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The Lecticans of Mammalian Brain Perineural Net Are O‑Mannosylated

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posted on 19.02.2016, 13:49 by Sandra Pacharra, Franz-Georg Hanisch, Martina Mühlenhoff, Andreas Faissner, Uwe Rauch, Isabelle Breloy
O-Mannosylation is an important protein modification in brain. During the last years, a few mammalian proteins have been identified as targets of the protein-O-mannosyltransferases 1 and 2. However, these still cannot explain the high content of O-mannosyl glycans in brain and the strong brain involvement of congenital muscular dystrophies caused by POMT mutations (Walker-Warburg syndrome, dystroglycanopathies). By fractionating and analyzing the glycoproteome of mouse and calf brain lysates, we could show that proteins of the perineural net, the lecticans, are O-mannosylated, indicating that major components of neuronal extracellular matrix are O-mannosylated in mammalian brain. This finding corresponds with the high content of O-mannosyl glycans in brain as well as with the brain involvement of dystroglycanopathies. In contrast, the lectican neurocan is not O-mannosylated when recombinantly expressed in EBNA-293 cells, revealing the possibility of different control mechanisms for the initiation of O-mannosylation in different cell types.