Growth factors downregulate vascular smooth muscle thromboxane receptors independent of cell growth

1992 ◽  
Vol 262 (4) ◽  
pp. C927-C933 ◽  
Author(s):  
G. W. Dorn ◽  
M. W. Becker
Keyword(s):  
Cell Proliferation ◽  
Smooth Muscle ◽  
Growth Factors ◽  
Growth Factor ◽  
Cell Growth ◽  
Vascular Smooth Muscle ◽  
Dna Synthesis ◽  
Thromboxane A2 ◽  
Rabbit Aorta ◽  
Thromboxane Receptors

Growth factors, in addition to being mitogenic, may modulate vascular smooth muscle differentiation. We tested whether serum or defined growth factors could regulate thromboxane A2 (TxA2) receptors in cultured rabbit aorta smooth muscle cells. Fetal bovine serum (10%) stimulated cell proliferation and DNA synthesis in subconfluent cell cultures. Binding of the thromboxane A2 agonist [1S-(1 alpha 2 beta(5Z),3 alpha(1E,3S),4 alpha)]-7-[3-(3-hydroxy-4-p- iodophenoxy-1-butenyl)-7-oxabicyclo[2.2.1]heptan-2-yl]-5-hep tenoic acid showed a 41% decrease in TxA2 receptors in cells treated with 10% serum compared with serum-deprived (0.1%) controls. Receptor downregulation by serum was gradually reversible upon serum withdrawal. Compared with serum-deprived cells, those exposed to 10% serum also had diminished TxA2-stimulated phosphatidylinositol hydrolysis. Regulatory actions of serum on TxA2 receptors were distinguished from mitogenic effects with heparin, which prevented cell growth but did not inhibit serum-induced downregulation of TxA2 receptors. Furthermore, low concentrations of platelet-derived growth factor and basic fibroblast growth factor decreased TxA2 receptors without stimulating cell proliferation or DNA synthesis. These observations describe a previously unrecognized regulatory action of growth factors on a vascular smooth muscle vasoconstrictor receptor, an action which is independent of effects on cell proliferation or DNA synthesis.

scholarly journals Ether-linked diglycerides inhibit vascular smooth muscle cell growth via decreased MAPK and PI3K/Akt signaling

2008 ◽  
Vol 295 (4) ◽  
pp. H1657-H1668 ◽  
Author(s):  
Kristy L. Houck ◽  
Todd E. Fox ◽  
Lakshman Sandirasegarane ◽  
Mark Kester
Keyword(s):  
Smooth Muscle ◽  
Growth Factors ◽  
Growth Factor ◽  
Cell Growth ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Inflammatory Cytokines ◽  
Muscle Cell ◽  
Akt Signaling ◽  
Smooth Muscle Cell Growth

Diglycerides (DGs) are phospholipid-derived second messengers that regulate PKC-dependent signaling pathways. Distinct species of DGs are generated from inflammatory cytokines and growth factors. Growth factors increase diacyl- but not ether-linked DG species, whereas inflammatory cytokines predominately generate alkyl, acyl- and alkenyl, acyl-linked DG species in rat mesenchymal cells. These DG species have been shown to differentially regulate protein kinase C (PKC) isotypes. Ester-linked diacylglycerols activate PKC-ε and cellular proliferation in contrast to ether-linked DGs, which lead to growth arrest through the inactivation of PKC-ε. It is now hypothesized that ether-linked DGs inhibit mitogenesis through the inactivation of ERK and/or Akt signaling cascades. We demonstrate that cell-permeable ether-linked DGs reduce vascular smooth muscle cell growth by inhibiting platelet-derived growth factor-stimulated ERK in a PKC-ε-dependent manner. This inhibition is specific to the ERK pathway, since ether-linked DGs do not affect growth factor-induced activation of other family members of the MAPKs, including p38 MAPK and c-Jun NH2-terminal kinases. We also demonstrate that ether-linked DGs reduce prosurvival phosphatidylinositol 3-kinase (PI3K)/Akt signaling, independent of PKC-ε, by diminishing an interaction between the subunits of PI3K and not by affecting protein phosphatase 2A or lipid (phosphatase and tensin homologue deleted in chromosome 10) phosphatases. Taken together, our studies identify ether-linked DGs as potential adjuvant therapies to limit vascular smooth muscle migration and mitogenesis in atherosclerotic and restenotic models.

scholarly journals Terminal complement proteins C5b-9 release basic fibroblast growth factor and platelet-derived growth factor from endothelial cells.

