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David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, USA
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( Armstrong et al . 1991 ). This fall in ATP levels in response to exercise stress ( Perrey & Rupp 2009 ) activates Pgc1α, AMPK and p38MAPK kinase signaling to allow cells to adapt ( Gibala 2009 ). This post-exercise response involves mitochondrial biogenesis
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stimulated the activation of signalling molecules ERK/MAPK and AKT. On the other hand, C5a and C5adR both inhibited the secretion of the inflammatory molecule, macrophage migration inhibitory factor (MIF) yet stimulated the secretion of ACTH. These data
Clinical Division, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong
YMU-HKBU Joint Laboratory of Traditional Natural Medicine, Yunnan Minzu University, Kunming, China
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YMU-HKBU Joint Laboratory of Traditional Natural Medicine, Yunnan Minzu University, Kunming, China
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cAMP- and MAPK-dependent mechanisms, has also been reported ( Mijiddorj et al . 2013 ). To date, a comprehensive model for the post-receptor signaling of PRL regulation by PACAP is still lacking and a systematic study on signal transduction based on
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Department of Biophysics and Life Sciences, Bioinformatics Project of Japan Science and Technology Agency, Laboratory of Exercise Biochemistry and Neuroendocrinology, Department of Urology, Graduate School of Arts and Sciences, University of Tokyo, 3‐8‐1 Komaba, Meguro‐ku, Tokyo 152-8902, Japan
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Department of Biophysics and Life Sciences, Bioinformatics Project of Japan Science and Technology Agency, Laboratory of Exercise Biochemistry and Neuroendocrinology, Department of Urology, Graduate School of Arts and Sciences, University of Tokyo, 3‐8‐1 Komaba, Meguro‐ku, Tokyo 152-8902, Japan
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Department of Biophysics and Life Sciences, Bioinformatics Project of Japan Science and Technology Agency, Laboratory of Exercise Biochemistry and Neuroendocrinology, Department of Urology, Graduate School of Arts and Sciences, University of Tokyo, 3‐8‐1 Komaba, Meguro‐ku, Tokyo 152-8902, Japan
Department of Biophysics and Life Sciences, Bioinformatics Project of Japan Science and Technology Agency, Laboratory of Exercise Biochemistry and Neuroendocrinology, Department of Urology, Graduate School of Arts and Sciences, University of Tokyo, 3‐8‐1 Komaba, Meguro‐ku, Tokyo 152-8902, Japan
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other hand, the application of 10 μM SP600125 (JNK inhibitor) did not alter the effect of CORT. These results indicate that 30 nM CORT promoted the spinogenesis via PKA, PKC, ERK MAPK, and LIMK signaling pathways. Since the concentrations of inhibitors
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production A role for MAPK activated signaling in LH-induced P 4 production was shown by incubating endometrial tissues from metestrus with LH and the MEK1/2 inhibitor, PD98059. For this, following 1.0-h pre-incubation with increasing doses of PD98059 (0
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Clinical and animal studies have shown that treatment with angiotensin-converting enzyme (ACE) inhibitors or angiotensin II (Ang II) receptor antagonists slows the progression of nephropathy in diabetes, indicating that Ang II plays an important role in its development. We have reported previously that insulin inhibits the stimulatory effect of high glucose levels on angiotensinogen (ANG) gene expression in rat immortalized renal proximal tubular cells (IRPTCs) via the mitogen-activated protein kinase (p44/42 MAPK) signal transduction pathway. We hypothesize that the suppressive action of insulin on ANG gene expression might be attenuated in renal proximal tubular cells (RPTCs) of rats with established diabetes. Two groups of male adult Wistar rats were studied: controls and streptozotocin (STZ)-induced diabetic rats at 2, 4, 8 and 12 weeks post-STZ administration. Kidney proximal tubules were isolated and cultured in either normal glucose (i.e. 5 mM) or high glucose (i.e. 25 mM) medium to determine the inhibitory effect of insulin on ANG gene expression. Immunoreactive rat ANG (IR-rANG) in culture media and cellular ANG mRNA were measured by a specific radioimmunoassay and reverse transcription-polymerase chain reaction assay respectively. Activation of the p44/42 MAPK signal transduction pathway in rat RPTCs was evaluated by p44/42 MAPK phosphorylation employing a PhosphoPlus p44/42 MAPK antibody kit. Insulin (10(-7) M) inhibited the stimulatory effect of high glucose levels on IR-rANG secretion and ANG gene expression and increased p44/42 MAPK phosphorylation in normal rat RPTCs. In contrast, it failed to affect these parameters in diabetic rat RPTCs. In conclusion, our studies demonstrate that hyperglycaemia induces insulin resistance on ANG gene expression in diabetic rat RPTCs by altering the MAPK signal transduction pathway.
