小鼠β-1,4-N-acetyl-galactosaminyl transferase II 蛋白在卵巢的功能探討

Abstract

Sda β-1,4-N-acetyl-galactosaminyl transferase Ⅱ(β4galNAcTⅡ,B4GALNT2 in human and B4galnt2 in mouse) catalyze the addition of GalNAc to the Gal of the [Neu5Acα2-3]Galβ1-4GlcNAcβ1 -3Gal terminal structure via the β-1,4 linkage to form Sda antigen. The Sda antigen was first reported as a human blood surface antigen, and in the later researches, it was found in several tissue types, including stomach, colon, kidney, and oocytes. Its presence was also demonstrated in various body fluids, such as saliva, milk, serum and urine. Current studies revealed that Sda antigen reduced remarkably in cancer lesions of the gastrointestinal tract. It indicated the significance of this antigen in biosystem and also associated it is importance to B4galnt2. In 2003, Dell’s group found Sda antigen in reproductive system firstly, however, the significance of Sda is still unclear. My research intends to approach biological characteristics of B4galnt2, and on it, can investigate physiological role of Sda in reproductive system. Female ICR mouse is selected as an animal model. B4galnt2 expression was detected in ovary, and Sda antigen was further confirmed in oocyte but not in cumulus cell. Based on that, Immunohistochemical analysis was used to investigate B4galnt2 distribution in whole cumulus-oocyte complexes (COCs) , and the B4galnt2 existing on plasma membrane of cumulus cell was observed. Blocking the COC cultivation with B4galnt2 antibody resulted in disturbing of cumulus expansion, and it indicated that B4galnt2 protein is essential for cumulus expansion, which is a critical step during oogenesis. Cumulus expansion depends on both FSH in the environment and B4galnt2 protein that exist on the cell membrane of cumulus cell, and may be associated with cell migration ability. B4GALNT2 silencing of HCT116 with transfecting the plasmid contained B4GALNT2-siRNA caused the cell migration slower, but blocking with antibody made no difference, and the similar result was obtained from the two other colonic cell-CaCo2 and SW480 in antibody blocking test.