scholarly journals Structural Basis of Protein Kinase C Isoform Function

2008 ◽  
Vol 88 (4) ◽  
pp. 1341-1378 ◽  
Author(s):  
Susan F. Steinberg
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Interactions ◽  
Structural Basis ◽  
Protein Protein Interactions ◽  
Subcellular Targeting ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Wide Range ◽  
In Cells

Protein kinase C (PKC) isoforms comprise a family of lipid-activated enzymes that have been implicated in a wide range of cellular functions. PKCs are modular enzymes comprised of a regulatory domain (that contains the membrane-targeting motifs that respond to lipid cofactors, and in the case of some PKCs calcium) and a relatively conserved catalytic domain that binds ATP and substrates. These enzymes are coexpressed and respond to similar stimulatory agonists in many cell types. However, there is growing evidence that individual PKC isoforms subserve unique (and in some cases opposing) functions in cells, at least in part as a result of isoform-specific subcellular compartmentalization patterns, protein-protein interactions, and posttranslational modifications that influence catalytic function. This review focuses on the structural basis for differences in lipid cofactor responsiveness for individual PKC isoforms, the regulatory phosphorylations that control the normal maturation, activation, signaling function, and downregulation of these enzymes, and the intra-/intermolecular interactions that control PKC isoform activation and subcellular targeting in cells. A detailed understanding of the unique molecular features that underlie isoform-specific posttranslational modification patterns, protein-protein interactions, and subcellular targeting (i.e., that impart functional specificity) should provide the basis for the design of novel PKC isoform-specific activator or inhibitor compounds that can achieve therapeutically useful changes in PKC signaling in cells.

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...

PKCε activation induces dichotomous cardiac phenotypes and modulates PKCε-RACK interactions and RACK expression

2001 ◽  
Vol 280 (3) ◽  
pp. H946-H955 ◽  
Author(s):  
Jason M. Pass ◽  
Yuting Zheng ◽  
William B. Wead ◽  
Jun Zhang ◽  
Richard C. X. Li ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Expression ◽  
Protein Interactions ◽  
Dominant Negative ◽  
The Other ◽  
Protein Protein Interactions ◽  
Kinase C ◽  
Transgenic Lines ◽  
Pkc Activation

Receptors for activated C kinase (RACKs) have been shown to facilitate activation of protein kinase C (PKC). However, it is unknown whether PKC activation modulates RACK protein expression and PKC-RACK interactions. This issue was studied in two PKCε transgenic lines exhibiting dichotomous cardiac phenotypes: one exhibits increased resistance to myocardial ischemia (cardioprotected phenotype) induced by a modest increase in PKCε activity (228 ± 23% of control), whereas the other exhibits cardiac hypertrophy and failure (hypertrophied phenotype) induced by a marked increase in PKCε activity (452 ± 28% of control). Our data demonstrate that activation of PKC modulates the expression of RACK isotypes and PKC-RACK interactions in a PKCε activity- and dosage-dependent fashion. We found that, in mice displaying the cardioprotected phenotype, activation of PKCε enhanced RACK2 expression (178 ± 13% of control) and particulate PKCε-RACK2 protein-protein interactions (178 ± 18% of control). In contrast, in mice displaying the hypertrophied phenotype, there was not only an increase in RACK2 expression (330 ± 33% of control) and particulate PKCε-RACK2 interactions (154 ± 14% of control) but also in RACK1 protein expression (174 ± 10% of control). Most notably, PKCε-RACK1 interactions were identified in this line. With the use of transgenic mice expressing a dominant negative PKCε, we found that the changes in RACK expression as well as the attending cardiac phenotypes were dependent on PKCε activity. Our observations demonstrate that RACK expression is dynamically regulated by PKCε and suggest that differential patterns of PKCε-RACK interactions may be important determinants of PKCε-dependent cardiac phenotypes.

scholarly journals Ex VivoBioactivity and HIV-1 Latency Reversal by Ingenol Dibenzoate and Panobinostat in Resting CD4+T Cells from Aviremic Patients

2015 ◽  
Vol 59 (10) ◽  
pp. 5984-5991 ◽  
Author(s):  
Adam M. Spivak ◽  
Alberto Bosque ◽  
Alfred H. Balch ◽  
David Smyth ◽  
Laura Martins ◽  
...  
Keyword(s):  
T Cells ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Ex Vivo ◽  
Viral Reactivation ◽  
Major Barrier ◽  
Kinase C ◽  
Wide Range ◽  
Hiv 1 ◽  
In Cells

