in HEK-293 cells showed that the mutant proteins have poor cell-surface localization. Calcium influx in response to the synthetic TRPV4 agonists GSK1016790A and 4αPDD was significantly reduced, and mutant channels did not respond to hypotonic stress. Others have shown that gain-of-function TRPV4 mutations cause skeletal dysplasias and peripheral neuropathies. Our data indicate that TRPV4 mutations that reduce channel activity cause a third phenotype, inherited osteoarthropathy, and show the importance of TRPV4 activity in articular cartilage homeostasis. Our data raise the possibility that TRPV4 may also have a role in age- or injury-related osteoarthritis.
authors.affiliation: Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia. shireen.lamande@mcri.edu.au
authors.forename: Shireen R
authors.initials: SR
authors.lastname: Lamandé
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yuan
authors.forename: Irma L
authors.initials: IL
authors.lastname: Gresshoff
authors.forename: Lynn
authors.initials: L
authors.lastname: Rowley
authors.forename: Daniele
authors.initials: D
authors.lastname: Belluoccio
authors.forename: Kumara
authors.initials: K
authors.lastname: Kaluarachchi
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Little
authors.forename: Elke
authors.initials: E
authors.lastname: Botzenhart
authors.forename: Klaus
authors.initials: K
authors.lastname: Zerres
authors.forename: David J
authors.initials: DJ
authors.lastname: Amor
authors.forename: William G
authors.initials: WG
authors.lastname: Cole
authors.forename: Ravi
authors.initials: R
authors.lastname: Savarirayan
authors.forename: Peter
authors.initials: P
authors.lastname: McIntyre
authors.forename: John F
authors.initials: JF
authors.lastname: Bateman
mesh_terms: D002460:Cell Line; D006801:Humans; D009154:Mutation; D050916:TRPV Cation Channels / Q000235:genetics* / Q000502:physiology
chemical_list: D050916:TRPV Cation Channels; C416986:TRPV4 protein, human