genome encodes six alpha-subunits of heterotrimeric G proteins. late stages of wing development. Introduction G protein-coupled receptors (GPCRs) represent the BG45 most populous receptor family in metazoans. Approximately 380 non-olfactory GPCRs are encoded by the human genome , corroborated by ca. 250 GPCRs in insect genomes , , making 1C1.5% of the total gene number dedicated to this receptor superfamily in invertebrates and mammals. GPCRs transmit their signals by activating heterotrimeric G protein complexes inside the cell. A heterotrimeric G protein consists of a GDP-bound -subunit and a -heterodimer. Ligand-stimulated GPCR serves as a guanine Rabbit polyclonal to IL20 nucleotide-exchange factor, activating the GDP-to-GTP exchange around the G-subunit. This leads to dissociation of the heterotrimeric complex into G-GTP and , which transmit the signal further inside the cell . The – and -subunit repertoire of the genome is usually reduced as compared with that of mammals: only two G and three G genes are present in flies (Table 1). G30A and G76C are components of the travel phototransduction cascade and are mostly expressed in the visual system , . G1 and G13F have been implicated in the asymmetric cell divisions and gastrulation , , while the function of G5 is as yet unknown. Table BG45 1 The list of G, G, and G subunits, with the information on their function and human homologies. Despite the fact that can activate signal effectors , the main BG45 selectivity in GPCR coupling and effector activation is usually provided by the G-subunits . Sixteen genes for the -subunits are present in the human genome, and six in (Table 1): Gi and Go belonging to the Gi/o subgroup; Gq belonging to the Gq/11 subgroup; Gs belonging to the Gs subgroup, and concertina (genome encodes for Gf which probably represents an insect-specific subfamily of G-subunits . Multiple functions have been allocated to different heterotrimeric G proteins in humans and flies , see Table 1. For example, in development is usually a crucial gastrulation regulator , Go is usually important for the transduction of the Wnt/Frizzled signaling cascade , , and Gi controls asymmetric cell divisions during generation of the central and peripheral nervous system  (the later in cooperation with Go , ). Gq is the phototransduction G-subunit, but probably has additional functions . Pleotropic effects arise from defects in Gs function , while the function of Gf has not yet been characterized. Among the developmental processes ascribed to the control by Gs are the latest stages of wing development. Newly hatched flies have soft and folded wings, which during the 1C2 hours post-eclosion expand and harden through intensive synthesis of components of the extracellular matrix. These processes are accompanied by epithelial-mesenchymal transition and apoptosis of the wing epithelial cells, producing a strong but mostly dead adult wing structure , , . Expression of the constitutively active form of Gs leads to precocious cell death in the wing epidermis, which results in failure of the closure of the dorsal and ventral wing sheets and accumulation of the hemolymph inside the wing, producing wing blistering , . Conversely, clonal elimination of Gs leads to BG45 autonomous prevention of the cell death. Kimura and co-workers have performed an extensive analysis of the signaling pathway controlling apoptosis at late stages of wing development . They provide evidence suggesting that this hormone bursicon, synthesized in the head of post-eclosion and secreted in the hemolymph, activates a GPCR on wing epithelial cells, which signals through Gs to activate the cAMP-PKA pathway, culminating at the induction of apoptosis . However, the identity and importance of the subunits in bursicon signaling, as well as possible involvement of other G proteins remained outside of their investigation. There also remain some uncertainties as to the phenotypic consequences of elimination of the bursicon-Gs-PKA pathway in wings , , . Here we describe a comprehensive functional analysis of the heterotrimeric G protein proteome using loss-of-function and overexpression experiments. We show.