scholarly journals Regulation of Caspase 9 through Phosphorylation by Protein Kinase C Zeta in Response to Hyperosmotic Stress

2005 ◽  
Vol 25 (23) ◽  
pp. 10543-10555 ◽  
Author(s):  
Suzanne C. Brady ◽  
Lindsey A. Allan ◽  
Paul R. Clarke
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
Caspase 3 ◽  
Hyperosmotic Stress ◽  
Intrinsic Apoptotic Pathway ◽  
Caspase 9 ◽  
Apoptotic Pathway ◽  
Kinase C ◽  
In Cells

ABSTRACT Caspase 9 is a critical component of the mitochondrial or intrinsic apoptotic pathway and is activated by Apaf-1 following release of cytochrome c from mitochondria in response to a variety of stimuli. Caspase 9 cleaves and activates effector caspases, mainly caspase 3, leading to the demise of the cell. Survival signaling pathways can impinge on this pathway to restrain apoptosis. Here, we have identified Ser144 of human caspase 9as an inhibitory site that is phosphorylated in a cell-free system and in cells in response to the protein phosphatase inhibitor okadaic acid. Inhibitor sensitivity and interactions with caspase 9 indicate that the predominant kinase that targets Ser144 is the atypical protein kinase C isoform zeta (PKCζ). Prevention of Ser144 phosphorylation by inhibition of PKCζ or mutation of caspase 9 promotes caspase 3 activation. Phosphorylation of serine 144 in cells is also induced by hyperosmotic stress, which activates PKCζ and regulates its interaction with caspase 9, but not by growth factors, phorbol ester, or other cellular stresses. These results indicate that phosphorylation and inhibition of caspase 9 by PKCζ restrain the intrinsic apoptotic pathway during hyperosmotic stress. This work provides further evidence that caspase 9 acts as a focal point for multiple protein kinase signaling pathways that regulate apoptosis.

Role of protein kinase C-η in cigarette smoke extract-induced apoptosis in MRC-5-cells

2014 ◽  
Vol 34 (9) ◽  
pp. 869-877 ◽  
Author(s):  
ES Son ◽  
SY Kyung ◽  
SP Lee ◽  
SH Jeong ◽  
JY Shin ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cigarette Smoke ◽  
Caspase 3 ◽  
Dominant Negative ◽  
Lung Fibroblasts ◽  
Apoptotic Pathway ◽  
Kinase C ◽  
Extrinsic Apoptotic Pathway ◽  
Infected Cells

Cigarette smoke (CS) is a major risk factor for emphysema, which causes cell death in structural cells of the lung by mechanisms that are still not completely understood. We demonstrated previously that CS extract (CSE) induces caspase activation in MRC-5 human lung fibroblasts, activated protein kinase C-η (PKC-η), and translocated PKC-η from the cytosol to the membrane. The objective of this study was to investigate the involvement of PKC-η activation in a CSE-induced extrinsic apoptotic pathway. We determined that CSE increases expression of caspase 3 and 8 cleavage in MRC-5 cells and overexpression of PKC-η significantly increased expression of caspase 3 and 8 cleavage compared with control LacZ-infected cells. In contrast, dominant negative (dn) PKC-η inhibited apoptosis in MRC-5 cells exposed to CSE and decreased expression of caspase 3 and 8 compared with control cells. Exposure to 10% CSE for >8 h significantly increased lactate dehydrogenase release in PKC-η-infected cells compared with LacZ-infected cells. Additionally, PKC-η-infected cells had an increased number of Hoechst 33342 stained nuclei compared with LacZ-infected cells, while dn PKC-η-infected cells exhibited fewer morphological changes than LacZ-infected cells under phase-contrast microscopy. In conclusion, PKC-η activation plays a pro-apoptotic role in CSE-induced extrinsic apoptotic pathway in MRC-5 cells. These results suggest that modulation of PKC-η may be a useful tool for regulating the extrinsic apoptosis of MRC-5 cells by CSE and may have therapeutic potential in the treatment of CS-induced lung injury.

scholarly journals Targeted disruption of PKC from AKAP Signaling Complexes

2021 ◽  
Author(s):  
Ameya J. Limaye ◽  
George N. Bendzunas ◽  
Eileen Kennedy
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
Protein Interactions ◽  
Protein Protein Interactions ◽  
Targeted Disruption ◽  
Physiological Processes ◽  
Kinase C ◽  
P Protein

Protein Kinase C (PKC) is a member of the AGC subfamily of kinases and regulates a wide array of signaling pathways and physiological processes. Protein-protein interactions involving PKC and its...

