SHOX And SHOX2 Share a Tissue-Specific Functional Redundancy in Temporomandibular Joint Formation

SHOX is a human pseudoautosomal gene that was first identified as a potential gene for the short stature phenotype of Turner Syndrome and Leri-Weill syndrome. Patients with Langer syndrome exhibit extremely short and bowed arm and leg zeugopod elements. That is, they have short radius/ulna and short tibia/fibula. This makes it important to investigate whether SHOX contributes to short stature phenotype and to assess the function of SHOX and SHOX2 in long bone development and in the formation of TMJ. Since there is no SHOX ortholog in the mouse genome, and the mouse Shox2 shares 99% identity at the amino acid level and exhibit a similar expression pattern to that of human SHOX2, replacing murine shox2 with human SHOX will be an effective model for studying the functional link between human SHOX and SHOX2 during embryogenesis, especially in the formation of the temporomandibular joint. This article gives a review of the role Shox2 plays in the formation of TMJ and the functional redundancy that exists between human SHOX and SHOX2 in TMJ formation. Overall, functional redundancy that exist between human SHOX and SHOX2 during temporomandibular joint formation is only in a tissue-specific manner.

Keywords: Temporomandibular joint; SHOX; SHOX2; Shox2; Indian hedgehog

Abbreviations: TMJ: Temporomandibular joint; SAN: Sinoatrial Node; Ihh: Indian hedgehog