The Mohawk homeobox gene is a critical regulator of tendon differentiation

Mohawk (Mkx) is a member of the Three Amino acid Loop Extension superclass of atypical homeobox genes that is expressed in developing tendons. To investigate the in vivo functions of Mkx, we generated [Mkx.sup.-/-] mice. These mice had hypoplastic tendons throughout the body. Despite the reduction in tendon mass, the cell number in tail tendon fiber bundles was similar between wild-type and [Mkx.sup.-/-] mice. We also observed small collagen fibril diameters and a down-regulation of type I collagen in [Mkx.sup.-/-] tendons. These data indicate that Mkx plays a critical role in tendon differentiation by regulating type I collagen production in tendon cells. doi/ 10.1073/pnas.1000525107