scholarly journals Human Papillomavirus Type 16 E6 Amino Acid 83 Variants Enhance E6-Mediated MAPK Signaling and Differentially Regulate Tumorigenesis by Notch Signaling and Oncogenic Ras

2004 ◽  
Vol 78 (11) ◽  
pp. 5934-5945 ◽  
Author(s):  
Oishee Chakrabarti ◽  
Karthikeyan Veeraraghavalu ◽  
Vinay Tergaonkar ◽  
Yun Liu ◽  
Elliot J. Androphy ◽  
...  
Keyword(s):  
Amino Acid ◽  
Notch Signaling ◽  
Signaling Pathways ◽  
Epidemiological Studies ◽  
Mapk Signaling ◽  
Human Papillomaviruses ◽  
Mitogen Activated Protein Kinase ◽  
Oncogenic Ras ◽  
Notch1 Signaling ◽  
Invasive Carcinomas

ABSTRACT Oncogenically high-risk human papillomaviruses (HPVs) are causally associated with the progression of major human neoplasia-like cancers of the cervix. Several studies have defined functions of the key E6 and E7 oncoproteins in epithelial cell immortalization. The roles of these oncogenes in the progression of immortalized epithelial cells to invasive tumors are still poorly understood. Here, we establish a novel link between the E6 oncoprotein and activation of mitogen-activated protein kinase (MAPK) signaling and show that this signaling involves Rap1. We find that activated MAPK signaling cooperates with deregulated Notch1 signaling to recreate features of HPV-driven invasive cervical carcinomas. We extend our analysis to evaluate an E6 (amino acid [aa] 83) variant that has been linked to invasive tumors. The variant enhances MAPK signaling and cooperative transformation with deregulated Notch1 signaling. Unlike E6, this variant surprisingly inhibits oncogenic Ras-mediated transformation. Our data reveal that the quantitative differences in activation of MAPK signaling by E6 and its variant correlate with differences in cooperative transformation with other signaling pathways, thus suggesting that thresholds of MAPK activation may define permissive conditions for other signaling pathways in tumorigenesis. Epidemiological studies have suggested the importance of E6 aa 83 variants in invasive carcinomas; our data support a key deterministic role for this variant in human cervical tumorigenesis. These observations, along with our recent data showing that deregulated Notch signaling activates phosphatidylinositol 3-kinase signaling, strengthen the possibility of the existence of Ras-independent mechanisms to recreate signaling through classical Ras effector pathways.

scholarly journals MAP Kinase OsMEK2 and OsMPK1 Signaling for Ferroptotic Cell Death in Rice-Magnaporthe oryzae Interactions

2020 ◽  
Author(s):  
Sarmina Dangol ◽  
Raksha Singh ◽  
Khoa Nam Nguyen ◽  
Yafei Chen ◽  
Juan Wang ◽  
...  
Keyword(s):  
Cell Death ◽  
Map Kinase ◽  
Signaling Pathways ◽  
Magnaporthe Oryzae ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Microbial Pathogens ◽  
Blast Disease ◽  
Related Cell ◽  
Mitogen Activated Protein

