In silico characterization and functional analysis of non-synonymous polymorphisms present in GPM6A?s extracellular coding regions

GABRIELA INÉS APARICIO; ANTONELLA LEÓN; CAMILA SCORTICATI; ALBERTO CARLOS FRASCH

Montreal

Congreso; 2019 ISN-ASN Meeting; 2019

International Society for Neurochemistry

Membrane glycoprotein M6a is mainly expressed in neurons of the central nervous system and it is involved in neuronal plasticity. M6a promotes neurite and axonal outgrowth, filopodia/spines formation and synaptogenesis in primary neuronal cultures and neuronal cell lines. Recently, altered expression or polymorphisms in the human M6a gene have been associated with neurological disorders such as schizophrenia, bipolar disorder, depression, claustrophobia and Alzheimer?s disease. However, the molecular mechanisms underlying the development of such pathologies remain unknown. M6a, together with M6b and PLP/DM20, belongs to the tetraspan proteolipid protein family. According to its structure, we speculate that certain amino acids within M6a?s extracellular loops mediate specific interactions with other proteins and those contribute to its function. Thus, out of more than a hundred submitted entries, we selected 13 non-synonymous SNPs from the NCBI dbSNP database located at the coding sequence of GPM6a?s extracellular loops (EC1 and EC2). The selected nsSNPs had to be validated by frecuency, cluster and/or 1000G. In silico analysis ?using -Polyphen and I-mutant 2.0- predicted that all nsSNPs might decrease protein stability and have a moderate to strong functional damaging effect. In the case of SNPs located in the EC1, none of them modify M6a neuronal membrane distribution and topology, however, some of them rs375144137 (G69E), rs370813625 (T71P) and rs747244424 (T76I) impair M6a neurite extension in N2a cell line. We speculate that these variants blocked M6a´s neurite extension because of the drastic single amino acid substitution (non polar to acid or basic residue and polar to non polar) that might affect extracellular loops interactions. The results obtained will allow us to determine if these gene variants could be used as biomarkers for disorders in which neuronal plasticity is diminished, thus advancing with their early diagnosis and providing new targets for potential treatments.