Modular elements of the MLC 1f/3f locus confer fiber-specific transcription regulation in transgenic mice

✍ Scribed by Neville, Craig ;Gonzales, Donald ;Houghton, Leslie ;McGrew, Michael J. ;Rosenthal, Nadia

• Book ID: 102660660
• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 710 KB
• Volume: 19
• Category: Article
• ISSN: 0192-253X
• DOI: 10.1002/(sici)1520-6408(1996)19:2<157::aid-dvg7>3.0.co;2-8

✦ Synopsis

The two proteins encoded by the fast alkali myosin light chain (MLC) lf/3f locus are developmentally regulated, muscle specific, and expressed exclusively in fast-twitch fibers. Their expression is independently regulated by two separate promoters and a downstream enhancer. Previous studies showed a reporter gene directed by the rat MLC I f promoter and MLC enhancer to exhibit correct skeletal muscle-specific expression in transgenic mice during development and to be preferentially expressed in fast-twitch Type llB fibers [Donoghueetal., (1991) J. Cell Biol. 115:423-4341. The MLC 3f promoter also directed musclespecific expression of a CAT reporter gene in adult transgenic mice and showed little dependence upon the enhancer. Here, we show that the MLC 3f promoter also directs transgene expression in the fast-twitch fibers of adult skeletal muscle, but almost exclusively to fiber Types IIA and IIX. MLC 3f transgene expression occurs in only a subset of the fiber types that express the endogenous locus, indicating modular elements included in the transgene confer fiber-specific transcription regulation. MyoD protein was also found to be restricted to fiber Types IIA and IIX, providing evidence for its possible role in mediating fiber-specific gene expression. @ 1996 Wiley-Liss, Inc.