scholarly journals IGF-I stimulation of proteoglycan synthesis by chondrocytes requires activation of the PI 3-kinase pathway but not ERK MAPK

2005 ◽  
Vol 389 (3) ◽  
pp. 723-729 ◽  
Author(s):  
Bela G. Starkman ◽  
John D. Cravero ◽  
Marcello Delcarlo ◽  
Richard F. Loeser
Keyword(s):  
Mapk Pathway ◽  
Signalling Pathway ◽  
Negative Regulator ◽  
Proteoglycan Synthesis ◽  
Human Articular Cartilage ◽  
Erk Mapk ◽  
Erk Phosphorylation ◽  
Igf I ◽  
Kinase Pathway ◽  
Stimulation Of

The IGF-I (insulin-like growth factor-I) signalling pathway responsible for regulation of proteoglycan synthesis in chondrocytes has not been defined and is the focus of the present study. Chondrocytes isolated from normal human articular cartilage were stimulated with IGF-I in monolayer culture or in suspension in alginate. IGF-I activated members of both the PI3K (phosphoinositide 3-kinase) pathway and the ERK (extracellular-signal-regulated kinase)/MAPK (mitogen-activated protein kinase) pathway. The PI3K inhibitors LY294002 and wortmannin blocked IGF-I-stimulated Akt phosphorylation without blocking ERK phosphorylation and this was associated with complete inhibition of proteoglycan synthesis. A decrease in IGF-I-stimulated proteoglycan synthesis was also observed upon inhibition of mTOR (mammalian target of rapamycin) and p70S6 kinase, both of which are downstream of Akt. The MEK (MAPK/ERK kinase) inhibitors PD98059 and U0126 blocked IGF-I-stimulated ERK phosphorylation but did not block the phosphorylation of Akt and did not decrease proteoglycan synthesis. Instead, in alginate- cultured chondrocytes, the MEK inhibitors increased IGF-I-stimulated proteoglycan synthesis when compared with cells treated with IGF-I alone. This is the first study to demonstrate that IGF-I stimulation of the PI3K signalling pathway is responsible for the ability of IGF-I to increase proteoglycan synthesis. Although IGF-I also activates the ERK/MAPK pathway, ERK activity is not required for proteoglycan synthesis and may serve as a negative regulator.

scholarly journals Expression of Spred2 in the urothelial tumorigenesis of the urinary bladder

2021 ◽  
Author(s):  
Shinsuke Oda ◽  
Masayoshi Fujisawa ◽  
Li Chunning ◽  
Toshihiro Ito ◽  
Takahiro Yamaguchi ◽  
...  
Keyword(s):  
Urothelial Carcinoma ◽  
Cancer Progression ◽  
Mapk Pathway ◽  
Negative Regulator ◽  
Mitogen Activated Protein Kinase ◽  
Ki67 Index ◽  
Erk Activation ◽  
Non Invasive ◽  
Erk Mapk

Aberrant activation of the Ras/Raf/ERK (extracellular-signal-regulated kinase)-MAPK (mitogen-activated protein kinase) pathway is involved in the progression of cancer, including urothelial carcinoma; but the negative regulation remains unclear. In the present study, we investigated pathological expression of Spred2 (Sprouty-related EVH1 domain-containing protein 2), a negative regulator of the Ras/Raf/ERK-MAPK pathway, and the relation to ERK activation and Ki67 index in various categories of 275 urothelial tumors obtained from clinical patients. In situ hybridization demonstrated that Spred2 mRNA was highly expressed in high-grade non-invasive papillary urothelial carcinoma (HGPUC), and the expression was decreased in carcinoma in situ (CIS) and infiltrating urothelial carcinoma (IUC). Immunohistochemically, membranous Spred2 expression, important to interact with Ras/Raf, was preferentially found in HGPUC. Interestingly, membranous Spred2 expression was decreased in CIS and IUC relative to HGPUC, while ERK activation and the expression of the cell proliferation marker Ki67 index were increased. HGPUC with membranous Spred2 expression correlated significantly with lower levels of ERK activation and Ki67 index as compared to those with negative Spred2 expression. Thus, our pathological findings suggest that Spred2 negatively regulates cancer progression in non-invasive papillary carcinoma possibly through inhibiting the Ras/Raf/ERK-MAPK pathway, but this regulatory mechanism is lost in cancers with high malignancy. Spred2 appears to be a key regulator in the progression of non-invasive bladder carcinoma.

