scholarly journals The ubiquitin-related protein PLIC-1 regulates heterotrimeric G protein function through association with Gβγ

2003 ◽  
Vol 163 (5) ◽  
pp. 1157-1165 ◽  
Author(s):  
Elsa-Noah N'Diaye ◽  
Eric J. Brown
Keyword(s):  
Wound Healing ◽  
Phospholipase C ◽  
G Proteins ◽  
Protein Function ◽  
Proteasome Inhibition ◽  
Selective Inhibition ◽  
Related Protein ◽  
Dependent Component ◽  
Direct Association ◽  
Signaling Components

PLIC-1, a newly described ubiquitin-related protein, inhibited both Jurkat migration toward SDF-1α and A431 wound healing, but the closely related PLIC-2 did not. PLIC-1 prevented the SDF-1α–induced activation of phospholipase C, decreased ligand-induced internalization of SDF-1α receptor CXCR4 and inhibited chemotaxis signaled by a transfected Gi-coupled receptor. However, PLIC-1 had no effect on Gs-mediated adenylyl cyclase activation, and inhibited only the Gβγ-dependent component of Gq-initiated increase in [Ca2+]i, which is consistent with selective inhibition of Gβγ function. PLIC-1 colocalized with G proteins in lamellae and pseudopods, and precipitated Gβγ in pull downs. Interaction with Gβγ did not require PLIC-1's ubiquitin-like or ubiquitin-associated domains, and proteasome inhibition had no effect on SDF-1α activation of phospholipase C, indicating that PLIC-1's inhibition of Gβγ did not result from effects on proteasome function. Thus, PLIC-1 inhibits Gi signaling by direct association with Gβγ; because it also interacts with CD47, a modulator of integrin function, it likely has a role integrating adhesion and signaling components of cell migration.

scholarly journals Norepinephrine exocytosis stimulated by α–latrotoxin requires both external and stored Ca 2+ and is mediated by latrophilin, G proteins and phospholipase C

1999 ◽  
Vol 354 (1381) ◽  
pp. 379-386 ◽  
Author(s):  
M. Atiqur Rahman ◽  
Anthony C. Ashton ◽  
Frédéric A. Meunier ◽  
Bazbek A. Davletov ◽  
J. Oliver Dolly ◽  
...  
Keyword(s):  
Phospholipase C ◽  
G Protein ◽  
G Proteins ◽  
Fluorescent Dyes ◽  
Transmembrane Protein ◽  
Clostridial Neurotoxins ◽  
Dependent Component ◽  
Intracellular Ca ◽  
Botulinum Neurotoxins ◽  
Vesicular Exocytosis

α–latrotoxin (LTX) stimulates massive release of neurotransmitters by binding to a heptahelical transmembrane protein, latrophilin. Our experiments demonstrate that latrophilin is a G–protein–coupled receptor that specifically associates with heterotrimeric G proteins. The latrophilin–G protein complex is very stable in the presence of GDP but dissociates when incubated with GTP, suggesting a functional interaction. As revealed by immunostaining, latrophilin interacts with Gα q/11 and Gα o but not with Gα s , Gα i or Gα z , indicating that this receptor may couple to several G proteins but it is not promiscuous. The mechanisms underlying LTX–evoked norepinephrine secretion from rat brain nerve terminals were also studied. In the presence of extracellular Ca 2+ , LTX triggers vesicular exocytosis because botulinum neurotoxins E, C1 or tetanus toxin inhibit the Ca 2+ –dependent component of the toxin–evoked release. Based on (i) the known involvement of Gα q in the regulation of inositol–1,4,5–triphosphate generation and (ii) the requirement of Ca 2+ in LTX action, we tested the effect of inhibitors of Ca 2+ mobilization on the toxin–evoked norepinephrine release. It was found that aminosteroid U73122, which inhibits the coupling of G proteins to phospholipase C, blocks the Ca 2+ –dependent toxin's action. Thapsigargin, which depletes intracellular Ca 2+ stores, also potently decreases the effect of LTX in the presence of extracellular Ca 2+ . On the other hand, clostridial neurotoxins or drugs interfering with Ca 2+ metabolism do not inhibit the Ca 2+ –independent component of LTX–stimulated release. In the absence of Ca 2+ , the toxin induces in the presynaptic membrane non–selective pores permeable to small fluorescent dyes; these pores may allow efflux of neurotransmitters from the cytoplasm. Our results suggest that LTX stimulates norepinephrine exocytosis only in the presence of external Ca 2+ provided intracellular Ca 2+ stores are unperturbed and that latrophilin, G proteins and phospholipase C may mediate the mobilization of stored Ca 2+ , which then triggers secretion.

