HYALURONAN SYNTHESIS IS REGULATED BY INTRACELLULAR O‐GLCNACYLATION OF HAS 2

The amount of hyaluronan (HA) often reflects the progression of the diseases involving extracellular matrix (ECM) as it promotes neo‐angiogenesis, cell migration and inflammation and its synthesis is regulated by several factors as the phosphorylation of synthetic enzyme HAS2. In this work, based on human smooth muscle cell model, we studied the intracellular regulation of HA synthesis at molecular level. The hexosamine biosynthetic pathway (HBP) may increase the concentration of HA precursor UDP‐Nacetylglucosamine leading to an increase of HA synthesis.We found that the inhibition of O‐GlcNacylation strongly reduced HA production whereas treatments that induced protein O‐GlcNacylation increased HA secretion. Gene expression studies done by quantitative RT‐PCR revealed that HAS2 mRNA was the most sensible to O‐GlcNacylation and accumulated after its induction. We found that the transcription regulator YY1 activates HAS2 expression after O‐GlcNacylation. Using IP and recombinant 6myc‐HAS2 we demonstrate the HAS2 residue O‐GlcNacylated and we quantified AoSMCs motility and monocytes binding and found that O‐GlcNacylation increased cell invasion and inflammatory cell recruitment. Moreover, using ChIP/sec approach we demonstrated that the O‐GlcNacylation is an epigenetic modification of protein interacting with HAS2 promoter.