scholarly journals Native and Polyubiquitinated Forms of Dihydroceramide Desaturase Are Differentially Linked to Human Embryonic Kidney Cell Survival

2018 ◽  
Vol 38 (23) ◽  
Author(s):  
Mariam Alsanafi ◽  
Samuel L. Kelly ◽  
Karawan Jubair ◽  
Melissa McNaughton ◽  
Rothwelle J. Tate ◽  
...  
Keyword(s):  
Cell Survival ◽  
Kinase Inhibitor ◽  
De Novo ◽  
Sphingosine Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Dihydroceramide Desaturase ◽  
Sphingosine Kinase Inhibitor ◽  
Dependent Mechanism

ABSTRACT There is controversy concerning the role of dihydroceramide desaturase (Degs1) in regulating cell survival, with studies showing that it can both promote and protect against apoptosis. We have therefore investigated the molecular basis for these opposing roles of Degs1. Treatment of HEK293T cells with the sphingosine kinase inhibitor SKi [2-(p-hydroxyanilino)-4-(p-chlorophenyl)thiazole] or fenretinide, but not the Degs1 inhibitor GT11 {N-[(1R,2S)-2-hydroxy-1-hydroxymethyl-2-(2-tridecyl-1-cyclopropenyl)ethyl]octan-amide}, induced the polyubiquitination of Degs1 (Mr = 40 to 140 kDa) via a mechanism involving oxidative stress, p38 mitogen-activated protein kinase (MAPK), and Mdm2 (E3 ligase). The polyubiquitinated forms of Degs1 exhibit “gain of function” and activate prosurvival pathways, p38 MAPK, c-Jun N-terminal kinase (JNK), and X-box protein 1s (XBP-1s). In contrast, another sphingosine kinase inhibitor, ABC294640 [3-(4-chlorophenyl)-adamantane-1-carboxylic acid (pyridin-4-ylmethyl)amide], at concentrations of 25 to 50 μM failed to induce formation of the polyubiquitinated forms of Degs1. In contrast to SKi, ABC294640 (25 μM) promotes apoptosis of HEK293T cells via a Degs1-dependent mechanism that is associated with increased de novo synthesis of ceramide. These findings are the first to demonstrate that the polyubiquitination of Degs1 appears to change its function from proapoptotic to prosurvival. Thus, polyubiquitination of Degs1 might provide an explanation for the reported opposing functions of this enzyme in cell survival/apoptosis.

Analysis of the mechanism(s) of metaphase I arrest in strain LT mouse oocytes: participation of MOS

Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 5107-5113
Author(s):  
Y. Hirao ◽  
J.J. Eppig
Keyword(s):  
Potential Role ◽  
Inbred Strains ◽  
Mitogen Activated Protein Kinase ◽  
Null Mutation ◽  
Mitogen Activated Protein ◽  
Cytostatic Factor ◽  
Almost All ◽  
Dependent Mechanism ◽  
Metaphase I

Oocytes of almost all vertebrates become arrested at metaphase II to await fertilization. Arrest is achieved with the participation of a protein complex known as cytostatic factor (CSF) that stabilizes histone H1 kinase activity. MOS and mitogen-activated protein kinase (MAPK) are important components of CSF. Strain LT/Sv mice, and strains related to LT/Sv, produce a high percentage of atypical oocytes that are arrested at metaphase I when normal oocytes have progressed to metaphase II. The potential role of MOS in metaphase I arrest was investigated using strain LT/Sv and LT-related recombinant inbred strains, LTXBO and CX8-4. MOS and MAPK are produced and functional in maturing LT oocytes. Two experimental paradigms were used to reduce or delete MOS in LT oocytes and assess effects on metaphase I arrest. First, sense and antisense Mos oligonucleotides were microinjected into metaphase I-arrested oocytes. Antisense, but not sense, Mos oligonucleotides promoted the activation of metaphase I-arrested oocytes. Second, mice carrying a Mos null mutation were crossed with LT mice, the null mutation was backcrossed three times to LT mice, and Mos(+/−) N3 mice were intercrossed to produce Mos(−/−), Mos(+/−) and Mos(+/+) N3F1 mice. Oocytes of all three Mos genotypes of N3F1 mice sustained meiotic arrest for 17 hours indicating that metaphase I arrest is not initiated by a MOS-dependent mechanism. However, unlike Mos(+/+) and Mos(+/−) CX8-4 N3F1 oocytes, metaphase I arrest of Mos(−/−) CX8-4 N3F1 oocytes was not sustained after 17 hours and became reversed gradually. These results, like the antisense Mos oligonucleotide microinjection experiments, suggest that MOS participates in sustaining metaphase I arrest in LT oocytes.

scholarly journals Mitogen-Activated Protein Kinase Hog1 Mediates Adaptation to G1 Checkpoint Arrest during Arsenite and Hyperosmotic Stress

