scholarly journals Dual Role of Src Homology Domain 2-Containing Inositol Phosphatase 2 in the Regulation of Platelet-Derived Growth Factor and Insulin-Like Growth Factor I Signaling in Rat Vascular Smooth Muscle Cells

Endocrinology ◽  
2003 ◽  
Vol 144 (9) ◽  
pp. 4204-4214 ◽  
Author(s):  
Toshiyasu Sasaoka ◽  
Kosei Kikuchi ◽  
Tsutomu Wada ◽  
Akira Sato ◽  
Hiroyuki Hori ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Phosphatase Activity ◽  
Mapk Pathway ◽  
Muscle Cells ◽  
Sh2 Domain ◽  
Pi3 Kinase ◽  
Inositol Phosphatase ◽  
Igf I

Abstract Src homology domain 2 (SH2)-containing inositol phosphatase 2 (SHIP2) possesses 5-phosphatase activity and an SH2 domain. The role of SHIP2 in platelet-derived growth factor (PDGF) and IGF-I signaling was studied by expressing wild-type (WT-) and a catalytically defective (ΔIP-) SHIP2 into rat aortic smooth muscle cells by adenovirus-mediated gene transfer. PDGF- and IGF-I-induced tyrosine phosphorylation of their respective receptors and phosphatidylinositol 3-kinase (PI3-kinase) activity were not affected by the expression of either WT- or ΔIP-SHIP2. SHIP2 possessed 5′-phosphatase activity to hydrolyze the PI3-kinase product phosphatidylinositol 3,4,5-trisphosphate in vivo. Akt and glycogen synthase kinase 3β are known to be downstream molecules of PI3-kinase, leading to the antiapoptotic effect. Overexpression of WT-SHIP2 inhibited PDGF- and IGF-I-induced phosphorylation of these molecules and the protective effect of poly(ADP-ribose) polymerase degradation, whereas these phosphorylations and the protective effect were enhanced by the expression of ΔIP-SHIP2, which functions in a dominant negative fashion. Regarding the Ras-MAPK pathway, PDGF- and IGF-I-induced tyrosine phosphorylation of Shc was not affected by the expression of either WT- or ΔIP-SHIP2, whereas both expressed SHIP2 associated with Shc. Importantly, PDGF and IGF-I stimulation of Shc/Grb2 binding, MAPK activation, and 5-bromo-2′-deoxyuridine incorporation were all decreased in both WT- and ΔIP-SHIP2 expression. These results indicate that SHIP2 plays a negative regulatory role in PDGF and IGF-I signaling in vascular smooth muscle cells. As the bifunctional role, our results suggest that SHIP2 regulates PDGF- and IGF-I-mediated signaling downstream of PI3-kinase, leading to the antiapoptotic effect via 5-phosphatase activity, and that SHIP2 regulates the growth factor-induced Ras-MAPK pathway mainly via the SH2 domain.

Regulation of insulin-like growth factor-I gene expression by growth factors in cultured vascular smooth muscle cells

1990 ◽  
Vol 125 (3) ◽  
pp. 381-386 ◽  
Author(s):  
K. E. Bornfeldt ◽  
H. J. Arnqvist ◽  
G. Norstedt
Keyword(s):  
Gene Expression ◽  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Basic Fgf ◽  
Aortic Smooth Muscle ◽  
Factor I ◽  
Igf I ◽  
I Gene

