title: N-acetylglucosaminyltransferase V modifies TrKA protein, regulates the receptor function.
abstract: 1. N-Acetylglucosaminyltransferases V (GnT-V/Mgat5) play a pivotal role in the processing of N-linked glycoproteins in the Golgi apparatus. The aim of the present study is to investigate whether the N-acetylglucosaminyltransferase V is able to modify TrKA, the high-affinity tyrosine kinase-type receptor for NGF, and thereby to regulate the receptor function. 2. Plasmids of the pcDNA3/GnT-V and pcDNA3 were transfected into PC12 cells. Expression of GnT-V protein was detected by Western blot. TrKA protein was examined by immunoprecipitation. Endocytosis of TrKA was investigated by the method of receptor internalization. 3. We report here that over-expression GnT-V directly modifies TrKA protein, accompanied by marked enhancement of axon outgrowth in rat pheochromocytoma cells (PC12) elicited by a low dose of NGF that alone is insufficient to induce neuronal differentiation. Further study indicated that modification of TrKA glycoprotein could directly enhance NGF-activated autophosphorylation of immunoprecipitated TrKA in vitro. To further elucidate the mechanism, we study the different time point of endocytosis of TrKA receptor. The results show that TrKA of GnT-V gene-transfected PC12 Cells delayed their removal by constitutive endocytosis as compared to the mock cells, suggesting high expression of GnT-V may affect their receptor TrKA endocytosis. 4. These results strongly suggest that N-acetylglucosaminyltransferase V functioning as a specific endogenous role of NGF receptor function, which appear to be due, at least in part, to the promotion of differentiation. This work is an important step toward intriguing innovative therapeutic strategies targeting glycosyltransferase.
authors.affiliation: Department of Molecular Pharmacology, Marine Drug and Food Institute, Ocean University of China, Qingdao, P.R. China. yang_xiaoyun@yahoo.com
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Meiyu
authors.initials: M
authors.lastname: Geng
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D005822:Genetic Vectors; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000502:physiology*; D020932:Nerve Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D016716:PC12 Cells; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D051381:Rats; D020917:Receptor, trkA / Q000819:agonists / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection
chemical_list: D011134:Polysaccharides; D020932:Nerve Growth Factor; D017351:N-Acetylglucosaminyltransferases; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase; D020917:Receptor, trkA