ABSTRACTThe human immunodeficiency virus type 1 (HIV-1) latent reservoir in resting CD4+T cells represents a major barrier to viral eradication. Small compounds capable of latency reversal have not demonstrated uniform responses acrossin vitroHIV-1 latency cell models. Characterizing compounds that demonstrate latency-reversing activity in resting CD4+T cells from aviremic patientsex vivowill help inform pilot clinical trials aimed at HIV-1 eradication. We have optimized a rapidex vivoassay using resting CD4+T cells from aviremic HIV-1+patients to evaluate both the bioactivity and latency-reversing potential of candidate latency-reversing agents (LRAs). Using this assay, we characterize the properties of two candidate compounds from promising LRA classes, ingenol 3,20-dibenzoate (a protein kinase C agonist) and panobinostat (a histone deacetylase inhibitor), in cells from HIV-1+antiretroviral therapy (ART)-treated aviremic participants, including the effects on cellular activation and cytotoxicity. Ingenol induced viral release at levels similar to those of the positive control (CD3/28 receptor stimulation) in cells from a majority of participants and represents an exciting LRA candidate, as it combines a robust viral reactivation potential with a low toxicity profile. At concentrations that blocked histone deacetylation, panobinostat displayed a wide range of potency among participant samples and consistently induced significant levels of apoptosis. The protein kinase C agonist ingenol 3,20-dibenzoate demonstrated significant promise in a rapidex vivoassay using resting CD4+T cells from treated HIV-1-positive patients to measure latent HIV-1 reactivation.

Defining Protein−Protein Interactions Using Site-Directed Spin-Labeling:  The Binding of Protein Kinase C Substrates to Calmodulin†

Biochemistry ◽  
1996 ◽  
Vol 35 (41) ◽  
pp. 13272-13276 ◽  
Author(s):  
Zhihai Qin ◽  
Stacey L. Wertz ◽  
Jaison Jacob ◽  
Yoko Savino ◽  
David S. Cafiso
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Interactions ◽  
Spin Labeling ◽  
Protein Protein Interactions ◽  
Kinase C ◽  
Site Directed Spin Labeling

Relationship between Protein kinase C isoforms, Telomerase and Alpha- fetoprotein through PI3K/AKT/mTOR pathway in Hepatocellular carcinoma

MedPharmRes ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 12-26
Author(s):  
Rita Ammoury ◽  
Roula Tahtouh ◽  
Nadine Mahfouz ◽  
Raia Doumit ◽  
Charbel Khalil ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Telomerase Activity ◽  
Mtor Pathway ◽  
Alpha Fetoprotein ◽  
Mrna Levels ◽  
Htert Expression ◽  
Kinase C ◽  
Pkc Isoforms

Protein kinase C (PKC) family has been an alluring objective for new cancer drug discovery. It has been reported to regulate telomerase in several cancer types. Our team had previously used telomerase to elucidate alpha-fetoprotein (AFP) modulation in hepatocellular carcinoma (HCC). The aim of this study was to investigate the interrelationships among PKC isoforms, telomerase and AFP in HCC. PKCα and PKCδ were the most expressed isoforms in HepG2/C3A, PLC/PRF/5, SNU-387 and SKOV-3 cells. Following the upregulation of AFP using pCMV3-AFP and the human telomerase reverse transcriptase (hTERT) using a construct expressing a wild-type hTERT, and after their inhibition with all-trans retinoic acid and hTERT siRNA each respectively, we found that the expression of PKCα, PKCβI, PKCβII and PKCδ was affected by the variation of AFP and hTERT mRNA levels. An increase in AFP expression and secretion was observed after gene silencing of PKCα, PKCβ, PKCδ, and PKCε in HepG2/C3A. A similar pattern was observed in transfected PLC/PRF/5 cells, however PKCδ isoform silencing decreased AFP expression. Furthermore, telomerase activity was quantified using quantitative telomeric repeat amplification protocol. The variations in hTERT expression and telomerase activity were similar to those of AFP. Further investigation showed that PKC isoforms regulate AFP and hTERT expression levels through PI3K/AKT/mTOR pathway in HepG2/C3A and PLC/PRF/5 cells. Thus, these results show for the first time a possible interrelationship that links PKC isoforms to both AFP and hTERT via PI3K/AKT/mTOR pathway in HCC.

