Identification of novel MyoD gene targets in proliferating myogenic stem cells.
A major control point for skeletal myogenesis revolves around the muscle basic helix-loop-helix gene family that includes MyoD, Myf-5, myogenin, and MRF4. Myogenin and MRF4 are thought to be essential to terminal differentiation events, whereas MyoD and Myf-5 are critical to establishing the myogenic cell lineage and producing committed, undifferentiated myogenic stem cells (myoblasts). Although mouse genetic studies have revealed the importance of MyoD and Myf-5 for myoblast development, the genetic targets of MyoD and Myf-5 activity in undifferentiated myoblasts remain unknown. In this study, we investigated the function of MyoD as a transcriptional activator in undifferentiated myoblasts. By using conditional expression of MyoD, in conjunction with suppression subtractive hybridizations, we show that the Id3 and NP1 (neuronal pentraxin 1) genes become transcriptionally active following MyoD induction in undifferentiated myoblasts. Activation of Id3 and NP1 represents a stable, heritable event that does not rely on continued MyoD activity and is not subject to negative regulation by an activated H-Ras G12V protein. These results are the first to demonstrate that MyoD functions as a transcriptional activator in myogenic stem cells and that this key myogenic regulatory factor exhibits different gene target specificities, depending upon the cellular environment.
Wyzykowski
Jeffrey C
JC
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA.
Winata
Therry I
TI
Mitin
Natalia
N
Taparowsky
Elizabeth J
EJ
Konieczny
Stephen F
SF
D000818:Animals; D002097:C-Reactive Protein / Q000096:biosynthesis / Q000235:genetics*; D002455:Cell Division; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D004958:Estradiol / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology; D020869:Gene Expression Profiling; D011905:Genes, ras; D051796:Inhibitor of Differentiation Proteins; D051379:Mice; D008809:Mice, Inbred C3H; D009124:Muscle Proteins / Q000096:biosynthesis / Q000235:genetics*; D018482:Muscle, Skeletal / Q000166:cytology* / Q000378:metabolism; D017570:MyoD Protein / Q000235:genetics / Q000502:physiology*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics*; D016133:Polymerase Chain Reaction; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D013382:Subtraction Technique; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D015533:Transcriptional Activation / Q000187:drug effects; D000099153:Pentraxins
D002097:C-Reactive Protein; D004268:DNA-Binding Proteins; D004958:Estradiol; D051796:Inhibitor of Differentiation Proteins; D009124:Muscle Proteins; D017570:MyoD Protein; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D016283:Proto-Oncogene Proteins p21(ras); D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D000099153:Pentraxins; C075640:ID3 protein, human