title: Translocation of activated heterotrimeric G protein Galpha(o) to ganglioside-enriched detergent-resistant membrane rafts in developing cerebellum.
abstract: The association of gangliosides with specific proteins in the central nervous system was examined by co-immunoprecipitation with an anti-ganglioside antibody. The monoclonal antibody to the ganglioside GD3 immunoprecipitated phosphoproteins of 40, 53, 56, and 80 kDa from the rat cerebellum. Of these proteins, the 40-kDa protein was identified as the alpha-subunit of a heterotrimeric G protein, G(o) (Galpha(o)). Using sucrose density gradient analysis of cerebellar membranes, Galpha(o), but not Gbetagamma, was observed in detergent-resistant membrane (DRM) raft fractions in which GD3 was abundant after the addition of guanosine 5'-O-(thiotriphosphate) (GTPgammaS), which stabilizes G(o) in its active form. On the other hand, both Galpha(o) and Gbetagamma were excluded from the DRM raft fractions in the presence of guanyl-5'-yl thiophosphate, which stabilizes G(o) in its inactive form. Only Galpha(o) was observed in the DRM fractions from the cerebellum on postnatal day 7, but not from that in adult. After pertussis toxin treatment, Galpha(o) was not observed in the DRM fractions, even from the cerebellum on postnatal day 7. These results indicate the activation-dependent translocation of Galpha(o) into the DRM rafts. Furthermore, Galpha(o) was concentrated in the neuronal growth cones. Treatment with stromal cell-derived factor-1alpha, a physiological ligand for the G protein-coupled receptor, stimulated [(35)S]GTPgammaS binding to Galpha(o) and caused Galpha(o) translocation to the DRM fractions and RhoA translocation to the membrane fraction, leading to the growth cone collapse of cerebellar granule neurons. The collapse was partly prevented by pretreatment with the cholesterol-sequestering and raft-disrupting agent methyl-beta-cyclodextrin. These results demonstrate the involvement of signal-dependent Galpha(o) translocation to the DRM in the growth cone behavior of cerebellar granule neurons.
authors.affiliation: Biomembrane Signaling Project 2, Tokyo Metropolitan Institute of Medical Science, Tokyo Metropolitan Organization for Medical Research, 3-18-22 Honkomagome Bunkyo-ku, Tokyo, 113-8613 Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Yuyama
authors.forename: Naoko
authors.initials: N
authors.lastname: Sekino-Suzuki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sanai
authors.forename: Kohji
authors.initials: K
authors.lastname: Kasahara
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D016466:CHO Cells; D002531:Cerebellum / Q000254:growth & development* / Q000378:metabolism; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism; D044388:GTP-Binding Protein gamma Subunits / Q000378:metabolism; D005732:Gangliosides / Q000378:metabolism*; D020439:Growth Cones / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D021962:Membrane Microdomains / Q000378:metabolism*; D037342:Pertussis Toxin / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D047392:beta-Cyclodextrins / Q000494:pharmacology; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D005732:Gangliosides; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D037342:Pertussis Toxin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020742:rhoA GTP-Binding Protein