Functional analysis of single nucleotide polymorphisms (SNPs) present in GPM6A?S transmembrane domains coding region

FORMOSO K; BROCCO MA; ALBERTO C. FRASCH; SCORTICATI C

Congreso; Reunión Anual SAN; 2011

Neuronal glycoprotein M6a is involved in neuronal plasticity (e.g. neurite outgrowth, filopodium and synapses formation) through unknown mechanisms. M6a has four transmembrane domains (TMs) and shares structural similarity# 87with the tetraspanin protein family. The function of several tetraspanins is mediated by their ability to self-associate and interact with different membrane proteins and lipids through specific alpha-helix residues. Our aim is to assess the association between genetic variants in GPM6A?s TMs and filopodium induction in hippocampal cultured neurons. Three replacement polymorphisms, here named SNP1 (F93C) and SNP2 (I97S) in TM2 and SNP3 (W141R) in TM3, were found in the TMs coding regions of the GPM6A gene. We used site-directed mutagenesis to construct a panel of mutants with the SNPs introduced into the M6a-EGFP-C1 plasmid. To study the ability of M6a to induce filopodium formation, the different mutants were overexpressed in primary culture of hippocampal neurons. Our results showed that overexpression of all SNPs significantly decreased filopodium density compared with control group. These results lead to the conclusion that M6a SNPs reduce neuronal plasticity, probably due to altered transmembrane helix interactions.