title: Hoxa-11 and Hoxa-13 are involved in repression of MyoD during limb muscle development.
abstract: Under the influence of the limb mesenchyme, Hoxa-11 is expressed in migrating and proliferating premyoblasts in the limb field and Hoxa-13 is induced in subdomains of congregated limb muscle masses. To evaluate the roles of Hoxa-11 and Hoxa-13 in myogenesis of the limb, we performed electroporation in ovo to force expression of these Hox genes in limb muscle precursors. In the presence of ectopic Hoxa-11, expression of MyoD was blocked transiently. In C2C12 myoblasts, transfection of Hoxa-11 also repressed the expression of endogenous MyoD. Forced expression of Hoxa-13 resulted in more pronounced repression of MyoD in both limb and C2C12 myoblasts. In contrast, targeted disruption of Hoxa-13 gave rise to enhanced expression of MyoD in the flexor carpi radialis muscle, a forearm muscle that normally expressed Hoxa-13. These results suggest that Hoxa-11 and Hoxa-13 are involved in the negative regulation of MyoD expression in limb muscle precursors.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 Japan. masakazu.yamamoto@uconn.edu
authors.forename: Masakazu
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kuroiwa
mesh_terms: D000818:Animals; D019521:Body Patterning; D002460:Cell Line; D002642:Chick Embryo; D002645:Chickens; D003062:Codon; D018076:DNA, Complementary / Q000378:metabolism; D018274:Electroporation; D005121:Extremities / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D009132:Muscles / Q000196:embryology*; D017570:MyoD Protein / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014162:Transfection
chemical_list: D003062:Codon; D018076:DNA, Complementary; D018398:Homeodomain Proteins; C094041:Hoxa11 protein, mouse; D017570:MyoD Protein; C099959:homeobox protein HOXA13