ABSTRACTMitogen-activated protein kinase (MAPK) signaling is required for plant cell death responses to invading microbial pathogens. Ferric ions and reactive oxygen species (ROS) accumulate in rice (Oryza sativa) tissues undergoing cell death during Magnaporthe oryzae infection. Here, we report that rice MAP kinase (OsMEK2 and OsMPK1) signaling cascades are involved in iron- and ROS-dependent ferroptotic cell death responses of rice to M. oryzae infection. OsMEK2 interacted with OsMPK1 in the cytoplasm, and OsMPK1 moved from the cytoplasm into the nucleus to bind to the OsWRKY90 transcription factor. OsMEK2 expression may trigger OsMPK1-OsWRKY90 signaling pathways in the nucleus. Avirulent M. oryzae infection in ΔOsmek2 mutant rice did not trigger iron and ROS accumulation and lipid peroxidation, and also downregulated OsMPK1, OsWRKY90, OsRbohB, and OsPR-1b expression. However, OsMEK2 overexpression induced ROS-and iron-dependent cell death in rice during M. oryzae infection. The downstream MAP kinase (OsMPK1) overexpression induced ROS- and iron-dependent ferroptotic cell death in the compatible rice-M. oryzae interaction. These data suggest that the OsMEK2-OsMPK1-OsWRKY90 signaling cascade is involved in the ferroptotic cell death in rice. The small-molecule inducer erastin triggered iron- and lipid ROS-dependent, but OsMEK2-independent, ferroptotic cell death in ΔOsmek2 mutant plants during M. oryzae infection. Disease-related cell death was lipid ROS-dependent and iron-independent in the ΔOsmek2 mutant plants. These combined results suggest that OsMEK2 and OsMPK1 expression positively regulates iron- and ROS-dependent ferroptotic cell death via OsMEK2-OsMPK1-OsWRKY90 signaling pathways, and blast disease (susceptibility)-related cell death was ROS-dependent but iron-independent in rice-M. oryzae interactions.

scholarly journals The effects of 50 Hz magnetic field–exposed cell culture medium on cellular functions in FL cells

2019 ◽  
Vol 60 (4) ◽  
pp. 424-431 ◽  
Author(s):  
Yue Fei ◽  
Liling Su ◽  
Haifeng Lou ◽  
Chuning Zhao ◽  
Yiqin Wang ◽  
...  
Keyword(s):  
Cell Viability ◽  
Signaling Pathways ◽  
Relative Permittivity ◽  
Culture Medium ◽  
Biological Effects ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Cell Counting ◽  
International Agency ◽  
Dependent Manner

Abstract Although extremely low frequency magnetic fields (ELF-MFs) have been classified as a possible carcinogen for humans by the International Agency for Research on Cancer (IARC), their biological effects and underlying mechanisms are still unclear. Our previous study indicated that ELF-MF exposure influenced the relative permittivity of the saline solution, suggesting that the MF exposure altered physical properties of the solution. To explore the biophysical mechanism of ELF-MF–induced biological effects, this study examined the effects of 50 Hz sinusoidal MF at 0–4.0 mT on the permittivity of culture medium with phase-interrogation surface plasmon resonance (SPR) sensing. Then, the biological effects of MF pre-exposed culture medium on cell viability, the mitogen-activated protein kinase (MAPK) signaling pathways, oxidative stress, and genetic stabilities were analyzed using Cell Counting Kit-8, western blot, flow cytometry, γH2AX foci formation, and comet assay. The results showed that SPR signals were decreased under MF exposure in a time- and dose-dependent manner, and the decreased SPR signals were reversible when the exposure was drawn off. However, MF pre-exposed culture medium did not significantly change cell viability, intracellular reactive oxygen species level, activation of the MARK signaling pathways, or genetic stabilities in human amniotic epithelial cells (FL cells). In conclusion, our data suggest that the relative permittivity of culture medium was influenced by 50 Hz MF exposure, but this change did not affect the biological processes in FL cells.

scholarly journals Understanding MAPK Signaling Pathways in Apoptosis

2020 ◽  
Vol 21 (7) ◽  
pp. 2346 ◽  
Author(s):  
Jicheng Yue ◽  
José M. López
Keyword(s):  
Signaling Pathways ◽  
Positive Feedback ◽  
Cell Model ◽  
Mapk Signaling ◽  
Feedback Loops ◽  
Mitogen Activated Protein Kinase ◽  
Cellular Mechanisms ◽  
Mitogen Activated Protein ◽  
Induced Apoptosis ◽  
Mapk Signaling Pathways

MAPK (mitogen-activated protein kinase) signaling pathways regulate a variety of biological processes through multiple cellular mechanisms. In most of these processes, such as apoptosis, MAPKs have a dual role since they can act as activators or inhibitors, depending on the cell type and the stimulus. In this review, we present the main pro- and anti-apoptotic mechanisms regulated by MAPKs, as well as the crosstalk observed between some MAPKs. We also describe the basic signaling properties of MAPKs (ultrasensitivity, hysteresis, digital response), and the presence of different positive feedback loops in apoptosis. We provide a simple guide to predict MAPKs’ behavior, based on the intensity and duration of the stimulus. Finally, we consider the role of MAPKs in osmostress-induced apoptosis by using Xenopus oocytes as a cell model. As we will see, apoptosis is plagued with multiple positive feedback loops. We hope this review will help to understand how MAPK signaling pathways engage irreversible cellular decisions.

