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Abstract: Human cytomegalovirus immediate early proteins (CMV IEs) are involved in transcriptional activities of both host and virus gene expression. This study shows that the transcriptional activity of myocardin in regulating cardiomyocyte hypertrophy is enhanced by co-expressing CMV IE2. Forced expression of IE2 increases the augmented cell size of neonatal rat cardiac myocytes induced by myocardin, as well as the mRNA and protein levels of hypertrophic genes, whereas deletion of CArG boxes in the atrial natriuretic factor (ANF) promoter attenuates the effect of CMV IE2 with myocardin. In conclusion, CMV IE2 synergistically stimulates myocardin transactivity in the hypertrophic marker gene ANF in a CArG box-dependent manner. Our study indicates that the association of CMV IEs with myocardin-induced transcription may be involved in myocardin-mediated cardiac hypertrophy. [Copyright &y& Elsevier]

Abstract: Red fluorescent protein (RFP) DsRed and its variants are widely applied in live-cell imaging experiments. However, a major factor that restricts the application of DsRed is its cytotoxicity. Here, we report that DsRed and its variant DsRed-Express2 inhibit the expression of B-cell lymphoma-extra large (Bcl-xL) in HeLa cells by translational regulation. Over-expression of Bcl-xL can reduce the cytotoxicity of DsRed. Meanwhile, Turbo RFP, a mutant RFP from Entacmaea quadricolor, does not affect Bcl-xL expression, suggesting that cytotoxic mechanisms of RFP from different species may be varied. Our results reveal a possible mechanism for the cytotoxicity of DsRed, providing a potential strategy to improve the application of DsRed and its variants. [Copyright &y& Elsevier]