scholarly journals Mitogenic Response of Murine B Lymphocytes to Salmonella typhimurium Lipopolysaccharide Requires Protein Kinase C-Dependent Late Tyrosine Phosphorylations

1998 ◽  
Vol 66 (6) ◽  
pp. 2547-2552 ◽  
Author(s):  
Anne Mey ◽  
Jean-Pierre Revillard
Keyword(s):  
Protein Synthesis ◽  
Protein Kinase C ◽  
B Cells ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Kinase Inhibitors ◽  
Cross Linking ◽  
Kinase Activation ◽  
Herbimycin A ◽  
Kinase C

ABSTRACT Unlike the cross-linking of membrane immunoglobulins, the activation of B cells by lipopolysaccharide (LPS) does not involve the phosphoinositol turnover and the initial activation of tyrosine kinases. However, LPS-induced B-cell proliferation was inhibited by the tyrosine kinase inhibitors genistein and herbimycin A even when added 48 h after the beginning of the culture. Tyrosyl-phosphorylated proteins were detected by Western blotting after 24 h of culture with LPS, reaching a maximum concentration after 72 h. Late tyrosine phosphorylations were also detected in B cells activated for 72 h with anti-immunoglobulin M antibody and were abrogated by the protein synthesis inhibitor cycloheximide, the tyrosine kinase inhibitors genistein and herbimycin A, and the protein kinase C inhibitor chelerythrine. The role of protein kinase C in late tyrosine kinase activation is independent of Ca2+mobilization and was confirmed by detection of a comparable but restricted pattern of tyrosine-phosphorylated substrates in B cells treated with phorbol myristate acetate alone or in association with ionomycin. Tyrosine kinase activation was dependent on de novo protein synthesis. However, culture supernatants of LPS-activated B cells were devoid of mitogenic activity and induced a phosphorylation pattern more restricted than that achieved by LPS. Altogether these data indicate that proliferation signals induced by LPS or by the cross-linking of membrane immunoglobulins are controlled by late tyrosine phosphorylations occurring throughout the first 3 days of culture, controlled in part by protein kinase C activation, and dependent on the synthesis of an intermediate protein(s) either not secreted in the culture supernatant or present but biologically inactive in naive B cells.

Genistein and tyrphostin 47 stimulate CFTR-mediated Cl- secretion in T84 cell monolayers

1995 ◽  
Vol 269 (6) ◽  
pp. G874-G882 ◽  
Author(s):  
C. L. Sears ◽  
F. Firoozmand ◽  
A. Mellander ◽  
F. G. Chambers ◽  
I. G. Eromar ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Secretory Pathway ◽  
Kinase Inhibitors ◽  
T84 Cells ◽  
Cl Secretion ◽  
Cyclic Monophosphate ◽  
3T3 Fibroblasts ◽  
Kinase C

The involvement of tyrosine phosphorylation in the regulation of epithelial cell Cl- secretion is unknown. Therefore, the purpose of these studies was to determine if tyrosine kinase activation was involved in the regulation of Cl- secretion, using the tyrosine kinase inhibitors, genistein and tyrphostin 47, and human intestinal epithelial cells (T84 cells) as an intestinal Cl- secretory model. Genistein rapidly but reversibly stimulated sustained apical Cl- secretion in monolayers of T84 cells without increasing intracellular cyclic nucleotides or Ca2+ levels. Tyrphostin 47 also stimulated Cl- secretion in T84 monolayers, although it was short-lived. Transfection experiments in 3T3 fibroblasts and IEC-6 intestinal cells utilizing wild-type cystic fibrosis transmembrane conductance regulator (CFTR) showed that genistein and tyrphostin 47 stimulated 125I efflux only in CFTR-transfected cells and not in CFTR-negative cells. Thus genistein- and tyrphostin 47-stimulated Cl- secretion involved CFTR. Genistein also acted synergistically with the Ca(2+)- and protein kinase C-dependent acetylcholine analogue, carbachol, to stimulate Cl- secretion in T84 monolayers. However, the Cl- secretory response to saturating concentrations of the adenosine 3',5'-cyclic monophosphate (cAMP) agonist, forskolin, or the guanosine 3',5'-cyclic monophosphate (cGMP) agonist, Escherichia coli heat-stable enterotoxin, was not further enhanced by genistein. Although the mechanism of activation of Cl- secretion is unclear, these data suggest that tyrosine kinase activity limits basal Cl- secretion in T84 cells and that inhibition of T84 cell tyrosine kinase(s) stimulates apical membrane Cl- secretion, most likely through activation of the CFTR-Cl- channel. Moreover, genistein does not itself act through cAMP or cGMP elevation but appears to share a common Cl- secretory pathway with cyclic nucleotide-dependent agonists, whereas it augments the secretory responses to a Ca(2+)- and protein kinase C-dependent agonist.

