scholarly journals Intracellular cleavage of glycosylphosphatidylinositol by phospholipase D induces activation of protein kinase Cα

1999 ◽  
Vol 342 (2) ◽  
pp. 449-455 ◽  
Author(s):  
Hiroshi TSUJIOKA ◽  
Noboru TAKAMI ◽  
Yoshio MISUMI ◽  
Yukio IKEHARA
Keyword(s):  
Signal Transduction ◽  
Endoplasmic Reticulum ◽  
Protein Kinase ◽  
Phospholipase D ◽  
Secretory Pathway ◽  
Gradient Centrifugation ◽  
Endoplasmic Reticulum Membrane ◽  
Gpi Anchor ◽  
Protein Kinase Cα ◽  
In Cells

Many proteins are anchored to the cell membrane by glycosylphosphatidylinositol (GPI). One of the functions proposed for the GPI anchor is as a possible mediator in signal transduction through its hydrolysis. GPI-specific phospholipase D (GPI-PLD) is a secretory protein that is suggested to be involved in the release of GPI-anchored protein from the membrane. In the present study we examined how GPI-PLD is involved in signal transduction. When introduced exogenously and overexpressed in cells, GPI-PLD cleaved the GPI anchors in the early secretory pathway, possibly in the endoplasmic reticulum, resulting in an increased production of diacylglycerol. Experiments in vitro and in vivo showed that the association of protein kinase Cα (PKCα) with membranes was increased markedly by expression of GPI-PLD in cells. Furthermore, sucrose-density-gradient centrifugation and immunofluorescence microscopy demonstrated that PKCα was translocated to the endoplasmic reticulum membrane in cells expressing GPI-PLD, in contrast with its association with the plasma membrane in cells treated with PMA. We also confirmed that the phosphorylation of c-Fos as well as PKCα itself was greatly enhanced by the expression of GPI-PLD. Taken together, these results suggest that GPI-PLD is involved in intracellular cleavage of the GPI anchor, which is a new potential source of diacylglycerol production to activate PKCα.

scholarly journals Ceramide chain length–dependent protein sorting into selective endoplasmic reticulum exit sites

2020 ◽  
Vol 6 (50) ◽  
pp. eaba8237
Author(s):  
Sofia Rodriguez-Gallardo ◽  
Kazuo Kurokawa ◽  
Susana Sabido-Bozo ◽  
Alejandro Cortes-Gomez ◽  
Atsuko Ikeda ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Chain Length ◽  
Secretory Pathway ◽  
Protein Sorting ◽  
Endoplasmic Reticulum Membrane ◽  
Lipid Chain ◽  
Secretory Transport ◽  
Dependent Protein ◽  
Cellular Compartmentalization

Protein sorting in the secretory pathway is crucial to maintain cellular compartmentalization and homeostasis. In addition to coat-mediated sorting, the role of lipids in driving protein sorting during secretory transport is a longstanding fundamental question that still remains unanswered. Here, we conduct 3D simultaneous multicolor high-resolution live imaging to demonstrate in vivo that newly synthesized glycosylphosphatidylinositol-anchored proteins having a very long chain ceramide lipid moiety are clustered and sorted into specialized endoplasmic reticulum exit sites that are distinct from those used by transmembrane proteins. Furthermore, we show that the chain length of ceramide in the endoplasmic reticulum membrane is critical for this sorting selectivity. Our study provides the first direct in vivo evidence for lipid chain length–based protein cargo sorting into selective export sites of the secretory pathway.

scholarly journals The unfolded protein response coordinates the production of endoplasmic reticulum protein and endoplasmic reticulum membrane.

1997 ◽  
Vol 8 (9) ◽  
pp. 1805-1814 ◽  
Author(s):  
J S Cox ◽  
R E Chapman ◽  
P Walter
Keyword(s):  
Endoplasmic Reticulum ◽  
Unfolded Protein Response ◽  
Secretory Pathway ◽  
Lipid Synthesis ◽  
Secretory Proteins ◽  
Endoplasmic Reticulum Membrane ◽  
Yeast Saccharomyces Cerevisiae ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

The endoplasmic reticulum (ER) is a multifunctional organelle responsible for production of both lumenal and membrane components of secretory pathway compartments. Secretory proteins are folded, processed, and sorted in the ER lumen and lipid synthesis occurs on the ER membrane itself. In the yeast Saccharomyces cerevisiae, synthesis of ER components is highly regulated: the ER-resident proteins by the unfolded protein response and membrane lipid synthesis by the inositol response. We demonstrate that these two responses are intimately linked, forming different branches of the same pathway. Furthermore, we present evidence indicating that this coordinate regulation plays a role in ER biogenesis.

