Opposing changes of trimeric G protein levels during ontogenetic development of rat brain

Abstract

Listen

Translate article

Developmental changes in the distribution of guanine nucleotide-binding regulatory proteins (G proteins) were investigated in the rat brain during postnatal development. Using a standard or high-resolution urea-SDS–PAGE and specific polyclonal antipeptide antibodies oriented against G iα1/G iα2, G iα3, G sα, G oα1/G oα2, G qα/G 11α and Gβ subunit, all these proteins were determined by quantitative immunoblotting in homogenates prepared from cortex, thalamus, hippocampus and pituitary of 1-, 7-, 12-, 18-, 25- and 90-day-old animals. The levels of the majority of G protein α subunits, namely G iα1, G iα2, G iα3, G oα1, G oα2, G qα, G 11α and Gβ, were high already at birth. Whereas the short variant of G sα, G sαS, rose sharply in all tested brain regions between postnatal day (PD) 1 and 90, the long variant of G sα, G sαL, was unchanged in cortex and thalamus and slightly increased in hippocampus. An increase was observed also in expression of G iα1/G iα2 and G oα1 protein, while G oα2 remained constant. Minority protein G oα* dramatically increased in cortex and thalamus, was unchanged in hippocampus and not detectable in pituitary. By contrast, the highest levels of G iα3 and G qα/G 11α were detected as early as at PD 1. During the next 90 days, the immunological signal of G iα3 almost disappeared and G qα/G 11α continuously declined to the levels corresponding to 50% of the levels determined at birth. Expression of Gβ subunit was basically unchanged during postnatal development. Our present analysis indicates that G sα, G iα/G oα and G qα/G 11α proteins are differently expressed in the course of brain development. Differential expression of the individual α subunits of trimeric G proteins during postnatal development suggests their different roles in maturation of the brain tissue.