High impact information on myHC

• The two myosin heavy chain isoforms also had distinct localizations throughout mitosis [1].
• When expressed in mouse pluripotential stem cells, Xlmf1 activates the muscle cell differentiation program, resulting in expression of endogenous MyoD1, myogenin, and myosin heavy-chain genes and formation of multinucleated myotubes [2].
• A Xenopus nonmuscle myosin heavy chain isoform is phosphorylated by cyclin-p34cdc2 kinase during meiosis [3].
• Androgen regulation of a laryngeal-specific myosin heavy chain mRNA isoform whose expression is sexually differentiated [4].
• In adults, all male laryngeal muscle fibers express the mRNA for a laryngeal-specific myosin heavy chain (MHC), LM; female laryngeal muscle expresses LM in a subset of fast-twitch fibers [4].

Biological context of myHC

• In vivo gene transfer and RNase protection assay were used to follow thyroid hormone (T3)-dependent regulation of myosin heavy chain (myHC) genes in Xenopus tadpole dorsal muscle [5].
• Hybrid fibre types containing two MHC isoforms exhibited stretch activation kinetics parameters that were intermediate between those of the corresponding pure fibre types [6].
• Differential expression of non-muscle myosin heavy chain genes during Xenopus embryogenesis [7].
• This muscle-less phenotype was analyzed by molecular approaches, and the results of analysis revealed that the spike expresses no myosin heavy chain or Pax7, suggesting that neither mature muscle tissue nor satellite cells exist in the spike [8].
• T3 effects on myosin heavy chain gene expression were analysed in muscles undergoing different fates during metamorphosis [9].

Anatomical context of myHC

• These results clearly show that the MHC isoforms expressed in Xenopus muscle are functionally different thereby validating the idea that MHC isoform composition is the most reliable criterion for vertebrate skeletal muscle fibre type classification [6].
• Whole-mount embryo in situ hybridization revealed the first XMRF4 transcripts in the more differentiated anterior myocytes of the embryo when the myosin heavy chain E3 mRNA begins to be detectable [10].
• The immunohistochemical localization of myosin in corneal epithelial cells was further supported by the electrophoretic and immunological identification of smooth muscle type myosin heavy chain in pure corneal epithelial abrasions [11].
• Expression of two embryonic forms of MyHC began simultaneously at the 25-30 somite stage and continued until approximately two weeks post-hatch [12].

Associations of myHC with chemical compounds

• Thus, LM appears to be a male-specific, testosterone-regulated MHC isoform in Xenopus laevis [13].

Analytical, diagnostic and therapeutic context of myHC

• Using a SDS-PAGE protocol that proved successful with mammalian muscle MHC isoforms, we were able to detect five MHC isoforms in Xenopus iliofibularis muscle [6].
• We have analyzed in adult Xenopus laevis, using in situ hybridization, the spatial and temporal expression patterns of MyoD, myogenin, and alpha-skeletal actin and fast myosin heavy chain mRNAs during muscle regeneration following cardiotoxin injury [14].

References