title: G alpha 3 regulates the cAMP signaling system in Dictyostelium.
abstract: The Dictyostelium discoideum developmental program is initiated by starvation and its progress depends on G-protein-regulated transmembrane signaling. Disruption of the Dictyostelium G-protein alpha-subunit G alpha 3 (g alpha 3-) blocks development unless the mutant is starved in the presence of artificial cAMP pulses. The function of G alpha 3 was investigated by examining the expression of several components of the cAMP transmembrane signaling system in the g alpha 3- mutant. cAMP receptor 1 protein, cyclic nucleotide phosphodiesterase, phosphodiesterase inhibitor, and aggregation-stage adenylyl cyclase mRNA expression were absent or greatly reduced when cells were starved without exogenously applied pulses of cAMP. However, cAMP receptor 1 protein and aggregation-stage adenylyl cyclase mRNA expression were restored by starving the g alpha 3- cells in the presence of exogenous cAMP pulses. Adenylyl cyclase activity was also reduced in g alpha 3- cells starved without exogenous cAMP pulses compared with similarly treated wild-type cells but was elevated to a level twofold greater than wild-type cells in g alpha 3- cells starved in the presence of exogenous cAMP pulses. These results suggest that G alpha 3 is essential in early development because it controls the expression of components of the transmembrane signaling system.
authors.affiliation: Department of Surgery, Wayne State University, Detroit, Michigan 48201, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Brandon
authors.forename: G J
authors.initials: GJ
authors.lastname: Podgorski
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000502:physiology*; D004023:Dictyostelium / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins; D004789:Enzyme Activation / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D019204:GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D015966:Gene Expression Regulation, Fungal; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics; D020962:Heterotrimeric GTP-Binding Proteins; D009154:Mutation; D012333:RNA, Messenger / Q000378:metabolism; D011953:Receptors, Cyclic AMP / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029721:Drosophila Proteins; D005656:Fungal Proteins; C097161:G protein a49B, Drosophila; D006023:Glycoproteins; D012333:RNA, Messenger; D011953:Receptors, Cyclic AMP; C068125:cyclic AMP receptor cAR1; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D019204:GTP-Binding Proteins; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins; D000262:Adenylyl Cyclases