scholarly journals Activation of hepatocyte protein kinase C by redox-cycling quinones

1989 ◽  
Vol 260 (2) ◽  
pp. 499-507 ◽  
Author(s):  
G E Kass ◽  
S K Duddy ◽  
S Orrenius
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Kinase Activity ◽  
Specific Activity ◽  
Active Oxygen Species ◽  
Redox Cycling ◽  
Active Oxygen ◽  
Oxygen Species ◽  
Cytosolic Protein ◽  
Kinase C

The effects of quinone-generated active oxygen species on rat hepatocyte protein kinase C were investigated. The specific activity of cytosolic protein kinase C was increased 2-3-fold in hepatocytes incubated with the redox-cycling quinones, menadione, duroquinone or 2,3-dimethoxy-1,4-naphthoquinone, without alterations in particulate protein kinase C specific activity or Ca2+- and lipid-independent kinase activities. Redox-cycling quinones did not stimulate translocation of protein kinase C; however, activated protein kinase C was redistributed from cytosol to the particulate fraction when quinone-treated hepatocytes were exposed to 12-O-tetradecanoylphorbol 13-acetate (TPA). Quinone treatment did not alter cytosolic phorbol 12,13-dibutyrate (PDBu) binding capacity, and the cytosol of both control and quinone-treated hepatocytes exhibited a Kd for PDBu binding of 2 nM. Quinone-mediated activation of cytosolic protein kinase C was reversed by incubation with 10 mM-beta-mercaptoethanol, dithiothreitol or GSH, at 4 degrees C for 24 h. Furthermore, protein kinase C specific activity in control cytosol incubated in air increased by over 100% within 3 h; this increase was reversed by thiol-reducing agents. Similarly, incubation of partially-purified rat brain protein kinase C in air, or with low concentrations of GSSG in the presence of GSH, resulted in a 2-2.5-fold increase in Ca2+- and lipid-dependent kinase activity. In contrast with the effects of the redox-cycling quinones, when hepatocytes were treated with the thiol agents N-ethylmaleimide (NEM), p-benzoquinone (pBQ) or p-chloromercuribenzoic acid (pCMB), the cytosolic Ca2+- and lipid-dependent kinase activity was significantly inhibited, but the particulate-associated protein kinase C activity was unaffected. The Ca2+- and lipid-independent kinase activity of both the cytosolic and particulate fractions was significantly stimulated by NEM, but was unaffected by pBQ and pCMB. These results show that hepatocyte cytosolic protein kinase C is activated to a high-Vmax form by quinone-generated active oxygen species, and this effect is due to a reduction-sensitive modification of the thiol/disulphide status of protein kinase C.

Diminished specific activity of cytosolic protein kinase C in sciatic nerve of streptozocin-induced diabetic rats and its correction by dietary myo-inositol

Diabetes ◽  
1991 ◽  
Vol 40 (11) ◽  
pp. 1545-1554 ◽  
Author(s):  
J. Kim ◽  
E. H. Rushovich ◽  
T. P. Thomas ◽  
T. Ueda ◽  
B. W. Agranoff ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Sciatic Nerve ◽  
Specific Activity ◽  
Diabetic Rats ◽  
Cytosolic Protein ◽  
Kinase C

Diminished Specific Activity of Cytosolic Protein Kinase C In Sciatic Nerve of Streptozocin-Induced Diabetic Rats and Its Correction by Dietary myo-Inositol

Diabetes ◽  
1991 ◽  
Vol 40 (11) ◽  
pp. 1545-1554 ◽  
Author(s):  
J. Kim ◽  
E. H. Rushovich ◽  
T. P. Thomas ◽  
T. Ueda ◽  
B. W. Agranoff ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Sciatic Nerve ◽  
Specific Activity ◽  
Diabetic Rats ◽  
Cytosolic Protein ◽  
Kinase C

scholarly journals Identification of Key Phospholipids That Bind and Activate Atypical PKCs

Biomedicines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 45
Author(s):  
Suresh Velnati ◽  
Sara Centonze ◽  
Federico Girivetto ◽  
Daniela Capello ◽  
Ricardo M. Biondi ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phosphatidic Acid ◽  
Kinase Activity ◽  
Membrane Lipids ◽  
Atypical Protein Kinase C ◽  
Atypical Protein Kinase ◽  
Kinase C ◽  
Specific Regulation ◽  
Phosphatidylinositol 4

PKCζ and PKCι/λ form the atypical protein kinase C subgroup, characterised by a lack of regulation by calcium and the neutral lipid diacylglycerol. To better understand the regulation of these kinases, we systematically explored their interactions with various purified phospholipids using the lipid overlay assays, followed by kinase activity assays to evaluate the lipid effects on their enzymatic activity. We observed that both PKCζ and PKCι interact with phosphatidic acid and phosphatidylserine. Conversely, PKCι is unique in binding also to phosphatidylinositol-monophosphates (e.g., phosphatidylinositol 3-phosphate, 4-phosphate, and 5-phosphate). Moreover, we observed that phosphatidylinositol 4-phosphate specifically activates PKCι, while both isoforms are responsive to phosphatidic acid and phosphatidylserine. Overall, our results suggest that atypical Protein kinase C (PKC) localisation and activity are regulated by membrane lipids distinct from those involved in conventional PKCs and unveil a specific regulation of PKCι by phosphatidylinositol-monophosphates.

scholarly journals N-Acetylcysteine and α-cyano-4-hydroxycinnamic acid alter protein kinase C (PKC)-δ and PKC-ζ and diminish dysmorphogenesis in rat embryos cultured with high glucose in vitro

2007 ◽  
Vol 192 (1) ◽  
pp. 207-214 ◽  
Author(s):  
Mattias Gäreskog ◽  
Parri Wentzel
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
High Glucose ◽  
Culture Medium ◽  
Hydroxycinnamic Acid ◽  
Oxygen Species ◽  
Rat Embryos ◽  
Protein Kinase C Inhibitors ◽  
Kinase C

Malformations and growth disturbances are two- to threefold more common in infants of diabetic mothers than in offspring of non-diabetic pregnancy. Several suggestions have emerged to explain the reasons for diabetic embryopathy, including enhanced mitochondrial production of reactive oxygen species leading to altered activation of protein kinase C. This study aimed to evaluate the effect of α-cyano-4-hydroxycinnamic acid (CHC) and N-acetylcysteine (NAC) addition on morphology and activity of protein kinase C-δ and protein kinase C-ζ in rat embryos exposed to a high glucose concentration in vitro. Day 9 embryos from normal rats were cultured in 10 or 30 mM glucose concentrations with or without supplementation of CHC, NAC, or protein kinase C inhibitors specific for protein kinase C-δ and protein kinase C-ζ. Embryos were evaluated for malformations, crown rump length, and somite number. Protein kinase C-δ and protein kinase C-ζ activities were estimated by western blot by separating membranous and cytosolic fractions of the embryo. We found increased malformations and growth retardation in embryos cultured in high versus low glucose concentrations. These abnormalities were diminished when CHC and NAC or specific protein kinase C-inhibitors were added to the culture medium. The activities of embryonic protein kinase C-δ and protein kinase C-ζ were increased in the high glucose environment after 24-h culture, but were normalized by the addition of CHC and NAC as well as respective inhibitor to the culture medium. These findings suggest that mitochondrial overproduction of reactive oxygen species is involved in diabetic embryopathy. Furthermore, such overproduction may affect embryonic development, at least partly, by enhancing the activities of protein kinase C-δ and protein kinase C-ζ.

Sign in / Sign up

Export Citation Format

Share Document