scholarly journals Targeting of Protein Kinase Cα to Caveolae

1998 ◽  
Vol 141 (3) ◽  
pp. 601-610 ◽  
Author(s):  
Chieko Mineo ◽  
Yun-Shu Ying ◽  
Christine Chapline ◽  
Susan Jaken ◽  
Richard G.W. Anderson
Keyword(s):  
Signal Transduction ◽  
Protein Kinase ◽  
Regulatory Domain ◽  
Calcium Dependent ◽  
High Affinity ◽  
Membrane Invagination ◽  
Protein Kinase Cα ◽  
Flanking Sequences ◽  
Modulate Signal ◽  
Regulatory Functions

Previously, we showed caveolae contain a population of protein kinase Cα (PKCα) that appears to regulate membrane invagination. We now report that multiple PKC isoenzymes are enriched in caveolae of unstimulated fibroblasts. To understand the mechanism of PKC targeting, we prepared caveolae lacking PKCα and measured the interaction of recombinant PKCα with these membranes. PKCα bound with high affinity and specificity to caveolae membranes. Binding was calcium dependent, did not require the addition of factors that activate the enzyme, and involved the regulatory domain of the molecule. A 68-kD PKCα-binding protein identified as sdr (serum deprivation response) was isolated by interaction cloning and localized to caveolae. Antibodies against sdr inhibited PKCα binding. A 100–amino acid sequence from the middle of sdr competitively blocked PKCα binding while flanking sequences were inactive. Caveolae appear to be a membrane site where PKC enzymes are organized to carry out essential regulatory functions as well as to modulate signal transduction at the cell surface.

scholarly journals How does Sec63 affect the conformation of Sec61 in yeast?

2021 ◽  
Vol 17 (3) ◽  
pp. e1008855
Author(s):  
Pratiti Bhadra ◽  
Lalitha Yadhanapudi ◽  
Karin Römisch ◽  
Volkhard Helms
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Endoplasmic Reticulum Membrane ◽  
Intermolecular Contact ◽  
Cryo Electron Microscopy ◽  
Ring Diameter ◽  
Lateral Gate ◽  
Co Precipitation ◽  
Dynamics Simulations ◽  
Sec61 Channel

The Sec complex catalyzes the translocation of proteins of the secretory pathway into the endoplasmic reticulum and the integration of membrane proteins into the endoplasmic reticulum membrane. Some substrate peptides require the presence and involvement of accessory proteins such as Sec63. Recently, a structure of the Sec complex from Saccharomyces cerevisiae, consisting of the Sec61 channel and the Sec62, Sec63, Sec71 and Sec72 proteins was determined by cryo-electron microscopy (cryo-EM). Here, we show by co-precipitation that the accessory membrane protein Sec62 is not required for formation of stable Sec63-Sec61 contacts. Molecular dynamics simulations started from the cryo-EM conformation of Sec61 bound to Sec63 and of unbound Sec61 revealed how Sec63 affects the conformation of Sec61 lateral gate, plug, pore region and pore ring diameter via three intermolecular contact regions. Molecular docking of SRP-dependent vs. SRP-independent peptide chains into the Sec61 channel showed that the pore regions affected by presence/absence of Sec63 play a crucial role in positioning the signal anchors of SRP-dependent substrates nearby the lateral gate.

Stimulation of phosphatidylcholine hydrolysis in type II alveolar epithelial cells

1992 ◽  
Vol 263 (1) ◽  
pp. L42-L50
Author(s):  
L. C. Dubrovin ◽  
L. A. Brown
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Alveolar Epithelial Cells ◽  
Type Ii ◽  
Alveolar Epithelial ◽  
Kinase C ◽  
Type Ii Pneumocytes ◽  
Stimulation Of ◽  
In Cells

