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- 저자 : Suena (검색결과 18 건)
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O-GlcNAcylation of Tubulin Inhibits Its Polymerization
Suena Ji,Jeong Gu Kang,Sang Yoon Park,JooHun Lee,Young J. Oh,Jin Won Cho 한국당과학회 2010 한국당과학회 학술대회 Vol.2010 No.1
The attachment of O-linked β-N-acetylglucosamine (O-GlcNAc) to proteins is an abundant and reversible modification that involves many cellular processes including transcription, translation, cell proliferation, apoptosis, and signal transduction. Here, we found that the O-GlcNAc modification pattern was altered during all-trans retinoic acid (tRA)-induced neurite outgrowth in the MN9D neuronal cell line. We identified several O-GlcNAcylated proteins using mass spectrometric analysis, including α- and β-tubulin. Further analysis of α- and β-tubulin revealed that O-GlcNAcylated peptides mapped between residues 173 and 185 of α-tubulin and between residues 216 and 238 of β-tubulin, respectively. We found that an increase in α-tubulin O-GlcNAcylation reduced heterodimerization and that O-GlcNAcylated tubulin did not polymerize into microtubules. Consequently, when O-GlcNAcase inhibitors were co-incubated with tRA, the extent of neurite outgrowth was decreased by 20% compared to control. Thus, our data indicate that the O-GlcNAcylation of tubulin negatively regulates microtubule formation.
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O-GlcNAc modification on tubulin disturbs it's polymerization
Suena Ji,Jeong Gu Kang,Sang Yoon Park,Eunah Kim,JooHun Lee,Young J. Oh,Jin Won Cho 한국당과학회 2011 한국당과학회 학술대회 Vol.2011 No.1
O-linked beta-N-acetylglucosamine (O-GlcNAc) modification is one of the post-translational modifications. Protein O-GlcNAcylation is reversibly regulated by O-GlcNAcase (OGA) and O-GlcNAc transferase (OGT). More than 800 proteins as diverse as transcription factors, enzymes, cytoskeletal proteins, ribosomal proteins and chaperones have been identified to be modified with O-GlcNAc. Thus, protein O-GlcNAcylation appears to be involved in many different cellular activities regulating in transcription, translation, protein degradation, protein localization and protein-protein interaction. Moreover, O-GlcNAc modification has important and global effects on various cellular signal pathways because of the reciprocal relationship between O-GlcNAc and O-phosphate. Recently, O-GlcNAc modification, as a sensor of cellular states, has been implicated in human diseases including diabetes, neurodegenerative diseases and cancer. We found that O-GlcNAcylation pattern is changed during all-trans retinoic acid (tRA)-induced neutrite outgrowth in the MN9D cell line. We identified several O-GlcNAcylated proteins including alpha- and beta-tubulin and detected O-GlcNAc modified regions between residues 173 and 185 of tubulin and between residues 216 and 238 of beta-tubulin by using mass spectrometry. Also, We found that overexpressing OGT or introducing OGA inhibitor such as NButGT, PUGNAc, increases O-GlcNAcylation on alpha-tubulin, which ultimately leads to inhibition of tubulin polymerization. Accordingly, Our data indicate that the O-GlcNAcylation of tubulin negatively regulates microtubule formation
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Hanbyeol Kim,Sang Yoon Park,Suena Ji,Jin Won Cho 한국당과학회 2012 한국당과학회 학술대회 Vol.2012 No.1
β-O-linked N-acetylglucosamine(O-GlcNAc) is dynamic post-translational modification in nucleus and cytosol and it is regulated by O-GlcNAc transferase(OGT) and O-GlcNAcase. Many proteins, such as transcription factors, enzymes, cytoskeletal proteins, ribosomal proteins and chaperones have been identified to be modified with O-GlcNAc. O-GlcNAc modification modifies at their Ser/Thr residues and affects their functions. The hexosamine biosynthesis pathway takes about 5% of glucose in total glucose flux, and it’s final product is UDP-GlcNAc, which is source of O-GlcNAc modification. O-GlcNAc modification is reported to involve in skeletal muscle metabolism and development process. We studied whether O-GlcNAc modification is involved in differentiation in myoblast C2C12 cell. We observed that total O-GlcNAc modification level was dynamically changed during myogenesis. After treatment NButGT, we observed that myogenin expression level decreased. Using RT PCR, we found that mRNA level of myogenin decrease after treatment NButGT. And we found that the promoter activity of myogenin decreases after NButGT using reporter gene assay. For finding the promoter region affected O -GlcNAc , we did reporter gene assay using shorter length promoter and found at least 169 base pair upstream region of myogenin is affected by O-GlcNAc. And using this region, we found that Mef2c protein can be important transcription factor regulated by O-GlcNAc using avidin-biotin complex DNA binding assay. We confirm that Mef2c is O-GlcNAcylated using immunoprecipitation and we found several O-GlcNAcylated sites on Mef2c using mass spectrometry. Based on the result, we made the Mef2c point mutants converted from Serine, Threonine of O-GlcNAcylated sites to Alanine. Additionally, we found O-GlcNAc modification could regulate DNA binding affinity and transcriptional complex formation.
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O-GlcNAc modification affects myogenin expression and differentiation of myoblast C2C12
Sang Yoon Park,Hanbyeol Kim,Suena Ji,Won Ho Yang,Jin Won Cho 한국당과학회 2011 한국당과학회 학술대회 Vol.2011 No.1
b-O-linked N-acetylglucosamine (O-GlcNAc) is dynamic post-translational modification in nucleus and cytosol. O-GlcNAc transferase(OGT) and O-GlcNAcase are involved in O-GlcNAc modification. Many proteins such as transcription factors, cytoskeletal proteins and proteins of variable signal transduction pathway are modified with O-GlcNAc at their Ser/Thr residues and their functions are affected by O-GlcNAc. The hexosamine biosynthesis pathway (HBP) consumes about 5% of glucose in total glucose flux, and it’s final product is UDP-GlcNAc, which is source of O-GlcNAc modification. It is reported that O-GlcNAc modification is involved in skeletal muscle metabolism and development process. We studied whether O-GlcNAc modification is involved in differentiation in myoblast C2C12 cell lines. Myoblast C2C12 is differentiated to myotube in differentiation media for 4-5 days. We observed that total O-GlcNAc modification level was dynamically changed during myogenesis. During first 24 hours after induction of myogenesis, total O-GlcNAc modification level decrease and increase again. Moreover, O-GlcNAcase activity increased and total cellular UDP-GlcNAc level decreased at the same time period. Also, we treated NAG-thiazoline derivative, specific O-GlcNAcase inhibitors and observed the block of the decrement of total O-GlcNAc modification and inhibition of myotube formation and expression of myogenic markers. Especially, after treatment NAG-thiazoline derivative, we observed that myogenin expression level decreased. So, we checked the myogenin protein stability using MG132 and mRNA level of myogenin using RT PCR. Even after treatment of MG132, the result of the experiment is same as previous experiment, thus myogenin protein stability is not involved with decrease of myogenin expression after treatment NAG-thiazoline derivative. And using RT PCR, we found that mRNA level of myogenin decrease after treatment NAG-thiazoline derivative. So we conclude that O-GlcNAc modification affect the transcription of myogenin.
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Jeong Gu Kang,Sang Yoon Park,Suena Ji,In Sook Jang,Su Jin Park,Hyeon Gyu Seo,Hanbyeol Kim,Eun Ah Kim,Ho Jung Seo,Yang Shin Lee,Jürgen Roth,Jin Won Cho 한국당과학회 2010 한국당과학회 학술대회 Vol.2010 No.1
The O-GlcNAc modification is a quite different fro m conventional glycosylation in two aspects. First, it occurs in cytoplasm and nucleus and does not in endoplasmic reticulum or Golgi apparatus. Second, this is a single sugar modification and is not a long chain oligosaccharide modification. O-GlcNAc is covalently modified on hydroxyl group of serine and threonine and usually this modification affects or competes with phosphorylation. Thus this modification might modulate many cellular events due to inhibiting or sometimes accelerating phosphorylation. O-GlcNAc transferase and O-GlcNAcase are two important enzymes for modifying proteins with O-GlcNAc. More than 800 proteins have been identified as O-GlcNAcylated proteins. Today I am going to summarize results obtained last 10 years and discuss about future aspects in O-GlcNAc biology.
