Fc Receptor Stimulation of PI 3-Kinase in NK Cells Is Associated with Protein Kinase C?independent Granule Release and Cell-mediated Cytotoxicity

1995 ◽  
Vol 766 (1 Receptor Acti) ◽  
pp. 209-213 ◽  
Author(s):  
JOY D. BONNEMA ◽  
LARRY M. KARNITZ ◽  
RENEE A. SCHOON ◽  
ROBERT T. ABRAHAM ◽  
Paul J. Leibson
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Nk Cells ◽  
Fc Receptor ◽  
Receptor Stimulation ◽  
Kinase C ◽  
Granule Release ◽  
Stimulation Of

scholarly journals Fc receptor stimulation of phosphatidylinositol 3-kinase in natural killer cells is associated with protein kinase C-independent granule release and cell-mediated cytotoxicity.

1994 ◽  
Vol 180 (4) ◽  
pp. 1427-1435 ◽  
Author(s):  
J D Bonnema ◽  
L M Karnitz ◽  
R A Schoon ◽  
R T Abraham ◽  
P J Leibson
Keyword(s):  
Protein Kinase C ◽  
Nk Cells ◽  
Cellular Cytotoxicity ◽  
Natural Cytotoxicity ◽  
Phosphatidylinositol 3 Kinase ◽  
Receptor Stimulation ◽  
Kinase C ◽  
Rapid Activation ◽  
Granule Release ◽  
Stimulation Of

Although diverse signaling events are initiated by stimulation of multichain immune recognition receptors on lymphocytes, it remains unclear as to which specific signal transduction pathways are functionally linked to granule exocytosis and cellular cytotoxicity. In the case of natural killer (NK) cells, it has been presumed that the rapid activation of protein kinase C (PKC) enables them to mediate antibody-dependent cellular cytotoxicity (ADCC) and "natural" cytotoxicity toward tumor cells. However, using cloned human NK cells, we determined here that Fc receptor stimulation triggers granule release and ADCC through a PKC-independent pathway. Specifically, pretreatment of NK cells with the selective PKC inhibitor, GF109203X (using concentrations that fully blocked phorbol myristate acetate/ionomycin-induced secretion) had no effect on FcR-initiated granule release or ADCC. In contrast, FcR ligation led to the rapid activation of phosphatidylinositol 3-kinase (PI 3-kinase), and inhibition of this enzyme with the selective inhibitor, wortmannin, blocked FcR-induced granule release and ADCC. Additional experiments showed that, whereas FcR-initiated killing was wortmannin sensitive and GF109203X insensitive, natural cytotoxic activity toward the tumor cell line K562 was wortmannin insensitive and GF109203X sensitive. Taken together, these results suggest that: (a) PI 3-kinase activation induced by FcR ligation is functionally coupled to granule exocytosis and ADCC; and (b) the signaling pathways involved in ADCC vs natural cytotoxicity are distinct.

scholarly journals Acetylcholine Receptor Stimulation Activates Protein Kinase C Mediated Internalization of the Dopamine Transporter

2021 ◽  
Vol 15 ◽  
Author(s):  
Suzanne M. Underhill ◽  
Susan G. Amara
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Surface ◽  
Dopamine Transporter ◽  
Muscarinic Receptor ◽  
Primary Cultures ◽  
Dopamine Neurons ◽  
Receptor Stimulation ◽  
Kinase C ◽  
Stimulation Of

The dopamine transporter (DAT) clears neurotransmitters from the extracellular space and serves as an important regulator of signal amplitude and duration at sites of dopamine release. Several different intracellular signaling pathways have been observed to modulate DAT activity through the regulation of the trafficking of the carriers to and from the cell surface. Acute activation of protein kinase C (PKC) by phorbol esters facilitates clathrin-dependent internalization of the DAT in a variety of model systems; however, the physiological stimuli and cell-surface receptor systems that activate PKC and regulate the DAT in dopamine neurons remain elusive. We report here that stimulation of M1/M5 muscarinic receptors in midbrain cultures decreases the ability of dopamine neurons to transport dopamine through DAT. Application of the cholinomimetic drug carbachol leads to a decrease in DAT activity in primary cultures while the M1/M5-specific antagonist, pirenzepine, blocks these effects. The M3 antagonist, DAU 5884, does not affect, but a positive modulator of M5, VU 0238429, enhances the loss of DAT function in response to carbachol and acetylcholine. These data implicate M1/M5 receptors on dopamine neurons in the modulation of DAT function. Bisindolylmaleimide, a PKC inhibitor, blocks the effects of carbachol stimulation on dopamine uptake, supporting a role for PKC in muscarinic receptor-mediated DAT internalization. Furthermore, as shown previously for PKC-induced internalization, downregulation of the DAT is dependent on both clathrin and dynamin. A Gq-specific inhibitor peptide also blocks the effects of carbachol on DAT in primary cultures, confirming Gq as the G-protein that couples M1/M5 receptors to PKC activation in these cells. In acute midbrain slices, biotinylation of cell-surface proteins revealed the loss of dopamine transport mediated by muscarinic receptor stimulation was, indeed, due to loss of membrane expression of the DAT in endogenous tissue. These data indicate that stimulation of cholinergic pathways can lead to modulation of dopamine through internalization of the DAT.