1994 ◽  
Vol 179 (3) ◽  
pp. 985-992 ◽  
Author(s):  
L R Benzaquen ◽  
A Nicholson-Weller ◽  
J A Halperin
Keyword(s):  
Cell Proliferation ◽  
Endothelial Cells ◽  
Smooth Muscle ◽  
Growth Factors ◽  
Growth Factor ◽  
Vascular Smooth Muscle ◽  
Fibroblast Growth Factor ◽  
Platelet Derived Growth Factor ◽  
Fibroblast Growth ◽  
Terminal Complement

Interactions between endothelium and vascular smooth muscle cells play a major role in the biology of the blood vessel wall. Growth factors released from endothelial cells control in part the normal and pathological proliferation of vascular smooth muscle cells. Endothelial deposits of C5b-9 proteins, the membrane attack complex of complement (MAC), have been found in a variety of pathological tissues in which cell proliferation is an early characteristic abnormality, including atherosclerosis. We have explored a possible bridging role for terminal complement C5b-9 proteins in eliciting focal signals for cell proliferation by releasing growth factors from endothelial cells. We found that both bovine aortic and human umbilical vein cells respond to the MAC by releasing basic fibroblast growth factor and platelet-derived growth factor. These mitogens stimulate DNA synthesis in Swiss 3T3, vascular smooth muscle, and glomerular mesangial cells. Based on these findings, we propose that complement-induced release of mitogens from endothelial cells is a novel pathogenic mechanism for proliferative disorders.

Modulation of thrombin and thrombin receptor peptide mitogenicity by human lung mast cell tryptase

1994 ◽  
Vol 267 (2) ◽  
pp. L113-L119 ◽  
Author(s):  
T. Hartmann ◽  
S. J. Ruoss ◽  
G. H. Caughey
Keyword(s):  
Mast Cell ◽  
Smooth Muscle ◽  
Growth Factors ◽  
Growth Factor ◽  
Vascular Smooth Muscle ◽  
Dna Synthesis ◽  
Human Lung ◽  
Thrombin Receptor ◽  
Mast Cell Tryptase

In previous studies, mast cell tryptase acted as a potent mitogen for fibroblasts from human lung and rodent embryonic tissue but failed to stimulate growth of cultured rat aortic vascular smooth muscle cells (VSMC). The current study shows that tryptase inhibits DNA synthesis in VSMC stimulated by thrombin. However, it does not affect the stimulation of DNA synthesis by the synthetic thrombin receptor peptide Ser-Phe-Phe-Leu-Arg-Asn-Pro (SFFLRNP), which mimics the amino-terminus of thrombin receptor proteolytically activated by thrombin. Nor does tryptase alter the mitogenic response of VSMC to purified growth factors, such as platelet-derived growth factor (PDGF). These data suggest that tryptase inhibits thrombin-induced DNA synthesis without interfering with intracellular mitogenic signaling pathways activated by thrombin or other growth factors. This study further suggests that tryptase neither cleaves nor inactivates thrombin. Therefore, inhibition of thrombin's mitogenic effects by tryptase is not mediated by destruction of thrombin itself. The inhibition by tryptase of thrombin-induced DNA synthesis in VSMC contrasts with the stimulatory effect of tryptase on fibroblasts, in which synergy is observed with thrombin, with thrombin receptor peptide and with other growth factors. These data provide in vitro evidence that mast cell tryptase interferes with thrombin-stimulated vascular smooth muscle growth and suggest that tryptase is a multifunctional growth factor whose actions are cell specific.

Abstract 1359: Only the Catalytic p110alpha Isoform Mediates Class IA PI 3-Kinase-Induced Atherogenic Signals in Vascular Smooth Muscle Cells

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Marius Vantler ◽  
Lenard Mustafov ◽  
Evren Caglayan ◽  
Stephan Rosenkranz
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Dna Synthesis ◽  
Vascular Smooth Muscle Cells ◽  
Fold Increase ◽  
And Migration ◽  
Induced Apoptosis ◽  
Stimulation Of