scholarly journals Growth Promotion or Osmotic Stress Response: How SNF1-Related Protein Kinase 2 (SnRK2) Kinases Are Activated and Manage Intracellular Signaling in Plants

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1443
Author(s):  
Yoshiaki Kamiyama ◽  
Sotaro Katagiri ◽  
Taishi Umezawa
Keyword(s):  
Protein Kinase ◽  
Plant Growth ◽  
Osmotic Stress ◽  
Protein Function ◽  
Intracellular Signaling ◽  
Growth Promotion ◽  
Research Field ◽  
Dependent Manner ◽  
Related Protein ◽  
Wide Range

Reversible phosphorylation is a major mechanism for regulating protein function and controls a wide range of cellular functions including responses to external stimuli. The plant-specific SNF1-related protein kinase 2s (SnRK2s) function as central regulators of plant growth and development, as well as tolerance to multiple abiotic stresses. Although the activity of SnRK2s is tightly regulated in a phytohormone abscisic acid (ABA)-dependent manner, recent investigations have revealed that SnRK2s can be activated by group B Raf-like protein kinases independently of ABA. Furthermore, evidence is accumulating that SnRK2s modulate plant growth through regulation of target of rapamycin (TOR) signaling. Here, we summarize recent advances in knowledge of how SnRK2s mediate plant growth and osmotic stress signaling and discuss future challenges in this research field.

scholarly journals Modulation of Ins(2,4,5)P3-stimulated Ca2+ mobilization by Ins(1,3,4,5)P4: enhancement by activated G-proteins, and evidence for the involvement of a GAP1 protein, a putative Ins(1,3,4,5)P4 receptor

1998 ◽  
Vol 331 (3) ◽  
pp. 947-952 ◽  
Author(s):  
Jefferson W. LOOMIS-HUSSELBEE ◽  
Christopher D. WALKER ◽  
Joanna R. BOTTOMLEY ◽  
Peter J. CULLEN ◽  
Robin F. IRVINE ◽  
...  
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Protein A ◽  
Related Protein ◽  
L1210 Cells ◽  
Putative Receptor ◽  
Specific Enhancement ◽  
Insp3 Receptor

