title: Analysis of CRE-mediated recombination driven by myosin light chain 1/3 regulatory elements in embryonic and adult skeletal muscle: a tool to study fiber specification.
abstract: An increasing number of genes have been implicated in skeletal muscle fiber diversity. To study the contribution of diverse genetic elements to the regulation of fiber-type composition, we generated a transgenic mouse in which CRE recombinase expression is driven by muscle-specific regulatory sequences of the myosin light chain 1/3 locus (MLC). Using ROSA26 conditional reporter mice, we detected expression of the MLC-Cre transgene starting from embryonic day 12.5 (E12.5). By E15, recombination was detected in all muscle-derived structures. Immunohistochemical analysis revealed CRE activity was restricted to fast-twitch (type II) and excluded from slow-twitch (type I) fibers of skeletal muscle. The MLC-Cre transgenic mouse can be used in conjunction with conditional alleles to study both developmental patterning and maintenance of fast fiber-type phenotypes.
authors.forename: Foteini
authors.initials: F
authors.lastname: Mourkioti
authors.forename: Esfir
authors.initials: E
authors.lastname: Slonimsky
authors.forename: Marion
authors.initials: M
authors.lastname: Huth
authors.forename: Valeria
authors.initials: V
authors.lastname: Berno
authors.forename: Nadia
authors.initials: N
authors.lastname: Rosenthal
mesh_terms: D000818:Animals; D005822:Genetic Vectors; D019426:Integrases / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000196:embryology / Q000378:metabolism*; D018994:Myosin Light Chains / Q000235:genetics* / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid
chemical_list: D018994:Myosin Light Chains; C045073:Cre recombinase; D019426:Integrases