Nuclear localization of G protein beta 5 and regulator of G protein signaling 7 in neurons and brain.
The role that Gbeta(5) regulator of G protein signaling (RGS) complexes play in signal transduction in brain remains unknown. The subcellular localization of Gbeta(5) and RGS7 was examined in rat PC12 pheochromocytoma cells and mouse brain. Both nuclear and cytosolic localization of Gbeta(5) and RGS7 was evident in PC12 cells by immunocytochemical staining. Subcellular fractionation of PC12 cells demonstrated Gbeta(5) immunoreactivity in the membrane, cytosolic, and nuclear fractions. Analysis by limited proteolysis confirmed the identity of Gbeta(5) in the nuclear fraction. Subcellular fractionation of mouse brain demonstrated Gbeta(5) and RGS7 but not Ggamma(2/3) immunoreactivity in the nuclear fraction. RGS7 and Gbeta(5) were tightly complexed in the brain nuclear extract as evidenced by their coimmunoprecipitation with anti-RGS7 antibodies. Chimeric protein constructs containing green fluorescent protein fused to wild-type Gbeta(5) but not green fluorescent fusion proteins with Gbeta(1) or a mutant Gbeta(5) impaired in its ability to bind to RGS7 demonstrated nuclear localization in transfected PC12 cells. These findings suggest that Gbeta(5) undergoes nuclear translocation in neurons via an RGS-dependent mechanism. The novel intracellular distribution of Gbeta(5).RGS protein complexes suggests a potential role in neurons communicating between classical heterotrimeric G protein subunits and/or their effectors at the plasma membrane and the cell nucleus.
Zhang
J H
JH
Metabolic Diseases Branch and the Diabetes Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Barr
V A
VA
Mo
Y
Y
Rojkova
A M
AM
Liu
S
S
Simonds
W F
WF
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D044387:GTP-Binding Protein beta Subunits; D019204:GTP-Binding Proteins; D049452:Green Fluorescent Proteins; D020962:Heterotrimeric GTP-Binding Proteins / Q000096:biosynthesis*; D015151:Immunoblotting; D007150:Immunohistochemistry; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D020932:Nerve Growth Factor / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D016716:PC12 Cells; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D020710:RGS Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection
D018076:DNA, Complementary; D044387:GTP-Binding Protein beta Subunits; C094668:Gnb5 protein, mouse; C490610:Gnb5 protein, rat; D008164:Luminescent Proteins; D020710:RGS Proteins; D011993:Recombinant Fusion Proteins; C492038:Rgs7 protein, mouse; C115771:Rgs7 protein, rat; D049452:Green Fluorescent Proteins; D020932:Nerve Growth Factor; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins