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Characterization of novel single sug...

Slawson, Chad Eric.

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Characterization of novel single sugar protein modifications in proliferative systems.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Characterization of novel single sugar protein modifications in proliferative systems./
作者:	Slawson, Chad Eric.
面頁冊數:	198 p.
附註:	Major Professor: Robert Potter.
Contained By:	Dissertation Abstracts International63-05B.
標題:	Chemistry, Biochemistry. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3052390
ISBN:	049366579X

Characterization of novel single sugar protein modifications in proliferative systems.
Slawson, Chad Eric.

Characterization of novel single sugar protein modifications in proliferative systems. - 198 p.

Major Professor: Robert Potter.

Thesis (Ph.D.)--University of South Florida, 2002.

A single N-acetylglucosamine (O-GlcNAc) residue attached to soluble proteins is a ubiquitous protein modification whose function is not well understood. The modification appears to be dynamic. The half-life of the modification is shorter than that of the protein modified. A set of soluble enzymes exists which add or remove the sugar, and these enzymes are responsive to cellular stimuli. Due to the sugar modification's similarity with phosphorylation, the modification might act in an analogues manner to protein phosphorylation or transiently block proteins from phosphorylation. In order to better understand the function of this modification and its role in proliferation, characterization of protein glycosylation was carried out in three different systems. Studies were performed on maturing and staged <italic>Xenopus leavis</italic> oocytes, breast cancer tissue, and breast cancer cell lines. A variety of techniques, such as western blotting, enzymatic assays, and pulse-chase experiments were used to characterize the modification. In oocytes, the levels of protein glycosylation change as the cell matures from a stage I oocyte to a stage VI oocyte. The level of O-GlcNAcase (the enzyme responsible for removing the sugar) also increases. When stage 6 oocytes were stimulated with progesterone to mature, compounds that increase glycosylation lead to a longer maturation time. Next, we decided to investigate O-GlcNAcase activity in primary breast tumors compared to matched adjacent tissue and to correlate enzymatic activity to the level of protein monoglycosylation. O-GlcNAcase appears to be upregulated in breast tumor tissue and is likely involved in the selective removal of O-GlcNAcase from certain proteins. Additionally, several proteins are modified by O-GlcNAcase in tumor tissue, but the amount on certain proteins is diminished compared to adjacent tissue. Finally, the levels of protein monoglycosylation were examined in several breast cancer cell lines during mitogenic stimulation. When tested on two different breast cancer cell lines, a striking affect was found on Mitogen Activated Protein Kinase (MAPK) activity in cells treated with glycosylation enhancing compounds prior to mitogenic stimulation. MDA-MB-468 cells demonstrated a decrease in activity after treatment, while SK-BR-3 showed an increase in activity. This ubiquitous modification appears to be a novel form of protein regulation.

ISBN: 049366579XSubjects--Topical Terms:

1017722
Chemistry, Biochemistry.

Characterization of novel single sugar protein modifications in proliferative systems.
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502 $a Thesis (Ph.D.)--University of South Florida, 2002.
520 $a A single N-acetylglucosamine (O-GlcNAc) residue attached to soluble proteins is a ubiquitous protein modification whose function is not well understood. The modification appears to be dynamic. The half-life of the modification is shorter than that of the protein modified. A set of soluble enzymes exists which add or remove the sugar, and these enzymes are responsive to cellular stimuli. Due to the sugar modification's similarity with phosphorylation, the modification might act in an analogues manner to protein phosphorylation or transiently block proteins from phosphorylation. In order to better understand the function of this modification and its role in proliferation, characterization of protein glycosylation was carried out in three different systems. Studies were performed on maturing and staged <italic>Xenopus leavis</italic> oocytes, breast cancer tissue, and breast cancer cell lines. A variety of techniques, such as western blotting, enzymatic assays, and pulse-chase experiments were used to characterize the modification. In oocytes, the levels of protein glycosylation change as the cell matures from a stage I oocyte to a stage VI oocyte. The level of O-GlcNAcase (the enzyme responsible for removing the sugar) also increases. When stage 6 oocytes were stimulated with progesterone to mature, compounds that increase glycosylation lead to a longer maturation time. Next, we decided to investigate O-GlcNAcase activity in primary breast tumors compared to matched adjacent tissue and to correlate enzymatic activity to the level of protein monoglycosylation. O-GlcNAcase appears to be upregulated in breast tumor tissue and is likely involved in the selective removal of O-GlcNAcase from certain proteins. Additionally, several proteins are modified by O-GlcNAcase in tumor tissue, but the amount on certain proteins is diminished compared to adjacent tissue. Finally, the levels of protein monoglycosylation were examined in several breast cancer cell lines during mitogenic stimulation. When tested on two different breast cancer cell lines, a striking affect was found on Mitogen Activated Protein Kinase (MAPK) activity in cells treated with glycosylation enhancing compounds prior to mitogenic stimulation. MDA-MB-468 cells demonstrated a decrease in activity after treatment, while SK-BR-3 showed an increase in activity. This ubiquitous modification appears to be a novel form of protein regulation.
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