2008 ◽  
Vol 7 (8) ◽  
pp. 1309-1317 ◽  
Author(s):  
Iwona Migdal ◽  
Yulia Ilina ◽  
Markus J. Tamás ◽  
Robert Wysocki
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Cell Cycle Arrest ◽  
Kinase Inhibitor ◽  
Hyperosmotic Stress ◽  
Mitogen Activated Protein Kinase ◽  
Hog Pathway ◽  
Cycle Arrest ◽  
Mitogen Activated Protein

ABSTRACT Cells slow down cell cycle progression in order to adapt to unfavorable stress conditions. Yeast (Saccharomyces cerevisiae) responds to osmotic stress by triggering G1 and G2 checkpoint delays that are dependent on the mitogen-activated protein kinase (MAPK) Hog1. The high-osmolarity glycerol (HOG) pathway is also activated by arsenite, and the hog1Δ mutant is highly sensitive to arsenite, partly due to increased arsenite influx into hog1Δ cells. Yeast cell cycle regulation in response to arsenite and the role of Hog1 in this process have not yet been analyzed. Here, we found that long-term exposure to arsenite led to transient G1 and G2 delays in wild-type cells, whereas cells that lack the HOG1 gene or are defective in Hog1 kinase activity displayed persistent G1 cell cycle arrest. Elevated levels of intracellular arsenite and “cross talk” between the HOG and pheromone response pathways, observed in arsenite-treated hog1Δ cells, prolonged the G1 delay but did not cause a persistent G1 arrest. In contrast, deletion of the SIC1 gene encoding a cyclin-dependent kinase inhibitor fully suppressed the observed block of G1 exit in hog1Δ cells. Moreover, the Sic1 protein was stabilized in arsenite-treated hog1Δ cells. Interestingly, Sic1-dependent persistent G1 arrest was also observed in hog1Δ cells during hyperosmotic stress. Taken together, our data point to an important role of the Hog1 kinase in adaptation to stress-induced G1 cell cycle arrest.

Protective effects of epoxyeicosatrienoic acids on human endothelial cells from the pulmonary and coronary vasculature

2006 ◽  
Vol 291 (2) ◽  
pp. H517-H531 ◽  
Author(s):  
Anuradha Dhanasekaran ◽  
Rula Al-Saghir ◽  
Bernardo Lopez ◽  
Daling Zhu ◽  
David D. Gutterman ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Survival ◽  
Kinase Inhibitor ◽  
Protective Action ◽  
Underlying Mechanism ◽  
Mitogen Activated Protein Kinase ◽  
Epoxyeicosatrienoic Acids ◽  
Protective Effects ◽  
Human Coronary Artery ◽  
Mitogen Activated Protein

Epoxyeicosatrienoic acids (EETs) are cytochrome P-450 (CYP) metabolites synthesized from the essential fatty acid arachidonic acid to generate four regioisomers, 14,15-, 11,12-, 8,9-, and 5,6-EET. Cultured human coronary artery endothelial cells (HCAECs) contain endogenous EETs that are increased by stimulation with physiological agonists such as bradykinin. Because EETs are known to modulate a number of vascular functions, including angiogenesis, we tested each of the four regioisomers to characterize their effects on survival and apoptosis of HCAECs and cultured human lung microvascular endothelial cells (HLMVECs). A single application of physiologically relevant concentration of 14,15-, 11,12-, and 8,9-EET but not 5,6-EET (0.75–300 nM) promoted concentration-dependent increase in cell survival of HLMVECs and HCAECs after removal of serum. The lipids also protected the same cells from death via the intrinsic, as well as extrinsic, pathways of apoptosis. EETs did not increase intracellular calcium concentration ([Ca2+]i) or phosphorylate mitogen-activated protein kinase p44/42 when applied to these cells, and their protective action was attenuated by the phosphotidylinositol-3 kinase inhibitor wortmannin (10 μM) but not the cyclooxygenase inhibitor indomethacin (20 μM). Our results demonstrate for the first time the capacity of EETs to enhance human endothelial cell survival by inhibiting both the intrinsic, as well as extrinsic, pathways of apoptosis, an important underlying mechanism that may promote angiogenesis and endothelial survival during atherosclerosis and related cardiovascular ailments.