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Eom, Dae-Seok,Choi, Won-Seok,Ji, Suena,Cho, Jin W.,Oh, Young J. Lippincott Williams Wilkins, Inc. 2005 NEUROREPORT - Vol.16 No.8
Recent studies indicate that activation of stress-activated protein kinases may be implicated in a broad range of biological activities including differentiation. To directly examine whether stress-activated protein kinases are involved in neuronal differentiation, we utilized retinoic acid-induced and spontaneous models of neurite outgrowth in dopaminergic neurons. Here, we show that retinoic acid-induced neurite outgrowth in MN9D dopaminergic neuronal cells was accompanied by activation of c-Jun N-terminal kinase but not p38. Consequently, cotreatment with a specific inhibitor of c-Jun N-terminal kinase or overexpression of c-Jun N-terminal kinase-binding domain of c-Jun N-terminal kinase-interacting protein-1 blocked retinoic acid-induced neurite outgrowth. In primary cultures of dopaminergic neurons, the extent of neurite outgrowth increased spontaneously in a time-dependent manner. When these cultures were treated with a specific inhibitor of c-Jun N-terminal kinase, the total extent of neurites, the primary neurite length and the number of neurites per cell were suppressed significantly. Thus, our data indicate that the c-Jun N-terminal kinase signal seems to play an important role during morphological differentiation in cultured dopaminergic neurons.
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O-GlcNAc Modification in various cellular events
Jeong Gu Kang,Sang Yoon Park,Suena Ji,Sujin Park,Insook Jang,Hyeon Gyu Seo,Yeon Jung Kim,Jin Won Cho 한국당과학회 2009 한국당과학회 학술대회 Vol.2009 No.1
β-O-linkedN-acetylglucosamine(O-GlcNAc) is a nucleocytosolic post-translational modification on serine and threonine residues that is dynamically regulated by O-GlcNActransferase and O-GlcNAcase. Many proteins are O-GlcNAcylated in response to various cellular processes, including transcription, proliferation, apoptosis and signal transduction. So, we have studied the function of O-GlcNAc modification on several proteins. We found that O-GlcNAcylated NF-kB was translocated into nucleus and had increased transcriptional activity. We report increased O-GlcNAcylation in non-small cell lung carcinoma A549 cells and various other cells in response to glucose deprivation. Also we show that glycogen degradation in response to glucose deprivation provides a source for UDP-GlcNAc required for increased O-GlcNAcylation under this condition. we demonstrate that Snail is O-GlcNAcylated and adjacent-site occupancy inhibits phosphorylation by GSK-3, resulting in increased Snail stability and attenuation of E-cadherin proximal promoter activity and transcription level. Furthermore, Overexpression of OGT induces in vivo invasion program of epithelial cancer cells by Snail-dependent manner. O-GlcNAc modification seems to be involved in neurite outgrowth in cultured neuronal cells. O-GlcNAcylation is highly conserved, so we were able to find several novel proteins modified with O-GlcNAc in Drosophila S2 cell line. Also we found O-GlcNAcylated site in ncOGT outside of TPR by using Q-TOF MS. Now we focus on the activities and function of ncOGT by mutagenesis studies. As stated above, O-GlcNAcylation is related to many cellular metabolism. And we already have found the function of O-GlcNAc modification on several important proteins. We'll keep on concentrating on this interesting post-translational modification. If you have any interest, feel free to contact us.
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