Perturbations in O-linked β-N-Acetylglucosamine Protein Modification Cause Severe Defects in Mitotic Progression and Cytokinesis
The dynamic modification of nuclear and cytoplasmic proteins with O-linked β-N-acetylglucosamine (O-GlcNAc) is a regulatory post-translational modification that is rapidly responsive to morphogens, hormones, nutrients, and cellular stress. Here we show that O-GlcNAc is an important regulator of the cell cycle. Increased O-GlcNAc (pharmacologically or genetically) results in growth defects linked to delays in G2/M progression, altered mitotic phosphorylation, and cyclin expression. Overexpression of O-GlcNAcase, the enzyme that removes O-GlcNAc, induces a mitotic exit phenotype accompanied by a delay in mitotic phosphorylation, altered cyclin expression, and pronounced disruption in nuclear organization. Overexpression of the O-GlcNAc transferase, the enzyme that adds O-GlcNAc, results in a polyploid phenotype with faulty cytokinesis. Notably, O-GlcNAc transferase is concentrated at the mitotic spindle and midbody at M phase. These data suggest that dynamic O-GlcNAc processing is a pivotal regulatory component of the cell cycle, controlling cell cycle progression by regulating mitotic phosphorylation, cyclin expression, and cell division. The dynamic modification of nuclear and cytoplasmic proteins with O-linked β-N-acetylglucosamine (O-GlcNAc) is a regulatory post-translational modification that is rapidly responsive to morphogens, hormones, nutrients, and cellular stress. Here we show that O-GlcNAc is an important regulator of the cell cycle. Increased O-GlcNAc (pharmacologically or genetically) results in growth defects linked to delays in G2/M progression, altered mitotic phosphorylation, and cyclin expression. Overexpression of O-GlcNAcase, the enzyme that removes O-GlcNAc, induces a mitotic exit phenotype accompanied by a delay in mitotic phosphorylation, altered cyclin expression, and pronounced disruption in nuclear organization. Overexpression of the O-GlcNAc transferase, the enzyme that adds O-GlcNAc, results in a polyploid phenotype with faulty cytokinesis. Notably, O-GlcNAc transferase is concentrated at the mitotic spindle and midbody at M phase. These data suggest that dynamic O-GlcNAc processing is a pivotal regulatory component of the cell cycle, controlling cell cycle progression by regulating mitotic phosphorylation, cyclin expression, and cell division. Because of the discovery of cyclins 22 years ago (1Evans T. Rosenthal E.T. Youngblom J. Distel D. Hunt T. Cell. 1983; 33: 389-396Abstract Full Text PDF PubMed Scopus (1006) Google Scholar), a working model of the cell cycle has slowly been constructed. The cell cycle oscillator is composed of protein phosphorylation, timed expression of cyclins, and well orchestrated cell division (2Murray A.M. Cell. 2004; 116: 221-234Abstract Full Text Full Text PDF PubMed Scopus (907) Google Scholar). Nevertheless, a detailed mechanism of the cell cycle is still incomplete. Knockouts of proteins thought critical for proper cell cycle function such as cyclin D only partially disrupt the cell cycle, and function can be completely restored by cyclin E knock-in (3Geng Y. Whoriskey W. Park M.Y. Bronson R.T. Medema R.H. Li T. Weinberg R.A. Sicinski P. Cell. 1999; 97: 767-777Abstract Full Text Full Text PDF PubMed Scopus (287) Google Scholar). However, cyclin E knockouts are viable (4Geng Y. Yu Q. Sicinska E. Das M. Schneider J.E. Bhattacharya S. Rideout III, W.M. Bronson R.T. Gardner H. Sicinski P. Cell. 2003; 114: 431-443Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar), and ablation of cyclin-dependent kinases (CDK2 and CDK4) do not cause cell death or cell cycle defects (5Rane S.G. Dubus P. Mettus R.V. Galbreath E.J. Boden G. Reddy E.P. Barbacid M. Nat. Genet. 