title: [Identification and differential expression of the microphthalmia-associated transcription factor in heart and isolated cardiomyocytes from Guinea pigs: possible role in hypertrophy and viability].
abstract: BACKGROUND
  The microphthalmia -associated transcription factor ( MITF ) regulates the expression of specific genes and its cardiac expression and function is not known.
  
  
  OBJECTIVE
  To identify the expression of MITF in hearts and isolated cardiomyocytes from Guinea pigs, to describe morphological changes associated with mRNA interference of MITF and to evaluate their relative changes in expression in isolated cardiomyocytes under ischemic preconditioning.
  
  
  METHODS
  The cardiac specific isoform, MITF-H, and relative expression level analysis, was determined by semi-quantitative real time PCR, sequencing and Western blotting. Reduction of mRNA-MITF-H was induced by transduction of specific-MITF-shRNAi interference. The cardiac morphological changes, diameter and number of cardiac fibers were evaluated by direct observation and light microscopy.
  
  
  RESULTS
  A cDNA fragment of 281 bp was amplified from heart and isolated ventricular cardiac myocytes. Sequence analysis confirmed the identity of the isoform MITF-H, exon 1. The MITF silencing was associated with an increase in cardiac index (heart weight/body weight vs . 5.46 x 10 -3 vs 4.6 x 10 -3 ) and higher diameter of cardiac fibers (50.2±16 µ m vs 38,7±14,7 µ m p<0.05, n=150). In isolated cardiac myocytes under ischemic preconditioning we observed a higher relative expression compared with that measured in myocytes exposed to normoxia and simulated ischemia (eighty and one hundred times, p <0.05, n = 5). Conclusion. The results suggest that MITF-H isoform may be involved in Guinea pig cardiac hypertrophy, response to stress by ischemia and cardiomyocytes survival.
authors.affiliation: Grupo de Fisiología Molecular, Subdirección de Investigación Científica y Tecnológica, Dirección de Investigación en Salud Pública, Instituto Nacional de Salud.
authors.forename: María Luz
authors.initials: ML
authors.lastname: Gunturiz
authors.affiliation: Grupo de Fisiología Molecular, Subdirección de Investigación Científica y Tecnológica, Dirección de Investigación en Salud Pública, Instituto Nacional de Salud.
authors.forename: Luis Alberto
authors.initials: LA
authors.lastname: Gómez
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002312:Cardiomyopathy, Hypertrophic / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D006168:Guinea Pigs; D019157:Ischemic Preconditioning, Myocardial; D051739:Microphthalmia-Associated Transcription Factor / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D017202:Myocardial Ischemia / Q000235:genetics / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D010100:Oxygen / Q000494:pharmacology; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D016415:Sequence Alignment; D017385:Sequence Homology
chemical_list: D018076:DNA, Complementary; D051739:Microphthalmia-Associated Transcription Factor; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D010100:Oxygen