Nucleocytoplasmic Shuttling of the NAD+-dependent Histone Deacetylase SIRT1

Abstract

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-γ. 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 signals and nuclear SIRT1 the of histone in C2C12 cells. only the nuclear the of C2C12 cells an that is a of SIRT1, in and in of 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-γ. 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 signals and nuclear SIRT1 the of histone in C2C12 cells. only the nuclear the of C2C12 cells an that is a of SIRT1, in and in of Sir2 (silent information regulator 2) a of histone found in to and histone the Sir2 the In Sir2 in Sir2 the of in the and the of a of the in to and the Sir2 an in this of the Sir2 of SIRT1 is the of SIRT1 in and in peroxisome proliferator-activated SIRT1 deacetylates the transcription the of and the of SIRT1 contributes to and the of the of FOXO is SIRT1, SIRT1 the of and of SIRT1 it deacetylates and a transcription that the of myoblast cells a of SIRT1 and in various including heart, and an SIRT1 in to a nuclear it is localized exclusively to the nucleus in cells and in cells SIRT1 the localization of SIRT1 in and in the subcellular localization of Sir2 the subcellular localization of SIRT1 and in to and SIRT1 deacetylates histones and various transcription factors, its subcellular localization its of to and of the nucleus, that the of the nuclear of a is a nuclear localization nuclear localization nuclear phosphoinositide leptomycin nuclear localization nuclear phosphoinositide leptomycin in the is a of and a is the of two of a of of the nucleus is nuclear signals of is a of and the subcellular localization of a the of the In is to an in this of this that the subcellular localization of SIRT1 in various tissues and cells. the of SIRT1 in SIRT1 is to the cytoplasm the of C2C12 myoblast cells. We found that the phosphoinositide the subcellular localization of LY294002, an inhibitor of the localization of SIRT1 in C2C12 the nuclear of SIRT1 We a heterokaryon to that SIRT1 is a We two and two in SIRT1 and of nuclear SIRT1 inhibited a of the of SIRT1 to a in the of and in and in to in and in a and a to in and the and and and day mouse and in of the cells and nuclear a mammalian histone histone and and cells in of the C2C12 cells a the cells of the leptomycin cells in and its and in cells and in the cells cells to the cells in a and and the cells the of and cells in the of the the of mouse SIRT1 its the the and and the SIRT1 and the and a and cells an in of the in a in the of the of the subcellular localization of SIRT1 in adult mouse and in cells of the SIRT1 expressed in the cytoplasm and in ependymal it expressed in both the cytoplasm and nucleus On the other hand, spermatocytes and expressed SIRT1 only in We the subcellular localization of SIRT1 localized exclusively to the nucleus in the of day 12.5 In the of adult and nuclear SIRT1 the in SIRT1 subcellular of day and adult SIRT1 only in the nuclear in the In the of the in the in the nuclear in the adult and SIRT1 the nucleus to the cytoplasm in in the myoblast expressed only in the nucleus in of the cells. after of the cells expressed in the cytoplasm of SIRT1 that SIRT1 the nucleus to the cytoplasm in to the that SIRT1 a localization of and SIRT1 in C2C12 cells. of and SIRT1, nuclear and B, of and the subcellular of C2C12 cells that the of SIRT1, strongly inhibited of C2C12 after of and is heterokaryon and and and and the of cells in the and of other and the FOXO that the subcellular of SIRT1 We the of various the localization of in C2C12 cells and found that LY294002, an inhibitor of the nucleus In the nuclear of an of the to cells LY294002, in the nucleus of of of and the the of a of inhibited the of of that the subcellular localization of SIRT1 the the of SIRT1, a heterokaryon and both of SIRT1 exclusively in the nucleus. cells SIRT1 shuttled between the nucleus and the cytoplasm in the found only in the nucleus, but in the nucleus. in in that in of the the cells it the nucleus the heterokaryon a of the the of an and this is inhibited inhibited the of the nucleus to the nucleus in the of in its p53, a the nuclear of the of that nuclear that SIRT1 is an of the in the nucleus. 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In found that in C2C12 cells of in the of that of and its to nuclear in the of two that nuclear SIRT1 the in C2C12 myoblast cells in the nuclear of SIRT1 an in and is in SIRT1 the nucleus and in SIRT1 cells in this is the SIRT1 is to and p53, in the of in cells in the of SIRT1 the of the the of of nuclear SIRT1 cells and and the nucleus, in SIRT1 to the of FOXO it is that SIRT1 and FOXO an found that the of SIRT1 that of FOXO a a transcription in the nucleus and it is is its nuclear localization both and other and of the localization of SIRT1 is of histone transcription that histone nuclear of SIRT1 and its localization to the of transcription SIRT1 to and a transcription the of SIRT1 the nucleus the of in differentiation. that SIRT1 the nucleus the of C2C12 cells is in this the of SIRT1 a its the nuclear of SIRT1 the to of the of SIRT1 to its nuclear a subcellular localization of SIRT1 to in cells nuclear of SIRT1, but expressed it in the cytoplasm in both the nucleus and cytoplasm. subcellular localization of SIRT1 two and two in its and the We found that only nuclear SIRT1 in histone and the Sir2 to its subcellular localization it is expressed in both the cytoplasm and it to the cytoplasm and it is to in both We found that Sir2 two in and and in a and and the of Sir2 and to that of in mouse SIRT1, Sir2 only two but that to and of mouse the of Sir2 a that is to yeast. In this the of the of the that both the heterokaryon that only the nuclear that in SIRT1, but it the of a of localization of SIRT1 that the is in C2C12 cells. In found that in C2C12 cells of in the of that of and its to nuclear in the of two We that nuclear SIRT1 the in C2C12 myoblast cells in the nuclear of SIRT1 an in and is in SIRT1 the nucleus and in SIRT1 cells in this is the SIRT1 is to and p53, in the of in cells in the of SIRT1 the of the the of of nuclear SIRT1 cells and and the nucleus, in SIRT1 to the of FOXO it is that SIRT1 and FOXO an found that the of SIRT1 that of FOXO a a transcription in the nucleus and it is is its nuclear localization both and other and of the localization of SIRT1 is of histone transcription that histone nuclear of SIRT1 and its localization to the of transcription SIRT1 to and a transcription the of SIRT1 the nucleus the of in differentiation. that SIRT1 the nucleus the of C2C12 cells is in this In the of SIRT1 a its the nuclear of SIRT1 the to of the of SIRT1 to its nuclear a