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

Saini, Deepak Kumar; Karunarathne, Ajith; Angaswamy, Nataraju; Saini, Deepika; Cho, Joon-Ho; Kalyanaraman, Vani; Gautam, N.

doi:10.1073/pnas.1003042107

Cited by 66 publications

(79 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This would generate free G␤␥ at the PM, which would then translocate to the TGN (19). In this regard, during the preparation of this report a study showed that overexpression of certain G␥ subunits that are able to translocate from the PM to the Golgi membrane upon activation of an overexpressed GPCR are able to induce Golgi fragmentation (55). In our experiments, the failure of PM-targeted GRK2ct to inhibit VSV-G transport argues against the second model (Fig.…”

Section: Discussionmentioning

confidence: 59%

Regulation of Constitutive Cargo Transport from the trans-Golgi Network to Plasma Membrane by Golgi-localized G Protein βγ Subunits

Irannejad

Wedegaertner

2010

Journal of Biological Chemistry

View full text Add to dashboard Cite

Observations of Golgi fragmentation upon introduction of G protein ␤␥ (G␤␥) subunits into cells have implicated G␤␥ in a pathway controlling the fission at the trans-Golgi network (TGN) of plasma membrane (PM)-destined transport carriers. However, the subcellular location where G␤␥ acts to provoke Golgi fragmentation is not known. Additionally, a role for G␤␥ in regulating TGN-to-PM transport has not been demonstrated. Here we report that constitutive or inducible targeting of G␤␥ 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 ␤ 1 ␥ 2 also activates protein kinase D. Moreover, the novel G␤␥ inhibitor, gallein, and the G␤␥-sequestering protein, GRK2ct, reveal that G␤␥ 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 G␤␥, endogenous G␤ was detected at the Golgi in HeLa cells. These results are the first to establish a role for Golgi-localized G␤␥ in regulating protein transport from the TGN to the cell surface.Heterotrimeric G proteins, composed of ␣, ␤, and ␥ subunits, are involved in a wide variety of signaling responses and act by coupling heptahelical G protein-coupled receptors (GPCRs) 2 to intracellular effector proteins. In its inactive state, the G␣ subunit is bound to GDP and is also tightly bound to the G␤␥ subunits. Upon receptor activation by ligand binding, the GPCR catalyzes the exchange of GDP for GTP on the G␣, resulting in dissociation of G␣ and G␤␥. The separated subunits are then able to elicit their own signaling cascades. Hydrolysis of GTP by G␣, followed by re-association of G␣ and G␤␥, completes the cycle (1, 2).

show abstract

Section: Discussionmentioning

confidence: 59%

Regulation of Constitutive Cargo Transport from the trans-Golgi Network to Plasma Membrane by Golgi-localized G Protein βγ Subunits

Irannejad

Wedegaertner

2010

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…G-protein α-and βγ-subunits were classically thought to act only at the plasma membrane, but recent findings suggest important new roles for G-protein subunits at intracellular locations (45)(46)(47). Whereas rapid diffusion of second messengers generated by G-protein effectors at the plasma membrane enables fast signal communication to other regions of the cell, βγ translocation to intracellular regions could enable more specific communication between the plasma membrane and internal membranes.…”

Section: Discussionmentioning

confidence: 99%

G-protein signaling leverages subunit-dependent membrane affinity to differentially control βγ translocation to intracellular membranes