1999; 22: 44-52Crossref PubMed Scopus (613) Google Scholar, 6Ortega S. Prieto I. Odajima J. Martin A. Dubus P. Sotillo R. Barbero J.L. Malumbres M. Barbacid M. Nat. Genet. 2003; 35: 25-31Crossref PubMed Scopus (713) Google Scholar). Recently, RNA-mediated interference was used to knockdown the Drosophila kinome (7Bettencourt-Dias M. Giet R. Sinka R. Mazumdar A. Lock W.G. Balloux F. Zafiropoulos P.J. Yamaguchi S. Winter S. Carthew R.W. Cooper M. Jones D. Frenz L. Glover D.M. Nature. 2004; 432: 980-987Crossref PubMed Scopus (294) Google Scholar). One-third of all kinases knocked down in this study caused cell cycle defects. Clearly, many pathways in the cell cycle have redundant features, and other mechanisms of growth control exist. Despite the publication of more than 7000 papers within the last 5 years on the roles of phosphorylation in the cell cycle, the mechanisms regulating cell cycle progression are still not well understood. Although phosphorylation is the molecular mechanism generally associated with the regulation of cell cycle proteins, another potential regulator that has not been studied in this context is the abundant post-translational modification O-GlcNAc 2The abbreviations used are: O-GlcNAc, O-linked β-N-acetylglucosamine; OGT, O-GlcNAc transferase; PUGNAc, phenylurethane of O-GlcNAc; DON, 6-diazo-5-oxo-l-norleucine; pRB, retinoblastoma protein; YY1, Yin Yang 1; GFP, green fluorescent protein; PBS, phosphate-buffered saline; OGlcNAcase, β-N-acetylglucosaminindase. (8Wells L. Vosseller K. Hart G.W. Science. 2001; 291: 2376-2378Crossref PubMed Scopus (805) Google Scholar). O-GlcNAc is a ubiquitous post-translational modification in which a single β-N-acetylglucosamine molecule is O-linked to serine or threonine residues on cytoplasmic and nuclear proteins (9Slawson C. Hart G.W. Curr. Opin. Struct. Biol. 2003; 13: 631-636Crossref PubMed Scopus (115) Google Scholar). O-GlcNAc is thought to act as a modulator of protein function in a manner analogous to protein phosphorylation; the addition of O-GlcNAc to the protein backbone is dynamic and responds to morphogens (10Kearse K.P. Hart G.W. Proc. Natl. Acad. Sci. U. S. A. 1991; 88: 1701-1705Crossref PubMed Scopus (192) Google Scholar), cellular stress (11Zachara N.E. O'Donnell N. Cheung W.D. Mercer J.J. Marth J.D. Hart G.W. J. Biol. Chem. 2004; 279: 30133-30142Abstract Full Text Full Text PDF PubMed Scopus (442) Google Scholar), and changes in glucose metabolism (12Vosseller K. Wells L. Lane M.D. Hart G.W. Proc. Natl. Acad. Sci. U. S. A. 2002; 99: 5313-5318Crossref PubMed Scopus (393) Google Scholar, 13McClain D.A. Lubas W.A. Cooksey R.C. Hazel M. Parker G.J. Love D.C. Hanover J.A. Proc. Natl. Acad. Sci. U. S. A. 2002; 99: 10695-10699Crossref PubMed Scopus (274) Google Scholar). O-GlcNAc transferase (OGT) (14Haltiwanger R.S. Blomberg M.A. Hart G.W. J. Biol. Chem. 1992; 267: 9005-9013Abstract Full Text PDF PubMed Google Scholar, 15Kreppel L.K. Hart G.W. J. Biol. Chem. 1999; 274: 32015-32022Abstract Full Text Full Text PDF PubMed Scopus (335) Google Scholar, 16Lubas W.A. Hanover J.A. J. Biol. Chem. 2000; 275: 10983-10988Abstract Full Text Full Text PDF PubMed Scopus (255) Google Scholar) adds and O-GlcNAcase removes O-GlcNAc (17Gao Y. Wells L. Comer F.I. Parker G.J. Hart G.W. J. Biol. Chem. 2001; 276: 9838-9845Abstract Full Text Full Text PDF PubMed Scopus (520) Google Scholar, 18Comtesse N. Maldner E. Meese E. Biochem. Biophys. Res. Commun. 