Myogenic factor 6 (also known as Mrf4 or herculin) is aprotein that in humans is encoded by the MYF6gene.[5]This gene is also known in the biomedical literature asMRF4 andherculin. MYF6 is amyogenic regulatory factor (MRF) involved in the process known asmyogenesis.[6][7]
MYF6/Mrf4 is a member of themyogenic factor (MRF) family of transcription factors that regulate skeletal musclemyogenesis and muscle regeneration. Myogenic factors arebasic helix-loop-helix (bHLH)transcription factors.MYF6 is a gene that encodes a protein involved in the regulation ofmyogenesis. The precise role(s) of Myf6/Mrf4 in myogenesis are unclear, although in mice it is able to initiate myogenesis in the absence of Myf5 and MyoD, two other MRFs.[8] The portion of the protein integral to myogenesis regulation requires the basic helix-loop-helix (bHLH) domain that is conserved among all of the genes in the MRF family.
MYF6 is expressed exclusively in skeletal muscle, and it is expressed at a higher levels in adult skeletal muscle than all of the other MRF family genes. In mouse, Myf6/Mrf4 differs somewhat from the other MRF genes due to its two-phase expression. Initially, Myf6 is transiently expressed along withMyf-5 in thesomites during the early stages of myogenesis. However, it is more noticeably expressed postnatally. This suggests that it serves an important role in the maintenance and repair of adult skeletal muscle.[9]
The MYF6 gene is physically linked to the MYF5 gene on chromosome 12, and similar linkage is observed in all vertebrates. Mutations in the mouse Myf6 gene typically exhibit reduced levels of Myf5.[10] Despite reductions in muscle mass of the back and defective rib formation, Myf6 mutants still exhibit fairly normal skeletal muscle. This demonstrates that Myf6 is not essential for the formation of most myofibers, at least in the strains of mice tested.
In zebrafish, Myf6/Mrf4 is expressed in all terminally differentiated muscle examined, but expression has not been reported in muscle precursor cells.[11]
^Cupelli L, Renault B, Leblanc-Straceski J, Banks A, Ward D, Kucherlapati RS, et al. (1996). "Assignment of the human myogenic factors 5 and 6 (MYF5, MYF6) gene cluster to 12q21 by in situ hybridization and physical mapping of the locus between D12S350 and D12S106".Cytogenetics and Cell Genetics.72 (2–3):250–251.doi:10.1159/000134201.PMID8978788.
^Arnold HH, Braun T (February 1996). "Targeted inactivation of myogenic factor genes reveals their role during mouse myogenesis: a review".The International Journal of Developmental Biology.40 (1):345–353.PMID8735947.
^Kerst B, Mennerich D, Schuelke M, Stoltenburg-Didinger G, von Moers A, Gossrau R, et al. (December 2000). "Heterozygous myogenic factor 6 mutation associated with myopathy and severe course of Becker muscular dystrophy".Neuromuscular Disorders.10 (8):572–577.doi:10.1016/S0960-8966(00)00150-4.PMID11053684.S2CID29535555.
Onions J, Hermann S, Grundström T (April 2000). "A novel type of calmodulin interaction in the inhibition of basic helix-loop-helix transcription factors".Biochemistry.39 (15):4366–4374.doi:10.1021/bi992533u.PMID10757985.
Cupelli L, Renault B, Leblanc-Straceski J, Banks A, Ward D, Kucherlapati RS, et al. (1996). "Assignment of the human myogenic factors 5 and 6 (MYF5, MYF6) gene cluster to 12q21 by in situ hybridization and physical mapping of the locus between D12S350 and D12S106".Cytogenetics and Cell Genetics.72 (2–3):250–251.doi:10.1159/000134201.PMID8978788.
Kosek DJ, Kim JS, Petrella JK, Cross JM, Bamman MM (August 2006). "Efficacy of 3 days/wk resistance training on myofiber hypertrophy and myogenic mechanisms in young vs. older adults".Journal of Applied Physiology.101 (2):531–544.doi:10.1152/japplphysiol.01474.2005.PMID16614355.
Kerst B, Mennerich D, Schuelke M, Stoltenburg-Didinger G, von Moers A, Gossrau R, et al. (December 2000). "Heterozygous myogenic factor 6 mutation associated with myopathy and severe course of Becker muscular dystrophy".Neuromuscular Disorders.10 (8):572–577.doi:10.1016/S0960-8966(00)00150-4.PMID11053684.S2CID29535555.