SHIP-1 Differentially Regulates Dense Granule Secretion in Platelets through Its Association with Protein Kinase C δ.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3630-3630
Author(s):  
Ramya Chari ◽  
Soochong Kim ◽  
Swaminathan Murugappan ◽  
James L. Daniel ◽  
Satya P. Kunapuli
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Dense Granule ◽  
Protease Activated Receptors ◽  
Kinase C ◽  
Inositol Phosphatases ◽  
Dense Granule Secretion ◽  
Granule Secretion ◽  
Granule Release ◽  
Stimulation Of

Abstract Collagen-induced glycoprotein (GP) VI-mediated and thrombin-induced protease activated receptors (PAR)-mediated activation are important signaling pathways regulating dense granule secretion in platelets. Protein kinase C (PKC) isoforms play a crucial role in platelet secretion and we have previously shown that PKCδ plays a ying-yang role in dense granule release by different agonists (Murugappan et al, J. Biol. Chem. 2004). PKCδ isoform positively regulates PAR-mediated platelet dense granule release, whereas it negatively regulates GPVI-mediated dense granule release. In this study, we investigated the mechanism of such differential regulation by PKCδ downstream of PAR and GPVI pathways. We hypothesize that the differential association of PKCδ with phosphatases downstream of GPVI and PAR receptors differentially regulate dense granule secretion. More specifically, we explored the functional relevance of the interaction of PKCδ with Src homology 2-domain containing Inositol Phosphatases (SHIP), 5′-inositol phosphatases in platelets. In our studies, SHIP-1 was tyrosine phosphorylated by both PARs and GPVI receptors and its phosphorylation followed different activation kinetics. Whereas PAR-mediated SHIP-1 phosphorylation (Y1020) was delayed and occurred as late as 120 seconds, the GPVI-mediated SHIP-1 phosphorylation was rapid, starting as early as 15 seconds and peaked at 60 seconds. Co-immunoprecipitation experiments revealed that SHIP-1, and not SHIP-2, associated with PKCδ upon stimulation of platelets with GPVI agonist, convulxin. However, such association did not occur with the PAR agonists. GPVI-mediated SHIP-1 phosphorylation failed to occur in platelets from mice lacking Lyn kinase suggesting a role for Lyn in regulating SHIP-1 phosphorylation. In murine platelets lacking either Lyn or SHIP-1, dense granule secretion was potentiated by convulxin and not by thrombin. We attribute the phosphorylation and association of SHIP-1 with PKCδ to be critical for the regulation of agonist-induced dense granule secretion in platelets. Based on the above results, we conclude that the preferential association of SHIP-1 with PKCδ upon stimulation of GPVI receptor results in the negative regulation of collagen-induced dense granule release in platelets.

scholarly journals Protein kinase C regulates the stimulated accumulation of 3-phosphorylated phosphoinositides in platelets

1991 ◽  
Vol 278 (2) ◽  
pp. 475-480 ◽  
Author(s):  
W G King ◽  
G L Kucera ◽  
A Sorisky ◽  
J Zhang ◽  
S E Rittenhouse
Keyword(s):  
Protein Kinase C ◽  
Growth Factor ◽  
Protein Kinase ◽  
Platelet Derived Growth Factor ◽  
Inhibitory Effects ◽  
Receptor Stimulation ◽  
Kinase C ◽  
Substrate Peptide ◽  
Inhibition Of Thrombin ◽  
Stimulation Of

We have shown that platelets stimulated with thrombin or guanosine 5′-[gamma-thio]triphosphate (GTP[S]), both of which activate phospholipase C and protein kinase C (PKC), show enhancement of 3-phosphorylated phosphoinositide accumulation (3-PPI). We now report the following. (1) Inhibition of thrombin- or GTP[S]-stimulated PKC by pseudo-substrate peptide (RFARK) added to permeabilized platelets markedly inhibits 3-PPI, whereas the serine/threonine phosphatase inhibitor, okadaic acid, promotes 3-PPI. PKC activity, insufficient in itself for fully activating 3-PPI, appears crucial to receptor and post-receptor stimulation of 3-PPI, even when tyrosine phosphorylation is unimpaired. (2) Alteration of Gi by ADP-ribosylation only slightly affects the stimulation of 3-PPI by thrombin, and activation of the G-protein Gi by adrenaline has no effect on 3-PPI. (3) Inhibition of PKC blocks activated secretion of platelet-derived growth factor (PDGF). However, PDGF cannot promote platelet 3-PPI, and thus cannot account for the inhibitory effects of RFARK on 3-PPI.

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