Department of Bioscience and Biotechnology, Sejong University, Seoul 143-747, Korea.
Nucleic Acids Res. 2010 Jan;38(3):822-31. doi: 10.1093/nar/gkp1056. Epub 2009 Nov 24.
Human sirtuin 1 (SIRT1) is a NAD(+)-dependent deacetylase that participates in cell death/survival, senescence and metabolism. Although its substrates are well characterized, no direct regulators have been defined. Here, we show that SIRT1 associates with SKI-interacting protein (SKIP) and modulates its activity as a coactivator of retinoic acid receptor (RAR). Binding assays indicated that SKIP interacts with RAR in a RA-dependent manner, through a region that overlaps the binding site for SIRT1. SKIP augmented the transcriptional activation activity of RAR by cooperating with SRC-1, and SIRT1 suppressed SKIP/SRC-1-enhanced RAR transactivation activity. The suppression was dependent on the deacetylase activity of SIRT1 and was enhanced by a SIRT1 activator, resveratrol. In contrast, the suppression was relieved by SIRT1 knockdown, overexpression of SKIP and treatment with a SIRT1 inhibitor, splitomicin. Upon SKIP overexpression, the recruitment of SIRT1 to the endogenous RARbeta2 promoter was severely impaired, and SKIP was recruited to the promoter instead. Finally, resveratrol treatment inhibited RA-induced neuronal differentiation of P19 cells, accompanied by reductions in the neuronal marker nestin and a RAR target gene, RARbeta2. This inhibition was relieved by either knockdown of SIRT1 or overexpression of SKIP. These data suggest that SIRT1 and SKIP play reciprocal roles in the regulation of RAR activity, which is implicated in the regulation of RA-induced neuronal differentiation of P19 cells.
人类 Sirtuin 1（SIRT1）是一种 NAD（+）依赖性去乙酰化酶，参与细胞死亡/存活、衰老和代谢。尽管其底物已得到很好的描述，但尚未定义直接的调节剂。在这里，我们表明 SIRT1 与 SKI 相互作用蛋白（SKIP）结合并调节其作为维甲酸受体（RAR）共激活剂的活性。结合实验表明，SKIP 通过与 SIRT1 结合位点重叠的区域，以 RA 依赖性的方式与 RAR 相互作用。SKIP 通过与 SRC-1 合作增强了 RAR 的转录激活活性，并且 SIRT1 抑制了 SKIP/SRC-1 增强的 RAR 反式激活活性。抑制作用依赖于 SIRT1 的去乙酰化酶活性，并通过 SIRT1 激活剂白藜芦醇增强。相比之下，SIRT1 敲低、SKIP 过表达和 SIRT1 抑制剂分裂霉素处理可缓解抑制作用。在 SKIP 过表达时，SIRT1 募集到内源性 RARbeta2 启动子的能力严重受损，而 SKIP 则募集到启动子。最后，白藜芦醇处理抑制 RA 诱导的 P19 细胞神经元分化，同时降低神经元标志物巢蛋白和 RAR 靶基因 RARbeta2。这种抑制作用可通过 SIRT1 敲低或 SKIP 过表达缓解。这些数据表明 SIRT1 和 SKIP 在 RAR 活性的调节中发挥相互作用，这与 RA 诱导的 P19 细胞神经元分化的调节有关。
