Specific protein 1 (SP1) might act as a critical transcription regulator in myocardial infarction (MI), but little evidence about its function in regulating cardiac apoptosis, a major cause of MI development, has been revealed. This study tried to investigate the role of SP1 in MI and its interaction with poly-ADP-ribose polymerase (PARP)-1 by using SP1 inhibitor, mithramycin A (mithA). Primary mouse cardiomyocytes and commercial mouse cardiomyocytes were subjected to mithA treatment under hypoxia conditions, while cell viability, Nix promoter activity, and its expression were detected correspondingly. PARP overexpression and knockdown were conducted, respectively, in mithA-treated and SP1-overexpressing cells. Co-immunoprecipitation was used to verify the interaction between PARP and SP1. For in vivo experiments, mithA administration was performed after the injections of adenovirus for PARP overexpression, and then, MI introduction was carried out. Infarct size and lactate dehydrogenase level were measured to assess MI injury. SP1 inhibitor mithA attenuated hypoxia-induced decrease of cell viability and Nix transcriptional activation, which could be inhibited by PARP overexpression. Knockdown of PARP prevented SP1-induced transcription of Nix and cell viability change, and PARP showed direct interaction with SP1. Furthermore, mithA administration reduced MI injuries, while PARP overexpression could suppress the improvement. The cardioprotective role of SP1 inhibitor mithA was demonstrated here expanding the role of SP1 in MI development involving hypoxia-induced cardiac apoptosis. Moreover, PARP acted as a transcriptional coactivator in Nix transcription involving its interaction with SP1.

特异性蛋白 1 (SP1) 可能在心肌梗死 (MI) 中充当关键的转录调节因子，但很少有证据表明其在调节心肌细胞凋亡（MI 发展的主要原因）方面的功能。本研究试图通过使用SP1抑制剂光神霉素A（mithA）来研究SP1在MI中的作用及其与聚ADP核糖聚合酶（PARP）-1的相互作用。原代小鼠心肌细胞和商品化小鼠心肌细胞在缺氧条件下进行mithA处理，并相应检测细胞活力、Nix启动子活性及其表达。分别在 mithA 处理的细胞和 SP1 过表达的细胞中进行 PARP 过表达和敲低。使用免疫共沉淀来验证 PARP 和 SP1 之间的相互作用。对于体内实验，在注射用于PARP过表达的腺病毒后进行mithA施用，然后进行MI引入。测量梗塞面积和乳酸脱氢酶水平以评估心肌梗死损伤。 SP1 抑制剂 mithA 可以减轻缺氧引起的细胞活力下降和 Nix 转录激活，而这种下降可以通过 PARP 过表达来抑制。 PARP 的敲低阻止了 SP1 诱导的 Nix 转录和细胞活力的变化，并且 PARP 显示与 SP1 的直接相互作用。此外，mithA 给药可减少 MI 损伤，而 PARP 过度表达可能会抑制这种改善。这里证明了 SP1 抑制剂 mithA 的心脏保护作用，扩大了 SP1 在涉及缺氧诱导的心脏细胞凋亡的 MI 发展中的作用。此外，PARP 在 Nix 转录中充当转录共激活因子，涉及其与 SP1 的相互作用。