scholarly journals Kisspeptin Activation of TRPC4 Channels in Female GnRH Neurons Requires PIP2 Depletion and cSrc Kinase Activation

Endocrinology ◽  
2013 ◽  
Vol 154 (8) ◽  
pp. 2772-2783 ◽  
Author(s):  
Chunguang Zhang ◽  
Martha A. Bosch ◽  
Oline K. Rønnekleiv ◽  
Martin J. Kelly
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Intracellular Signaling ◽  
Transient Receptor Potential ◽  
Trpc Channels ◽  
Kinase Activation ◽  
Trpc Channel ◽  
Kinase C ◽  
Gnrh Neurons

Abstract Kisspeptin signaling via its Gαq-coupled receptor GPR54 plays a crucial role in modulating GnRH neuronal excitability, which controls pituitary gonadotropins secretion and ultimately reproduction. Kisspeptin potently depolarizes GnRH neurons primarily through the activation of canonical transient receptor potential (TRPC) channels, but the intracellular signaling cascade has not been elucidated. Presently, we have established that kisspeptin activation of TRPC channels requires multiple membrane and intracellular signaling molecules. First, phosphatidylinositol-4,5-bisphosphate (PIP2) hydrolysis by phospholipase Cβ is required because whole-cell dialysis of Dioctanoylglycerol-PIP2 (DiC8-PIP2) inhibited the kisspeptin activation of TRPC channels, and the phosphatidylinositol 4-kinase inhibitor wortmannin, which attenuates PIP2 synthesis, prolonged TRPC channel activation. Using single cell RT-PCR, we identified that the mRNA for the PIP2-interacting TRPC channel subunit, TRPC4α, is expressed in GnRH neurons. Depletion of intracellular Ca2+ stores by thapsigargin and inositol 1,4,5-trisphosphate had no effect, indicating that the TRPC channels are not store-operated. Neither removing extracellular Ca2+ nor buffering intracellular Ca2+ with EGTA or BAPTA had any effect on the kisspeptin activation of the TRPC channels. However, the Ca2+ channel blocker Ni2+ inhibited the kisspeptin-induced inward current. Moreover, inhibition of protein kinase C by bisindolylmaleimide-I or calphostin C had no effect, but activation of protein kinase C by phorbol 12,13-dibutyrate occluded the kisspeptin-activated current. Finally, inhibition of the cytoplasmic tyrosine kinase cSrc by genistein or the pyrazolo-pyrimidine PP2 blocked the activation of TRPC channels by kisspeptin. Therefore, TRPC channels in GnRH neurons are receptor-operated, and kisspeptin activates TRPC channels through PIP2 depletion and cSrc tyrosine kinase activation, which is a novel signaling pathway for peptidergic excitation of GnRH neurons.

scholarly journals Does dopamine use several signal pathways to inhibit Na-Pi transport in OK cells?