2001; 283: 634-640Crossref PubMed Scopus (139) Google Scholar) in a dynamic manner at sites on the protein backbone similar to those modified by protein kinases and is reciprocal with phosphorylation on some well studied proteins, such as RNA polymerase II (19Kelly W.G. Dahmus M.E. Hart G.W. J. Biol. Chem. 1993; 268: 10416-10424Abstract Full Text PDF PubMed Google Scholar), estrogen receptor-β (20Cheng X. Cole R.N. Zaia J. Hart G.W. Biochemistry. 2000; 39: 11609-11620Crossref PubMed Scopus (152) Google Scholar), and the c-Myc proto-oncogene product (21Chou T.Y. Hart G.W. Dang C.V. J. Biol. Chem. 1995; 270: 18961-18965Abstract Full Text Full Text PDF PubMed Scopus (361) Google Scholar). These data suggest a mechanism by which O-GlcNAc modulates cellular function by competing with phosphorylation. Accumulating evidence suggests O-GlcNAc may function as a global regulator of cell growth and division. Deletion of OGT in mouse embryonic fibroblasts is associated with delayed growth, increased expression of the cyclin inhibitor p27, and death (22O'Donnell N. Zachara N.E. Hart G.W. Marth J.D. Mol. Cell. Biol. 2004; 24: 1680-1690Crossref PubMed Scopus (340) Google Scholar, 23Shafi R. Iyer S.P.N. Ellies L.G. O'Donnell N. Marek K.W. Chui D. Hart G.W. Marth J.D. Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 5735-5739Crossref PubMed Scopus (598) Google Scholar). A reduction in O-GlcNAc levels, the result of lowering UDP-GlcNAc levels (substrate for OGT) to 5% of normal, results in cell growth defects (24Boehmelt G. Wakeham A. Elia A. Sasaki T. Plyte S. J. Yang Y. E. J. J.D. J. 2000; PubMed Scopus Google Scholar). in defects in with which O-GlcNAc residues and O-GlcNAc Res. 2001; PubMed Scopus Google Scholar). of with the O-GlcNAcase inhibitor Hart G.W. J. Biol. Chem. Full Text PDF PubMed Google Scholar, R.S. K. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar) altered progression of C. S. J. R. Biophys. 2002; PubMed Scopus Google Scholar). this study we show that global O-GlcNAc protein modification is in a cell and this dynamic regulation is for cell cycle of O-GlcNAc or of OGT or O-GlcNAcase results in cell cycle defects. we show that the processing of O-GlcNAc is critical for proper progression, and mitotic protein phosphorylation. These data suggest O-GlcNAc a in the regulation of protein function for cell cycle progression and cell division. used in this study are cyclin cyclin E cyclin retinoblastoma protein green fluorescent protein A and F.I. Vosseller K. Wells L. M.A. Hart G.W. Biochem. 2001; PubMed Scopus Google Scholar). OGT L.K. Hart G.W. J. Biol. Chem. 1999; 274: 32015-32022Abstract Full Text Full Text PDF PubMed Scopus (335) Google Scholar) and O-GlcNAcase in was a at the of on and was was and cell in modified with and or in to for for an this or was or and at in to in modified with and mitotic by the addition of and Lane M.D. J. Biol. Chem. Full Text PDF PubMed Google Scholar) in modified with and to Lane M.D. J. Biol. Chem. Full Text PDF PubMed Google Scholar). and was (17Gao Y. Wells L. Comer F.I. Parker G.J. Hart G.W. J. Biol. Chem. 2001; 276: 9838-9845Abstract Full Text Full Text PDF PubMed Scopus (520) Google O-GlcNAcase was and the was and in to was by was by to OGT was a of at E. M. M. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). The was the of at the with O-GlcNAcase, OGT, or control at a of or the the been for of and as (11Zachara N.E. O'Donnell N. Cheung W.D. Mercer J.J. Marth J.D. Hart G.W. J. Biol. Chem. 2004; 279: 30133-30142Abstract Full Text Full Text PDF PubMed Scopus (442) Google Scholar). the protein by on to and with in and with at for in and and with and as with in The was as the and the was at II with the of in in in in for and as The in with and with at in with and for at and for in with and as and a at the and and as and in The in of with The at with and in and for cell cycle at the a was to the by and Lane Lane M.D. 1999; 13: PubMed Scopus Google Scholar). O-GlcNAc for the that dynamic O-GlcNAc protein modification is a control mechanism for cellular growth, we global levels of O-GlcNAc the O-GlcNAcase inhibitor and the growth of cell was control and at and pronounced at 5 cell O-GlcNAc levels the growth However, only a of growth is to the of in and at M we O-GlcNAc levels in a cell at the with R.S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). proteins in cell by with an F.I. Vosseller K. Wells L. M.A. Hart G.W. Biochem. 2001; PubMed Scopus Google Scholar). O-GlcNAc was with control Although the O-GlcNAc levels in and O-GlcNAc on a proteins completely an in O-GlcNAc is on proteins the of phosphorylation the is to M Proc. Natl. Acad. Sci. U. S. A. 1983; PubMed Scopus Google Scholar). the show a in the levels of of that the levels of of the or proteins not not O-GlcNAc and phosphorylation we in with Because O-GlcNAcase, the enzyme for the we the in O-GlcNAc levels in and Although increased the of on many proteins in not the of proteins in phosphorylation is not Although of was on phosphorylation, we changes on proteins not at the that O-GlcNAc levels on proteins and not the levels of the we at regulatory proteins to be R. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar) and M. Jones H. D. A. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, M. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). is and the levels of O-GlcNAc on this an in in a molecular of and a in in a molecular is the of O-GlcNAc modification the is similar to The protein expression of is and the is completely is to the not The an in at M with in the protein expression not are with PUGNAc, the levels of the are of in which OGT levels and O-GlcNAcase of O-GlcNAc the of O-GlcNAc in cell cycle we the of cell cycle progression by in the with to O-GlcNAc levels or with DON, to O-GlcNAc levels to to the enzyme of the which the for OGT S. J. Biol. Chem. 1991; Full Text PDF PubMed Google Scholar, N.E. O'Donnell N. Cheung W.D. Mercer J.J. Marth J.D. Hart G.W. J. Biol. Chem. 2004; 279: 30133-30142Abstract Full Text Full Text PDF PubMed Scopus (442) Google Scholar). with O-GlcNAc a delay in G2/M progression control of the M and to only of to with O-GlcNAc the cell cycle at an with control and by of the to with only in is a of and the of is with DON, at similar to control or progression, was in by at control at 5 and at we in an model of cell cycle that not on to These are to of is by of cell cycle progression mitotic Lane M.D. Proc. Natl. Acad. Sci. U. S. A. 2003; PubMed Scopus Google Scholar). with or of mitotic and at with O-GlcNAc delays in cell cycle progression with The delay with the results in the with to the of the cell cycle. The addition of to at the of mitotic or in to However, at of not with cell growth not is with which show defects in to with not to altered the expression of O-GlcNAcase and OGT O-GlcNAc by caused a in the expression of OGT and an in O-GlcNAcase expression. The was OGT and O-GlcNAcase G2/M cell we to the levels of the O-GlcNAcase and O-GlcNAc transferase in the expression of and are to N. E. K. W. M. D. and G. W. a of that only caused a or in O-GlcNAc levels was not and exit and G2/M and and by a of the to the a in M progression was more than of control to of still in M phase. result was in at a in the of was in the to was not to a M the of the of and the of the increased of as the and M phase. and only a of Overexpression of O-GlcNAcase and