Nucleocytoplasmic shuttling of the NAD+-dependent histone deacrtylase SIRT1
Nucleocytoplasmic shuttling of the NAD+-dependent histone deacrtylase SIRT1
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DOI：
10.1074/jbc.m609554200
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发表时间：
2007-03-02
影响因子：
4.8
通讯作者：
Horio, Yoshiyuki
中科院分区：
文献类型：
--
作者：
Tanno, Masaya;Sakamoto, Jun;Horio, Yoshiyuki
Sir 2（沉默信息调节器2）是一种NAD（+）依赖性组蛋白脱乙酰酶，有助于酵母的长寿。SIRT 1是哺乳动物Sir 2的直系同源物，可使组蛋白和各种转录因子脱乙酰基，包括p53、FOXO蛋白和过氧化物酶体增殖物激活受体-γ。我们发现，它的亚细胞定位在不同组织的成年小鼠。一些神经元亚群主要在细胞质中表达SIRT 1，但室管膜细胞在细胞核和细胞质中都表达SIRT 1。另一方面，精母细胞仅在细胞核中表达SIRT 1。12.5天小鼠胚胎的心肌细胞仅在细胞核中表达SIRT 1，但在成年心脏中，它们在细胞质和细胞核中都表达SIRT 1。C2 C12成肌细胞在细胞核中表达SIRT 1，但在分化后定位于细胞质。磷酸肌醇3-羟激酶抑制剂LY 294002可明显抑制SIRT 1在未分化C2 C12细胞中的核定位。在异核体分析中，SIRT 1穿梭于细胞核和细胞质之间，并且来普霉素B（CRM 1介导的核输出的抑制剂）抑制这种穿梭。两个核定位信号和两个核输出信号被确定为缺失和定点突变分析。在C2 C12细胞中，核内过表达的SIRT 1（而非胞质或显性阴性）增强了组蛋白H3的去乙酰化。此外，只有核的形式抑制抗霉素A，氧化应激诱导的C2 C12细胞凋亡。这些发现表明，核质穿梭是SIRT 1的一种新的调节机制，可能参与分化和抑制细胞死亡。
Sir2 (silent information regulator 2) is an NAD(+)-dependent histone deacetylase that contributes to longevity in yeast. SIRT1, a mammalian Sir2 ortholog, deacetylates histones and various transcription factors, including p53, FOXO proteins, and peroxisome proliferator-activated receptor-gamma. We found that its subcellular localization varied in different tissues of the adult mouse. Some subsets of neurons predominantly expressed SIRT1 in the cytoplasm, but ependymal cells expressed it in both the nucleus and cytoplasm. On the other hand, spermatocytes expressed SIRT1 only in the nucleus. Cardiomyocytes in the day 12.5 mouse embryo expressed SIRT1 exclusively in the nucleus, but in the adult heart, they expressed it in both the cytoplasm and nucleus. C2C12 myoblast cells expressed SIRT1 in the nucleus, but it localized to the cytoplasm after differentiation. LY294002, an inhibitor of phosphoinositide 3-hydroxykinase, strongly inhibited the nuclear localization of SIRT1 in undifferentiated C2C12 cells. In a heterokaryon assay, SIRT1 shuttled between the nucleus and cytoplasm, and leptomycin B, an inhibitor of CRM1-mediated nuclear exportation, inhibited this shuttling. Two nuclear localization signals and two nuclear export signals were identified by deletion and site-directed mutation analyses. Overexpressed nuclear (but not cytoplasmic or dominant-negative) SIRT1 enhanced the deacetylation of histone H3 in C2C12 cells. Moreover, only the nuclear form suppressed the apoptosis of C2C12 cells induced by antimycin A, an oxidative stressor. These findings indicate that nucleocytoplasmic shuttling is a novel regulatory mechanism of SIRT1, which may participate in differentiation and in inhibition of cell death.