JAWS coordinates chondrogenesis and synovial joint positioning.
Properly positioned synovial joints are crucial to coordinated skeletal movement. Despite their importance for skeletal development and function, the molecular mechanisms that underlie joint positioning are not well understood. We show that mice carrying an insertional mutation in a previously uncharacterized gene, which we have named Jaws (joints abnormal with splitting), die perinatally with striking skeletal defects, including ectopic interphalangeal joints. These ectopic joints develop along the longitudinal axis and persist at birth, suggesting that JAWS is uniquely required for the orientation and consequent positioning of interphalangeal joints within the endochondral skeleton. Jaws mutant mice also exhibit severe chondrodysplasia characterized by delayed and disorganized maturation of growth plate chondrocytes, together with impaired chondroitin sulfation and abnormal metabolism of the chondroitin sulfate proteoglycan aggrecan. Our findings identify JAWS as a key regulator of chondrogenesis and synovial joint positioning required for the restriction of joint formation to discrete stereotyped locations in the embryonic skeleton.
Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, Center for Integrative Genomics, University of California, Berkeley, CA 94720, USA. sohaskey@berkeley.edu
Michael L
ML
Sohaskey
Jane
J
Yu
Michael A
MA
Diaz
Anna H
AH
Plaas
Richard M
RM
Harland
D000818:Animals; D002356:Cartilage / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D002460:Cell Line; D020219:Chondrogenesis; D002809:Chondroitin Sulfates / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006132:Growth Plate / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D053823:Hedgehog Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010744:Phosphoric Monoester Hydrolases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013583:Synovial Membrane / Q000166:cytology* / Q000196:embryology / Q000378:metabolism*
D053823:Hedgehog Proteins; C514061:ihh protein, mouse; D002809:Chondroitin Sulfates; C531173:JAWS protein, mouse; D010744:Phosphoric Monoester Hydrolases