Involvement of protein kinase C, tyrosine kinases, and Rho kinase in Ca2+ handling of human small arteries

2000 ◽  
Vol 279 (3) ◽  
pp. H1228-H1238 ◽  
Author(s):  
M. Carmen Martínez ◽  
Voahanginirina Randriamboavonjy ◽  
Patrick Ohlmann ◽  
Narcisse Komas ◽  
Juan Duarte ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
Tyrosine Kinases ◽  
Rho Kinase ◽  
Free Medium ◽  
Kinase C ◽  
Intracellular Ca ◽  
Pkc Inhibitors ◽  
Continuous Presence

The mechanisms of Ca2+ handling and sensitization were investigated in human small omental arteries exposed to norepinephrine (NE) and to the thromboxane A2 analog U-46619. Contractions elicited by NE and U-46619 were associated with an increase in intracellular Ca2+ concentration ([Ca2+]i), an increase in Ca2+-independent signaling pathways, or an enhancement of the sensitivity of the myofilaments to Ca2+. The two latter pathways were abolished by protein kinase C (PKC), tyrosine kinase (TK), and Rho-associated protein kinase (ROK) inhibitors. In Ca2+-free medium, both NE and U-46619 elicited an increase in tension that was greatly reduced by PKC inhibitors and abolished by caffeine or ryanodine. After depletion of Ca2+ stores with NE and U-46619 in Ca2+-free medium, addition of CaCl2 in the continuous presence of the agonists produced increases in [Ca2+]i and contractions that were inhibited by nitrendipine and TK inhibitors but not affected by PKC inhibitors. NE and U-46619 induced tyrosine phosphorylation of a 42- or a 58-kDa protein, respectively. These results indicate that the mechanisms leading to contraction elicited by NE and U-46619 in human small omental arteries are composed of Ca2+ release from ryanodine-sensitive stores, Ca2+ influx through nitrendipine-sensitive channels, and Ca2+ sensitization and/or Ca2+-independent pathways. They also show that the TK pathway is involved in the tonic contraction associated with Ca2+ entry, whereas TK, PKC, and ROK mechanisms regulate Ca2+-independent signaling pathways or Ca2+sensitization.

p21ras and protein kinase C function in distinct and interdependent signaling pathways in C3H 10T1/2 fibroblasts

1993 ◽  
Vol 13 (3) ◽  
pp. 1471-1479
Author(s):  
A Krook ◽  
M J Rapoport ◽  
S Anderson ◽  
H Pross ◽  
Y C Zhou ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
Tyrosine Kinases ◽  
Signal Pathways ◽  
Mrna Levels ◽  
Ras Gene ◽  
Kinase C ◽  
Tetradecanoyl Phorbol Acetate ◽  
Cellular Signal

Both p21ras and protein kinase C (PKC) are believed to function downstream of plasma membrane-associated tyrosine kinases in cellular signal transduction pathways. However, it has remained controversial whether they function in the same pathway and, if so, what their relative position and functional relationship in such a pathway are. We investigated the possibilities that p21ras and PKC function either upstream or downstream of each other in a common linear pathway or that they function independently in colinear signal pathways. Either decreased expression of endogenous normal ras in fibroblasts transfected with an inducible antisense ras construct or overexpression of a mutant ras gene reduced the capacity of the phorbol ester tetradecanoyl phorbol acetate to trigger expression of the tetradecanoyl phorbol acetate-responsive and ras-dependent reporter gene osteopontin (OPN). PKC depletion decreased basal OPN mRNA levels, and the overexpression of ras restored OPN expression to the level of non-PKC-depleted cells. We propose a model in which ras and PKC function in distinct and interdependent signaling pathways.

scholarly journals Nedd4-2 but not Nedd4-1 is critical for protein kinase C-regulated ubiquitination, expression, and transport activity of human organic anion transporter 1

2016 ◽  
Vol 310 (9) ◽  
pp. F821-F831 ◽  
Author(s):  
Da Xu ◽  
Haoxun Wang ◽  
Qiang Zhang ◽  
Guofeng You
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Surface ◽  
Organic Anion ◽  
The Body ◽  
Organic Anion Transporter ◽  
Transport Activity ◽  
Kinase C ◽  
Anion Transporter ◽  
In Cells