ABSTRACT The aim of this investigation was to study the regulation of insulin-like growth factor-I (IGF-I) gene expression in cultured rat aortic smooth muscle cells. Near-confluent cells were deprived of serum for 24 h and then exposed to IGF-I, insulin, serum, basic fibroblast growth factor (basic FGF), platelet-derived growth factor (PDGF-BB; consisting of B-chain homodimer) or GH for 24 h. Levels of IGF-I mRNA were measured by solution hybridization. The level of IGF-I mRNA was markedly decreased by 10% (v/v) newborn calf serum (78 ± 4 (s.e.m.) % decrease), 1 nmol basic FGF/1 (53 ± 8%), and 1 nmol PDGF-BB/1 (40 ± 3%) when measured after 24 h. The effect of PDGF-BB was significant after 6 h and became more marked after 24 h. GH (1 nmol/l or 0.1 μmol/l or insulin (1 nmol/l had no effect after 24 h, whereas IGF-I (1 nmol/l and insulin (10 μmol/l increased IGF-I mRNA 64 ± 20% and 46±14% respectively. The increase caused by IGF-I was demonstrated after 3 h, and was most marked after 24 h. Using Northern blot analysis of cultured aortic smooth muscle cells, IGF-I transcripts of 7-4, 1.7 and 1.1–0.8 kilobases were observed. Exposure of the cells to 10% serum, 1 nmol basic FGF/1 or 1 nmol PDGF-BB/1 for 48 h increased the cell number by 104 ±7%, 64 ± 3% and 61±22% respectively, while IGF-I, insulin and GH had little effect. In conclusion, IGF-I, and high concentrations of insulin, increased IGF-I mRNA in vascular smooth muscle cells, whereas factors which were stronger mitogens decreased IGF-I gene expression. Journal of Endocrinology (1990) 125, 381–386

Cyclic stretch activates p38 SAPK2-, ErbB2-, and AT1-dependent signaling in bladder smooth muscle cells

2000 ◽  
Vol 279 (4) ◽  
pp. C1155-C1167 ◽  
Author(s):  
Hiep T. Nguyen ◽  
Rosalyn M. Adam ◽  
Samuel H. Bride ◽  
John M. Park ◽  
Craig A. Peters ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Dna Synthesis ◽  
Mapk Pathway ◽  
Muscle Cells ◽  
Cyclic Stretch ◽  
Bladder Smooth Muscle ◽  
Erk Mapk

Cyclic mechanical stretch of bladder smooth muscle cells (SMC) increases rates of DNA synthesis and stimulates transcription of the gene for heparin-binding epidermal growth factor-like growth factor (HB-EGF), an ErbB1/EGF receptor ligand that has been linked to hypertrophic bladder growth. In this study we sought to clarify the signaling pathways responsible for mechanotransduction of the stretch stimulus. HB-EGF mRNA levels, DNA synthesis, and AP-1/Ets DNA binding activities were induced by repetitive stretch of primary culture rat bladder SMC. Inhibitors of the p38 SAPK2 pathway, the angiotensin receptor type 1 (AT1), and the ErbB2 tyrosine kinase reduced each of these activities, while an inhibitor of the extracellular signal-regulated kinase mitogen-activated protein kinase (Erk-MAPK) pathway had no effect. Stretch rapidly activated stress-activated protein kinase 2 (p38 SAPK2) and Jun NH2-terminal kinase (JNK)/SAPK pathways but not the Erk-MAPK pathway and induced ErbB2 but not ErbB1 phosphorylation. Angiotensin II (ANG II) a bladder SMC mitogen previously linked to the stretch response, did not activate ErbB2, and ErbB2 activation occurred in response to stretch in the presence of an ANG receptor inhibitor, indicating that activation of the AT1-mediated pathway and the ErbB2-dependent pathway occurs by independent mechanisms. p38 SAPK2 and JNK/SAPK signaling also appeared to be independent of the ErbB2 and AT1 pathways. These findings indicate that stretch-stimulated DNA synthesis and gene expression in normal bladder SMC occur via multiple independent receptor systems (e.g., AT1 and ErbB2) and at least one MAPK pathway (p38 SAPK2). Further, we show that the Erk-MAPK pathway, which in most systems is linked to receptor-dependent cell growth responses, is not involved in progression to DNA synthesis or in the response of the HB-EGF gene to mechanical forces.

IGF-I increases IGFBP-5 and collagen α1(I) mRNAs by the MAPK pathway in rat intestinal smooth muscle cells

2004 ◽  
Vol 286 (5) ◽  
pp. G777-G783 ◽  
Author(s):  
Xiping Xin ◽  
Yong Tai Hou ◽  
Lina Li ◽  
Phyllissa Schmiedlin-Ren ◽  
Gregory M. Christman ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Smooth Muscle ◽  
Crohn’S Disease ◽  
Smooth Muscle Cells ◽  
Mapk Pathway ◽  
Muscle Cells ◽  
Intestinal Smooth Muscle ◽  
Concurrent Treatment ◽  
Igf I ◽  
Docking Proteins

