Disease relevance of Gnas

• Introduction of a transgene expressing Gsalpha, one of several gene products that include Gnas exon 2, into Gnas(E2-/E2-) cells prevented premature hypertrophy [1].
• Wild-type mice developed within-session tolerance to ethanol-induced hypothermia whereas Gnas mice did not [2].
• Increased glucose tolerance and reduced adiposity in the absence of fasting hypoglycemia in mice with liver-specific Gs alpha deficiency [3].
• Supporting these concerns is the demonstration that transgenic mice with cardiac overexpression of Gs alpha and enhanced myocardial responsiveness to isoproterenol develop myocardial fibrosis [4].
• Pretreatment but not post-treatment of the melanoma cells with POH, however, markedly reduced levels of UV-induced reactive oxygen species [5].

Psychiatry related information on Gnas

• These results indicate a role of maternally expressed Nesp55 in controlling exploratory behavior and are the first demonstration that imprinted genes affect such a fundamental behavior [6].
• Behavioral analysis of adult Nesp55 mutants revealed, in three separate tasks, abnormal reactivity to novel environments independent of general locomotor activity and anxiety [6].
• The relationship between voluntary alcohol consumption and brain monoamine levels was studied in the inbred strains of C57BL/6N, C57BL/6J, A/J, BALB/cA, CBA/N, C3H/He and DBA/2cr mice; the congeneric mouse strain, B10.Br/Sg, and the senescence accelerated mouse (SAM P1, SAM P2) [7].

High impact information on Gnas

• Uniquely, the Nespas DMR acts on the downstream ICR at exon 1A to regulate tissue-specific imprinting of the Gnas gene [8].
• This rescues the abnormal phenotype of mice with a maternally derived Gnas mutation [9].
• Mice with mutations in Gnasxl have poor postnatal growth and survival and a spectrum of phenotypic effects that indicate that XL alpha s controls a number of key postnatal physiological adaptations, including suckling, blood glucose and energy homeostasis [10].
• We show that in the oocyte, truncated RNAs are produced by RNA polymerase II with 5' ends at the P1 and P2 promoters and 3' ends at two T stretches (sites I and II) near the exon 1/intron 1 junction [11].
• P2 protein-reactive T-lymphocyte lines from Lewis rats were transduced with a recombinant retrovirus containing the mouse nerve growth factor (NGF) gene [12].

Chemical compound and disease context of Gnas

• Propranolol prevents enhanced stress signaling in Gs alpha cardiomyopathy: potential mechanism for beta-blockade in heart failure [13].
• Here we show that cholera toxin, which ADP-ribosylates and activates the G protein subunit Gs alpha, blocks the induction of differentiation, whereas increasing intracellular cyclic AMP directly with the dibutyryl analogue or indirectly with pertussis toxin or forskolin does not affect differentiation [14].
• The subcellular distribution of Gs alpha was characterized in S49 lymphoma cells with two polyclonal antisera directed against specific COOH- and NH2-terminal epitopes [15].
• Ethanol did not alter expression of Gs alpha as assessed by immunoblot analysis, cholera toxin-dependent ADP-ribosylation, or by the ability of detergent extracted Gs alpha to reconstitute a functional adenylylcyclase in membranes from S49 cyc- murine lymphoma cells, a cell line which genetically lacks Gs alpha [16].
• Transcriptional activation of Gs alpha expression by retinoic acid and parathyroid hormone-related protein in F9 teratocarcinoma cells [17].

Biological context of Gnas

• Gnas is an imprinted gene with multiple gene products resulting from alternative splicing of different first exons onto a common exon 2 [18].
• The Gnas locus in distal mouse chromosome (Chr) 2 is emerging as a complex genomic region [19].
• Heterozygotes with maternal (m-/+) and paternal (+/p-) inheritance of the Gnas null allele have distinct phenotypes, suggesting that Gnas is an imprinted gene [20].
• Alternative Gnas gene products have opposite effects on glucose and lipid metabolism [18].
• We propose that Nespas is an additional control element in the imprinting region of mouse distal Chr 2; it adds further complexity to the Gnas-imprinted gene cluster [19].

Anatomical context of Gnas

• Gnas is also imprinted in brown and white adipose tissue [20].
• The in vivo role of Gsalpha in skeletogenesis is largely unknown, because of early embryonic lethality of mice with disruption of Gnas exon 2 (Gnas(E2-/E2-)) and the absence of easily detectable phenotypes in growth plate chondrocytes of heterozygous mutant mice (Gnas(+/E2-)) [1].
• We now report the generation of murine cell lines that carry homozygous disruption of Gnas exon 2, and are therefore null for endogenous XLalpha(s) and Gs(alpha) (Gnas(E2-/E2-)) [21].
• Targeted disruption of Gnas in embryonic stem cells [22].
• Mutational analysis of the Edn3 and Gnas genes will determine whether either gene is responsible for the neural crest deficiencies observed in ls/ls mice [23].

