Objectives To study the effects of angiotensin Ⅱ, as a mediator of cardiac hypertrophy, on expression of connexin 43 （Cx43） in cultured neonatal rat ventricular myocytes and correlation of expression of Cx43 and ca...Objectives To study the effects of angiotensin Ⅱ, as a mediator of cardiac hypertrophy, on expression of connexin 43 （Cx43） in cultured neonatal rat ventricular myocytes and correlation of expression of Cx43 and cardiomyocyte hypertrophy. Methods Cardiomyocytes were isolated from newborn SD rats. Angiotensin Ⅱwas added into the media to induce myocyte hypertrophy. Cultures were exposed to 10 ～ 6 mol/L angiotensin Ⅱ for 72 h, Cx43 expression was characterized by RT-PCR and Immunofluorescence methods. Results Immunofluorescence analysis revealed decreased Cx43 immunoreactivity in cells treated for 72 h with angiotensin Ⅱ. RT-PCR analysis demonstrated there was an obvious decrease of Cx43 mRNA level in cells exposed to angiotensin U for 72 h. The changes of expression of connexin 43 were related to its entrance into S phase of the cell cycle. Cultured neonatal rat cardiomyocytes were exposed for 72 h to increase concentrations of angiotensin II （ 1.0 × 10^ -9 ～ 1.0 × 10^ -6mol/L）, resulting in significantly decreased Cx43 expression. Conclusions Angiotensin/I leads to a concentration-dependent decrease in Cx43 protein in cultured neonatal rat ventricular myocytes by decreasing Cx43 mRNA synthesis. Signal transduction pathways activated by angiotensin II under pathophysiologic conditions of cardiac hypertrophy could initiate remodeling of gap junctions.展开更多
Gap junctional intercellular communicationexchange of small molecules and ions between contiguous cells through membranous gap junctional channelsis essential for growth control and tissue homecotasis. This work conce...Gap junctional intercellular communicationexchange of small molecules and ions between contiguous cells through membranous gap junctional channelsis essential for growth control and tissue homecotasis. This work concerns the functional expression of gap junction protein connexin 43 (Cx43) in normal human lung cells and the changes in lung carcinoma cells. By. using Northern blot hybridization analysis and Cx43 immunocytochemical methods, it was otherved that cultured normal human embryonic lung cells expressed a high level of Cx43 in both mRNA and protein levels.The Cx43 immunofluorescence was localized at cell membrane regions corresponding to the location of gap junctions. These normal lung cells were competent of intercellular communication function as detected by Lucifer yellow dye transfer. In contrast to normal celis, Cx43 mRNA and protein was not detectable in the carcinoma PG cell line. These tumor cells were defective of intercellular communication function. These results demonstrate that Cx43 is expressed in normal cultured human embryonic lung cells but not in lung tumor cells. The lack of intercellular communication in the lung tumor cell line correlates with dysfunctional intercellular communication. The suggestive role of Cx as a tumor suppersor gene is discussed.展开更多
文摘Objectives To study the effects of angiotensin Ⅱ, as a mediator of cardiac hypertrophy, on expression of connexin 43 （Cx43） in cultured neonatal rat ventricular myocytes and correlation of expression of Cx43 and cardiomyocyte hypertrophy. Methods Cardiomyocytes were isolated from newborn SD rats. Angiotensin Ⅱwas added into the media to induce myocyte hypertrophy. Cultures were exposed to 10 ～ 6 mol/L angiotensin Ⅱ for 72 h, Cx43 expression was characterized by RT-PCR and Immunofluorescence methods. Results Immunofluorescence analysis revealed decreased Cx43 immunoreactivity in cells treated for 72 h with angiotensin Ⅱ. RT-PCR analysis demonstrated there was an obvious decrease of Cx43 mRNA level in cells exposed to angiotensin U for 72 h. The changes of expression of connexin 43 were related to its entrance into S phase of the cell cycle. Cultured neonatal rat cardiomyocytes were exposed for 72 h to increase concentrations of angiotensin II （ 1.0 × 10^ -9 ～ 1.0 × 10^ -6mol/L）, resulting in significantly decreased Cx43 expression. Conclusions Angiotensin/I leads to a concentration-dependent decrease in Cx43 protein in cultured neonatal rat ventricular myocytes by decreasing Cx43 mRNA synthesis. Signal transduction pathways activated by angiotensin II under pathophysiologic conditions of cardiac hypertrophy could initiate remodeling of gap junctions.
文摘Gap junctional intercellular communicationexchange of small molecules and ions between contiguous cells through membranous gap junctional channelsis essential for growth control and tissue homecotasis. This work concerns the functional expression of gap junction protein connexin 43 (Cx43) in normal human lung cells and the changes in lung carcinoma cells. By. using Northern blot hybridization analysis and Cx43 immunocytochemical methods, it was otherved that cultured normal human embryonic lung cells expressed a high level of Cx43 in both mRNA and protein levels.The Cx43 immunofluorescence was localized at cell membrane regions corresponding to the location of gap junctions. These normal lung cells were competent of intercellular communication function as detected by Lucifer yellow dye transfer. In contrast to normal celis, Cx43 mRNA and protein was not detectable in the carcinoma PG cell line. These tumor cells were defective of intercellular communication function. These results demonstrate that Cx43 is expressed in normal cultured human embryonic lung cells but not in lung tumor cells. The lack of intercellular communication in the lung tumor cell line correlates with dysfunctional intercellular communication. The suggestive role of Cx as a tumor suppersor gene is discussed.