O-GlcNAc the of OGT and O-GlcNAcase on and mitotic phosphorylation was levels of O-GlcNAc in a in O-GlcNAc levels and a on an protein phosphorylation, as by is and phosphorylation with is The in the of is a the in phosphorylation in the is mitotic phosphorylation; a the and is not in the and and are in a of M than A and at as by the of phosphorylation is and mitotic kinases cyclin-dependent and for and changes in the of the cell cycle is is not in cyclin-dependent The expression of the regulator protein is by was not the levels of this protein the cell cycle. The protein is by phosphorylation on threonine at by a cyclin-dependent D and to proteins T. S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, Biophys. 2001; Google Scholar). The show delayed and phosphorylation with levels of phosphorylation at to the of O-GlcNAc expression levels of cyclins cyclins A and show expression M (9Slawson C. Hart G.W. Curr. Opin. Struct. Biol. 2003; 13: 631-636Crossref PubMed Scopus (115) Google Scholar, K.P. Hart G.W. Proc. Natl. Acad. Sci. U. S. A. 1991; 88: 1701-1705Crossref PubMed Scopus (192) Google Scholar, N.E. O'Donnell N. Cheung W.D. Mercer J.J. Marth J.D. Hart G.W. J. Biol. Chem. 2004; 279: 30133-30142Abstract Full Text Full Text PDF PubMed Scopus (442) Google Scholar, K. Wells L. Lane M.D. Hart G.W. Proc. Natl. Acad. Sci. U. S. A. 2002; 99: 5313-5318Crossref PubMed Scopus (393) Google and a with data (1Evans T. Rosenthal E.T. Youngblom J. Distel D. Hunt T. Cell. 1983; 33: 389-396Abstract Full Text PDF PubMed Scopus (1006) Google Scholar). and protein levels of cyclins A and to expression of cyclins A and was in with A similar of cyclin expression was in and cyclin E expression is at M and as the cyclin E protein levels at a than as the cyclin E expression is E expression is in The cyclin D in of expression with the expression of the cyclin-dependent inhibitor in as to in and are by cellular (2Murray A.M. Cell. 2004; 116: 221-234Abstract Full Text Full Text PDF PubMed Scopus (907) Google Scholar), the to have on of the cyclins Increased O-GlcNAc and the M defects to the of O-GlcNAcase and OGT at and M and of have on and for and O-GlcNAcase or OGT control cytoplasmic for O-GlcNAcase and for OGT M O-GlcNAcase ubiquitous the the enzyme is the nuclear of the O-GlcNAcase and OGT and the result the for to is the cell the more with and the is The to and the a the of the show this that is modified by O-GlcNAc J.E. J. 2003; PubMed Scopus Google may O-GlcNAc levels on and disrupt proper OGT ubiquitous the cell OGT is concentrated with the mitotic spindle M OGT concentrated the of the mitotic A in with the spindle is the to OGT is concentrated at the spindle the OGT concentrated at the at of the are other still have the A of the of the is the concentrated in a the nuclear of OGT with was by the of a green the spindle and within the midbody the is a of Increased midbody is with more OGT concentrated in this the at the midbody and to and The at the midbody is the still to growth and division are the result of which are by protein expression, protein and protein phosphorylation. this study we show that dynamic O-GlcNAc, a in cell cycle progression and cell division. The of this the or O-GlcNAc levels results in changes in cell cycle of global O-GlcNAc levels induces changes in the expression of OGT and of or mitotic phosphorylation and the timed expression of cyclin OGT to the mitotic spindle and midbody cell of OGT results in to cytokinesis. and in O-GlcNAc cell growth delays in cell was to have on growth R.S. K. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). this study with was in the The on growth may result in changes to cell cycle on and this and These data with that increased UDP-GlcNAc levels cell growth and in G. M. M. G. E. A. J. Biol. Chem. Full Text PDF PubMed Google Scholar). A of this model was in Hanover J.A. Biochem. Biophys. 1999; PubMed Scopus Google Scholar). nuclear proteins are modified by O-GlcNAc A. R.S. L. Hart G.W. J. Biol. PubMed Scopus Google Scholar), and proteins are as to M Hanover J.A. Biochem. Biophys. 1999; PubMed Scopus Google Scholar). These proteins are modified by O-GlcNAc and Hanover J.A. Biochem. Biophys. 1999; PubMed Scopus Google Scholar), O-GlcNAc proteins are with by defects in to Res. 2001; PubMed Scopus Google Scholar). are in nuclear is delayed C. S. J. R. Biophys. 2002; PubMed Scopus Google Scholar). phosphorylation, the O-GlcNAc protein modification is in a cell O-GlcNAc levels M phosphorylation, a of However, an in is on some protein not changes in R.S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google study the that is for the O-GlcNAc of we at the and expression of and is that is modified by post-translational phosphorylation, and O-GlcNAc M. Jones H. D. A. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, M. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, and Yang W.M. E. Mol. Cell. Biol. 2001; PubMed Scopus Google Scholar). O-GlcNAc levels on responsive in a cell and is is to with increased of to M. Jones H. D. A. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). of to is at M. Jones H. D. A. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). this study we an in O-GlcNAc modification at M which is is and to with for dynamic of the modification can be in protein proteins in are at M the protein is modified by O-GlcNAc and is P. C. J.L. 2004; PubMed Scopus Google Scholar). not all O-GlcNAc modified proteins a in O-GlcNAc at M phase. of increased an in phosphorylation the J. Biol. Chem. 1993; 268: Full Text PDF PubMed Google Scholar, R.S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). O-GlcNAc levels with to defects in Although show show defects in progression These data are in OGT knockouts of show delays in cell cycle progression and (22O'Donnell N. Zachara N.E. Hart G.W. Marth J.D. Mol. Cell. Biol. 2004; 24: 1680-1690Crossref PubMed Scopus (340) Google Scholar). data a model in which result in O-GlcNAc levels, and this cell cycle are are to levels of is the for and division (2Murray A.M. Cell. 2004; 116: 221-234Abstract Full Text Full Text PDF PubMed Scopus (907) Google Scholar). with dynamic of O-GlcNAc levels regulating cell cycle progression, the lowering O-GlcNAc levels with phase. A potential for is that proteins are concentrated at with W.G. Hart G.W. Cell. Full Text PDF PubMed Scopus Google Scholar). is is the more 2003; PubMed Scopus Google Scholar). O-GlcNAc on proteins of which and is modified by O-GlcNAc, and in a with and OGT X. F. J.E. Cell. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). O-GlcNAcase is a of J. 2002; PubMed Scopus Google Scholar, C. J.E. J. Biol. Chem. 2004; 279: Full Text Full Text PDF PubMed Scopus Google Scholar). data suggests that OGT and O-GlcNAcase may by is used to O-GlcNAc levels in (11Zachara N.E. O'Donnell N. Cheung W.D. Mercer J.J. Marth J.D. Hart G.W. J. Biol. Chem. 2004; 279: 30133-30142Abstract Full Text Full Text PDF PubMed Scopus (442) Google Scholar, C. S. J. R. Biophys. 