Increased expression of Gs(alpha) enhances activation of the adenylyl cyclase signal transduction cascade.
Expression of the stimulatory G protein, G(S)alpha, can vary over a 3-fold range in human tissues and in rodent central nervous system. In fact, the offspring of alcoholics have higher levels of G(S)alpha expression in certain tissues compared with the offspring of nonalcoholics. The aim of this research was to test the hypothesis that a causal relationship exists between the level of expression of G(S)alpha and induction of the adenylyl cyclase (AC) cascade. The methodology employed transient transfection of HEK 293 cells with a cDNA for the 52-kDa form of G(S)alpha under regulation by inducible metallothionein promoters. Transfectants were exposed to varying concentrations (0-125 microM) of zinc sulfate that produced a 3-fold range of membrane G(S)alpha expression. The range of G(S)alpha expression produced was found to mimic a physiologically relevant spectrum of G(S)alpha expression in membranes derived from human tissues and rat brain. It was observed that induction of G(S)alpha expression increased constitutive as well as stimulated cAMP accumulation. Moreover, induction of G(S)alpha expression increased events distal to the accumulation of cAMP including the phosphorylation of the transcription factor, cAMP response element binding protein and transcriptional activation of cAMP-dependent reporter genes. In summary, these studies show that the amount of G(S)alpha expression has a marked impact on the level of activity of the AC cascade from the membrane through to the nucleus. It is hypothesized that individuals who differ in G(S)alpha expression may also differ in the expression of certain cAMP-dependent genes.
Yang
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Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Lee
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Wand
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GS
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000527:Alprostadil / Q000494:pharmacology; D000818:Animals; D001773:Blood Cells / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000187:drug effects / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology; D008214:Lymphocytes / Q000378:metabolism; D010766:Phosphorylation; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D051381:Rats; D015398:Signal Transduction; D014162:Transfection; D015032:Zinc / Q000494:pharmacology
D017362:Cyclic AMP Response Element-Binding Protein; D010975:Platelet Aggregation Inhibitors; D000242:Cyclic AMP; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases; D000527:Alprostadil; D015032:Zinc; D015056:1-Methyl-3-isobutylxanthine