O’Neill¹,

Karunarathne²,

Kalyanaraman³

et al. 2012

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

Self Cite

View full text Add to dashboard Cite

Activation of G-protein heterotrimers by receptors at the plasma membrane stimulates βγ-complex dissociation from the α-subunit and translocation to internal membranes. This intermembrane movement of lipid-modified proteins is a fundamental but poorly understood feature of cell signaling. The differential translocation of G-protein βγ-subunit types provides a valuable experimental model to examine the movement of signaling proteins between membranes in a living cell. We used live cell imaging, mathematical modeling, and in vitro measurements of lipidated fluorescent peptide dissociation from vesicles to determine the mechanistic basis of the intermembrane movement and identify the interactions responsible for differential translocation kinetics in this family of evolutionarily conserved proteins. We found that the reversible translocation is mediated by the limited affinity of the βγ-subunits for membranes. The differential kinetics of the βγ-subunit types are determined by variations among a set of basic and hydrophobic residues in the γ-subunit types. Gprotein signaling thus leverages the wide variation in membrane dissociation rates among different γ-subunit types to differentially control βγ-translocation kinetics in response to receptor activation. The conservation of primary structures of γ-subunits across mammalian species suggests that there can be evolutionary selection for primary structures that confer specific membrane-binding affinities and consequent rates of intermembrane movement.protein-membrane interaction | spatio-temporal dynamics | G protein-coupled receptors C ompared with the vast biochemical information available for signaling proteins from cell-disruptive techniques, much less is known about their spatiotemporal dynamics in the 3D space of an intact living cell. Many important signaling proteins are posttranslationally modified with lipid groups that facilitate their interactions with membranes. Live cell imaging has so far revealed important roles for constitutive cycles that maintain proper localization of lipidated proteins (1) and for dynamic protein redistribution throughout the cell in response to a signal (2), but the detailed nature of lipid-modified protein movement between membranes is generally not well understood.Heterotrimeric G proteins consist of lipid-modified α-and βγ-subunits (3). They are central transducers of the most important signaling pathways in mammals, yet little is known about their intracellular movement. Inactive heterotrimers consist of a GDP-bound α-subunit in complex with a stable βγ-dimer and localize to the plasma membrane (3). Extracellular signals activate transmembrane G-protein-coupled receptors (GPCRs) that catalyze nucleotide exchange on the G-protein α-subunit (3). The βγ-complex can then dissociate from the active α-subunit and translocate from the plasma membrane to intracellular membranes (4-6). βγ translocation has been observed for many different cell types and receptor types, suggesting that it is a common feature of G-protein signaling (4-...

show abstract

“…Of these three lipid-metabolizing enzymes, only sphingomyelin synthase is widely believed to localize to the Golgi. PLD localization at this organelle is controversial (14 -16), and phospholipase C action has not been widely studied (17).…”

Section: Dagmentioning

confidence: 99%

Phospholipid Synthesis Participates in the Regulation of Diacylglycerol Required for Membrane Trafficking at the Golgi Complex

Sarri¹,

Sicart²,

Lázaro‐Diéguez³

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

The lipid metabolite diacylglycerol (DAG) is required for transport carrier biogenesis at the Golgi, although how cells regulate its levels is not well understood. Phospholipid synthesis involves highly regulated pathways that consume DAG and can contribute to its regulation. Here we altered phosphatidylcholine (PC) and phosphatidylinositol synthesis for a short period of time in CHO cells to evaluate the changes in DAG and its effects in membrane trafficking at the Golgi. We found that cellular DAG rapidly increased when PC synthesis was inhibited at the non-permissive temperature for the rate-limiting step of PC synthesis in CHO-MT58 cells. DAG also increased when choline and inositol were not supplied. The major phospholipid classes and triacylglycerol remained unaltered for both experimental approaches. The analysis of Golgi ultrastructure and membrane trafficking showed that 1) the accumulation of the budding vesicular profiles induced by propanolol was prevented by inhibition of PC synthesis, 2) the density of KDEL receptor-containing punctated structures at the endoplasmic reticulum-Golgi interface correlated with the amount of DAG, and 3) the postGolgi transport of the yellow fluorescent temperature-sensitive G protein of stomatitis virus and the secretion of a secretory form of HRP were both reduced when DAG was lowered. We confirmed that DAG-consuming reactions of lipid synthesis were present in Golgi-enriched fractions. We conclude that phospholipid synthesis pathways play a significant role to regulate the DAG required in Golgi-dependent membrane trafficking.

show abstract

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

Cited by 66 publications

References 30 publications

Regulation of Constitutive Cargo Transport from the trans-Golgi Network to Plasma Membrane by Golgi-localized G Protein βγ Subunits

Regulation of Constitutive Cargo Transport from the trans-Golgi Network to Plasma Membrane by Golgi-localized G Protein βγ Subunits

G-protein signaling leverages subunit-dependent membrane affinity to differentially control βγ translocation to intracellular membranes

Phospholipid Synthesis Participates in the Regulation of Diacylglycerol Required for Membrane Trafficking at the Golgi Complex

Contact Info

Product

Resources

About