2002; PubMed Scopus Google Scholar, S. J. Biol. Chem. 1991; Full Text PDF PubMed Google Scholar), is a and have in the and growth of cell E.P. J. J. PubMed Scopus Google Scholar) are to of and I. J. Biol. Chem. Full Text PDF PubMed Google Scholar). this in with is of with which of the with can be partially to changes in O-GlcNAc levels O-GlcNAc the of O-GlcNAcase and a of O-GlcNAc by controlling the protein expression of the and caused a in OGT levels and an in O-GlcNAcase levels, in caused a reciprocal a cellular to to changes in the this regulation at the or is not of the of the to O-GlcNAc levels to growth and or to the of such as and (9Slawson C. Hart G.W. Curr. Opin. Struct. Biol. 2003; 13: 631-636Crossref PubMed Scopus (115) Google Scholar). O-GlcNAcase and O-GlcNAc levels in C. J. R. Biophys. 2001; PubMed Scopus Google Scholar). a component of in is modified with A in is in of a of with increased phosphorylation as the Cole R.N. M. Hart G.W. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, J. 2004; PubMed Scopus Google Scholar). O-GlcNAcase and O-GlcNAc of and mitotic phosphorylation. The delay in M phosphorylation the data in which a of was delayed in M with the levels of mitotic phosphorylation with the data that a of is in M of a protein in cell cycle is of and of the phosphorylation be to changes in cell cycle proteins and These data suggest that in the expression of O-GlcNAcase or OGT to a mitotic exit phenotype be caused by in the expression of the O-GlcNAc as a of the cell cycle, the expression of cyclins cyclin-dependent which in cell cycle (2Murray A.M. Cell. 2004; 116: 221-234Abstract Full Text Full Text PDF PubMed Scopus (907) Google Scholar). The of O-GlcNAcase and OGT proper cyclin are at the cyclin is have similar levels of cyclin E to levels than or control the data in which O-GlcNAc levels phase. However, levels of cyclin E with control at the in M The expression of cyclin E expression. These levels of cyclin E at the and to the cyclin at the for mitotic exit in The mitotic cyclins A and show expression or and and data suggest delays or in proper progression in the disruption in cyclin expression to the phosphorylation in and of the cyclin oscillator is timed of the cyclin by the (2Murray A.M. Cell. 2004; 116: 221-234Abstract Full Text Full Text PDF PubMed Scopus (907) Google Scholar), of which are modified by O-GlcNAc M. E. A. Biochem. Biophys. Res. Commun. 2003; PubMed Scopus Google Scholar). Increased O-GlcNAc protein modification with function F. K. Yang X. J.E. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). the of the expression of the cyclins is not to the function of the O-GlcNAc not the F. K. Yang X. J.E. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). However, this be for and Overexpression of OGT with potential mechanism for the increased of in is to the of to Notably, OGT with the spindle at M phase. are to the with kinases such as and E. J. Sci. Google Scholar, C. A. R. C. T. A. N. J. Biol. 2003; PubMed Scopus Google Scholar). The of OGT at the spindle suggests that OGT in with mitotic kinases to cell division. OGT O-GlcNAc to proteins or act as a M. J. E. Hanover J.A. E. Nat. Struct. Biol. 2004; Scopus Google Scholar) to proteins to the spindle such as D. J. 2003; 22: PubMed Scopus Google Scholar), and control of by with proteins M. U. M. Nature. 2004; PubMed Scopus Google Scholar). OGT is to with protein and L. L.K. Comer F.I. Hart G.W. J. Biol. Chem. 2004; 279: Full Text Full Text PDF PubMed Scopus Google OGT act as an protein to the spindle of the of OGT with of the spindle by of to the increased of in M phase. is by the cellular cytokinesis. to and control the of is to proper cellular O-GlcNAc, a and stress the cell with a mechanism to cellular to cell cycle regulation of the to for proper cell cycle progression and cytokinesis. to O-GlcNAc to cell cycle and such as and and the and of the for and the Lane for in working with and for the OGT we the Hart for the with