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.

Down-regulation of SM22/transgelin gene expression during H9c2 cells differentiation

LONIGRO, Incoronata;DI LORETO, Carla;TELL, Gianluca;DAMANTE, Giuseppe
2009

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.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11390/865046
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