Proliferation, migration, and apoptosis of vascular smooth muscle cells (VSMC) are pivotal determinants of the pathogenesis of vascular diseases, which are mainly controlled by growth factor dependent activation of PI 3-Kinase (PI3K). Growth factors like platelet-derived growth factor (PDGF) activate class IA PI3Ks containing one of three p110 catalytic subunits (p110alpha, p110beta, and p110delta). We investigated the specific function of these isoforms for PDGF-controlled proliferation, migration, and apoptosis of VSMC using novel isoform-specific inhibitors. PDGF-dependent proliferation and migration solely depended on p110alpha. Stimulation of VSMC with PDGF-BB (50 ng/ml) mediated a 2.5±0.4 increase ( p <0.05) of DNA-synthesis (BrdU incorporation assay) and induced a 3.4+/−0.7 fold increase ( p <0.05) of VSMC migration (modified Boyden-chamber). Inhibition of p110alpha with PIK075 (1 μ M, Ki=100 nM) completely abrogated PDGF-dependent DNA-synthesis and migration ( p <0,05), whereas inhibitors against p110beta (TGX 221, 1 μ M) or p110delta (IC87114 1 μ M) had no influence. Consistently, PDGF-induced DNA-synthesis and migration were suppressed by siRNA-dependent downregulation of p110alpha ( p <0,05) whereas p110beta or p110delta knockdown had no effect. Interestingly, stimulation of VSMC with PDGF-BB (50 ng/ml) induced anti- or proapoptotic effects depending on the duration of PDGFR activation. Incubation of VSMC with H 2 O 2 (50 μ M, 16h) led to a 2.8±0.7 fold increase ( p >0.05) of apoptosis (Cell Death Detection ELISA). Simultanous addition of PDGF-BB (50 ng/ml) significantly diminished the H 2 O 2 -induced apoptosis (52±7%, p >0.05). In contrast, prestimulation with PDGF-BB 24h prior to the addition of H 2 O 2 led to an increase of H 2 O 2 -induced apoptosis (7.8±1.3, p >0.05). The anti- as well as the proapoptotic effect depended strictly on p110alpha as PIK075 (1 μ M, p <0,05) or p110alpha specific siRNA completely abrogated PDGF-BB-mediated pro- as well as antiapoptotic effects. Our results demonstrate that only the catalytical PI3K subunit p110alpha mediates the growth factor-induced atherogenic responses. Therefore, p110alpha represents an interesting therapeutic target for prevention of atherosclerosis and restenosis formation.

Abstract 315: Krüppel-like Factor 5 Promotes Vascular Remodeling in a Biphasic Manner by Inhibiting Vascular Smooth Muscle Cell Apoptosis and Stimulating Cell Growth

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Daigo Sawaki ◽  
Toru Suzuki ◽  
Kenichi Aizawa ◽  
Takayoshi Matsumura ◽  
Nanae Kada ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Smooth Muscle ◽  
Cell Growth ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Cyclin D1 ◽  
Muscle Cell ◽  
Vascular Smooth Muscle Cell ◽  
Vascular Remodeling ◽  
Neointimal Formation

Introduction: Vascular remodeling is characterized by cell proliferation and/or apoptosis with further phenotypic change of vascular cells. Vascular smooth muscle cell (VSMC)s, in particular, play a major role in the proliferative process such as neointimal formation and restenosis after angioplasty. In deciphering the transcriptional regulatory mechanisms in cardiovascular remodeling, Krüppel-like factor 5 (KLF5) was originally isolated as a regulatory factor of phenotypically modulated VSMCs. Past studies collectively have shown that KLF5 can induce cell growth pathologically in non-cardiovascular cells. However, how KLF5 contributes to vascular remodeling, notably its effects on apoptosis in the vascular lesion, had yet to be addressed. In the present study, we have aimed to address the effects of KLF5 not only on VSMC growth but also on apoptosis in vascular remodeling. Methods&Results: We performed adenoviral overexpression of KLF5 and other related factors after rat carotid balloon injury. In the early phase (48 hours after injury), KLF5 administered animals showed significantly decreased TUNEL positive cells in the medial layer. In the chronic phase (14 days after injury), apoptotic cells were recognized neither in the KLF5 animals nor in the others. While, neointimal formation and PCNA labeling index significantly increased in the KLF5 animals. Rat VSMCs transfected with KLF5 showed marked increase in cell proliferation and BrdU uptake. Additionally, cleavage of caspase-3 recognized in the quiescent VSMCs was attenuated after transfection of KLF5. Even under apoptotic stimulation using anisomysin, KLF5 overexpression resulted in significant inhibition of apoptosis induction. Further, KLF5 up-regulated gene expression of cell cycle factors such as cyclin D1, and conversely, knockdown of KLF5 by RNA interference showed down-regulation of cyclin D1 and impairment of VSMC proliferation. Conclusion: These findings taken together suggest that KLF5 plays a central role in VSMC proliferative pathologies such as vascular remodeling through biphasic contribution; inhibition of apoptosis and growth stimulation. Therapeutic intervention targeted against KLF5 may be potentially exploitable for VSMC proliferative pathology.

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