Xylosyltransferase 1 is an enzyme that in humans is encoded by the XYLT1gene.
Xylosyltransferase (XT; EC 18.104.22.168) catalyzes the transfer of UDP-xylose to serine residues within XT recognition sequences of target proteins. Addition of this xylose to the core protein is required for the biosynthesis of the glycosaminoglycan chains characteristic of proteoglycans.[supplied by OMIM]
Clinical relevance: Neurons use the presence of extracellular matrix molecules as clues whether to promote or suppress extension of axons. Chondroitin sulfate proteoglycans suppress the extension of axons over the glial scar, a barrier which develops after lesioning the spinal cord. Proteoglycans consist of one relatively small protein core and attached large glycosaminoglycan side chains. To block the very formation of these side chains xylosyltransferase (XYLT1) which attaches xylose to a serine of the protein core as initiation for glycosaminoglycan chain extension, was targeted by a class of designed DNA molecules. These molecules are called DNA-enzymes which were designed to specifically cleave XYLT1 mRNA within cells. DNA-enzymes are readily taken up by mammalian cells, but are more stable and require much lower concentrations then e.g. siRNA. And indeed, XTYL1 DNA-enzyme in co-cultures of neurons with neurocan secreting cells displayed a marked increase of axon outgrowth. Rats with defined spinal cord lesions, i.a. the clinically relevant contusion injury, treated with XTYL1 DNA-enzyme administered by micro-infusion pumps or systemically achieved improvements in the horizontal ladder task, enhanced axonal plasticity, growth of the corticospinal tract, no effect on neuropathic pain when using mechanical and thermal allodynia tests and no toxicological or pathological side effects compared to control animals.
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