Author:
Tai Phillip WL,Fisher-Aylor Katherine I,Himeda Charis L,Smith Catherine L,MacKenzie Alexandra P,Helterline Deri L,Angello John C,Welikson Robert E,Wold Barbara J,Hauschka Stephen D
Abstract
AbstractBackgroundHundreds of genes, including muscle creatine kinase (MCK), are differentially expressed in fast- and slow-twitch muscle fibers, but the fiber type-specific regulatory mechanisms are not well understood.ResultsModulatory region 1 (MR1) is a 1-kb regulatory region withinMCKintron 1 that is highly active in terminally differentiating skeletal myocytesin vitro. AMCKsmall intronic enhancer (MCK-SIE) containing a paired E-box/myocyte enhancer factor 2 (MEF2) regulatory motif resides within MR1. The SIE's transcriptional activity equals that of the extensively characterized 206-bpMCK5'-enhancer, but theMCK-SIE is flanked by regions that can repress its activity via the individual and combined effects of about 15 different but highly conserved 9- to 24-bp sequences. ChIP and ChIP-Seq analyses indicate that the SIE and theMCK5'-enhancer are occupied by MyoD, myogenin and MEF2. Many other E-boxes located within or immediately adjacent to intron 1 are not occupied by MyoD or myogenin. Transgenic analysis of a 6.5-kbMCKgenomic fragment containing the 5'-enhancer and proximal promoter plus the 3.2-kb intron 1, with and without MR1, indicates that MR1 is critical forMCKexpression in slow- and intermediate-twitch muscle fibers (types I and IIa, respectively), but is not required for expression in fast-twitch muscle fibers (types IIb and IId).ConclusionsIn this study, we discovered that MR1 is critical forMCKexpression in slow- and intermediate-twitch muscle fibers and that MR1's positive transcriptional activity depends on a paired E-box MEF2 site motif within a SIE. This is the first study to delineate the DNA controls forMCKexpression in different skeletal muscle fiber types.
Publisher
Springer Science and Business Media LLC
Subject
Cell Biology,Molecular Biology,Orthopedics and Sports Medicine
Cited by
27 articles.
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