scholarly journals Hyperglycemia Alters the Responsiveness of Smooth Muscle Cells to Insulin-Like Growth Factor-I

Endocrinology ◽  
2007 ◽  
Vol 148 (5) ◽  
pp. 2435-2443 ◽  
Author(s):  
Laura A. Maile ◽  
Byron E. Capps ◽  
Yan Ling ◽  
Gang Xi ◽  
David R. Clemmons
Keyword(s):  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Mapk Pathway ◽  
Extracellular Matrix Proteins ◽  
Matrix Proteins ◽  
Downstream Signaling ◽  
Igf I ◽  
Cell Migration And Proliferation ◽  
Stimulation Of ◽  
In Cells

IGF-I stimulation of smooth muscle cell (SMC) migration and proliferation requires αVβ3 ligand occupancy. We hypothesized that changes in the levels of extracellular matrix proteins induced by alterations in glucose concentrations may regulate the ability of SMCs to respond to IGF-I. IGF-I stimulated migration and proliferation of SMCs that had been maintained in 25 mm glucose containing media, but it had no stimulatory effect when tested using SMCs that had been grown in 5 mm glucose. IGF-I stimulated an increase in Shc phosphorylation and enhanced activation of the MAPK pathway in SMCs grown in 25 mm glucose, whereas in cells maintained in 5 mm glucose, IGF-I had no effect on Shc phosphorylation, and the MAPK response to IGF-I was markedly reduced. In cells grown in 25 mm glucose, the levels of αVβ3 ligands, e.g. osteopontin, vitronectin, and thrombospondin, were all significantly increased, compared with cells grown in 5 mm glucose. The addition of these αVβ3 ligands to SMCs grown in 5 mm glucose was sufficient to permit IGF-I-stimulated Shc phosphorylation and downstream signaling. Because we have shown previously that αVβ3 ligand occupancy is required for IGF-I-stimulated Shc phosphorylation and stimulation of SMC growth, our data are consistent with a model in which 25 mm glucose stimulates increases in the concentrations of these extracellular matrix proteins, thus enhancing αVβ3 ligand occupancy, which leads to increased Shc phosphorylation and enhanced cell migration and proliferation in response to IGF-I.

scholarly journals Regulation of the renal Na-HCO3 cotransporter. XI. Signal transduction underlying CO2stimulation

1999 ◽  
Vol 277 (4) ◽  
pp. F580-F586 ◽  
Author(s):  
Ofelia S. Ruiz ◽  
R. Brooks Robey ◽  
Yi-Yong Qiu ◽  
Long Jiang Wang ◽  
Cheng Jin Li ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Mapk Pathway ◽  
Selective Inhibitor ◽  
Src Family Kinases ◽  
Negative Regulator ◽  
Protein Tyrosine Kinases ◽  
Renal Epithelial Cells ◽  
Stimulation Of

We have previously shown that CO2 stimulation of the renal Na-HCO3 cotransporter (NBC) activity is abrogated by general inhibitors of protein tyrosine kinases. The more selective inhibitor herbimycin also blocked this effect at concentrations known to preferentially inhibit Src family kinases (SFKs). We therefore examined a role for SFKs in CO2-stimulated NBC activity. To this end, we engineered OK cells to express the COOH-terminal Src kinase (Csk), a negative regulator of SFKs. CO2 stimulated NBC activity normally in β-galactosidase-expressing and untransfected control cells. In contrast, Csk-expressing cells had normal baseline NBC activity that was not stimulated by CO2. CO2 stimulation increased both total SFK activity and specific tyrosine phosphorylation of Src. The specific MEK1/2 inhibitor PD-98059 completely inhibited the CO2 stimulation of NBC activity as well as the accompanying phosphorylation and activation of ERK1/2. Our data suggest the involvement of both SFKs, probably Src, and the “classic” MAPK pathway in mediating CO2-stimulated NBC activity in renal epithelial cells.