IGF-I is a potent fibrogenic growth factor that stimulates proliferation of intestinal smooth muscle cells and increases synthesis of collagen and IGF-I-binding proteins by the cells. These processes contribute to intestinal fibrosis that develops in patients with Crohn's disease and in Lewis-strain rats with experimental Crohn's disease. The aim of this study was to determine which early docking proteins are associated with IGF-I receptor signal transduction and which transduction pathway is involved in IGF-I-mediated gene regulation in intestinal smooth muscle cells. Primary cultures of smooth muscle cells isolated from the muscularis externa of the distal colon of Lewis rats were treated with IGF-I (100 ng/ml). Immunoprecipitation studies demonstrated that IGF-I stimulation resulted in tyrosine phosphorylation of IRS-1, IRS-2, and Shc. Coimmunoprecipitation demonstrated a close association between the IGF-I receptor and these three early docking proteins. Concurrent treatment with the MAPK inhibitor PD98059 (10 μM) resulted in an inhibition of the IGF-I-mediated increase in IGFBP-5 and collagen α1(I) mRNAs, while concurrent treatment with the phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin (100 nM) had no effect. In additional experiments, cells were transiently transfected with adenoviral vectors dominantly expressing inactive mutant Akt or constitutively expressing wild-type Akt. In both cases, the IGF-I-mediated increase in collagen I protein did not differ from that observed in control cultures that had been transfected with an adenoviral vector carrying the LacZ reporter gene. These results suggest that the MAPK pathway is key to IGF-I-mediated gene regulation in intestinal smooth muscle cells, whereas data do not suggest a role for the Akt-dependent pathway in our system.

scholarly journals Platelet-Derived Growth Factor BB Induces Nuclear Export and Proteasomal Degradation of CREB via Phosphatidylinositol 3-Kinase/Akt Signaling in Pulmonary Artery Smooth Muscle Cells

2006 ◽  
Vol 26 (13) ◽  
pp. 4934-4948 ◽  
Author(s):  
Chrystelle V. Garat ◽  
Dana Fankell ◽  
Paul F. Erickson ◽  
Jane E.-B. Reusch ◽  
Natalie N. Bauer ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Nuclear Export ◽  
Muscle Cells ◽  
Proteasomal Degradation ◽  
Akt Signaling ◽  
Pi3 Kinase ◽  
Platelet Derived Growth Factor ◽  
Chimeric Proteins

ABSTRACT Cyclic AMP response element binding protein (CREB) content is diminished in smooth muscle cells (SMCs) in remodeled pulmonary arteries from animals with pulmonary hypertension and in the SMC layers of atherogenic systemic arteries and cardiomyocytes from hypertensive individuals. Loss of CREB can be induced in cultured SMCs by chronic exposure to hypoxia or platelet-derived growth factor BB (PDGF-BB). Here we investigated the signaling pathways and mechanisms by which PDGF elicits depletion of SMC CREB. Chronic PDGF treatment increased CREB ubiquitination in SMCs, while treatment of SMCs with the proteasome inhibitor lactacystin prevented decreases in CREB content. The nuclear export inhibitor leptomycin B also prevented depletion of SMC CREB alone or in combination with lactacystin. Subsequent studies showed that PDGF activated extracellular signal-regulated kinase, Jun N-terminal protein kinase, and phosphatidylinositol 3 (PI3)-kinase pathways in SMCs. Inhibition of these pathways blocked SMC proliferation in response to PDGF, but only inhibition of PI3-kinase or its effector, Akt, blocked PDGF-induced CREB loss. Finally, chimeric proteins containing enhanced cyan fluorescent protein linked to wild-type CREB or CREB molecules with mutations in several recognized phosphorylation sites were introduced into SMCs. PDGF treatment reduced the levels of each of these chimeric proteins except for one containing mutations in adjacent serine residues (serines 103 and 107), suggesting that CREB loss was dependent on CREB phosphorylation at these sites. We conclude that PDGF stimulates nuclear export and proteasomal degradation of CREB in SMCs via PI3-kinase/Akt signaling. These results indicate that in addition to direct phosphorylation, proteolysis and intracellular localization are key mechanisms regulating CREB content and activity in SMCs.