Autocrine regulation of interleukin-8 production in human monocytes

2000 ◽  
Vol 279 (6) ◽  
pp. L1129-L1136 ◽  
Author(s):  
Darren D. Browning ◽  
Wade C. Diehl ◽  
Matthew H. Hsu ◽  
Ingrid U. Schraufstatter ◽  
Richard D. Ye
Keyword(s):  
Mononuclear Cells ◽  
De Novo ◽  
Human Peripheral Blood ◽  
Surface Expression ◽  
Polymorphonuclear Neutrophils ◽  
Mitogen Activated Protein Kinase ◽  
Cell Surface Expression ◽  
Peripheral Blood Mononuclear ◽  
Mitogen Activated Protein

Interleukin (IL)-8 is a C-X-C chemokine that plays an important role in acute inflammation through its G protein-coupled receptors CXCR1 and CXCR2. In this study, we investigated the role of IL-8 as an autocrine regulator of IL-8 production and the signaling mechanisms involved in human peripheral blood mononuclear cells (MNCs). Sepharose-immobilized IL-8 stimulated a sevenfold increase in IL-8 production within 2 h. IL-8 induced the expression of its own message, and IL-8 biosynthesis was inhibited by cycloheximide and actinomycin D, indicating de novo RNA and protein synthesis. In contrast to MNCs, polymorphonuclear neutrophils did not respond to the immobilized IL-8 with IL-8 production despite cell surface expression of CXCR1 and CXCR2. Melanoma growth-stimulatory activity/growth-related protein-α (MGSA/GROα), which binds CXCR2 but not CXCR1, was unable to either stimulate IL-8 secretion in MNCs or desensitize these cells to respond to immobilized IL-8. The involvement of mitogen-activated protein kinase (MAPK) in IL-8-induced IL-8 biosynthesis was suggested by the ability of PD-98059, an inhibitor of MAPK kinase, to block this function. Furthermore, IL-8 induced a significant increase in extracellular signal-regulated kinase 2 phosphorylation, whereas MGSA/GROα was much less effective. These findings support the role of IL-8 as an autocrine regulator of IL-8 production and suggest that this function is mediated by CXCR1 through activation of MAPK.

scholarly journals Thrombin inhibits Bim (Bcl-2-interacting mediator of cell death) expression and prevents serum-withdrawal-induced apoptosis via protease-activated receptor 1

2003 ◽  
Vol 375 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Claire J. CHALMERS ◽  
Kathryn BALMANNO ◽  
Kathryn HADFIELD ◽  
Rebecca LEY ◽  
Simon J. COOK
Keyword(s):  
Cell Death ◽  
Cell Survival ◽  
De Novo ◽  
Fibroblast Cell ◽  
Mitogen Activated Protein Kinase ◽  
Serum Withdrawal ◽  
Mitogen Activated Protein ◽  
Protease Activated Receptor 1 ◽  
Induced Apoptosis ◽  
Ccl39 Cells

To investigate the role of thrombin in regulating apoptosis, we have used CCl39 cells, a fibroblast cell line in which thrombin-induced cell proliferation has been extensively studied. Withdrawal of serum from CCl39 cells resulted in a rapid apoptotic response that was completely prevented by the inclusion of thrombin. The protective effect of thrombin was reversed by pertussis toxin, suggesting that cell-survival signalling pathways are activated via a Gi or Go heterotrimeric GTPase. Serum-withdrawal-induced death required de novo gene expression and was preceded by the rapid de novo expression of the pro-apoptotic ‘BH3-only’ protein Bim (Bcl-2-interacting mediator of cell death). Thrombin strongly inhibited the up-regulation of both Bim protein and Bim mRNA. The ability of thrombin to repress Bim expression, and to protect cells from apoptosis, was reversed by U0126, a MEK1/2 [MAPK (mitogen-activated protein kinase) or ERK (extracellular-signal-regulated kinase) 1/2] inhibitor, or LY294002, a phosphoinositide 3′-kinase (PI3K) inhibitor, suggesting that both the Raf→MEK→ERK1/2 and PI3K pathways co-operate to repress Bim and promote cell survival. A PAR1p (protease-activated receptor 1 agonist peptide) was also able to protect cells from serum-withdrawal-induced apoptosis, suggesting that thrombin acts via PAR1 to prevent apoptosis.

scholarly journals The Thrombopoietin Receptor Can Mediate Proliferation without Activation of the Jak-STAT Pathway

1997 ◽  
Vol 186 (12) ◽  
pp. 1947-1955 ◽  
Author(s):  
Marion Dorsch ◽  
Pang-Dian Fan ◽  
Nika N. Danial ◽  
Paul B. Rothman ◽  
Stephen P. Goff
Keyword(s):  
Tyrosine Kinases ◽  
Kinase Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Signal Transducers ◽  
Thrombopoietin Receptor ◽  
Mitogen Activated Protein ◽  
Mutant Receptors ◽  
Nonreceptor Tyrosine Kinases ◽  
Stat Pathway

