Department of Surgery, Roger William Medical Center, Boston University Medical School, Providence, Rhode Island 02908, USA.
J Cell Biochem. 2011 Nov;112(11):3246-55. doi: 10.1002/jcb.23251.
Histone deacetylase (HDAC) inhibition plays a crucial role in mediating cardiogenesis and myocardial protection, whereas HDAC degradation has recently attracted attention in mediating the biological function of HDACs. However, it remains unknown whether HDAC inhibition modulates cardiogenesis and embryonic stem cell (ESC) survival through the proteasome pathway. Using the well-established mouse ESC culture, we demonstrated that HDAC inhibitors, both trichostatin A (TSA,50 nmol/L) and sodium butyrate (NaB, 200 µmol/L) that causes the pronounced reduction of HDAC4 activity, decreased cell death and increased viability of ESCs in response to oxidant stress. HDAC inhibition reduced the cleaved caspases 3, 6, 9, PARP, and TUNEL positive ESCs, which were abrogated with MG132 (0.5 µmol/L), a specific proteasome inhibitor. Furthermore, HDAC inhibition stimulates the growth of embryoid bodies (EB), which are associated with a faster spontaneous rhythmic contraction. HDAC inhibition increases the up-regulation of GATA4, MEF2C, Nkx2.5, cardiac actin, and α-SMA mRNA and protein levels that were abrogated by MG132. TSA and NaB resulted in a significant increase in cardiac lineage commitments that were blocked by the proteasome inhibition. Notably, HDAC inhibitors led to noticeable HDAC4 degradation, which was effectively prevented by MG132. Luciferase assay demonstrates an activation of MEF2 cardiac transcriptional factor by HDAC inhibition, which was repressed by MG132, revealing that the degradation of HDAC4 allows for the activation of MEF2. Taken together, our study is the first to demonstrate that HDAC inhibition through proteasome pathway forms a novel signaling to determine the cardiac lineage commitment and elicits the survival pathway.
组蛋白去乙酰化酶（HDAC）抑制在介导心脏发生和心肌保护中起着至关重要的作用，而 HDAC 的降解最近在介导 HDAC 的生物学功能方面引起了关注。然而，HDAC 抑制是否通过蛋白酶体途径调节心脏发生和胚胎干细胞（ESC）存活尚不清楚。使用成熟的小鼠 ESC 培养物，我们证明了 HDAC 抑制剂，即曲古抑菌素 A（TSA，50 nmol/L）和丁酸钠（NaB，200 μmol/L），导致 HDAC4 活性明显降低，减少细胞死亡并增加 ESC 在氧化应激下的活力。HDAC 抑制减少了 cleaved caspase 3、6、9、PARP 和 TUNEL 阳性的 ESC，而蛋白酶体抑制剂 MG132（0.5 μmol/L）则消除了这种情况。此外，HDAC 抑制刺激胚状体（EB）的生长，这与自发节律性收缩更快有关。HDAC 抑制增加了 GATA4、MEF2C、Nkx2.5、心脏肌动蛋白和α-SMA mRNA 和蛋白水平的上调，而 MG132 则消除了这种上调。TSA 和 NaB 导致心脏谱系承诺显著增加，而蛋白酶体抑制阻止了这种增加。值得注意的是，HDAC 抑制剂导致明显的 HDAC4 降解，而 MG132 可有效阻止这种降解。荧光素酶测定表明 HDAC 抑制激活了 MEF2 心脏转录因子，而 MG132 抑制了这种激活，表明 HDAC4 的降解允许 MEF2 的激活。总之，我们的研究首次表明，通过蛋白酶体途径的 HDAC 抑制形成了一种新的信号通路，决定了心脏谱系的承诺，并引发了存活途径。
