Homeobox protein Mohawk, also known as iroquois homeobox protein-like 1, is a protein that in humans is encoded by the MKX (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]
Function
MKX is a transcription factor that regulates tendon differentiation during embryological development. Knocking out this gene in mouse embryos results in them developing hypoplastic tendons 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]
Robertson NG, Khetarpal U, Gutiérrez-Espeleta GA, Bieber FR, Morton CC (September 1994). "Isolation of novel and known genes from a human fetal cochlear cDNA library using subtractive hybridization and differential screening". Genomics. 23 (1): 42–50. doi:10.1006/geno.1994.1457. PMID7829101.
Weinmann A, Galle PR, Teufel A (September 2005). "In silico characterization of an Iroquois family-related homeodomain protein". International Journal of Molecular Medicine. 16 (3): 443–8. doi:10.3892/ijmm.16.3.443. PMID16077953.