We have previously shown that addition of Ins(1,3,4,5)P4 to permeabilized L1210 cells increases the amount of Ca2+ mobilized by a submaximal concentration of Ins(2,4,5)P3, and we suggested that, in doing this, Ins(1,3,4,5)P4 is not working via an InsP3 receptor but indirectly via an InsP4 receptor [Loomis-Husselbee, Cullen, Dreikhausen, Irvine and Dawson (1996) Biochem. J. 314, 811–816]. Here we have investigated whether this effect might be mediated by GAP1IP4BP, recently identified as a putative receptor for Ins(1,3,4,5)P4. GAP1IP4BP is a protein that interacts with one or more monomeric G-proteins, so we sought evidence for involvement of monomeric G-proteins in the effects of Ins(1,3,4,5)P4 in permeabilized L1210 cells. Guanosine 5´-[γ-thio]triphosphate (GTP[S]) enhanced the effect of Ins(1,3,4,5)P4 on Ins(2,4,5)P3-stimulated Ca2+ mobilization, but had no effect on the action of Ins(2,4,5)P3 alone. A specific enhancement of only the action of Ins(1,3,4,5)P4 was also seen with GTP[S]-loaded R-Ras or Rap1a (two G-proteins known to interact with GAP1IP4BP), whereas H-Ras was inactive at similar concentrations. Guanosine 5´-[β-thio]diphosphate (GDP[S]) did not alter the action of either Ins(2,4,5)P3 or Ins(1,3,4,5)P4. Finally, the addition of exogenous GAP1IP4BP, purified from platelets, markedly enhanced the effect of Ins(1,3,4,5)P4, and again, the amount of Ca2+ mobilized by Ins(2,4,5)P3 alone was unaltered. We conclude that the increase in Ins(2,4,5)P3-stimulated Ca2+ mobilization by Ins(1,3,4,5)P4 may be mediated by GAP1IP4BP or a closely related protein (such as GAP1m), and if so, the action of the GAP1 is not solely to regulate GTP loading of a G-protein, but rather it acts with a G-protein to cause its effect.

Stimulation by G Protein βγ Subunits of Phospholipase C β Isoforms in Human Platelets

1998 ◽  
Vol 79 (05) ◽  
pp. 1008-1013 ◽  
Author(s):  
Yoshiko Banno ◽  
Tomiko Asano ◽  
Yoshinori Nozawa
Keyword(s):  
Phospholipase C ◽  
G Protein ◽  
G Proteins ◽  
Human Platelet ◽  
Minor Component ◽  
Similar Efficacy ◽  
Human Platelets ◽  
Bovine Brain ◽  
Γ Subunit ◽  
A Minor

SummaryDifferent phospholipase C (PLC) isoforms were located in human platelet cytosol and membranes. PLCγ2 and PLCβ3b were mainly located in the cytosol and PLCβ2 and PLCβ3a were in both cytosol and membranes by using specific antibodies against PLC isozymes (Banno Y, Nakashima S, Ohzawa M, Nozawa Y. J Biol Chem 1996; 271: 14989-94). Three PLC fractions activated by G protein βγ subunits were purified from human platelet cytosol and membrane fractions. Two PLC fractions from membranes were identified as PLCβ2 and PLCβ3a, and one from cytosol was PLCβ3b. These PLCβ isoforms were activated by the purified βγ subunits of brain G proteins in the order PLCβ3b > PLCβ3a > PLCβ2. Western blot analysis of γ subunits of the purified platelet G proteins with antibodies against various standard γ subunits revealed that the major component of the γ subunit of Gi2 and Gq was γ5, and that γ7 was a minor component. Studies using various subtypes of βγ subunits, βγ2, βγ3, and βγ7 purified from bovine brain, βγ5 from bovine lung, or βγ12 from bovine spleen, failed to show differences in their ability to stimulate the isolated platelet PLCβ isoforms. These results suggest that the βγ subunits of Gi2 and Gq have similar efficacy in regulation of effectors in human platelets.

scholarly journals Control of protein function through oxidation and reduction of persulfidated states

2020 ◽  
Vol 6 (1) ◽  
pp. eaax8358 ◽  
Author(s):  
É. Dóka ◽  
T. Ida ◽  
M. Dagnell ◽  
Y. Abiko ◽  
N. C. Luong ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Protein Function ◽  
Mouse Liver ◽  
Cellular Responses ◽  
Selenium Supplementation ◽  
Related Protein ◽  
Loss Of Function ◽  
Quantitative Mass Spectrometry ◽  
Irreversible Oxidation ◽  
Thioredoxin System