The effects of phorbol 12-myristate 13-acetate (TPA) or ATP on phosphatidylcholine (PC) hydrolysis were investigated in cultured type II pneumocytes prelabeled with [3H]choline or 1-O-[3H]octadecyl-sn-glycero-3-phosphocholine ([3H]lyso-PAF). In cells prelabeled with [3H]choline, TPA or ATP stimulated an increase in [3H]choline, [3H]phosphocholine, and [3H]glycerophosphocholine. The formation of these choline metabolites was associated with a concomitant loss of [3H]PC but not from disaturated PC or phosphatidylinositol. In cells prelabeled with [3H]lyso-PAF, the formation of [3H]phosphatidic acid (PA) and then [3H]1,2-DG was stimulated by TPA or ATP and was associated with a loss of 3H from PC but not from disaturated PC or phosphatidylinositol. There was a concentration-dependent formation of [3H]1,2-DG and [3H]PA in response to ATP. Downregulation of protein kinase C with TPA abolished the stimulation of PC hydrolysis. In addition to the generation of metabolites indicative of phospholipase C and/or D activity, [3H]lyso-PC, a product of phospholipase A2, was also generated in response to TPA. These findings suggest an important role for PC breakdown in signal transduction in type II pneumocytes.

scholarly journals Interleukin 1-β-induced protein kinase C-ζ activation is mimicked by exogenous phospholipase D

1997 ◽  
Vol 321 (2) ◽  
pp. 497-502 ◽  
Author(s):  
Cristina LIMATOLA ◽  
Benedetta BARABINO ◽  
Anna NISTA ◽  
Angela SANTONI
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Biological Effects ◽  
Interleukin 1 ◽  
Signal Transduction Pathways ◽  
Kinase C ◽  
Pkc Ζ

Interleukin 1-α (IL1-α) is a pleiotropic cytokine that stimulates a number of signal transduction pathways in cells, leading to different cellular responses. In this study we investigated the signal transduction pathways activated by IL1-α in two different human cell lines: RD/TE671, a rhabdomyosarcoma, and EJ, a bladder-derived carcinoma. We showed that this cytokine induced the activation of protein kinase C-ζ (PKC-ζ) and the accumulation of a putative physiological PKC-ζ activator, phosphatidic acid [Limatola, Schaap, Moolenaar and van Blitterswijk (1994) Biochem. J. 304, 1001Ő1008]. Exogenously supplied phospholipase D, which generated cellular phosphatidic acid, was able to mimic the cytokine effect, supporting the hypothesis that this lipid second messenger might contribute to cytokine-induced PKC-ζ activation. In addition, we show that IL1-α stimulation of BOSC23 cells, transiently overexpressing PKC-ζ, induced an increase in PKC-ζ autophosphorylation. These results give the first direct evidence that IL1-α can activate this atypical PKC isoform and suggest that this enzyme might be involved in mediating some of the biological effects induced by IL1-α.

scholarly journals Matrix-specific Suppression of Integrin Activation in Shear Stress Signaling

2006 ◽  
Vol 17 (11) ◽  
pp. 4686-4697 ◽  
Author(s):  
A. Wayne Orr ◽  
Mark H. Ginsberg ◽  
Sanford J. Shattil ◽  
Hans Deckmyn ◽  
Martin A. Schwartz
Keyword(s):  
Protein Kinase ◽  
Cellular Responses ◽  
Nuclear Factor Κb ◽  
Extracellular Matrices ◽  
Stress Signaling ◽  
Nuclear Factor ◽  
Active Suppression ◽  
Specific Suppression ◽  
Protein Kinase Cα ◽  
In Cells

Atherosclerotic plaque develops at sites of disturbed flow. We previously showed that flow activates endothelial cell integrins, which then bind to the subendothelial extracellular matrix (ECM), and, in cells on fibronectin or fibrinogen, trigger nuclear factor-κB activation. Additionally, fibronectin and fibrinogen are deposited into the subendothelial ECM at atherosclerosis-prone sites at early times. We now show that flow activates ECM-specific signals that establish patterns of integrin dominance. Flow induced α2β1 activation in cells on collagen, but not on fibronectin or fibrinogen. Conversely, α5β1 and αvβ3 are activated on fibronectin and fibrinogen, but not collagen. Failure of these integrins to be activated on nonpermissive ECM is because of active suppression by the integrins that are ligated. Protein kinase A is activated specifically on collagen and suppresses flow-induced αvβ3 activation. Alternatively, protein kinase Cα is activated on fibronectin and mediates α2β1 suppression. Thus, integrins actively cross-inhibit through specific kinase pathways. These mechanisms may determine cellular responses to complex extracellular matrices.

Role of protein kinase Cα in melatonin signal transduction

2006 ◽  
Vol 252 (1-2) ◽  
pp. 82-87 ◽  
Author(s):  
S.R. Sampson ◽  
Z. Lupowitz ◽  
L. Braiman ◽  
N. Zisapel
Keyword(s):  
Signal Transduction ◽  
Protein Kinase ◽  
Protein Kinase Cα
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