Gβγ-Mediated Regulation of Golgi Organization Is through the Direct Activation of Protein Kinase D

We show that receptor induced G protein βγ subunit translocation from the plasma membrane to the Golgi allows a receptor to initiate fragmentation and regulate secretion. A lung epithelial cell line, A549, was shown to contain an endogenous translocating G protein γ subunit and exhibit receptor-induced Golgi fragmentation. Receptor-induced Golgi fragmentation was inhibited by a shRNA specific to the endogenous translocating γ subunit. A kinase defective protein kinase D and a phospholipase C β inhibitor blocked receptor-induced Golgi fragmentation, suggesting a role for this process in secretion. Consistent with βγ translocation dependence, fragmentation induced by receptor activation was inhibited by a dominant negative nontranslocating γ3. Insulin secretion was shown to be induced by muscarinic receptor activation in a pancreatic β cell line, NIT-1. Induction of insulin secretion was also inhibited by the dominant negative γ3 subunit consistent with the Golgi fragmentation induced by βγ complex translocation playing a role in secretion.G protein-coupled receptors | live cell imaging | signaling | insulin

show abstract

“…The G protein βγ complex has been shown to activate PKD1 (24). We examined whether the Golgi fragmentation detected here is mediated by PKD.…”

Section: M3 Induced Golgi Fragmentation Through Translocating G Protementioning

confidence: 94%

Regulation of Golgi structure and secretion by receptor-induced G protein βγ complex translocation

Saini

Karunarathne²,

Angaswamy³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…To explore this possibility, we investigated whether chemicals that perturb microtubule-dependent membrane transport from the ER affect Bap31 localization. H89 blocks protein export out of the ER (Jamora et al, 1999) perhaps by mildly inhibiting the binding of COPII proteins to ER exit sites (Aridor and Balch, 2000;Lee and Linstedt, 2000), where COPII-coated vesicles involved in ER-to-Golgi transport are formed (Gurkan et al, 2006). It also blocks Golgi disassembly occurring during mitosis, likely by keeping Arf1, a small GTPase that regulates the recruitment of COPI to membranes (LippincottSchwartz and Liu, 2006), in an active state (Altan-Bonnet et al, 2003).…”

Section: Bap31 Accumulates At the Juxtanuclear Region By H89 Treatmentmentioning

confidence: 99%

Bap31 Is an Itinerant Protein That Moves between the Peripheral Endoplasmic Reticulum (ER) and a Juxtanuclear Compartment Related to ER-associated Degradation

Wakana

Takai

Nakajima

et al. 2008

MBoC

102

View full text Add to dashboard Cite

Certain endoplasmic reticulum (ER)-associated degradation (ERAD) substrates with transmembrane domains are segregated from other ER proteins and sorted into a juxtanuclear subcompartment, known as the ER quality control compartment. Bap31 is an ER protein with three transmembrane domains, and it is assumed to be a cargo receptor for ER export of some transmembrane proteins, especially those prone to ERAD. Here, we show that Bap31 is a component of the ER quality control compartment and that it moves between the peripheral ER and a juxtanuclear ER or ER-related compartment distinct from the conventional ER-Golgi intermediate compartment. The third and second transmembrane domains of Bap31 are principally responsible for the movement to and recycling from the juxtanuclear region, respectively. This cycling was blocked by depolymerization of microtubules and disruption of dynein-dynactin function. Overexpression of Sar1p and Arf1 mutants affected Bap31 cycling, suggesting that this cycling pathway is related to the conventional vesicular transport pathways. INTRODUCTIONThe endoplasmic reticulum (ER) exhibits a reticular tubular network that extends from the nucleus to the cell periphery along microtubule tracks. It performs a variety of functions, including the synthesis, posttranslational modifications, quality control, and export of secretory and membrane proteins; the synthesis of lipids; stress response; Ca 2ϩ storage; and apoptosis. Most, if not all, of these functions are managed by subdomains, such as the rough and smooth ER and transitional ER sites. Each subdomain contains a unique set of proteins that are responsible for its function and organization. ER subdomains are relatively stable, but they can be transformed into alternative structures in response to cellular conditions (for review, see Voeltz et al., 2002;Levine and Rabouille, 2005;Borgese et al., 2006;Vedrenne and Hauri, 2006).Several studies showed the presence of a specialized ER subdomain that is related to ER-associated degradation (ERAD). ERAD is part of a quality control system that ensures the delivery of only correctly folded or assembled secretory and membrane proteins to their final destinations. Newly synthesized proteins that fail to fold or assemble correctly are retained in the ER, retrotranslocated to the cytosol, and degraded by the ubiquitin-proteasome system (for review, see Ellgaard and Helenius, 2003;Meusser et al., 2005;Rö misch, 2005). Studies using mammalian cells demonstrated that transmembrane ERAD substrates are segregated into "ER quality control compartments," which become discernible at the juxtanuclear region upon inhibition of ERAD by proteasome inhibitors (Kamhi-Nesher et al., 2001;Spiliotis et al., 2002). In Saccharomyces cerevisiae, ectopically expressed cystic fibrosis transmembrane conductance regulator (CFTR) is segregated from other ER proteins and accumulates in ER-associated compartments (Kiser et al., 2001;Zhang et al., 2001;Huyer et al., 2004). Degradation of CFTR in yeast is independent of ER-to-Golgi tr...

