Heterotrimeric G proteins (subunit composition alpha.Beta/gamma) mediate the effects of a large family of receptors by virtue of their activating or deactivating effects on effector systems. The last years have seen the elucidation of the primary functions of 14 out of the 16 G protein alpha subunits that are now known, as well as for Beta/gamma dimers that form as a result of G proteins activation by GTP under the receptor influence. Recent studies have shown involvement of trimeric G proteins not only in regulation of adenylyl cyclases (AC's), phospholipases (PL's), phosphodiesterases and ion channels, but also in processes such as vesicle budding from endoplasmic reticulum and Golgi networks, and in endosome acidification. Broader roles that mere signal transduction are indicated for G proteins. Mutations of the Galpha subunits that cause constitutive activation have been found in neoplasms and tumors and it has been hypothesized that some alpha subunits may be proto-oncogenes. The molecular cloning and ensuing elucidation of the predicted primary structure of AC led to the discovery of a large degree of molecular and functional diversity (8 genes with products sub-classifiable on the basis of response to Ca2+, calmodulin, Beta/gamma, and possibly activated Gi/alpha's). Up to 5 AC subtypes may be expressed in a single cell as seen with a pituitary tumor cell widely used to study regulation of adenylyl cyclase, phospholipase, ion channel and hormone secretion. During this last term we established in out laboratory the technology required to inactivate or mutate genes in embryonic stem cells and generate via injection into blastocysts animals with an altered genome. Applying this technique to knock out the alpha subunit of Gi2 we gained new information not only about its suspected role in mediating hormonal inhibition of adenylyl cyclase, but also discovered that mice deficient in alphai2 have abnormal T cell-development and function and develop an inflammatory bowel disease resembling ulcerative colitis. Whether these phenomena are causally related is not known. Research proposed in this application focusses wholly on generating novel mouse strains in which genes for alpha/0, alpha/i1, alpha i3 are inactivated and in which alpha/s and alpha/13 and alpha /i2 are mutationally activated. Through breeding, we will combine one or more of these mutations. Other modifications or inactivation of G protein subunits (e.g. alpha/o1 vs. alpha/o2) will be considered and performed depending on outcome and the speed of progress. It is hoped that these studies will 1. test for role(s) of G proteins in developmental processes as well as in cellular functions not yet thought of as targets of G protein regulation; 2. critically test the proto-oncogene potential of Galpha's in the background of a normal mouse; and 3. test for possible functions of alpha subunits for which no function is thus far known.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK019318-19
Application #
2137304
Study Section
Physiological Chemistry Study Section (PC)
Program Officer
Abraham, Kristin M
Project Start
1994-09-12
Project End
1998-06-30
Budget Start
1995-07-01
Budget End
1996-06-30
Support Year
19
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Tang, Guanghua; Wang, Ying; Park, Sangeun et al. (2012) Go2 G protein mediates galanin inhibitory effects on insulin release from pancreatic ? cells. Proc Natl Acad Sci U S A 109:2636-41
Fan, Hongkuan; Williams, David L; Zingarelli, Basilia et al. (2007) Differential regulation of lipopolysaccharide and Gram-positive bacteria induced cytokine and chemokine production in macrophages by Galpha(i) proteins. Immunology 122:116-23
Gohla, Antje; Klement, Karinna; Piekorz, Roland P et al. (2007) An obligatory requirement for the heterotrimeric G protein Gi3 in the antiautophagic action of insulin in the liver. Proc Natl Acad Sci U S A 104:3003-8
Pero, Ralph S; Borchers, Michael T; Spicher, Karsten et al. (2007) Galphai2-mediated signaling events in the endothelium are involved in controlling leukocyte extravasation. Proc Natl Acad Sci U S A 104:4371-6
Fan, Hongkuan; Williams, David L; Zingarelli, Basilia et al. (2006) Differential regulation of lipopolysaccharide and Gram-positive bacteria induced cytokine and chemokine production in splenocytes by Galphai proteins. Biochim Biophys Acta 1763:1051-8
Wei, Bo; Velazquez, Peter; Turovskaya, Olga et al. (2005) Mesenteric B cells centrally inhibit CD4+ T cell colitis through interaction with regulatory T cell subsets. Proc Natl Acad Sci U S A 102:2010-5
Pineda, Victor V; Athos, Jaime I; Wang, Hongbing et al. (2004) Removal of G(ialpha1) constraints on adenylyl cyclase in the hippocampus enhances LTP and impairs memory formation. Neuron 41:153-63
Foerster, Katharina; Groner, Ferdi; Matthes, Jan et al. (2003) Cardioprotection specific for the G protein Gi2 in chronic adrenergic signaling through beta 2-adrenoceptors. Proc Natl Acad Sci U S A 100:14475-80
Dhingra, Anuradha; Jiang, Meisheng; Wang, Tian-Li et al. (2002) Light response of retinal ON bipolar cells requires a specific splice variant of Galpha(o). J Neurosci 22:4878-84
Jiang, M; Spicher, K; Boulay, G et al. (2001) Most central nervous system D2 dopamine receptors are coupled to their effectors by Go. Proc Natl Acad Sci U S A 98:3577-82

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