Interaction of angiotensin II and the insulin-like growth factor system in vascular smooth muscle cells

1999 ◽  
Vol 277 (2) ◽  
pp. H499-H507 ◽  
Author(s):  
Thomas Gustafsson ◽  
Peter Andersson ◽  
Yun Chen ◽  
Jan Olof Magnusson ◽  
Hans J. Arnqvist
Keyword(s):  
Gene Expression ◽  
Smooth Muscle ◽  
Growth Factor ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Dna Synthesis ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Ang Ii ◽  
Igf I

We studied the effects and interactions of ANG II and the insulin-like growth factor (IGF) system in cultured rat aortic smooth muscle cells. ANG II (1 μM) and IGF-I (10 nM) stimulated both DNA and protein synthesis. The effects of the two peptides in combination were additive or more than additive. The AT1 receptor antagonist losartan (10 and 100 μM) blocked their synergistic effect on DNA synthesis. IGF binding protein (IGFBP)-1 inhibited the effect of IGF-I but not that of ANG II on DNA synthesis. IGF-I stimulated gene expression of IGFBP-2 and IGFBP-4. ANG II decreased IGF-I, IGFBP-2, and IGFBP-4 transcripts but increased the IGF-I receptor transcript. IGF-I and ANG II in combination had similar effects on gene expression as ANG II alone. The IGFBP-2 and IGFBP-4 peptides could be detected in the conditioned medium. Our results show that ANG II and IGF-I have synergistic effects on vascular smooth muscle cells and that they interact in several ways.

IGF-I increases bFGF-induced mitogenesis and upregulates FGFR-1 in rabbit vascular smooth muscle cells

1996 ◽  
Vol 270 (4) ◽  
pp. H1141-H1148 ◽  
Author(s):  
T. J. Reape ◽  
J. M. Kanczler ◽  
J. P. Ward ◽  
C. R. Thomas
Keyword(s):  
Smooth Muscle ◽  
Growth Factors ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Dna Synthesis ◽  
Fibroblast Growth Factor ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Fibroblast Growth ◽  
Igf I

Insulin-like growth factor-I (IGF-I) and basic fibroblast growth factor (bFGF) have both been implicated in the abnormal proliferation of vascular smooth muscle cells (VSMC) that occurs after injury to the arterial wall in vivo. We have investigated the effects of these growth factors on proliferation of rabbit aortic smooth muscle cells (RASMC) in vitro. IGF-I, in contrast to bFGF, is a weak mitogen for RASMC. However, when IGF-I (10 ng/ml) was added in combination with bFGF for 24 h, the effect of the two growth factors on DNA synthesis was synergistic at all concentrations tested (P > 0.001 compared with summed values of bFGF alone plus IGF-I alone), and this synergy was also observed at the level of RASMC proliferation (P < 0.001). Time-course experiments indicated that although bFGF was able to stimulate DNA synthesis after 16 h, activity peaked at 24 h, and a synergistic response with IGF-I was not observed before 24 h. Northern blot analysis demonstrated that IGF-I (10 ng/ml) could selectively upregulate fibroblast growth factor receptor-1 (FGFR-1) mRNA 4.0 +/- 0.24-fold (P < 0.001) without a significant effect on FGFR-2, and this induction in FGFR-1 mRNA occurs in a time- and dose-dependent manner. In addition, IGF-I increases FGFR-1 protein levels in RASMC 2.7 +/- 0.12-fold (P < 0.01), as demonstrated by Western blotting, and this upregulation occurs before the peak in DNA synthesis. These results suggest that IGF-I may be capable of increasing the responsiveness of VSMC to bFGF through modulation of FGFR-1.

scholarly journals Insulin-like growth factor-binding protein-5 stimulates growth of human intestinal muscle cells by activation of Gαi3

2009 ◽  
Vol 297 (6) ◽  
pp. G1232-G1238 ◽  
Author(s):  
Robert S. Flynn ◽  
Sunila Mahavadi ◽  
Karnam S. Murthy ◽  
John M. Kellum ◽  
John F. Kuemmerle
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
G Proteins ◽  
P38 Mapk ◽  
Muscle Growth ◽  
Muscle Cells ◽  
Insulin Like Growth Factor ◽  
Mapk Activation ◽  
Igf I

