Detection and characterization of functional heteromeric recerptors composed of the alpha7 nicotinic subunit and its duplicate form

LASALA, M.; CORRADI J.; DIONISIO, L.; ESANDI, M.; BOUZAT, C.

San Miguel de Tucuman

Congreso; IIILAFeBS, IX Iberoamerican Congress of Biophysics and XLV SAB Annual Meeting; 2016

The alpha7 nicotinic receptor subunit gene, CHRNA7, codes for a subunit that forms the homomeric alpha7 receptor, which is involved in learning and memory. Exons 5-10 of CHRNA7 were duplicated and fused to the FAM7A gene. The product of the resulting chimeric gene, dupalpha7, is a truncated subunit that lacks part of the ACh binding site. We here combine cell expression and electrophysiological recordings in HEK cells to understand the functional role of the dupalpha7 subunit. By confocal microscopy and flow cytometry we found that cells trasnfected with dupalpha7 do not show cell surface binding of alpha-bungarotoxin, a specific antagonist of alpha7. The incorporation of dupalpha7cDNA during cell transfection with alpha7 cDNA reduced alpha-bungarotoxin binding compared to that determined with alpha7 alone, indicating a negative modulatory role of the duplicated subunit.To determine if dupalpha7 forms functional pentamers, we recorded single-channel and macroscopic currents elicited by an allosteric agonist that binds to a transmembrane site that is conserved between alpha7 and dupalpha7.