title: Down-regulation of SM22/transgelin gene expression during H9c2 cells differentiation.
abstract: The embryonic rat ventricle H9c2 cells maintain a proliferative state (P condition) in the presence of 10% FCS. However, by reducing serum concentration and in the presence of retinol acetate, proliferation is stopped, myogenic transdifferentiation is inhibited while cardiac differentiation is preserved (D condition). Two-dimensional gel electrophoresis and mass spectrometry analysis was used to define the modifications of the nuclear proteome occurring during the P-to-D transition. Among the proteins observed as modified, a reduced expression of the SM22/transgelin protein was associated with the D state. Also SM22 mRNA levels were reduced during P-to-D transition. Cell transfection experiments indicated that this decrease was partially due to a reduction of the SM22 promoter activity. GATA-4 had a repressive effect on SM22 promoter activity. Thus, since GATA-4 is known as a target of retinoids and may act as a transcriptional repressor, a mechanism to explain the SM22 reduction during the P-to-D transition is tentatively proposed. Immunohistochemical studies on heart cells confirmed the nuclear localization of SM22. Moreover, a differential expression of this protein in different districts of the human heart embryo was detected. Therefore, these data suggest that SM22 expression is regulated during heart development.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biomediche, Università di Udine, Piazzale Kolbe 1, 33100 Udine, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Bregant
authors.forename: Giovanni
authors.initials: G
authors.lastname: Renzone
authors.forename: Renata
authors.initials: R
authors.lastname: Lonigro
authors.forename: Nadia
authors.initials: N
authors.lastname: Passon
authors.forename: Carla
authors.initials: C
authors.lastname: Di Loreto
authors.forename: Maura
authors.initials: M
authors.lastname: Pandolfi
authors.forename: Andrea
authors.initials: A
authors.lastname: Scaloni
authors.forename: Gianluca
authors.initials: G
authors.lastname: Tell
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Damante
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D002467:Cell Nucleus / Q000378:metabolism; D015536:Down-Regulation; D004622:Embryo, Mammalian / Q000378:metabolism; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D008840:Microfilament Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D009124:Muscle Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
chemical_list: D008840:Microfilament Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; C051615:transgelin