Mutations in SIRT2 deacetylase which regulate enzymatic activity but not its interaction with HDAC6 and tubulin

Abstract

Human SIRT2 is a cytoplasmic NAD-dependent deacetylase implicated in the mitotic regulation of microtubule dynamics by its association with the class II histone deacetylase 6 (HDAC6). We have previously reported that SIRT2 is multiply phosphorylated in a cell cycle dependent pattern. Here, we demonstrate that HDAC6 binds to both phosphorylated and unphosphorylated forms of SIRT2 and that tubulin binds only to the SIRT2-HDAC6 complex. Tubulin does not bind to either HDAC6 or SIRT2 individually. In addition, we show that replacement of specific serines with alanines in either isoform of SIRT2 regulates its enzymatic activity. We also found that overexpression of isoform2 was deleterious to cell survival. SIRT2 was found to be phosphorylated at serines 368 and 372, outside the conserved core domain of the Sir2 protein family. Double replacement of S368A and S372A reduced SIRT2 deacetylase activity by 44% compared to wildtype activity. Replacements of other serine, threonine, and tyrosine residues, which did not alter the phosphorylation pattern, had varying effects on SIRT2 deacetylase activity but no effect on tubulin/HDAC6 binding.

Association of SIRT2 gene polymorphisms with body measurement and growth traits of Qinchuan cattle

“…Moreover, a recent study revealed that SIRT2 suppresses adipocyte differentiation by deacetylating FOXO1 and enhancing its repressive interaction with PPARγ (Wang and Tong, 2009). Moreover, several previous studies have confirmed that SIRT2 plays an important role in the cell cycle, and overexpression of the wild-type SIRT2 gene can prolong the mitotic phase in the cell cycle (Dryden et al, 2003;North and Verdin, 2007;Nahhas et al, 2007). These studies indicate that the SIRT2 gene may mediate, directly or indirectly, meat production traits in animals.…”

Regulation of microtubule dynamics by inhibition of the tubulin deacetylase HDAC6

“…These include histone deacetylase 6 (HDAC6), a member of the class II histone deacetylases (Boyault et al, 2007a;Hubbert et al, 2002;Matsuyama et al, 2002;Zhang et al, 2003), and SIRT2, a class III NAD-dependent histone deacetylase (North et al, 2003). HDAC6 and SIRT2 form a cytoplasmic complex, and probably function in concert (Nahhas et al, 2007;North et al, 2003), though manipulation with HDAC6 alone is sufficient to significantly change the level of microtubule acetylation. HDAC6 overexpression leads to complete deacetylation of microtubules, whereas inhibition of HDAC6 by specific inhibitors, RNAi-mediated knockdown, or genetic knockout increased microtubule acetylation (Haggarty et al, 2003;Hubbert et al, 2002;Matsuyama et al, 2002;Zhang et al, 2008;Zhang et al, 2003).…”

Role of Sirtuins in Stem Cell Differentiation

“…In vivo, it can deacetylate microtubules and chromatin. [25][26][27][28] Acetylation in α-tubulin was reported to stabilize microtubules, although SIRT2…”

“…69 SIRT2 is also clearly associated with neural and fat differentiation and has been shown to function as an α-tubulin deacetylase and key regulator of cell division. [25][26][27][28] It is expressed in all tissues but is particularly abundant in the brain, especially in myelin sheaths and in mature and premyelinating oligodendrocytes. 70 During the differentiation of glial progenitors into premyelinating oligodendrocytes, both levels of SIRT2 and microtubule acetylation increase, which appears to be contradictory since SIRT2 is the major microtubule deacetylase in oligodendrocytes.…”