scholarly journals Regulation of H2O2-induced necrosis by PKC and AMP-activated kinase signaling in primary cultured hepatocytes

2008 ◽  
Vol 295 (1) ◽  
pp. C50-C63 ◽  
Author(s):  
Behnam Saberi ◽  
Mie Shinohara ◽  
Maria D. Ybanez ◽  
Naoko Hanawa ◽  
William A. Gaarde ◽  
...  
Keyword(s):  
Protective Effect ◽  
Signaling Pathways ◽  
Time Course ◽  
Lag Phase ◽  
Primary Hepatocytes ◽  
Pkc Inhibitor ◽  
Compound C ◽  
Pkc Isoforms ◽  
Pkc Inhibitors ◽  
Inhibitor Treatment

Recent studies have suggested that, in certain cases, necrosis, like apoptosis, may be programmed, involving the activation and inhibition of many signaling pathways. In this study, we examined whether necrosis induced by H2O2 is regulated by signaling pathways in primary hepatocytes. A detailed time course revealed that H2O2 treated to hepatocytes is consumed within minutes, but hepatocytes undergo necrosis several hours later. Thus, H2O2 treatment induces a “lag phase” where signaling changes occur, including PKC activation, Akt (PKB) downregulation, activation of JNK, and downregulation of AMP-activated kinase (AMPK). Investigation of various inhibitors demonstrated that PKC inhibitors were effective in reducing necrosis caused by H2O2 (∼80%). PKC inhibitor treatment decreased PKC activity but, surprisingly, also upregulated Akt and AMPK, suggesting that various PKC isoforms negatively regulate Akt and AMPK. Akt did not appear to play a significant role in H2O2-induced necrosis, since PKC inhibitor treatment protected hepatocytes from H2O2 even when Akt was inhibited. On the other hand, compound C, a selective AMPK inhibitor, abrogated the protective effect of PKC inhibitors against necrosis induced by H2O2. Furthermore, AMPK activators protected against H2O2-induced necrosis, suggesting that much of the protective effect of PKC inhibition was mediated through the upregulation of AMPK. Work with PKC inhibitors suggested that atypical PKC downregulates AMPK in response to H2O2. Knockdown of PKC-α using antisense oligonucleotides also slightly protected (∼22%) against H2O2. Taken together, our data demonstrate that the modulation of signaling pathways involving PKC and AMPK can alter H2O2-induced necrosis, suggesting that a signaling “program” is important in mediating H2O2-induced necrosis in primary hepatocytes.

Functional Properties of p-Anisoylated Plasmin-Staphylokinase Complex

1993 ◽  
Vol 70 (02) ◽  
pp. 326-331 ◽  
Author(s):  
H R Lijnen ◽  
B Van Hoef ◽  
R A G Smith ◽  
D Collen
Keyword(s):  
Human Plasma ◽  
Rate Constant ◽  
Time Course ◽  
Bolus Injection ◽  
Similar Rate ◽  
Clot Lysis ◽  
Lag Phase ◽  
Plasma Clot ◽  
Rapid Clearance ◽  
Stoichiometric Complex

SummaryThe kinetic and fibrinolytic properties of a reversibly acylated stoichiometric complex between human plasmin and recombinant staphylokinase (plasmin-STAR complex) were evaluated. The acylation rate constant of plasmin-STAR by p-amidinophenyl-p’-anisate-HCI was 52 M-1 s-1 and its deacylation rate constant 1.2 × 10-4 s-1 (t½ of 95 min) which are respectively 50-fold and around 3-fold lower than for the plasmin-streptokinase complex. The acylated complex was stable as evidenced by binding to lysine-Sepharose. However, following an initial short lag phase, the acylated plasmin-STAR complex activated plasminogen at a similar rate as the unblocked complex, whereas the acylated plasmin-streptokinase complex did not activate plasminogen. These findings indicate that STAR, unlike streptokinase, dissociates from its acylated complex with plasmin in the presence of excess plasminogen. In agreement with this hypothesis, the time course of the lysis of a 125I-fibrin labeled plasma clot submerged in citrated human plasma, is similar for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR (50% clot lysis in 2 h requires 12 nM of each agent). The plasma clearances of STAR-related antigen following bolus injection in hamsters were 1.0 to 1.5 ml/min for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR, as a result of short initial half-lives of 2.0 to 2.5 min.The dissociation of the anisoylated plasmin-STAR complex and its consequent rapid clearance suggest that it has no apparent advantages as compared to free STAR for clinical thrombolysis.

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.

PKC-ε is upstream and PKC-α is downstream of mitoKATP channels in the signal transduction pathway of ischemic preconditioning of human myocardium

2004 ◽  
Vol 287 (5) ◽  
pp. C1418-C1425 ◽  
Author(s):  
Ashraf Hassouna ◽  
Bashir M. Matata ◽  
Manuel Galiñanes
Keyword(s):  
Ischemic Preconditioning ◽  
Signal Transduction Pathway ◽  
Human Myocardium ◽  
Right Atrial ◽  
Elective Cardiac Surgery ◽  
Simulated Ischemia ◽  
Pkc Isoforms ◽  
Pkc Inhibitors ◽  
To Receive ◽  
Scion Image