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Synthetic glucocorticoids (GCs) potently inhibit the expression of pro-inflammatory genes and are widely used in the treatment of inflammatory diseases. However, some patients are resistant to the therapeutic effects of GCs, and many suffer deleterious side effects from these drugs. Furthermore, the precise mechanisms by which GCs inhibit pro-inflammatory gene expression remain unclear. A number of recent papers report that GCs induce the sustained expression of MAP kinase (MAPK) phosphatase 1 (MKP-1), a negative regulator of MAPK signal transduction pathways. The potential relevance of MKP-1 to some of the biological effects of GCs is discussed.
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Trophoblast giant cells are one of the primary endocrine cell types of the rodent placenta. Placental lactogen-I (PL-I) is the initial prolactin (PRL) family member expressed as trophoblast giant cells differentiate. In this report, we use the Rcho-1 trophoblast cell line as a model for studying the regulation of PL-I gene expression during trophoblast giant cell differentiation. Evidence is provided for trophoblast cell expression of epidermal growth factor receptor (EGFR), ErbB2, fibroblast growth factor receptor 1 (FGFR1), transforming growth factor-alpha, and heparin-binding EGF. EGF and FGF-2 stimulated PL-I mRNA and protein accumulation and PL-I promoter activity in a concentration-dependent manner. These latter growth factor actions on PL-I promoter activities were specifically inhibited by cotransfection with dominant negative constructs for EGFR and FGFRs respectively. Utilization of the mitogen-activated protein kinase (MAPK) pathway by EGF and FGF-2 in trophoblast cells was demonstrated by growth factor stimulation of a Gal4 DNA binding/Elk1 transactivational domain fusion construct, and more specifically by activation of extracellular signal regulated kinase and p38 MAPK. PL-I gene activation was also sensitive to disruption of MAPK and activation protein-1 (AP-1) signaling pathways. In conclusion, autocrine/paracrine pathways involving EGFR and FGFR1, MAPK and AP-1 are shown to participate in the regulation of the PL-I gene in differentiating trophoblast cells.
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The putative hypophysiotropic factor pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates glycoprotein hormone alpha-subunit (alpha GSU) gene transcription and secretion in the clonal gonadotroph alpha T3-1 cell line. The specific signalling pathways regulating these actions of PACAP have not been clearly defined. We have examined the possibility that mitogen activated protein kinases (MAPKs) may play a role in mediating the effects of PACAP on alpha T3-1 gonadotrophs. Treatment of alpha T3-1 cells with PACAP (100 nM) or epidermal growth factor (EGF, 10 nM) for 5 min significantly stimulated extracellular signal-regulated kinase activity (ERK, a component of the MAPK pathway) as determined by an immunocomplex assay. Pre-treatment of alpha T3-1 cells with the specific MAPK kinase (MEK) inhibitor, U0126, blocked PACAP and EGF-induced activation of ERK. Transcriptional stimulation of a human alpha GSU-luciferase reporter construct by PACAP was unaffected by U0126 treatment. However, pre-treatment with U0126 significantly inhibited PACAP stimulation of [(3)H]-thymidine incorporation in alpha T3-1 cells. Thus our results suggest that PACAP stimulates ERK activation in alpha T3-1 cells, and that the functional effect of this ERK activation is increased DNA synthesis and cell proliferation rather then transcriptional activation of the alpha GSU gene.
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Recently we reported that calcitonin (CT) induces growth arrest at the G2 stage of the cell cycle in HEK-293 cell lines expressing the most abundant, insert-negative, isoform of the human CT receptor (insert -ve hCTR). The present study investigates the involvement of the MAPK signalling pathway in the anti-proliferative actions of CT and compares the activity of an isoform of the hCTR that contains a 16 amino acid insert in the first putative intracellular loop (insert +ve hCTR). Comparison of HEK-293 cells stably transfected with the insert -ve or the insert +ve hCTR, showed that accumulation of cAMP and intracellular free calcium in response to CT were specific for the insert -ve receptor isoform. However, a novel acidification of the extracellular medium was mediated by both isoforms. Treatment with CT of cells expressing the insert -ve hCTR, caused a decrease in cell growth associated with an induction of p21(WAF1/CIP1). Analysis by fluorescence-activated cell scanning showed that growth inhibition was associated with an accumulation of cells in G2. CT treatment of cells expressing the insert -ve, but not insert +ve hCTR, induced the phosphorylation of Erk1/2 MAPK, which persisted for at least 72 h. Treatment of cells expressing the insert -ve hCTR with the MAPK kinase (MEK) inhibitor, PD-98059, inhibited the phosphorylation of Erk1/2 and abrogated the growth inhibitory effects of salmon CT, the accumulation of cells in G2, and the associated induction of p21(WAF1/CIP1). These data suggest that activation of Erk1/2 are downstream effectors of the insert -ve hCTR in modulating cell cycle progression.
