scholarly journals Phosphorylation of androgen receptor isoforms

2004 ◽  
Vol 383 (2) ◽  
pp. 267-276 ◽  
Author(s):  
Hao Yun WONG ◽  
Jan A. BURGHOORN ◽  
Marije van LEEUWEN ◽  
Petra E. de RUITER ◽  
Esther SCHIPPERS ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
De Novo ◽  
Major Change ◽  
Reversed Phase ◽  
Mitogen Activated Protein Kinase ◽  
Reversed Phase Hplc ◽  
De Novo Synthesis ◽  
Elution Pattern ◽  
Receptor Isoforms ◽  
Mitogen Activated Protein

Phosphorylation of the human AR (androgen receptor) is directly correlated with the appearance of at least three AR isoforms on an SDS/polyacrylamide gel. However, it is still not clear to what extent phosphorylation is involved in the occurrence of isoforms, which sites are phosphorylated and what are the functions of these phosphosites. The human AR was expressed in COS-1 cells and AR phosphorylation was studied further by mutational analyses and by using reversed-phase HPLC and MS. The reversed-phase HPLC elution pattern of the three isoforms revealed that Ser-650 was phosphorylated constitutively. After de novo synthesis, only Ser-650 was phosphorylated in the smallest isoform of 110 kDa and both Ser-650 and Ser-94 were phosphorylated in the second isoform of 112 kDa. The hormone-induced 114 kDa isoform shows an overall increase in phosphorylation of all the isolated peptides. The activities of the Ser–Ala substitution mutant S650A (Ser-650→Ala) was found to be identical with wild-type AR activation in four different cell lines and three different functional analyses, e.g. transactivation, N- and C-terminal-domain interaction and co-activation by transcriptional intermediary factor 2. This was also found for mutants S94A and S515A with respect to transactivation. However, the S515A mutation, which should eliminate phosphorylation of the potential mitogen-activated protein kinase site, Ser-515, resulted in an unphosphorylated form of the peptide containing Ser-650. This suggests that Ser-515 can modulate phosphorylation at another site. The present study shows that the AR isoform pattern from AR de novo synthesis is directly linked to differential phosphorylation of a distinct set of sites. After mutagenesis of these sites, no major change in functional activity of the AR was observed.

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.

Review of treatment and therapeutic targets in brain arteriovenous malformation

2021 ◽  
pp. 0271678X2110267
Author(s):  
Peipei Pan ◽  
Shantel Weinsheimer ◽  
Daniel Cooke ◽  
Ethan Winkler ◽  
Adib Abla ◽  
...  
Keyword(s):  
Animal Models ◽  
De Novo ◽  
Mapk Pathway ◽  
Treatment Options ◽  
Therapeutic Targets ◽  
Current Treatment ◽  
Mitogen Activated Protein Kinase ◽  
De Novo Mutations ◽  
Genetic Syndromes ◽  
Mitogen Activated Protein

Brain arteriovenous malformations (bAVM) are an important cause of intracranial hemorrhage (ICH), especially in younger patients. The pathogenesis of bAVM are largely unknown. Current understanding of bAVM etiology is based on studying genetic syndromes, animal models, and surgically resected specimens from patients. The identification of activating somatic mutations in the Kirsten rat sarcoma viral oncogene homologue (KRAS) gene and other mitogen-activated protein kinase ( MAPK) pathway genes has opened up new avenues for bAVM study, leading to a paradigm shift to search for somatic, de novo mutations in sporadic bAVMs instead of focusing on inherited genetic mutations. Through the development of new models and understanding of pathways involved in maintaining normal vascular structure and functions, promising therapeutic targets have been identified and safety and efficacy studies are underway in animal models and in patients. The goal of this paper is to provide a thorough review or current diagnostic and treatment tools, known genes and key pathways involved in bAVM pathogenesis to summarize current treatment options and potential therapeutic targets uncovered by recent discoveries.

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.

Importance of post-transcriptional regulation of chemokine genes by oxidative stress

2001 ◽  
Vol 360 (2) ◽  
pp. 321-333 ◽  
Author(s):  
Claire JOSSE ◽  
Johan R. BOELAERT ◽  
Martin BEST-BELPOMME ◽  
Jacques PIETTE
Keyword(s):  
Oxidative Stress ◽  
Nuclear Translocation ◽  
De Novo ◽  
Nuclear Factor Κb ◽  
Mitogen Activated Protein Kinase ◽  
U937 Cells ◽  
Transient Transfection Assay ◽  
Mrna Species ◽  
Inflammatory Protein ◽  
Mitogen Activated Protein

The transcription factor, nuclear factor κB (NF-κB), is activated by various stimuli including cytokines, radiation, viruses and oxidative stress. Here we show that, although induction with H2O2 gives rise to NF-κB nuclear translocation in both lymphocyte (CEM) and monocyte (U937) cells, it leads only to the production of mRNA species encoding interleukin-8 (IL-8) and macrophage inflammatory protein 1α in U937 cells. Under similar conditions these mRNA species are not observed in CEM cells. With the use of a transient transfection assay of U937 cells transfected with reporter constructs of the IL-8 promoter and subsequently treated with H2O2, we show that (1) IL-8-promoter-driven transcription is stimulated in both U937 and CEM cells and (2) the NF-κB site is crucial for activation because its deletion abolishes activation by H2O2. The production of IL-8 mRNA in U937 cells is inhibited by the NF-κB inhibitors clasto-lactacystin-β-lactone and E-64D (l-3-trans-ethoxycarbonyloxirane-2-carbonyl-l-leucine-3-methyl amide) but requires protein synthesis de novo. Moreover, inhibition of the p38 mitogen-activated protein kinase also decreases the IL-8 mRNA up-regulation mediated by H2O2. Taken together, these results show the importance of post-transcriptional events controlled by a p38-dependent pathway in the production of IL-8 mRNA in U937. The much lower activation of p38 in CEM cells in response to H2O2 could explain the lack of stabilization of IL-8 mRNA in these cells.

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.

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