In human intestinal smooth muscle cells, endogenous insulin-like growth factor-I (IGF-I) regulates growth and IGF-binding protein-5 (IGFBP-5) expression. The effects of IGF-I are facilitated by IGFBP-5. We previously showed that IGFBP-5 acts independently of IGF-I in human intestinal muscle to stimulate proliferation and upregulate IGF-I production by activation of Erk1/2 and p38 MAPK. Thus a positive feedback loop exists between IGF-I and IGFBP-5, whereby both stimulate muscle growth and production of the other factor. In Crohn's disease, IGF-I and IGFBP-5 expression are increased and contribute to stricture formation through this effect on muscle growth. To determine the signaling pathways coupling IGFBP-5 to MAPK activation and growth, smooth muscle cells were isolated from muscularis propria of human intestine and placed into primary culture. Erk1/2 and p38 MAPK activation and type I collagen production were measured by immunoblot. Proliferation was measured by [3H]thymidine incorporation. Activation of specific G proteins was measured by ELISA. AG1024, an IGF-I receptor tyrosine kinase inhibitor, was used to isolate the IGF-I-independent effects of IGFBP-5. IGFBP-5-induced phosphorylation of Erk1/2 and p38 MAPK and proliferation were abolished by pertussis toxin, implying the participation of Gi. IGFBP-5 specifically activated Gi3 but not other G proteins. Transfection of an inhibitory Gαi minigene specifically inhibited MAPK activation, proliferation, and both collagen-I and IGF-I production. Our results indicate that endogenous IGFBP-5 activates Gi3 and regulates smooth muscle growth, IGF-I production, and collagen production via the α-subunit of Gi3, independently of IGF-I, in normal human intestinal muscle cells.

Endogenous IGF-I protects human intestinal smooth muscle cells from apoptosis by regulation of GSK-3β activity

2005 ◽  
Vol 288 (1) ◽  
pp. G101-G110 ◽  
Author(s):  
John F. Kuemmerle
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Smooth Muscle Cell ◽  
Caspase 3 ◽  
Muscle Cells ◽  
Pi3 Kinase ◽  
Intestinal Smooth Muscle ◽  
Igf I ◽  
Gsk 3Β ◽  
Dependent Mechanism

We have previously shown that endogenous IGF-I regulates human intestinal smooth muscle cell proliferation by activation of phosphatidylinositol 3 (PI3)-kinase- and Erk1/2-dependent pathways that jointly regulate cell cycle progression and cell division. Whereas insulin-like growth factor-I (IGF-I) stimulates PI3-kinase-dependent activation of Akt, expression of a kinase-inactive Akt did not alter IGF-I-stimulated proliferation. In other cell types, Akt-dependent phosphorylation of glycogen synthase kinase-3β (GSK-3β) inhibits its activity and its ability to stimulate apoptosis. The aim of the present study was to determine whether endogenous IGF-I regulates Akt-dependent GSK-3β phosphorylation and activity and whether it regulates apoptosis in human intestinal muscle cells. IGF-I elicited time- and concentration-dependent GSK-3β phosphorylation (inactivation) that was measured by Western blot analysis using a phospho-specific GSK-3β antibody. Endogenous IGF-I stimulated GSK-3β phosphorylation and inhibited GSK-3β activity (measured by in vitro kinase assay) in these cells. IGF-I-dependent GSK-3β phosphorylation and the resulting GSK-3β inactivation were mediated by activation of a PI3-kinase-dependent, phosphoinositide-dependent kinase-1 (PDK-1)-dependent, and Akt-dependent mechanism. Deprivation of serum induced β-catenin phosphorylation, increased in caspase 3 activity, and induced apoptosis of muscle cells, which was inhibited by either IGF-I or a GSK-3β inhibitor. Endogenous IGF-I inhibited β-catenin phosphorylation, caspase 3 activation, and apoptosis induced by serum deprivation. IGF-I-dependent inhibition of apoptosis, similar to GSK-3β activity, was mediated by a PI3-kinase-, PDK-1-, and Akt-dependent mechanism. We conclude that endogenous IGF-I exerts two distinct but complementary effects on intestinal smooth muscle cell growth: it stimulates proliferation and inhibits apoptosis. The growth of intestinal smooth muscle cells is regulated jointly by the net effect of these two processes.

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