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 Modeled microgravity-induced protein kinase C isoform expression in human lymphocytes

2004 ◽  
Vol 96 (6) ◽  
pp. 2028-2033 ◽  
Author(s):  
A. Sundaresan ◽  
D. Risin ◽  
N. R. Pellis
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Type I Collagen ◽  
Human Lymphocytes ◽  
Receptor Interaction ◽  
Type I ◽  
Modeled Microgravity ◽  
Calcium Dependent ◽  
Kinase C ◽  
Pkc Isoforms

In long-term space travel, the crew is exposed to microgravity and radiation that invoke potential hazards to the immune system. T cell activation is a critical step in the immune response. Receptor-mediated signaling is inhibited in both microgravity and modeled microgravity (MMG) as reflected by diminished DNA synthesis in peripheral blood lymphocytes and their locomotion through gelled type I collagen. Direct activation of protein kinase C (PKC) bypassing cell surface events using the phorbol ester PMA rescues MMG-inhibited lymphocyte activation and locomotion, whereas the calcium ionophore ionomycin had no rescue effect. Thus calcium-independent PKC isoforms may be affected in MMG-induced locomotion inhibition and rescue. Both calcium-dependent isoforms and calcium-independent PKC isoforms were investigated to assess their expression in lymphocytes in 1 g and MMG culture. Human lymphocytes were cultured and harvested at 24, 48, 72, and 96 h, and serial samples were assessed for locomotion by using type I collagen and expression of PKC isoforms. Expression of PKC-α, -δ, and -ϵ was assessed by RT-PCR, flow cytometry, and immunoblotting. Results indicated that PKC isoforms δ and ϵ were downregulated by >50% at the transcriptional and translational levels in MMG-cultured lymphocytes compared with 1- g controls. Events upstream of PKC, such as phosphorylation of phospholipase Cγ in MMG, revealed accumulation of inactive enzyme. Depressed calcium-independent PKC isoforms may be a consequence of an upstream lesion in the signal transduction pathway. The differential response among calcium-dependent and calcium-independent isoforms may actually result from MMG intrusion events earlier than PKC, but after ligand-receptor interaction.

scholarly journals Protein Kinase C Mediates the Mitogenic Action of Thrombopoietin in c-Mpl–Expressing UT-7 Cells

Blood ◽  
1998 ◽  
Vol 91 (3) ◽  
pp. 813-822 ◽  
Author(s):  
Ying Hong ◽  
Dominique Dumènil ◽  
Bernd van der Loo ◽  
Frédérique Goncalves ◽  
William Vainchenker ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Subcellular Distribution ◽  
Membrane Fraction ◽  
Induced Expression ◽  
Gm Csf ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Mitogenic Action ◽  
Pkc Activation

Protein kinase C (PKC) has been implicated in signal transduction events elicited by several hematopoietic growth factors. Thrombopoietin (TPO) is the major regulator of megakaryocytic lineage development, and its receptor, c-Mpl, transduces signals for the proliferation and differentiation of hematopoietic progenitors. In this study we have examined the effect of TPO on the subcellular distribution of PKC (a measure of enzyme activation) in a growth factor-dependent pluripotent hematopoietic cell line that was engineered to express the c-Mpl receptor (UT-7/mpl). In addition, we have assessed the significance of this activation for the induction of both mitogenesis and differentiation. Using a PKC translocation assay, TPO was found to stimulate a time- and dose-dependent increase in the total content of PKC activity present in the membrane fraction of UT-7/mpl cells (maximum increase = 2.3-fold above basal level after 15 minutes with 40 ng/mL TPO, EC50 = 7 ng/mL). Accordingly, a decrease of PKC content in the cytosolic fraction was observed. Immunoblot analysis using PKC isotype-specific antibodies showed that TPO treatment led to a marked increase of the Ca2+/diacylglycerol-sensitive PKC isoforms α and β found in the membrane fraction. In contrast, the subcellular distribution of these isoforms did not change after treatment with granulocyte-macrophage colony-stimulating factor (GM-CSF). Exposure of UT-7/mpl cells to the selective PKC inhibitor GF109203X completely inhibited the PKC activity associated to the membrane fraction after TPO treatment, and blocked the mitogenic effect of TPO. In contrast, GF109203X had no effect on the TPO-induced expression of GpIIb, a megakaryocytic differentiation antigen. Downregulation of PKC isoforms α and β to less than 25% of their initial level by treatment with phorbol 12,13-dibutyrate also abolished the TPO-induced mitogenic response, but had no significant effect when this response was induced by GM-CSF. Taken together, these findings suggest that (1) TPO stimulates the activation of PKC, (2) PKC activation mediates the mitogenic action of TPO, and (3) PKC activation is not required for TPO-induced expression of megakaryocytic surface markers.

Protein Kinase C Protein Interactions

2003 ◽  
pp. 389-395
Author(s):  
Peter J. Parker ◽  
Joanne Durgan ◽  
Xavier Iturrioz ◽  
Sipeki Szabolcs
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Interactions ◽  
C Protein ◽  
Kinase C
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