1998 ◽  
Vol 9 (9) ◽  
pp. 1604-1612
Author(s):  
A D Baines ◽  
R Drangova
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Protein Kinase A ◽  
Tyrosine Kinase Inhibitors ◽  
Phorbol Ester ◽  
Kinase Inhibitors ◽  
Ok Cells ◽  
Kinase C ◽  
Kinase A

In opossum kidney (OK) cells, L-dihydroxyphenylalanine (10 microM) raised dopamine to 10 nM and inhibited Na-inorganic phosphate (Pi) uptake 20% (P = 0.001). Inhibition was completely blocked by carbidopa or SCH23390. Dopamine (1 microM) inhibited uptake 55% (half-maximal inhibition, 0.03 microM). Fenoldopam (0.1 microM, DA1 agonist) inhibited uptake 45 +/- 2%. DA1 antagonists (SKF83566 and SCH23390), but not DA2-antagonist (sulpiride), blocked dopamine inhibition. Quinpirole (DA2 agonist) did not modify Pi uptake. Bisindolylmaleimide (10 microM), a protein kinase C inhibitor, blocked inhibition of Pi uptake by phorbol ester but had no effect on the response to dopamine. Dopamine inhibited Pi uptake in cells that had been exposed to phorbol ester for 18 to 24 h. Dopamine inhibition was not reduced by 1 microM U73,122 but was reduced 20% by 10 microM, which is 10 times the concentration reported to completely inhibit phospholipase C in OK cells. Adenylate cyclase inhibitors SQ 22536 (100 microM) and 2,5-dideoxyadenosine (100 microM) reduced dopamine-stimulated cAMP production, but not dopamine inhibition of Pi uptake. Rp-cAMPS counteracted the inhibition of Pi uptake by Sp-cAMPS but had no effect on the dopamine response. H-89 inhibited dopamine-stimulated protein kinase A activity, but neither H-89 nor H-9 alone or with bisindolylmaleimide altered dopamine inhibition of Pi uptake. Genistein and herbimycin A (tyrosine kinase inhibitors) reduced Pi uptake. However, dopamine, a benzoquinone like several tyrosine kinase inhibitors, did not inhibit tyrosine kinase activity. Thus, dopamine inhibited Pi uptake in this OK cell clone by activating a G protein-linked pathway that operates independently from adenylyl cyclase, protein kinase A, protein kinase C, and protein tyrosine kinase.

scholarly journals Protein Kinase C β Controls Nuclear Factor κB Activation in B Cells Through Selective Regulation of the IκB Kinase α

2002 ◽  
Vol 195 (12) ◽  
pp. 1647-1652 ◽  
Author(s):  
Kaoru Saijo ◽  
Ingrid Mecklenbräuker ◽  
Angela Santana ◽  
Michael Leitger ◽  
Christian Schmedt ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
B Cells ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
B Cell ◽  
B Cell Antigen Receptor ◽  
Nuclear Factor ◽  
Cell Antigen ◽  
Kinase C ◽  
Iκb Kinase

Activation of the nuclear factor (NF)-κB transcription complex by signals derived from the surface expressed B cell antigen receptor controls B cell development, survival, and antigenic responses. Activation of NF-κB is critically dependent on serine phosphorylation of the IκB protein by the multi-component IκB kinase (IKK) containing two catalytic subunits (IKKα and IKKβ) and one regulatory subunit (IKKγ). Using mice deficient for protein kinase C β (PKCβ) we show an essential role of PKCβ in the phosphorylation of IKKα and the subsequent activation of NF-κB in B cells. Defective IKKα phosphorylation correlates with impaired B cell antigen receptor–mediated induction of the pro-survival protein Bcl-xL. Lack of IKKα phosphorylation and defective NF-κB induction in the absence of PKCβ explains the similarity in immunodeficiencies caused by PKCβ or IKKα ablation in B cells. Furthermore, the well established functional cooperation between the protein tyrosine kinase Bruton's tyrosine kinase (Btk), which regulates the activity of NF-κB and PKCβ, suggests PKCβ as a likely serine/threonine kinase component of the Btk-dependent NF-κB activating signal transduction chain downstream of the BCR.

scholarly journals Induction of bcl-2 expression by phosphorylated CREB proteins during B-cell activation and rescue from apoptosis.

