MyoR is expressed in nonmyogenic cells and can inhibit their differentiation.
The development of skeletal muscle in mammals is promoted by the muscle-specific basic helix-loop-helix transcription factors of the MyoD family. Evidence also suggests that there are basic helix-loop-helix proteins that specifically inhibit skeletal myogenesis, including Mtwist, Mist1, and the most recently described, MyoR. It has been suggested that MyoR expression is limited to the precursors of the skeletal muscle lineage and acts as a transcriptional repressor of the muscle differentiation program. However, our results demonstrate that MyoR is expressed in several different, nonmuscle adult tissues. Furthermore, MyoR is expressed in the embryonic ectoderm of blastocyst stage mouse embryos, well before skeletal muscle specification and even before delineation of the mesodermal germ layer. Using embryonic ectoderm analogous stem cells, we demonstrate that in these nonmuscle cells, as in skeletal muscle precursor cells, expression of MyoR is inversely correlated with the extent of cellular differentiation as induced by retinoic acid. Our preliminary results indicate that overexpression of exogenous MyoR inhibits retinoic-acid-induced differentiation in EC cells and is lethal to early mouse embryos. Our results suggest a much broader role for MyoR in the repression and/or determination of embryonic cell differentiation.
Yu
Liming
L
Center for Functional Genomics, The University at Albany, East Campus, 1 University Place, A-202, Rensselaer, NY 12144, USA.
Mikloucich
Jerome
J
Sangster
Niquiche
N
Perez
Ana
A
McCormick
Paulette J
PJ
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D019070:Cell Lineage / Q000187:drug effects / Q000502:physiology; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004475:Ectoderm / Q000166:cytology / Q000378:metabolism*; D005333:Fetus; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D005804:Genes, Lethal / Q000187:drug effects / Q000235:genetics; D005809:Genes, Regulator / Q000187:drug effects / Q000502:physiology; D051379:Mice / Q000196:embryology* / Q000378:metabolism; D008822:Mice, Transgenic / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009124:Muscle Proteins; D012097:Repressor Proteins / Q000187:drug effects / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology
D018076:DNA, Complementary; C478342:GIJJM protein, mouse; D009124:Muscle Proteins; C498449:Ostn protein, mouse; D012097:Repressor Proteins; D014157:Transcription Factors; D014212:Tretinoin