Hydrogen peroxide and epidermal growth factor activate phosphatidylinositol 3-kinase and increase sodium transport in A6 cell monolayers

2005 ◽  
Vol 288 (6) ◽  
pp. F1201-F1212 ◽  
Author(s):  
Nicolas Markadieu ◽  
Raphaël Crutzen ◽  
Daniel Blero ◽  
Christophe Erneux ◽  
Renaud Beauwens
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Sodium Transport ◽  
Kinase Activity ◽  
Mapk Pathway ◽  
Phosphatidylinositol 3 Kinase ◽  
Cell Monolayers ◽  
Epidermal Growth ◽  
Kinase Pathway ◽  
Stimulation Of

Activation of phosphatidylinositol 3-kinase (PI 3-kinase) is required for insulin stimulation of sodium transport in A6 cell monolayers. In this study, we investigate whether stimulation of the PI 3-kinase by other agents also provoked an increase in sodium transport. Both epidermal growth factor (EGF) and H2O2 provoked a rise in sodium transport that was inhibited by LY-294002, an inhibitor of PI 3-kinase activity. PI 3-kinase activity was estimated in extracts from A6 cell monolayers directly by performance of a PI 3-kinase assay. We also estimated the relative importance of the PI 3-kinase pathway by two different methods: 1) coprecipitation of the p85 regulatory subunit with anti-phosphotyrosine antibodies and 2) phosphorylation of PKB on both Ser 473 and Thr 308 residues observed by Western blotting. Since the mitogen-activated protein kinase (MAPK) pathway has also been implicated in the regulation of sodium transport, we also investigated whether this pathway is turned on by insulin, H2O2, or EGF. Phosphorylation of ERK1/2 was increased only transiently by insulin and H2O2 but quite sustainedly by EGF. Inhibitors of this pathway (U-0126 and PD-98059) failed to affect the insulin and H2O2 stimulation of sodium transport but increased substantially the stimulation induced by EGF. The latter effect was associated with an increase in PKB phosphorylation, thus suggesting that the stimulation of the MAPK pathway prevents, in part, the stimulation of the PI 3-kinase pathway in the transport of sodium stimulated by EGF.

Roles of CD19 Molecules That Suppress Proliferation and Induce Apoptosis in Human Myeloma Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4843-4843
Author(s):  
Xu Zheng ◽  
Hideaki Ishikawa ◽  
Naohiro Tsuyama ◽  
Saeid Abroun ◽  
Shangqin Liu ◽  
...  
Keyword(s):  
B Cell ◽  
Plasma Cells ◽  
Mapk Pathway ◽  
Myeloma Cell ◽  
Negative Regulator ◽  
Myeloma Cells ◽  
P70s6 Kinase ◽  
Igf I ◽  
Cd19 Expression ◽  
Human Myeloma Cells

Abstract CD19 is a B cell-specific membrane protein belonging to immunoglobulin superfamily, and acts as a positive or negative regulator in B cell signaling. Although plasma cells still express CD19, CD19 expression is lost in malignant plasma cells with the progression of multiple myeloma (MM) including monoclonal gammopathy of undermined significance (MGUS). To understand the pathological significance of loss of CD19 in human myelomas, we examined the biological effect of CD19 expression on myeloma cells by generating CD19 transfectants of a myeloma cell line, U266. CD19 transfectants showed slower growth rate in vitro than controls, such as mock and ΔCD19 transected with a truncated form of CD19. The growth-inhibitory effect was CD19-specific and presumably due to the intracellular signaling events via CD19 because this effect was not observed in ΔCD19. Furthermore, serum withdrawal rapidly induced the apoptosis of the CD19-transfectants that was rescued by insulin-like growth factor (IGF-I) as compared with CD19− controls. These may suggest that the CD19 transfectants are likely to be dependent on the growth factors, such as IGF-I, to survive and proliferate, and thus, susceptible to the serum deprivation-induced apoptosis. IGF-I activates extracellular signal-regulated kinase (ERK) 1/2 and phosphatidylinositol-3-kinase (PI-3K) that are important for proliferation of myeloma cells. Western bolt analysis showed that IGF-1-induced activation of ERK1/2 was reduced in the CD19 transfectants, although the similar levels of IGF-I receptors were expressed in the CD19 transfectants and CD19− controls. In contract, CD19 failed to inhibit the IGF-I-mediated PI-3K/AKT activation, whereas a downstream target in the PI-3K pathway, p70S6 kinase activation was decreased in the CD19 transfectants. However, the p70S6 kinase activity could be influenced by both ERK1/2 and PI-3K pathways after IGF-1 stimulation, and the MAPK pathway seems to be a major regulator for myeloma cell growth. Our results, therefore, suggest that the recovering expression of CD19 molecules and genes in human myeloma cells may be an important consideration in therapeutic approaches in human MM.

scholarly journals Berberine Modulates LPA Function to Inhibit the Proliferation and Inflammation of FLS-RA via p38/ERK MAPK Pathway Mediated by LPA1

