Filopodia Formation Driven by M6a depends upon M6a 's oligomerization

FORMOSO, K; GARCIA, M; FRASCH, AC; CAMILA SCORTICATI

Huerta Grande, Cordoba

Congreso; XXIX Annual Meeting and SAN-ISN small Conference and Course; 2014

Sociedad Argentina de Investigación en Neurociencias

M6a is a tetraspan neuronal membrane glycoprotein that belongs to the proteolipid protein family (PLP). In our laboratory we showed that M6a induces filopodia formation and neurite extension, but the mechanisms underlying this functions remain unknown. Our hypothesis is that M6a interacts with an external stimuli that could produce homo- or hetero-associations of M6a, driven by its transmembrane domains (TMD). Then, the M6a auto/phosphorylation would lead to filopodia formation. Here we studied if M6a oligomerization and interaction through its TMDs are involved in M6a´s function. We determined by crosslinking assays that M6a forms oligomers in the neuronal membrane and we performed an assay designed to determine homotypic interactions between TMDs (TOXCAT) and found that the interactions between M6a´s TMDs might be aiding this oligomerization. We found that certain glycine residues present in TMD2 and TMD4 are necessary to drive this interaction. Consistently, in neurons these residues are needed for filopodia formation. Moreover, we studied three non-synonymous SNPs from the NCBI database present in the sequence of GPM6A of the coding sequence of the TMDs and found that the presence of one of this SNPs impairs TMD2 interaction. We also found that all SNPs impair M6a induced filopodia formation. In this work we found evidence that the interactions between M6a´s TMDs might be involved in the signal transmission of the M6a signalling pathway, reinforcing our hypothesis.