Protein kinase C (PKC) is involved in the process of ischemic preconditioning (IPC), although the precise mechanism is still a subject of debate. Using specific PKC inhibitors, we investigated which PKC isoforms were involved in IPC of the human atrial myocardium sections and to determine their temporal relationship to the opening of mitochondrial potassium-sensitive ATP (mitoKATP) channels. Right atrial muscles obtained from patients undergoing elective cardiac surgery were equilibrated and then randomized to receive any of the following protocols: aerobic control, 90-min simulated ischemia/120-min reoxygenation, IPC using 5-min simulated ischemia/5-min reoxygenation followed by 90-min simulated ischemia/120-min reoxygenation and finally, PKC inhibitors were added 10 min before and 10 min during IPC followed by 90-min simulated ischemia/120-min reoxygenation. The PKC isoforms inhibitors investigated were V1–2 peptide, GO-6976, rottlerin, and LY-333531 for PKC-ε, -α, -δ and -β, respectively. To investigate the relation of PKC isoforms to mitoKATP channels, PKC inhibitors found to be involved in IPC were added 10 min before and 10 min during preconditioning by diazoxide followed by 90-min simulated ischemia/120-min reoxygenation in a second experiment. Creatine kinase leakage and methylthiazoletetrazolium cell viability were measured. Phosphorylation of PKC isoforms after activation of the sample by either diazoxide or IPC was detected by using Western blot analysis and then analyzed by using Scion image software. PKC-α and -ε inhibitors blocked IPC, whereas PKC-δ and -β inhibitors did not. The protection elicited by diazoxide, believed to be via mitoKATP channels opening, was blocked by the inhibition of PKC-α but not -ε isoforms. In addition, diazoxide caused increased phosphorylation of PKC-α to the same extent as IPC but did not affect the phosphorylation of PKC-ε, a process believed to be critical in PKC activation. The results demonstrate that PKC-α and -ε are involved in IPC of the human myocardium with PKC-ε being upstream and PKC-α being downstream of mitoKATP channels.

Synthesis and turnover of proteins and mRNA in germinating wheat embryos

1982 ◽  
Vol 60 (3) ◽  
pp. 389-397 ◽  
Author(s):  
Zbyszko F. Grzelczak ◽  
Mark H. Sattolo ◽  
Linda K. Hanley-Bowdoin ◽  
Theresa D. Kennedy ◽  
Byron G. Lane
Keyword(s):  
Growth Phase ◽  
Time Course ◽  
Phase 1 ◽  
Major Product ◽  
Lag Phase ◽  
Wheat Embryo ◽  
Phase Development ◽  
Wheat Embryos

The most prominent methionine-labeled protein made when cell-free systems are programmed with bulk mRNA from dry wheat embryos has been identified with what may be the most abundant protein in dry wheat embryos. The protein has been brought to purity and has a distinctive amino acid composition, Gly and Glx accounting for almost 40% of the total amino acids. Designated E because of its conspicuous association with early imbibition of dry wheat embryos, the protein and its mRNA are abundant during the "early" phase (0–1 h) of postimbibition development, and easily detected during "lag" phase (1–5 h), but they are almost totally degraded soon after entry into the "growth" phase of development, by about 10 h postimbibition.The most prominent methionine-labeled protein peculiar to the cell-free translational capacity of bulk mRNA from "growth" phase embryos is not detected as a product of in vivo synthesis. Its electrophoretic properties and its time course of emergence, after 5 h postimbibition development, suggest that this major product of cell-free synthesis may be an in vitro counterpart to a prominent methionine-labeled protein made only in vivo, by "growth" phase embryos. Designated G because of its conspicuous association with "growth" phase development, the cell-free product does not comigrate with any prominent dye-stained band in electrophoretic distributions of wheat proteins. The suspected cellular counterpart to G, also, does not comigrate with a prominent dye-stained wheat protein during electrophoresis, and although found in particulate as well as soluble fractions of wheat embryo homogenates it is not concentrated in either nuclei or mitochondria, as isolated.

scholarly journals Protective Effect of Sulfated Polysaccharides from Celluclast-Assisted Extract of Hizikia fusiforme Against Ultraviolet B-Induced Skin Damage by Regulating NF-κB, AP-1, and MAPKs Signaling Pathways In Vitro in Human Dermal Fibroblasts

Marine Drugs ◽  
2018 ◽  
Vol 16 (7) ◽  
pp. 239 ◽  
Author(s):  
Lei Wang ◽  
WonWoo Lee ◽  
Jae Oh ◽  
Yong Cui ◽  
BoMi Ryu ◽  
...  
Keyword(s):  
Protective Effect ◽  
Signaling Pathways ◽  
Dermal Fibroblasts ◽  
Sulfated Polysaccharides ◽  
Dependent Manner ◽  
Human Dermal Fibroblasts ◽  
Skin Damage ◽  
Hizikia Fusiforme ◽  
Hdf Cells

Our previous study evaluated the antioxidant activities of sulfated polysaccharides from Celluclast-assisted extract of Hizikia fusiforme (HFPS) in vitro in Vero cells and in vivo in zebrafish. The results showed that HFPS possesses strong antioxidant activity and suggested the potential photo-protective activities of HFPS. Hence, in the present study, we investigated the protective effects of HFPS against ultraviolet (UV) B-induced skin damage in vitro in human dermal fibroblasts (HDF cells). The results indicate that HFPS significantly reduced intracellular reactive oxygen species (ROS) level and improved the viability of UVB-irradiated HDF cells in a dose-dependent manner. Furthermore, HFPS significantly inhibited intracellular collagenase and elastase activities, remarkably protected collagen synthesis, and reduced matrix metalloproteinases (MMPs) expression by regulating nuclear factor kappa B (NF-κB), activator protein 1 (AP-1), and mitogen-activated protein kinases (MAPKs) signaling pathways in UVB-irradiated HDF cells. These results suggest that HFPS possesses strong UV protective effect, and can be a potential ingredient in the pharmaceutical and cosmetic industries.

Sign in / Sign up

Export Citation Format

Share Document