Homeobox protein Mohawk,also known asiroquois homeobox protein-like 1,is aproteinthat in humans is encoded by theMKX(mohawk homeobox)gene.[5]MKX is a member of an Iroquois (IRX) family-related class of 'three-amino acid loop extension' (TALE) atypical homeobox proteins characterized by 3 additional amino acids in the loop region between helix I and helix II of the homeodomain.[5][6]
MKX is a transcription factor that regulates tendon differentiation during embryological development. Knocking out this gene in mouse embryos results in them developinghypoplastictendons containing less type I collagen.[7]MKX binds directly to the promoter of MyoD and represses its expression, negatively regulating muscle differentiation.[8]
Expression of MKX is maintained in adult tendon tissues, decreasing as a result of ageing or osteoarthritis. Collagen fibres in tendons become more dense and thick following mechanical stimulation as a result of exercise,[9]and MKX is essential in this mechanosensory process.[10]
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