O-glycosylation of Sp1 and transcriptional regulation of the calmodulin gene by insulin and glucagon

American Journal of Physiology - Endocrinology and Metabolism - Tập 285 Số 3 - Trang E584-E591 - 2003
Gipsy Majumdar1, Ashley Harmon, Rosalind P. Candelaria, Antonio Martinez-Hernandez, Rajendra Raghow, Solomon S. Solomon
1Research Services, Veterans Affairs Medical Center, Memphis, TN 38104, USA.

Tóm tắt

Both insulin and glucagon stimulate steady-state levels of Sp1 transcription factor, but only insulin stimulates transcription of the calmodulin (CaM) gene in liver. Because O-glycosylation of Sp1 by O-linked N-acetylglucosamine ( O-GlcNAc) is thought to regulate its ability to activate transcription, we assayed the levels of Sp1 with anti-Sp1 and anti- O-GlcNAc antibodies in Western blots by use of extracts of H-411E liver cells treated with insulin (10,000 μU/ml) or glucagon (1.5 × 10-5M). We also assessed subcellular localization of the native and glycosylated Sp1 in H411E cells treated with either hormone in the presence of deoxynorleucine (DON, an indirect inhibitor of O-glycosylation) or streptozotocin (STZ, an indirect stimulator of O-glycosylation). Insulin stimulated both total and O-GlcNAc-modified Sp1 primarily in the nucleus and induced CaM gene transcription ( P < 0.0001). In contrast, glucagon promoted accumulation of Sp1 in the cytoplasm but not the nucleus, without significantly stimulating ( P = not significant) either its O-glycosylation or transcription of the CaM gene. DON inhibited O-glycosylation of Sp1 and its ability to migrate to the nucleus and transactivate CaM gene transcription. In contrast, cotreatment of cells with STZ and glucagon enhanced O-glycosylation of Sp1, promoting its migration to the nucleus and resulting in increased CaM gene transcription. Thus O-glycosylation of Sp1 by insulin, but not glucagon, apparently enhances its (Sp1) nuclear recruitment and results in activation of CaM gene transcription.

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Tài liệu tham khảo

10.1016/0092-8674(89)90241-9

10.1073/pnas.97.22.12222

10.1523/JNEUROSCI.13-06-02424.1993

10.1074/jbc.M010420200

10.1128/MCB.17.5.2550

10.1146/annurev.biochem.66.1.315

10.1351/pac199567101637

Holt GDand Hart GW.The subcellular distribution of terminal N-acetylglucosamine moieties. Localization of a novel protein-saccharide linkage, O-linked GlcNAc.J Biol Chem261: 8049-8057, 1986.

10.1016/0092-8674(88)90015-3

10.1073/pnas.88.5.1701

10.1210/endo.143.4.8756

10.1073/pnas.152346899

10.1210/endo.142.4.8083

10.1067/mlc.2000.108149

Roos MD, Xie W, Su K, Clark JA, Yang X, Chin E, Paterson AJ, and Kudlow JE.Streptozotocin, an analog of N-acetylglucosamine, blocks the removal of O-GlcNAc from intracellular proteins.Proc Assoc Am Physicians110: 422-432, 1998.

10.1021/bi951918j

10.1016/0006-291X(80)91248-6

Solomon SS, Palazzolo MR, Takahashi T, and Raghow R.Insulin stimulates rat calmodulin I gene transcription through activation of Sp1.Proc Assoc Am Physicians109: 470-477, 1997.

10.1210/endo.138.11.5648

Solomon SSand Raghow R.Molecular mechanisms of insulin modulated signaling and regulation of gene transcription.Recent Res Devel Endocrinol3: 79-99, 2002.

10.1126/science.1058714

White MFand Kahn CR.The insulin signaling system.J Biol Chem269: 1-4, 1994.

10.1073/pnas.111099998

10.1016/S0092-8674(02)00810-3

10.1021/cr000406u

10.1146/annurev.bi.64.070195.002533

Thông tin
Thông tin xuất bản

American Journal of Physiology - Endocrinology and Metabolism

Tập 285 Số 3

E584-E591

Thông tin tác giả