Human organic anion transporter 1 (hOAT1) expressed at the membrane of the kidney proximal tubule cells mediates the body disposition of a diverse array of clinically important drugs, including anti-HIV therapeutics, antitumor drugs, antibiotics, antihypertensives, and antiinflammatories. Therefore, understanding the regulation of hOAT1 will provide significant insights into kidney function and dysfunction. We previously established that hOAT1 transport activity is inhibited by activation of protein kinase C (PKC) through accelerating hOAT1 internalization from cell surface into intracellular endosomes and subsequent degradation. We further established that PKC-induced hOAT1 ubiquitination is an important step preceding hOAT1 internalization. In the current study, we identified two closely related E3 ubiquitin ligases, neural precursor cell expressed, developmentally downregulated 4-1 and 4-2 (Nedd4-1 and Nedd4-2), as important regulators for hOAT1: overexpression of Nedd4-1 or Nedd4-2 enhanced hOAT1 ubiquitination, reduced the hOAT1 amount at the cell surface, and suppressed hOAT1 transport activity. In further exploring the relationship among PKC, Nedd4-1, and Nedd4-2, we discovered that PKC-dependent changes in hOAT1 ubiquitination, expression, and transport activity were significantly blocked in cells transfected with the ligase-dead mutant of Nedd4-2 (Nedd4-2/C821A) or with Nedd4-2-specific siRNA to knockdown endogenous Nedd4-2 but not in cells transfected with the ligase-dead mutant of Nedd4-1 (Nedd4-1/C867S) or with Nedd4-1-specific siRNA to knockdown endogenous Nedd4-1. In conclusion, this is the first demonstration that both Nedd4-1 and Nedd4-2 are important regulators for hOAT1 ubiquitination, expression, and function. Yet they play distinct roles, as Nedd4-2 but not Nedd4-1 is a critical mediator for PKC-regulated hOAT1 ubiquitination, expression, and transport activity.

scholarly journals Biogenesis of P-TEFb in CD4+ T cells to reverse HIV latency is mediated by protein kinase C (PKC)-independent signaling pathways

2021 ◽  
Author(s):  
Uri Mbonye ◽  
Konstantin Leskov ◽  
Meenakshi Shukla ◽  
Saba Valadkhan ◽  
Jonathan Karn
Keyword(s):  
T Cells ◽  
Protein Kinase C ◽  
T Cell ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
Cd4 T Cells ◽  
Hiv Latency ◽  
Kinase C ◽  
Latent Hiv ◽  
Memory Cd4 T Cells

The switch between HIV latency and productive transcription is regulated by an auto-feedback mechanism initiated by the viral trans-activator Tat, which functions to recruit the host transcription elongation factor P-TEFb to proviral HIV. A heterodimeric complex of CDK9 and one of three cyclin T subunits, P-TEFb is expressed at vanishingly low levels in resting memory CD4 + T cells and cellular mechanisms controlling its availability are central to regulation of the emergence of HIV from latency. Using a well-characterized primary T-cell model of HIV latency alongside healthy donor memory CD4 + T cells, we characterized specific T-cell receptor (TCR) signaling pathways that regulate the generation of transcriptionally active P-TEFb, defined as the coordinate expression of cyclin T1 and phospho-Ser175 CDK9. Protein kinase C (PKC) agonists, such as ingenol and prostratin, stimulated active P-TEFb expression and reactivated latent HIV with minimal cytotoxicity, even in the absence of intracellular calcium mobilization with an ionophore. Unexpectedly, inhibition-based experiments demonstrated that PKC agonists and TCR-mobilized diacylglycerol signal through MAP kinases ERK1/2 rather than through PKC to effect the reactivation of both P-TEFb and latent HIV. Single-cell and bulk RNA-seq analyses revealed that of the four known isoforms of the Ras guanine nucleotide exchange factor RasGRP, RasGRP1 is by far the predominantly expressed diacylglycerol-dependent isoform in CD4 + T cells. RasGRP1 should therefore mediate the activation of ERK1/2 via Ras-Raf signaling upon TCR co-stimulation or PKC agonist challenge. Combined inhibition of the PI3K-mTORC2-AKT-mTORC1 pathway and the ERK1/2 activator MEK prior to TCR co-stimulation abrogated active P-TEFb expression and substantially suppressed latent HIV reactivation. Therefore, contrary to prevailing models, the coordinate reactivation of P-TEFb and latent HIV in primary T cells following either TCR co-stimulation or PKC agonist challenge is independent of PKC but rather involves two complementary signaling arms of the TCR cascade, namely, RasGRP1-Ras-Raf-MEK-ERK1/2 and PI3K-mTORC2-AKT-mTORC1.

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