scholarly journals Targeting ERK-Hippo Interplay in Cancer Therapy

2020 ◽  
Vol 21 (9) ◽  
pp. 3236 ◽  
Author(s):  
Karel Vališ ◽  
Petr Novák
Keyword(s):  
Cancer Therapy ◽  
Signaling Pathways ◽  
Signaling Pathway ◽  
Cross Talk ◽  
Mapk Signaling ◽  
Mapk Signaling Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Cancer Therapies ◽  
Anti Cancer ◽  
Targeted Inhibition

Extracellular signal-regulated kinase (ERK) is a part of the mitogen-activated protein kinase (MAPK) signaling pathway which allows the transduction of various cellular signals to final effectors and regulation of elementary cellular processes. Deregulation of the MAPK signaling occurs under many pathological conditions including neurodegenerative disorders, metabolic syndromes and cancers. Targeted inhibition of individual kinases of the MAPK signaling pathway using synthetic compounds represents a promising way to effective anti-cancer therapy. Cross-talk of the MAPK signaling pathway with other proteins and signaling pathways have a crucial impact on clinical outcomes of targeted therapies and plays important role during development of drug resistance in cancers. We discuss cross-talk of the MAPK/ERK signaling pathway with other signaling pathways, in particular interplay with the Hippo/MST pathway. We demonstrate the mechanism of cell death induction shared between MAPK/ERK and Hippo/MST signaling pathways and discuss the potential of combination targeting of these pathways in the development of more effective anti-cancer therapies.

scholarly journals Leptin-mediated differential regulation of microsomal triglyceride transfer protein in the intestine and liver affects plasma lipids

2020 ◽  
Vol 295 (13) ◽  
pp. 4101-4113 ◽  
Author(s):  
Jahangir Iqbal ◽  
Eduardo Mascareno ◽  
Streamson Chua ◽  
M. Mahmood Hussain
Keyword(s):  
Signaling Pathways ◽  
Short Form ◽  
Microsomal Triglyceride Transfer Protein ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Chow Diet ◽  
Peripheral Tissues ◽  
Transfer Protein ◽  
Hepatic Cells ◽  
Huh7 Cells

The hormone leptin regulates fat storage and metabolism by signaling through the brain and peripheral tissues. Lipids delivered to peripheral tissues originate mostly from the intestine and liver via synthesis and secretion of apolipoprotein B (apoB)-containing lipoproteins. An intracellular chaperone, microsomal triglyceride transfer protein (MTP), is required for the biosynthesis of these lipoproteins, and its regulation determines fat mobilization to different tissues. Using cell culture and animal models, here we sought to identify the effects of leptin on MTP expression in the intestine and liver. Leptin decreased MTP expression in differentiated intestinal Caco-2 cells, but increased expression in hepatic Huh7 cells. Similarly, acute and chronic leptin treatment of chow diet-fed WT mice decreased MTP expression in the intestine, increased it in the liver, and lowered plasma triglyceride levels. These leptin effects required the presence of leptin receptors (LEPRs). Further experiments also suggested that leptin interacted with long-form LEPR (ObRb), highly expressed in the intestine, to down-regulate MTP. In contrast, in the liver, leptin interacted with short-form LEPR (ObRa) to increase MTP expression. Mechanistic experiments disclosed that leptin activates signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase (MAPK) signaling pathways in intestinal and hepatic cells, respectively, and thereby regulates divergent MTP expression. Our results also indicated that leptin-mediated MTP regulation in the intestine affects plasma lipid levels. In summary, our findings suggest that leptin regulates MTP expression differentially by engaging with different LEPR types and activating distinct signaling pathways in intestinal and hepatic cells.