1996 ◽  
Vol 16 (10) ◽  
pp. 5546-5556 ◽  
Author(s):  
B E Wilson ◽  
E Mochon ◽  
L M Boxer
Keyword(s):  
Protein Kinase C ◽  
B Cells ◽  
Protein Kinase ◽  
B Cell ◽  
Regulatory Element ◽  
Regulatory Region ◽  
Cross Linking ◽  
Surface Immunoglobulin ◽  
Kinase C ◽  
Upstream Regulatory Element

Engagement of surface immunoglobulin on mature B cells leads to rescue from apoptosis and to proliferation. Levels of bcl-2 mRNA and protein increase with cross-linking of surface immunoglobulin. We have located the major positive regulatory region for control of bcl-2 expression in B cells in the 5'-flanking region. The positive region can be divided into an upstream and a downstream regulatory region. The downstream regulatory region contains a cyclic AMP-responsive element (CRE). We show by antibody supershift experiments and UV cross-linking followed by denaturing polyacrylamide gel electrophoresis that both CREB and ATF family members bind to this region in vitro. Mutations of the CRE site that result in loss of CREB binding also lead to loss of functional activity of the bcl-2 promoter in transient-transfection assays. The presence of an active CRE site in the bcl-2 promoter implies that the regulation of bcl-2 expression is linked to a signal transduction pathway in B cells. Treatment of the mature B-cell line BAL-17 with either anti-immunoglobulin M or phorbol 12-myristate 13-acetate leads to an increase in bcl-2 expression that is mediated by the CRE site. Treatment of the more immature B-cell line, Ramos, with phorbol esters rescues the cells from calcium-dependent apoptosis. bcl-2 expression is increased following phorbol ester treatment, and the increased expression is dependent on the CRE site. These stimuli result in phosphorylation of CREB at serine 133. The phosphorylation of CREB that results in activation is mediated by protein kinase C rather than by protein kinase A. Although the CRE site is necessary, optimal induction of bcl-2 expression requires participation of the upstream regulatory element, suggesting that phosphorylation of CREB alters its interaction with the upstream regulatory element. The CRE site in the bcl-2 promoter appears to play a major role in the induction of bcl-2 expression during the activation of mature B cells and during the rescue of immature B cells from apoptosis. It is possible that the CRE site is responsible for induction of bcl-2 expression in other cell types, particularly those in which protein kinase C is involved.

Btk regulation in human and mouse B cells via protein kinase C phosphorylation of IBtkγ

Blood ◽  
2011 ◽  
Vol 117 (24) ◽  
pp. 6520-6531 ◽  
Author(s):  
Elzbieta Janda ◽  
Camillo Palmieri ◽  
Antonio Pisano ◽  
Marilena Pontoriero ◽  
Enrico Iaccino ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
B Cells ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
B Cell ◽  
Serine Phosphorylation ◽  
Negative Regulator ◽  
B Cell Differentiation ◽  
Kinase C ◽  
Bruton Tyrosine Kinase

Abstract The inhibitor of Bruton tyrosine kinase γ (IBtkγ) is a negative regulator of the Bruton tyrosine kinase (Btk), which plays a major role in B-cell differentiation; however, the mechanisms of IBtkγ-mediated regulation of Btk are unknown. Here we report that B-cell receptor (BCR) triggering caused serine-phosphorylation of IBtkγ at protein kinase C consensus sites and dissociation from Btk. By liquid chromatography and mass-mass spectrometry and functional analysis, we identified IBtkγ-S87 and -S90 as the critical amino acid residues that regulate the IBtkγ binding affinity to Btk. Consistently, the mutants IBtkγ carrying S87A and S90A mutations bound constitutively to Btk and down-regulated Ca2+ fluxes and NF-κB activation on BCR triggering. Accordingly, spleen B cells from Ibtkγ−/− mice showed an increased activation of Btk, as evaluated by Y551-phosphorylation and sustained Ca2+ mobilization on BCR engagement. These findings identify a novel pathway of Btk regulation via protein kinase C phosphorylation of IBtkγ.

Sign in / Sign up

Export Citation Format

Share Document