Myh7b/miR-499 gene expression is transcriptionally regulated by MRFs and Eos.
The sarcomeric myosin gene, Myh7b, encodes an intronic microRNA, miR-499, which regulates cardiac and skeletal muscle biology, yet little is known about its transcriptional regulation. To identify the transcription factors involved in regulating Myh7b/miR-499 gene expression, we have mapped the transcriptional start sites and identified an upstream 6.2 kb region of the mouse Myh7b gene whose activity mimics the expression pattern of the endogenous Myh7b gene both in vitro and in vivo. Through promoter deletion analysis, we have mapped a distal E-box element and a proximal Ikaros site that are essential for Myh7b promoter activity in muscle cells. We show that the myogenic regulatory factors, MyoD, Myf5 and Myogenin, bind to the E-box, while a lymphoid transcription factor, Ikaros 4 (Eos), binds to the Ikaros motif. Further, we show that through physical interaction, MyoD and Eos form an active transcriptional complex on the chromatin to regulate the expression of the endogenous Myh7b/miR-499 gene in muscle cells. We also provide the first evidence that Eos can regulate expression of additional myosin genes (Myosin 1 and β-Myosin) via the miR-499/Sox6 pathway. Therefore, our results indicate a novel role for Eos in the regulation of the myofiber gene program.
Department of Molecular, Cellular, and Developmental Biology and Biofrontiers Institute, University of Colorado, Boulder, Colorado 80309, USA.
Fan
F
Yeung
Eunhee
E
Chung
Martin G
MG
Guess
Matthew L
ML
Bell
Leslie A
LA
Leinwand
D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D024721:E-Box Elements; D005786:Gene Expression Regulation; D006801:Humans; D051740:Ikaros Transcription Factor / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism; D017570:MyoD Protein / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000378:metabolism* / Q000502:physiology; D018995:Myosin Heavy Chains / Q000096:biosynthesis / Q000235:genetics*; D024462:Myosin Type II / Q000096:biosynthesis / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D011401:Promoter Regions, Genetic; D054730:Protein Interaction Domains and Motifs; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C573190:MIRN499 microRNA, mouse; D035683:MicroRNAs; C483905:Myh14 protein, mouse; D017570:MyoD Protein; D018006:Myogenic Regulatory Factors; D009419:Nerve Tissue Proteins; C118760:Zfpn1a4 protein, mouse; D051740:Ikaros Transcription Factor; D024462:Myosin Type II; D018995:Myosin Heavy Chains