Electromyostimulation with blood flow restriction enhances activation of mTOR and MAPK signaling pathways in rat gastrocnemius muscles

2019 ◽  
Vol 44 (6) ◽  
pp. 637-644
Author(s):  
Toshiharu Natsume ◽  
Toshinori Yoshihara ◽  
Hisashi Naito
Keyword(s):  
Blood Flow ◽  
Signaling Pathways ◽  
Muscle Hypertrophy ◽  
Gastrocnemius Muscle ◽  
Lactate Concentration ◽  
Mapk Signaling ◽  
Blood Flow Restriction ◽  
Mitogen Activated Protein Kinase ◽  
Flow Restriction ◽  
Mapk Signaling Pathways

Neuromuscular electrical stimulation (NMES) combined with blood flow restriction (BFR) induces muscle hypertrophy. However, cellular mechanisms underlying the muscle hypertrophy induced by NMES combined with BFR remain unclear. We tested the hypothesis that NMES combined with BFR would enhance the mechanistic target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK) signaling pathways. Age-matched male Wistar rats (6 months old, n = 7 per group) were assigned randomly to control, BFR alone (BFR), NMES alone (NMES), and NMES combined with BFR (NMES/BFR) groups. NMES induced 25 isometric contractions lasting 8 s with 4-s resting periods between contractions in the gastrocnemius muscle. Four sets in total were performed, with 1-min intervals between sets. A latex cuff was placed on the proximal portion of the hind limb and BFR at 200 mm Hg was conducted in 4 sets (each set 5 min) with 1-min rest intervals between sets. Venous blood was collected from the lateral tail vein to determine pH, H+ concentration, and lactate concentration before and immediately after the treatments. Expression levels of proteins related to muscle hypertrophy were determined by Western blot analysis. The application of NMES/BFR promoted muscle fatigue more than NMES alone. NMES/BFR induced greater changes in accumulation of metabolites and increase in gastrocnemius muscle weight. The phosphorylation of mTOR and MAPK signaling-related proteins was also enhanced following NMES/BFR, compared with other conditions. Thus, NMES enhanced the activation of mTOR and MAPK signaling pathways when combined with BFR.

scholarly journals Melanogenic Effects of Maclurin Are Mediated through the Activation of cAMP/PKA/CREB and p38 MAPK/CREB Signaling Pathways

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Young Sun Hwang ◽  
Sae Woong Oh ◽  
See-Hyoung Park ◽  
Jienny Lee ◽  
Ju Ah. Yoo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathways ◽  
P38 Mapk ◽  
Adenosine Monophosphate ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Protective Agent ◽  
Protective Effects ◽  
Skin Disorders ◽  
Creb Phosphorylation

Melanogenesis is the biological process which the skin pigment melanin is synthesized to protect the skin against ultraviolet irradiation and other external stresses. Abnormal biology of melanocytes is closely associated with depigmented skin disorders such as vitiligo. In this study, we examined the effects of maclurin on melanogenesis and cytoprotection. Maclurin enhanced cellular tyrosinase activity as well as cellular melanin levels. We found that maclurin treatment increased the expression of microphthalmia-associated transcription factor (MITF), tyrosinase-related protein- (TRP-) 1, TRP-2, and tyrosinase. Mechanistically, maclurin promoted melanogenesis through cyclic adenosine monophosphate (cAMP) response element binding (CREB) protein-dependent upregulation of MITF. CREB activation was found to be mediated by p38 mitogen-activated protein kinase (MAPK) or cAMP-protein kinase A (PKA) signaling. In addition, maclurin-induced CREB phosphorylation was mediated through the activation of both the cAMP/PKA and the p38 MAPK signaling pathways. Maclurin-induced suppression of p44/42 MAPK activation also contributed to its melanogenic activity. Furthermore, maclurin showed protective effects against H2O2 treatment and UVB irradiation in human melanocytes. These findings indicate that the melanogenic effects of maclurin depend on increased MITF gene expression, which is mediated by the activation of both p38 MAPK/CREB and cAMP/PKA/CREB signaling. Our results thus suggest that maclurin could be useful as a protective agent against hypopigmented skin disorders.

MAPK signaling pathways are needed for survival of H9c2 cardiac myoblasts under extracellular alkalosis

2008 ◽  
Vol 295 (3) ◽  
pp. H1319-H1329 ◽  
Author(s):  
Konstantina Stathopoulou ◽  
Isidoros Beis ◽  
Catherine Gaitanaki
Keyword(s):  
Signaling Pathways ◽  
P38 Mapk ◽  
Cardiac Myocyte ◽  
Consensus Sequence ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Selective Inhibitors ◽  
Cardiac Myoblasts ◽  
Mapk Signaling Pathways

pH is one of the most important physiological parameters, with its changes affecting the function of vital organs like the heart. However, the effects of alkalosis on the regulation of cardiac myocyte function have not been extensively investigated. Therefore, we decided to study whether the mitogen-activated protein kinase (MAPK) signaling pathways [c-Jun NH2-terminal kinases (JNKs), extracellular signal-regulated kinases (ERKs), and p38 MAPK] are activated by alkalosis induced with Tris-Tyrode buffer at two pH values, 8.5 and 9.5, in H9c2 rat cardiac myoblasts. These buffers also induced intracellular alkalinization comparable to that induced by 1 mM NH4Cl. The three MAPKs examined presented differential phosphorylation patterns that depended on the severity and the duration of the stimulus. Inhibition of Na+/H+ exchanger (NHE)1 by its inhibitor HOE-642 prevented alkalinization and partially attenuated the alkalosis (pH 8.5)-induced activation of these kinases. The same stimulus also promoted c-Jun phosphorylation and enhanced the binding at oligonucleotides bearing the activator protein-1 (AP-1) consensus sequence, all in a JNK-dependent manner. Additionally, mitogen- and stress-activated kinase 1 (MSK1) was transiently phosphorylated by alkalosis (pH 8.5), and this was abolished by the selective inhibitors of either p38 MAPK or ERK pathways. JNKs also mediated Bcl-2 phosphorylation in response to incubation with the alkaline medium (pH 8.5), while selective inhibitors of the three MAPKs diminished cell viability under these conditions. All these data suggest that alkalosis activates MAPKs in H9c2 cells and these kinases, in turn, modify proteins that regulate gene transcription and cell survival.

scholarly journals Weaning Induced Hepatic Oxidative Stress, Apoptosis, and Aminotransferases through MAPK Signaling Pathways in Piglets

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Zhen Luo ◽  
Wei Zhu ◽  
Qi Guo ◽  
Wenli Luo ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Signaling Pathways ◽  
Redox Status ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Control Group ◽  
Hepatic Oxidative Stress ◽  
Mitogen Activated Protein ◽  
D 20 ◽  
Mapk Signaling Pathways

This study investigated the effects of weaning on the hepatic redox status, apoptosis, function, and the mitogen-activated protein kinase (MAPK) signaling pathways during the first week after weaning in piglets. A total of 12 litters of piglets were weaned at d 21 and divided into the weaning group (WG) and the control group (CG). Six piglets from each group were slaughtered at d 0 (d 20, referred to weaning), d 1, d 4, and d 7 after weaning. Results showed that weaning significantly increased the concentrations of hepatic free radicals H2O2and NO, malondialdehyde (MDA), and 8-hydroxy-2′-deoxyguanosine (8-OHdG), while significantly decreasing the inhibitory hydroxyl ability (IHA) and glutathione peroxidase (GSH-Px), and altered the level of superoxide dismutase (SOD). The apoptosis results showed that weaning increased the concentrations of caspase-3, caspase-8, caspase-9 and the ratio of Bax/Bcl-2. In addition, aspartate aminotransferase transaminase (AST) and alanine aminotransferase (ALT) in liver homogenates increased after weaning. The phosphorylated JNK and ERK1/2 increased, while the activated p38 initially decreased and then increased. Our results suggested that weaning increased the hepatic oxidative stress and aminotransferases and initiated apoptosis, which may be related to the activated MAPK pathways in postweaning piglets.

Sign in / Sign up

Export Citation Format

Share Document