Irreversible oxidation of Cys residues to sulfinic/sulfonic forms typically impairs protein function. We found that persulfidation (CysSSH) protects Cys from irreversible oxidative loss of function by the formation of CysSSO1-3H derivatives that can subsequently be reduced back to native thiols. Reductive reactivation of oxidized persulfides by the thioredoxin system was demonstrated in albumin, Prx2, and PTP1B. In cells, this mechanism protects and regulates key proteins of signaling pathways, including Prx2, PTEN, PTP1B, HSP90, and KEAP1. Using quantitative mass spectrometry, we show that (i) CysSSH and CysSSO3H species are abundant in mouse liver and enzymatically regulated by the glutathione and thioredoxin systems and (ii) deletion of the thioredoxin-related protein TRP14 in mice altered CysSSH levels on a subset of proteins, predicting a role for TRP14 in persulfide signaling. Furthermore, selenium supplementation, polysulfide treatment, or knockdown of TRP14 mediated cellular responses to EGF, suggesting a role for TrxR1/TRP14-regulated oxidative persulfidation in growth factor responsiveness.

Dual Regulation of Phospolipase C Activity by G Proteins

Physiology ◽  
1993 ◽  
Vol 8 (2) ◽  
pp. 61-63
Author(s):  
H Deckmyn ◽  
C Van Geet ◽  
J Vermylen
Keyword(s):  
Adenylate Cyclase ◽  
Phospholipase C ◽  
G Protein ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Inhibitory Pathway ◽  
Close Parallelism

Some subtypes of phosphatidylinositide-specific phospholipase C (PLC) are activated via pertussis toxin-sensitive or -insensitive G proteins. However, a G protein-dependent PLC inhibitory pathway also may exist. The resultant picture is of dual regulation of PLC, showing a close parallelism with the dual regulation of adenylate cyclase.

scholarly journals Towards Selective Mycobacterial ClpP1P2 Inhibitors with Reduced Activity against the Human Proteasome

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Wilfried Moreira ◽  
Sridhar Santhanakrishnan ◽  
Grace J. Y. Ngan ◽  
Choon Bing Low ◽  
Kanda Sangthongpitag ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Aqueous Solubility ◽  
Structural Data ◽  
Proteasome Inhibition ◽  
Selective Inhibition ◽  
Lead Target ◽  
Content Type ◽  
Bacterial Agent ◽  
Human Liver Cell ◽  
Oral Pharmacokinetics

ABSTRACT Mycobacterium tuberculosis is responsible for the greatest number of deaths worldwide due to a bacterial agent. We recently identified bortezomib (Velcade; compound 1) as a promising antituberculosis (anti-TB) compound. We showed that compound 1 inhibits the mycobacterial caseinolytic proteases P1 and P2 (ClpP1P2) and exhibits bactericidal activity, and we established compound 1 and ClpP1P2 as an attractive lead/target couple. However, compound 1 is a human-proteasome inhibitor currently approved for cancer therapy and, as such, exhibits significant toxicity. Selective inhibition of the bacterial protease over the human proteasome is desirable in order to maintain antibacterial activity while reducing toxicity. We made use of structural data in order to design a series of dipeptidyl-boronate derivatives of compound 1. We tested these derivatives for whole-cell ClpP1P2 and human-proteasome inhibition as well as bacterial-growth inhibition and identified compounds that were up to 100-fold-less active against the human proteasome but that retained ClpP1P2 and mycobacterial-growth inhibition as well as bactericidal potency. The lead compound, compound 58, had low micromolar ClpP1P2 and anti-M. tuberculosis activity, good aqueous solubility, no cytochrome P450 liabilities, moderate plasma protein binding, and low toxicity in two human liver cell lines, and despite high clearance in microsomes, this compound was only moderately cleared when administered intravenously or orally to mice. Higher-dose oral pharmacokinetics indicated good dose linearity. Furthermore, compound 58 was inhibitory to only 11% of a panel of 62 proteases. Our work suggests that selectivity over the human proteasome can be achieved with a drug-like template while retaining potency against ClpP1P2 and, crucially, anti-M. tuberculosis activity.

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