show abstract

“…In addition to G protein-coupled receptor (GPCR)-mediated activation of G protein signaling, nature has evolved other modes of signal input to G proteins that either act independent of a GPCR or modulate signal transfer from receptor to G protein. Recent studies also indicate a role of G␣ and G␤␥ in the processing of signals within the cell distinct from those that they mediate following activation by a cell-surface GPCRs (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). In such situations, the G protein subunits (G␣ and G␤␥) may actually be complexed with alternative binding partners independent of the typical heterotrimeric G␣␤␥.…”

mentioning

confidence: 99%

Identification of a receptor-independent activator of G protein signaling (AGS8) in ischemic heart and its interaction with Gβγ

Sato

Cismowski

Toyota

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

As part of a broader effort to identify postreceptor signal regulators involved in specific diseases or organ adaptation, we used an expression cloning system in Saccharomyces cerevisiae to screen cDNA libraries from rat ischemic myocardium, human heart, and a prostate leiomyosarcoma for entities that activated G protein signaling in the absence of a G protein coupled receptor. We report the characterization of activator of G protein signaling (AGS) 8 (KIAA1866), isolated from a rat heart model of repetitive transient ischemia. AGS8 mRNA was induced in response to ventricular ischemia but not by tachycardia, hypertrophy, or failure. Hypoxia induced AGS8 mRNA in isolated adult ventricular cardiomyocytes but not in rat aortic smooth muscle cells, endothelial cells, or cardiac fibroblasts, suggesting a myocyte-specific adaptation mechanism involving remodeling of G protein signaling pathways. The bioactivity of AGS8 in the yeast-based assay was independent of guanine nucleotide exchange by G␣, suggesting an impact on subunit interactions. Subsequent studies indicated that AGS8 interacts directly with G␤␥ and this occurs in a manner that apparently does not alter the regulation of the effector PLC-␤ 2 by G␤␥. Mechanistically, AGS8 appears to promote G protein signaling by a previously unrecognized mechanism that involves direct interaction with G␤␥.accessory protein ͉ signal adaptation ͉ hypoxia

show abstract

Gβγ-Mediated Regulation of Golgi Organization Is through the Direct Activation of Protein Kinase D

Cited by 260 publications

References 28 publications

Regulation of Golgi structure and secretion by receptor-induced G protein βγ complex translocation

Regulation of Golgi structure and secretion by receptor-induced G protein βγ complex translocation

Bap31 Is an Itinerant Protein That Moves between the Peripheral Endoplasmic Reticulum (ER) and a Juxtanuclear Compartment Related to ER-associated Degradation

Identification of a receptor-independent activator of G protein signaling (AGS8) in ischemic heart and its interaction with Gβγ

Contact Info

Product

Resources

About