Cytokine receptors of the hematopoietic receptor superfamily lack intrinsic tyrosine kinase domains for the intracellular transmission of their signals. Instead all members of this family associate with Jak family nonreceptor tyrosine kinases. Upon ligand stimulation of the receptors, Jaks are activated to phosphorylate target substrates. These include STAT (signal transducers and activators of transcription) proteins, which after phosphorylation translocate to the nucleus and modulate gene expression. The exact role of the Jak-STAT pathway in conveying growth and differentiation signals remains unclear. Here we describe a deletion mutant of the thrombopoietin receptor (c-mpl) that has completely lost the capacity to activate Jaks and STATs but retains its ability to induce proliferation. This mutant still mediates TPO-induced phosphorylation of Shc, Vav, mitogen-activated protein kinase (MAPK) and Raf-1 as well as induction of c-fos and c-myc, although at somewhat reduced levels. Furthermore, we show that both wild-type and mutant receptors activate phosphatidylinositol (PI) 3-kinase upon thrombopoietin stimulation and that thrombopoietin-induced proliferation is inhibited in the presence of the PI 3-kinase inhibitor wortmannin. These results demonstrate that the Jak-STAT pathway is dispensable for the generation of mitogenic signals by a cytokine receptor.

scholarly journals De Novo Synthesis of Sphingolipids Is Required for Cell Survival by Down-Regulating c-Jun N-Terminal Kinase inDrosophila Imaginal Discs

1999 ◽  
Vol 19 (10) ◽  
pp. 7276-7286 ◽  
Author(s):  
Takashi Adachi-Yamada ◽  
Tomokazu Gotoh ◽  
Isamu Sugimura ◽  
Minoru Tateno ◽  
Yasuyoshi Nishida ◽  
...  
Keyword(s):  
Cell Survival ◽  
Compound Eye ◽  
De Novo ◽  
Imaginal Discs ◽  
Mitogen Activated Protein Kinase ◽  
Serine Palmitoyltransferase ◽  
De Novo Synthesis ◽  
Jnk Pathway ◽  
Activation Of Transcription ◽  
Mitogen Activated Protein

ABSTRACT Mitogen-activated protein kinase (MAPK) is a conserved eukaryotic signaling factor that mediates various signals, cumulating in the activation of transcription factors. Extracellular signal-regulated kinase (ERK), a MAPK, is activated through phosphorylation by the kinase MAPK/ERK kinase (MEK). To elucidate the extent of the involvement of ERK in various aspects of animal development, we searched for a Drosophila mutant which responds to elevated MEK activity and herein identified a lace mutant. Mutants with mild lace alleles grow to become adults with multiple aberrant morphologies in the appendages, compound eye, and bristles. These aberrations were suppressed by elevated MEK activity. Structural and transgenic analyses of the lace cDNA have revealed that the lace gene product is a membrane protein similar to the yeast protein LCB2, a subunit of serine palmitoyltransferase (SPT), which catalyzes the first step of sphingolipid biosynthesis. In fact, SPT activity in the fly expressing epitope-tagged Lace was absorbed by epitope-specific antibody. The number of dead cells in various imaginal discs of a lace hypomorph was considerably increased, thereby ectopically activating c-Jun N-terminal kinase (JNK), another MAPK. These results account for the adult phenotypes of thelace mutant and suppression of the phenotypes by elevated MEK activity: we hypothesize that mutation of lace causes decreased de novo synthesis of sphingolipid metabolites, some of which are signaling molecules, and one or more of these changes activates JNK to elicit apoptosis. The ERK pathway may be antagonistic to the JNK pathway in the control of cell survival.

Role of tyrosine kinase and p44/42 MAPK in D2-like receptor-mediated stimulation of Na+, K+-ATPase in kidney

2002 ◽  
Vol 282 (4) ◽  
pp. F697-F702 ◽  
Author(s):  
Vihang Narkar ◽  
Tahir Hussain ◽  
Mustafa Lokhandwala
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Mapk Pathway ◽  
Rat Kidney ◽  
Receptor Activation ◽  
Proximal Tubules ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Stimulation Of

Our laboratory has shown that dopamine D2-like receptor activation causes stimulation of Na+, K+-ATPase (NKA) activity in the proximal tubules of the rat kidney. The present study was designed to investigate the cellular signaling mechanisms mediating this response to D2-like receptor activation. We measured the stimulation of NKA activity by bromocriptine (D2-like receptor agonist) in the absence and presence of PD-98059 [p44/42 mitogen-activated protein kinase (MAPK) kinase inhibitor] and genistein (tyrosine kinase inhibitor) in renal proximal tubules. Both agents inhibited bromocriptine-mediated stimulation of NKA, suggesting the involvement of p44/42 MAPK and tyrosine kinase in this response. Additionally, we found that bromocriptine increased the phosphorylation of p44/42 MAPK in the proximal tubules, which was blocked by PD-98059 and genistein. These results show that D2-like receptor activation causes stimulation of NKA activity by means of a tyrosine kinase-p44/42 MAPK pathway in the proximal tubules of the kidney.

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