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Hui Wang ◽  
Shenghao Tu ◽  
Sisi Yang ◽  
Pan Shen ◽  
Yao Huang ◽  
...  
Keyword(s):  
Lysophosphatidic Acid ◽  
Mapk Pathway ◽  
Specific Inhibitor ◽  
Healthy Controls ◽  
Cvd Risk ◽  
Protein Targets ◽  
Erk Mapk ◽  
Clinical Drug Development ◽  
Erk Phosphorylation ◽  
Promising Therapeutic Target

Objective. This study aimed to investigate whether berberine exerted anti-inflammatory and antiproliferative effects on the fibroblast-like synoviocytes of rheumatoid arthritis (FLS-RA) through regulating the lysophosphatidic acid (LPA) function. Methods. Firstly, the expression levels of LPA and lysophosphatidic acid receptor 1 (LPA1) in RA patients, osteoarthritis (OA) patients, and healthy controls were detected. Moreover, molecular docking was employed to characterize the binding sites of berberine in the predicted protein targets. Later, FLS-RA were stimulated using berberine, LPA, and the specific inhibitor (Ki16425) of LPA1, thereafter, the effects on the proliferation, apoptosis, the release of inflammatory mediators of FLS-RA, and the MAPK pathway were observed. Results. Compared with healthy controls (n = 25), the plasma LPA level (n = 28) and synovial fluid (n = 10) were markedly higher in RA patients. LPA1 was highly expressed in RA patients (n = 4) relative to that in OA patients (n = 4). Berberine remarkably inhibited the proliferation and the excessive production of IL-6 and TNF-α in FLS-RA, whereas suppressing the expression of K-ras, c-Raf, and p-38/ERK-phosphorylation. In addition, berberine inhibited the LPA-induced p-38/ERK-phosphorylation through binding to LPA1. Conclusions. LPA plays a certain role in promoting the proliferation and inflammation of FLS-RA. Berberine potentially modulates LPA function to suppress the proliferation and inflammation of FLS-RA through blocking the p38/ERK MAPK pathway mediated by LPA1. These findings suggest that, berberine possesses potential lipid-regulating, antiarthritis, and synovial hyperplasia inhibition activities against RA, which may provide a promising therapeutic target for the clinical drug development for RA patients with dyslipidemia and high CVD risk.

PKC isoenzymes differentially modulate the effect of thrombin on MAPK-dependent RPE proliferation

2008 ◽  
Vol 28 (6) ◽  
pp. 307-317 ◽  
Author(s):  
Jose P. Palma-Nicolas ◽  
Edith López ◽  
Ana María López-Colomé
Keyword(s):  
Cell Proliferation ◽  
Protein Kinase ◽  
Mapk Pathway ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Traumatic Injury ◽  
Mitogen Activated Protein Kinase ◽  
Erk Phosphorylation ◽  
Pkc Isoforms ◽  
Stimulation Of

Thrombin signalling through PAR (protease-activated receptor)-1 is involved in cellular processes, such as proliferation, differentiation and cell survival. Following traumatic injury to the eye, thrombin signalling may participate in disorders, such as PVR (proliferative vitreoretinopathy), a human eye disease characterized by the uncontrolled proliferation, transdifferentiation and migration of otherwise quiescent RPE (retinal pigment epithelium) cells. PARs activate the Ras/Raf/MEK/ERK MAPK pathway (where ERK is extracellular-signal-regulated kinase, MAPK is mitogen-activated protein kinase and MEK is MAPK/ERK kinase) through the activation of Gα and Gβγ heterotrimeric G-proteins, and the downstream stimulation of the PLC (phospholipase C)-β/PKC (protein kinase C) and PI3K (phosphoinositide 3-kinase) signalling axis. In the present study, we examined the molecular signalling involved in thrombin-induced RPE cell proliferation, using rat RPE cells in culture as a model system for PVR pathogenesis.  Our results showed that thrombin activation of PAR-1 induces RPE cell proliferation through Ras-independent activation of the Raf/MEK/ERK1/2 MAPK signalling cascade. Pharmacological analysis revealed that the activation of ‘conventional’ PKC isoforms is essential for proliferation, although thrombin-induced phosphorylation of ERK1/2 requires the activation of atypical PKCζ by PI3K. Consistently, thrombin-induced ERK1/2 activation and RPE cell proliferation were prevented completely by PI3K or PKCζ inhibition. These results suggest that thrombin induces RPE cell proliferation by joint activation of PLC-dependent and atypical PKC isoforms and the Ras-independent downstream stimulation of the Raf/MEK/ERK1/2 MAPK cascade. The present study is the first report demonstrating directly thrombin-induced ERK phosphorylation in the RPE, and the involvement of atypical PKCζ in this process.