Associations of Gnas with chemical compounds

• The maximal physiological response to vasopressin (urinary concentrating ability) is normal in both m-/+ and +/p- mice and Gnas is not imprinted in the renal inner medulla (the site of vasopressin action) [20].
• Here we show Oed-Sml to be a point mutation in Gnas exon 6, resulting in a valine to glutamate substitution at residue 159 (V159E) [24].
• The gene for alpha-stimulating guanine-nucleotide binding polypeptide, Gnas, has been considered as a candidate for the imprinting effects ascribed to distal mouse Chromosome (Chr) 2 [25].
• P2 purinoceptor antagonists (suramin, reactive blue 2) inhibited the ATP-induced increase in [(3)H]thymidine incorporation [26].
• RESULTS: During the initial exposure to ethanol, mice with the targeted disruption of one Gsalpha allele (Gnas) were more sensitive to the sedative effects of ethanol compared with wild-type littermates [2].

Physical interactions of Gnas

• In reconstitution experiments in vitro, phosphorylation of Gs alpha by immune-complexed pp60c-src resulted in enhanced rates of receptor-mediated guanosine 5'-[gamma-thio]triphosphate (GTP[S]) binding and GTP hydrolysis [Hausdorff, Pitcher, Luttrell, Linder, Kurose, Parsons, Caron and Lefkowitz (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 5720-5724] [27].
• Thus structural and functional analysis reveals that the P3-4 element is a key regulatory element of P3 that contains two separate binding sites for proteins essential for the basal activity of IGF-II P3 [28].
• Transgenic mice express the mutant form of the alpha subunit of the adenylate cyclase-coupled G alpha s with mutations at codon 201 (R201H) [29].
• Intracellular Gs alpha immunoreactive binding sites did not colocalize with gold-conjugated transferrin in cells preincubated with this ligand to mark a classical endocytotic pathway [15].

Enzymatic interactions of Gnas

• We report here that Gs alpha is phosphorylated on two residues by pp60c-src, namely, Tyr-37 and Tyr-377 [27].

Regulatory relationships of Gnas

• These cells showed a significant increase of intracellular cAMP levels and produced a higher amount of IL-6 than the cells transfected with control vector or wild-type Gs alpha expression vector [30].
• P3 is also the most active promoter in tumour tissues and cell lines expressing IGF-II [28].
• Isolation of clones of NCB20 cells expressing high levels of the beta 2 adrenoceptor also resulted in a specific agonist-induced down-regulation of Gs alpha [31].
• Deletion within the amino-terminal region of Gs alpha impairs its ability to interact with beta gamma subunits and to activate adenylate cyclase [32].
• Expression of activated G alpha s in NIH 3T3 cells increased intracellular concentrations of adenosine 3',5'-monophosphate (cAMP) and inhibited H-Ras-stimulated DNA synthesis and mitogen-activated protein kinase activity [33].

Other interactions of Gnas

• Imprinting of alternative transcripts, Nesp, Gnasxl and Nespas (ref. 13), in the cluster is unaffected [9].
• Only Edn3 and Gnas did not recombine with the ls mutation [23].
• Heterozygous disruption of Gnas, the gene encoding the stimulatory G-protein alpha subunit (G(s)alpha), leads to distinct phenotypes depending on whether the maternal (m-/+) or paternal (+/p-) allele is disrupted [34].
• This review considers the strength of evidence in support of this hypothesis for imprinted genes in four "clusters," associated with the imprinted loci Igf2, Igf2r, callipyge, and Gnas [35].
• This assignment predicts a location of the murine homologue, Rpn-2, to the syntenic segment on mouse chromosome 2 in close proximity to Ada, Src and Gnas [36].

Analytical, diagnostic and therapeutic context of Gnas

• RNA in situ hybridization revealed high levels of Gnas mRNA in glomeruli of PatDp2 embryos at late gestation and lower levels in glomeruli of MatDp2 embryos [25].
• Using 30 polymorphic sites across the Gnas1 gene region in (C57BL/6JxMus spretus) F(1) mice and chromatin immunoprecipitation (ChIP) assays we identified two allelic switch regions (ASRs) that mark boundaries of epigenetic information [37].
• Despite this marked increase in mRNA, Western blotting identified only a 2.8-fold increase in the content of the Gs alpha short isoform, whereas Gs activity was increased by 88% [38].
• Cultured cardiac myocytes from newborn Gsalpha transgenic mice showed increased TUNEL staining and internucleosomal DNA fragmentation compared with wild-type controls when treated with the beta-agonist isoproterenol [39].
• In the hearts of 15- to 18-month-old Gsalpha transgenic mice, histochemistry and electron microscopy illustrated the existence of numerous myocytes with abnormal nuclei embedded in collagen-rich connective tissue [39].

References