{"doi":"10.1152/ajpheart.01192.2010","title":"Myocardin is differentially required for the development of smooth muscle cells and cardiomyocytes","abstract":"<jats:p>Myocardin is a serum response factor (SRF) coactivator exclusively expressed in cardiomyocytes and smooth muscle cells (SMCs). However, there is highly controversial evidence as to whether myocardin is essential for normal differentiation of these cell types, and there are no data showing whether cardiac or SMC subtypes exhibit differential myocardin requirements during development. Results of the present studies showed the virtual absence of myocardin<jats:sup>−/−</jats:sup>visceral SMCs or ventricular myocytes in chimeric myocardin knockout (KO) mice generated by injection of myocardin<jats:sup>−/−</jats:sup>embryonic stem cells (ESCs) into wild-type (WT; i.e., myocardin<jats:sup>+/+</jats:sup>ESC) blastocysts. In contrast, myocardin<jats:sup>−/−</jats:sup>ESCs readily formed vascular SMC, albeit at a reduced frequency compared with WT ESCs. In addition, myocardin<jats:sup>−/−</jats:sup>ESCs competed equally with WT ESCs in forming atrial myocytes. The ultrastructural features of myocardin<jats:sup>−/−</jats:sup>vascular SMCs and cardiomyocytes were unchanged from their WT counterparts as determined using a unique X-ray microprobe transmission electron microscopic method developed by our laboratory. Myocardin<jats:sup>−/−</jats:sup>ESC-derived SMCs also showed normal contractile properties in an in vitro embryoid body SMC differentiation model, other than impaired thromboxane A2 responsiveness. Together, these results provide novel evidence that myocardin is essential for development of visceral SMCs and ventricular myocytes but is dispensable for development of atrial myocytes and vascular SMCs in the setting of chimeric KO mice. In addition, results suggest that as yet undefined defects in development and/or maturation of ventricular cardiomyocytes may have contributed to early embryonic lethality observed in conventional myocardin KO mice and that observed deficiencies in development of vascular SMC may have been secondary to these defects.</jats:p>","journal":"American Journal of Physiology-Heart and Circulatory Physiology","year":2011,"id":689012,"datarank":0.5837730447165941,"base_score":3.8918202981106265,"endowment":3.8918202981106265,"self_citation_contribution":0.5837730447165941,"citation_network_contribution":0.0,"self_endowment_contribution":0.5837730447165941,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":48,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":431978,"name":"Ronald L. 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Results of the present studies showed the virtual absence of myocardin<jats:sup>−/−</jats:sup>visceral SMCs or ventricular myocytes in chimeric myocardin knockout (KO) mice generated by injection of myocardin<jats:sup>−/−</jats:sup>embryonic stem cells (ESCs) into wild-type (WT; i.e., myocardin<jats:sup>+/+</jats:sup>ESC) blastocysts. In contrast, myocardin<jats:sup>−/−</jats:sup>ESCs readily formed vascular SMC, albeit at a reduced frequency compared with WT ESCs. In addition, myocardin<jats:sup>−/−</jats:sup>ESCs competed equally with WT ESCs in forming atrial myocytes. The ultrastructural features of myocardin<jats:sup>−/−</jats:sup>vascular SMCs and cardiomyocytes were unchanged from their WT counterparts as determined using a unique X-ray microprobe transmission electron microscopic method developed by our laboratory. Myocardin<jats:sup>−/−</jats:sup>ESC-derived SMCs also showed normal contractile properties in an in vitro embryoid body SMC differentiation model, other than impaired thromboxane A2 responsiveness. Together, these results provide novel evidence that myocardin is essential for development of visceral SMCs and ventricular myocytes but is dispensable for development of atrial myocytes and vascular SMCs in the setting of chimeric KO mice. In addition, results suggest that as yet undefined defects in development and/or maturation of ventricular cardiomyocytes may have contributed to early embryonic lethality observed in conventional myocardin KO mice and that observed deficiencies in development of vascular SMC may have been secondary to these defects.</jats:p>","is_dataset_classified":null,"base_score":3.8918202981106265,"endowment":3.8918202981106265,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"21357509","pmcid":"PMC3094091","openalex_id":"https://openalex.org/W2083336842","authors":[],"funders":[{"funder_name":"NHLBI NIH HHS","grant_id":"P01 HL48807-15","title":null},{"funder_name":"NHLBI NIH HHS","grant_id":"R01 HL098538","title":null},{"funder_name":"NHLBI NIH HHS","grant_id":"R01 HL38854","title":null},{"funder_name":"NHLBI NIH HHS","grant_id":"P01 HL19242","title":null},{"funder_name":"NIGMS NIH HHS","grant_id":"T32 GM007267","title":null},{"funder_name":"NHLBI NIH HHS","grant_id":"R37 HL57353","title":null}],"total_grants":6,"fwci":3.2856,"citation_percentile":0.93068954,"influential_citations":0,"citation_trend":[{"year":2012,"count":9},{"year":2013,"count":9},{"year":2014,"count":5},{"year":2015,"count":2},{"year":2016,"count":1},{"year":2017,"count":2},{"year":2019,"count":1},{"year":2020,"count":3},{"year":2021,"count":1},{"year":2022,"count":8},{"year":2023,"count":2},{"year":2025,"count":1}],"oa_status":"green","license":null,"oa_locations":[{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/3094091","host_type":"repository"},{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/3094091","host_type":"repository"},{"url":"https://www.physiology.org/doi/pdf/10.1152/ajpheart.01192.2010","host_type":"publisher"},{"url":"https://doi.org/10.1152/ajpheart.01192.2010","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/21357509","host_type":"repository"}],"fields_of_study":["Congenital heart defects research","Cardiac Fibrosis and Remodeling","Signaling Pathways in Disease"],"mesh_terms":["Myocardin","Animals","Urinary Bladder","Cell Differentiation","Cell Survival","Cells, Cultured","Heart Ventricles","Nuclear Proteins","Viscera","Trans-Activators","Mice, Knockout","Gene Expression Regulation, Developmental","Models, Animal","Myocytes, Cardiac","Myocytes, Smooth Muscle","Mice","Embryonic Stem Cells"],"keywords":["Myocardin","Myocyte","Cell biology","Biology","Serum response factor","Embryonic stem cell","Vascular smooth muscle","Endocrinology","Smooth muscle","Genetics","Transcription factor"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Good health and well-being"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[{"name":"gen"}],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-19T21:22:03.928717Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}