title: Suppression of adenylyl cyclase-mediated cAMP production by plasma membrane associated cytoskeletal protein 4.1G.
abstract: It has been shown lately that activity of G protein-coupled receptors (GPCRs) is regulated by an array of proteins binding to carboxy (C)-terminus of GPCRs. Proteins of 4.1 family are subsets of subcortical cytoskeletal proteins and are known to stabilize cellular structures and proteins at the plasma membrane. One of the 4.1 family proteins, 4.1G has been shown to interact with the C-terminus of GPCRs and regulate intracellular distribution of the receptors, including parathyroid hormone (PTH)/PTH-related protein receptor (PTHR). PTHR is coupled to trimeric G proteins G(s) and G(q), which activate the adenylyl cyclase/cyclic AMP (cAMP) pathway and phospholipase C pathway, respectively. During the course of investigation of the role of 4.1G on adenylyl cyclase/cAMP signaling pathway, we found that 4.1G suppressed forskolin-induced cAMP production in cells. The cAMP accumulation induced by forskolin was decreased in HEK293 cells overexpressing 4.1G or increased in 4.1G-knockdown cells. Furthermore, PTH -(1-34)-stimulated cAMP production was also suppressed in the presence of exogenously expressed 4.1G despite its activity to increase the distribution of PTHR to the cell surface. In cells overexpressing FERM domain-deleted 4.1G, a mutant form of the protein deficient in plasma membrane distribution, neither forskolin-induced nor PTH -(1-34)-stimulated cAMP production was not altered. The suppression of the forskolin-induced cAMP production was observed even in membrane preparations of 4.1G-overexpressing cells. In 4.1G-knockdown HEK293 cells, plasma membrane distribution of adenylyl cyclase 6, one of the major subtypes of the enzyme in the cells, showed a slight decrease, in spite of the increased production of cAMP in those cells when stimulated by forskolin. Also, cytochalasin D treatment did not cause any influence on forskolin-induced cAMP production in HEK293 cells. These data indicate that plasma membrane-associated 4.1G regulates GPCR-mediated G(s) signaling by suppressing adenylyl cyclase-mediated cAMP production.
authors.affiliation: Department of Cellular Signaling, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba 6-3, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Goto
authors.forename: Ayano
authors.initials: A
authors.lastname: Chiba
authors.forename: Jun
authors.initials: J
authors.lastname: Sukegawa
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Yanagisawa
authors.forename: Masaki
authors.initials: M
authors.lastname: Saito
authors.forename: Norimichi
authors.initials: N
authors.lastname: Nakahata
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D015638:Cytochalasin D / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D011863:Radioimmunoassay; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection
chemical_list: D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D010281:Parathyroid Hormone; D034741:RNA, Small Interfering; D044168:Receptor, Parathyroid Hormone, Type 1; C028841:erythrocyte membrane band 4.1 protein; D005576:Colforsin; D015638:Cytochalasin D; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; C121100:adenylyl cyclase 6