scholarly journals Insulin-like growth factor I and II regulate the life cycle of trophoblast in the developing human placenta

2008 ◽  
Vol 294 (6) ◽  
pp. C1313-C1322 ◽  
Author(s):  
Karen Forbes ◽  
Melissa Westwood ◽  
Philip N. Baker ◽  
John D. Aplin
Keyword(s):  
Mapk Pathway ◽  
Indirect Evidence ◽  
First Trimester ◽  
Cell Populations ◽  
Placental Development ◽  
Igf I ◽  
Signaling Inhibitors ◽  
Phosphoinositide 3 Kinase ◽  
Kinase Pathway ◽  
Insulin Like Growth Factors

The main disorders of human pregnancy are rooted in defective placentation. Normal placental development depends on proliferation, differentiation, and fusion of cytotrophoblasts to form and maintain an overlying syncytiotrophoblast. There is indirect evidence that the insulin-like growth factors (IGFs), which are aberrant in pregnancy disorders, are involved in regulating trophoblast turnover, but the processes that control human placental growth are poorly understood. Using an explant model of human first-trimester placental villus in which the spatial and ontological relationships between cell populations are maintained, we demonstrate that cytotrophoblast proliferation is enhanced by IGF-I/IGF-II and that both factors can rescue cytotrophoblast from apoptosis. Baseline cytotrophoblast proliferation ceases in the absence of syncytiotrophoblast, although denuded cytotrophoblasts can proliferate when exposed to IGF and the rate of cytotrophoblast differentiation/fusion and, consequently, syncytial regeneration, increases. Use of signaling inhibitors suggests that IGFs mediate their effect on cytotrophoblast proliferation/syncytial formation through the MAPK pathway, whereas effects on survival are regulated by the phosphoinositide 3-kinase pathway. These results show that directional contact between cytotrophoblast and syncytium is important in regulating the relative amounts of the two cell populations. However, IGFs can exert an exogenous regulatory influence on placental growth/development, suggesting that manipulation of the placental IGF axis may offer a potential therapeutic route to the correction of inadequate placental growth.

scholarly journals Expression of Spred2 in the urothelial tumorigenesis of the urinary bladder

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0254289
Author(s):  
Shinsuke Oda ◽  
Masayoshi Fujisawa ◽  
Li Chunning ◽  
Toshihiro Ito ◽  
Takahiro Yamaguchi ◽  
...  
Keyword(s):  
Urothelial Carcinoma ◽  
Cancer Progression ◽  
Mapk Pathway ◽  
Negative Regulator ◽  
Mitogen Activated Protein Kinase ◽  
Ki67 Index ◽  
Erk Activation ◽  
Non Invasive ◽  
Erk Mapk

Aberrant activation of the Ras/Raf/ERK (extracellular-signal-regulated kinase)-MAPK (mitogen-activated protein kinase) pathway is involved in the progression of cancer, including urothelial carcinoma; but the negative regulation remains unclear. In the present study, we investigated pathological expression of Spred2 (Sprouty-related EVH1 domain-containing protein 2), a negative regulator of the Ras/Raf/ERK-MAPK pathway, and the relation to ERK activation and Ki67 index in various categories of 275 urothelial tumors obtained from clinical patients. In situ hybridization demonstrated that Spred2 mRNA was highly expressed in high-grade non-invasive papillary urothelial carcinoma (HGPUC), and the expression was decreased in carcinoma in situ (CIS) and infiltrating urothelial carcinoma (IUC). Immunohistochemically, membranous Spred2 expression, important to interact with Ras/Raf, was preferentially found in HGPUC. Interestingly, membranous Spred2 expression was decreased in CIS and IUC relative to HGPUC, while ERK activation and the expression of the cell proliferation marker Ki67 index were increased. HGPUC with membranous Spred2 expression correlated significantly with lower levels of ERK activation and Ki67 index as compared to those with negative Spred2 expression. Thus, our pathological findings suggest that Spred2 counters cancer progression in non-invasive papillary carcinoma possibly through inhibiting the Ras/Raf/ERK-MAPK pathway, but this regulatory mechanism is lost in cancers with high malignancy. Spred2 appears to be a key regulator in the progression of non-invasive bladder carcinoma.

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