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Follistatin in chondrocytes: the link between TRPV4 channelopathies and skeletal malformations
Author(s) -
Leddy Holly A.,
McNulty Amy L.,
Lee Suk Hee,
Rothfusz Nicole E.,
Gloss Bernd,
Kirby Margaret L.,
Hutson Mary R.,
Cohn Daniel H.,
Guilak Farshid,
Liedtke Wolfgang
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.13-245936
Subject(s) - trpv4 , channelopathy , follistatin , medicine , dysplasia , mutation , pathogenesis , endocrinology , transfection , endochondral ossification , point mutation , biology , anatomy , genetics , gene , cartilage , transient receptor potential channel , receptor
Point mutations in the calcium‐permeable TRPV4 ion channel have been identified as the cause of autosomal‐dominant human motor neuropathies, arthropathies, and skeletal malformations of varying severity. The objective of this study was to determine the mechanism by which TRPV4 channelopathy mutations cause skeletal dysplasia. The human TRPV4 V620I channelopathy mutation was transfected into primary porcine chondrocytes and caused significant (2.6‐fold) up‐regulation of follistatin ( FST ) expression levels. Pore altering mutations that prevent calcium influx through the channel prevented significant FST up‐regulation (1.1‐fold). We generated a mouse model of theTRPV4 V620I mutation, and found significant skeletal deformities ( e.g ., shortening of tibiae and digits, similar to the human disease brachyolmia) and increases in Fst/TRPV4 mRNA levels (2.8‐fold). FST was significantly up‐regulated in primary chondrocytes transfected with 3 different dysplasia‐causing TRPV4 mutations (2‐ to 2.3‐fold), but was not affected by an arthropathy mutation (1.1‐fold). Furthermore, FST‐loaded microbeads decreased bone ossification in developing chick femora (6%) and tibiae (11%). FST gene and protein levels were also increased 4‐fold in human chondrocytes from an individual natively expressing the TRPV4 T89I mutation. Taken together, these data strongly support that up‐regulation of FST in chondrocytes by skeletal dysplasia‐inducing TRPV4 mutations contributes to disease pathogenesis.—Leddy, H. A., McNulty, A. L., Lee, S. H., Rothfusz, N. E., Gloss, B., Kirby, M. L., Hutson, M. R., Cohn, D. H., Guilak, F., Liedtke, W. Follistatin in chondrocytes: the link between TRPV4 channelopathies and skeletal malformations. FASEB J . 28, 2525–2537 (2014). www.fasebj.org