Analysis of odorant receptor expression in heterologous cells and the impact of SNPs on their targeting to the plasma membrane.

Abstract

Odorant receptors (ORs) compose the biggest gene family of G protein-coupled receptors in mammals. Originally, they are expressed in the olfactory epithelium and function as detectors of odorant molecules, leading to signal transduction in the olfactory neuron. Exclusive sets of ORs are activated by certain odorants, and it is possible to determine this activation through the expression of these receptors in heterologous systems. However, when expressed in heterologous cells, there is no expression or little expression of ORs in the plasmatic membrane, because the receptor is retained in the endoplasmic reticulum.In face of this problem, previous studies were demonstrated that the addition of a Rho-tag at the N-terminal end of ORs, as well as the presence of receptor transporting proteins (RTPs) can promote the functional expression of ORs in HEK293T cells and increase the response to odorant stimuli.Considering the existence of genetic diversity in ORs genes, it is possible to occur changes of a nucleotide along the gene sequence, denominated as SNP. Its consequences for the function of an OR are still uncertain, thus, our research group has sought to evaluate the presence of distinct SNPs and at different frequencies in genes of olfactory receptors of Amazon and Mexico's native people, based on the genome sequence carried out by the Human Genome Diversity Project (HDGP).Given the above, this project aims to verify the influence of SNPs on the transport of ORs to the plasmatic membrane, in order to evaluate their effects on the functional expression of olfactory receptor genes in HEK293T heterologous cells through immunofluorescence.