Glycosyltransferases: Structure and Function I


On 20 June morning, the session of Glycosyltransferases: Structure and Function I     was successfully conducted at the Triumphant Hall of the Seaview Garden Hotel.       Prof. Naoyuki  Taniguchi  and  Prof. Jianxin  Gu  chaired  this  session. Prof. Robert S.   Haltiwanger,  Prof. Hisashi Narimatsu,  Prof. Jin Won Cho  and Prof. Jianguo Gu made   wonderful presentations. The overview of this session is as follows:

Prof. Robert S. Haltiwanger

Professor Robert S. Haltiwanger  ( University of Georgia, USA )  made a presentation   about the O-glucosyltransferase. He and his co-workers have identified two homologs of POGLUT1, POGLUT1 and POGLUT2.These enzymes add glucose to the novel site on EGF11.  Elimination  of  the novel  O-glucose  site  on  EGF11 by mutagenesis reduces Notch1 activity,  suggesting  that  POGLUT2  and  POGLUT3  are  novel modulators of   Notch activity. These results enhance the understanding of Notch O-glycosylation and how it regulates Notch signaling.

Prof. Hisashi Narimatsu

Professor Hisashi Narimatsu (AIST, Japan) introduced the WFA lectin-binding LacdiNAc     structures synthesized in vivo. B3GALNT2 can synthesize type I LacdiNAc structures,       GalNAcβ1, 3GlcNAc,  on O-mannose  of α-dystroglycan,  which  are  associated  with      human congenital muscular dystrophy (CMD). Prof. Hisashi Narimatsu’s group confirmed that  WFA-positive  N-glycosylated  glycoproteins  were  increased  dependent  on  the     expression of functional B3GALNT2.They examined glycopeptides captured with WFA,   and  identified  several  type  I  LacdiNAc  N-glycosylated  glycoproteins.  These results   demonstrated  the  presence  of  glycoproteins  with  type I  LacdiNAc  structures  on       N-glycans and O-glycans in vivo.

Prof. Jin Won Cho

Professor  Jin  Won Cho  (Yonsei University, Korea)’s talk is about the O-GlcNAcylation on    X-linked inhibitor apoptosis protein (XIAP), a well-known caspase inhibitor. They showed    XIAP can promote the proteasome-dependent degradation of OGT in vivo and in vitro.        In their study, the HCT116 cells stably over expressing XIAP showed reduced OGT protein    levels and decreased growth rate and colony formation compared to the control  HCT116  cells. Their study suggests that a novel function of XIAP in the regulation of OGT, which is    distinctly different from its well characterized anti-apoptotic properties.

Prof. Jianguo Gu

In Professor Jianguo Gu (Tohoku Medical and Pharmaceutical University, Japan)’s talk, they    remodel N-glycans by several glycosyltransferases such as N-acetylglucosaminyltransferase     III, V and β-Galactoside α2,6 Sialyltranferase 1, in cell adhesion and the process of epithelial-mesenchymal transition (EMT). The potential roles of N-glycans in integrin-meditated cell      adhesion and migration are  also their research directions. Recently, Jianguo Gu’s group also  found that the N-glycosylation on integrin α5β1 can serve as an on/off switch to regulate cell proliferation and adhesion.