Regulation of constitutive cargo transport from the trans-Golgi network to plasma membrane by Golgi-localized G protein betagamma subunits.
Observations of Golgi fragmentation upon introduction of G protein βγ (Gβγ) subunits into cells have implicated Gβγ in a pathway controlling the fission at the trans-Golgi network (TGN) of plasma membrane (PM)-destined transport carriers. However, the subcellular location where Gβγ acts to provoke Golgi fragmentation is not known. Additionally, a role for Gβγ in regulating TGN-to-PM transport has not been demonstrated. Here we report that constitutive or inducible targeting of Gβγ to the Golgi, but not other subcellular locations, causes phospholipase C- and protein kinase D-dependent vesiculation of the Golgi in HeLa cells; Golgi-targeted β(1)γ(2) also activates protein kinase D. Moreover, the novel Gβγ inhibitor, gallein, and the Gβγ-sequestering protein, GRK2ct, reveal that Gβγ is required for the constitutive PM transport of two model cargo proteins, VSV-G and ss-HRP. Importantly, Golgi-targeted GRK2ct, but not a PM-targeted GRK2ct, also blocks protein transport to the PM. To further support a role for Golgi-localized Gβγ, endogenous Gβ was detected at the Golgi in HeLa cells. These results are the first to establish a role for Golgi-localized Gβγ in regulating protein transport from the TGN to the cell surface.
Irannejad
Roshanak
R
Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Wedegaertner
Philip B
PB
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D011493:Protein Kinase C / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D010738:Type C Phospholipases / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D014966:Xanthenes / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism*
D004791:Enzyme Inhibitors; C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D021122:Protein Subunits; D014764:Viral Proteins; D014966:Xanthenes; C007820:gallein; C089212:protein kinase D; D011493:Protein Kinase C; D010738:Type C Phospholipases