title: Isoproterenol cytotoxicity is dependent on the differentiation state of the cardiomyoblast H9c2 cell line.
abstract: H9c2 cells are used as a surrogate for cardiac cells in several toxicological studies, which are usually performed with cells in their undifferentiated state, raising questions on the applicability of the results to adult cardiomyocytes. Since H9c2 myoblasts have the capacity to differentiate into skeletal and cardiac muscle cells under different conditions, the hypothesis of the present work was that cells in different differentiation states differ in their susceptibility to toxicants. In order to test the hypothesis, the effects of the cardiotoxicant isoproterenol (ISO) were investigated. The present work demonstrates that differentiated H9c2 cells are more susceptible to ISO toxicity. Cellular content of beta(1)-adrenergic receptors (AR), beta(3)-AR, and calcineurin is decreased as cells differentiate, as opposed to the content on the mitochondrial voltage-dependent anion channel (VDAC) and phosphorylated p38-MAPK, which increase. After ISO treatment, the pro-apoptotic protein Bax increases in all experimental groups, although only undifferentiated myoblasts up-regulate the anti-apoptotic Bcl-2. Calcineurin is decreased in differentiated H9c2 cells, which suggests an important role against ISO-induced cell death. The results indicate that the differentiation state of H9c2 myoblasts influence ISO toxicity, which may involve calcineurin, p38-MAPK, and Bax/Bcl-2 alterations. The data also provide new insights into cardiovascular toxicology during early development.
authors: Center for Neuroscience and Cell Biology, Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
authors: Ana F
authors: AF
authors: Branco
authors: Sandro L
authors: SL
authors: Pereira
authors: Ana C
authors: AC
authors: Moreira
authors: Jon
authors: J
authors: Holy
authors: Vilma A
authors: VA
authors: Sardão
authors: Paulo J
authors: PJ
authors: Oliveira
mesh_terms: D000318:Adrenergic beta-Agonists / Q000633:toxicity*; D000818:Animals; D019703:Calcineurin / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D007545:Isoproterenol / Q000633:toxicity*; D032386:Myoblasts, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D018342:Receptors, Adrenergic, beta-1 / Q000187:drug effects / Q000378:metabolism; D022702:Receptors, Adrenergic, beta-3 / Q000187:drug effects / Q000378:metabolism; D050994:Voltage-Dependent Anion Channels / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C547789:Adrb1 protein, rat; D000318:Adrenergic beta-Agonists; C494828:Bax protein, rat; D019253:Proto-Oncogene Proteins c-bcl-2; D018342:Receptors, Adrenergic, beta-1; D022702:Receptors, Adrenergic, beta-3; D050994:Voltage-Dependent Anion Channels; D051028:bcl-2-Associated X Protein; D048051:p38 Mitogen-Activated Protein Kinases; D019703:Calcineurin; D007545:Isoproterenol