Inhibition of ischemia induced-apoptosis in cardiac myocytes by ATF3 and its implication in gene therapy

ATF3（激活转录因子3）是ATF/CREB家族的成员，与CRE和AP-1一致序列结合。我们最近报道了ATF3抑制DOX诱导的培养新生大鼠心肌细胞凋亡。DOX刺激可立即在转录和翻译水平诱导ATF3，分别在1小时和3小时达到峰值。为了进一步了解ATF3在dox诱导的细胞凋亡中的生理功能，我们制作了含有ATF3编码序列的腺病毒载体（AdATF3），并在心肌细胞中定向过表达ATF3。流式细胞术、细胞活力测定和TUNEL染色分析显示AdATF3对dox诱导的细胞凋亡有抑制作用。我们进一步证明，ATF3在接受或未接受DOX处理的细胞中均与c-Jun形成异二聚体，这表明ATF3异二聚体和同二聚体的不适当形成可能导致AdATF3抑制心肌细胞凋亡。我们进一步研究了AdATF3对心肌缺血诱导的细胞凋亡的抑制作用。AdATF3抑制体外缺氧刺激诱导的细胞凋亡。我们还发现AdATF3抑制缺血再灌注诱导的细胞凋亡。综上所述，这些结果表明ATF3过表达抑制心肌细胞凋亡，提示ATF3具有心脏保护作用。我们的数据可能为基因治疗多种心血管疾病引起的心肌损伤开辟一条新的途径。

ATF3 (activating transcription factor 3) is a member of the ATF/CREB family, which binds to CRE and AP-1 consensus sequences. We have recently reported that ATF3 inhibits apoptosis of cultured neonatal rat cardiac myocytes induced by DOX. ATF3 was immediately induced at transcriptional and translational level by stimulation of DOX, peaking at 1 hour and at 3 hours respectively. To extend our understanding of the physiological functions of ATF3 in the DOX-induced apoptosis, we produced the adenovirus vector containing coding sequences of ATF3 (AdATF3) and directed overexpression of ATF3 in cardiac myocytes. The inhibition of DOX-induced apoptosis by AdATF3 was shown by flow cytometry, cefi viabih'ty assay and TUNEL staining analyzes. We further demonstrated that ATF3 formed heterodimer with c-Jun both in the cells with or without DOX treatment, suggesting that inappropriate formation of hetero- and homodimer of ATF3 may result in the inhibition of apoptosis in cardiac myocytes with AdATF3.We further investigated AdATF3 can inhibit apoptosis induced by ischemia in cardiac myocytes. AdATF3 inhibited apoptosis induced by hypoxic stimulation in vitro. We also showed that AdATF3 inhibited apoptosis induced by ischemia-reperfusion.In conclusion, these results indicate that overexpression of ATF3 inhibits apoptosis in cardiac myocytes, and suggest a cardio protective role of ATF3. Our data may open a new avenue for gene therapy against myocardial damage by a variety of cardiovascular diseases.