Glycobiology and Extracellular Matrices
A complex between phosphatidylinositol 4-kinase IIα and integrin α3β1 is required for N-glycan sialylation in cancer cells
Aberrant N-glycan sialylation of glycoproteins is closely associated with malignant phenotypes of cancer cells and metastatic potential, which includes cell adhesion, migration, and growth. Recently, phosphatidylinositol 4-kinase IIα (PI4KIIα), which is localized to the trans-Golgi network, was identified as a regulator of Golgi phosphoprotein 3 (GOLPH3) and of vesicle transport in the Golgi apparatus. GOLPH3 is a target of PI4KIIα and helps anchor sialyltransferases and thereby regulates sialylation of cell surface receptors.O-GlcNAcylation regulates integrin-mediated cell adhesion and migration via formation of focal adhesion complexes
O-GlcNAcylation is a post-translational modification of a protein serine or threonine residue catalyzed by O-GlcNAc transferase (OGT) in the nucleus and cytoplasm. O-GlcNAcylation plays important roles in the cellular signaling that affect the different biological functions of cells, depending upon cell type. However, whether or not O-GlcNAcylation regulates cell adhesion and migration remains unclear. Here, we used the doxycycline-inducible short hairpin RNA (shRNA) system to establish an OGT knockdown (KD) HeLa cell line and found that O-GlcNAcylation is a key regulator for cell adhesion, migration, and focal adhesion (FA) complex formation.Integrin α5 Suppresses the Phosphorylation of Epidermal Growth Factor Receptor and Its Cellular Signaling of Cell Proliferation via N-Glycosylation
Background: The functions of integrin α5 on cell proliferation and the underlying mechanisms remain unclear.Results: Loss of N-glycosylation on α5 increased the phosphorylation and internalization of EGFR and abolished its inhibitory effects on cell proliferation.Conclusion: Integrin α5 regulates EGFR-mediated signaling through N-glycosylation.Significance: N-Glycosylation plays important roles in the cross-talk between integrins and growth factor receptors.Loss of α1,6-Fucosyltransferase Decreases Hippocampal Long Term Potentiation: IMPLICATIONS FOR CORE FUCOSYLATION IN THE REGULATION OF AMPA RECEPTOR HETEROMERIZATION AND CELLULAR SIGNALING
Core fucosylation is catalyzed by α1,6-fucosyltransferase (FUT8), which transfers a fucose residue to the innermost GlcNAc residue via α1,6-linkage on N-glycans in mammals. We previously reported that Fut8-knock-out (Fut8−/−) mice showed a schizophrenia-like phenotype and a decrease in working memory. To understand the underlying molecular mechanism, we analyzed early form long term potentiation (E-LTP), which is closely related to learning and memory in the hippocampus. The scale of E-LTP induced by high frequency stimulation was significantly decreased in Fut8−/− mice.
