scholarly journals Transforming growth factor-β downregulates sGC subunit expression in pulmonary artery smooth muscle cells via MEK and ERK signaling

2019 ◽  
Vol 316 (1) ◽  
pp. L20-L34 ◽  
Author(s):  
Lili Du ◽  
Jesse D. Roberts
Keyword(s):  
Smooth Muscle ◽  
Lung Injury ◽  
Pulmonary Artery ◽  
Protein Expression ◽  
Erk Signaling ◽  
Type I ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Pulmonary Artery Smooth Muscle ◽  
Erk Activity

TGFβ activation during newborn lung injury decreases the expression of pulmonary artery smooth muscle cell (PASMC)-soluble guanylate cyclase (sGC), a critical mediator of nitric oxide signaling. Using a rat PASMC line (CS54 cells), we determined how TGFβ downregulates sGC expression. We found that TGFβ decreases sGC expression through stimulating its type I receptor; TGFβ type I receptor (TGFβR1) inhibitors prevented TGFβ-1-mediated decrease in sGCα1 subunit mRNA levels in the cells. However, TGFβR1-Smad mechanisms do not regulate sGC; effective knockdown of Smad2 and Smad3 expression and function did not protect sGCα1 mRNA levels during TGFβ-1 exposure. A targeted small-molecule kinase inhibitor screen suggested that MEK signaling regulates sGC expression in TGFβ-stimulated PASMC. TGFβ activates PASMC MEK/ERK signaling; CS54 cell treatment with TGFβ-1 increased MEK and ERK phosphorylation in a biphasic, time- and dose-dependent manner. Moreover, MEK/ERK activity appears to be required for TGFβ-mediated sGC expression inhibition in PASMC; MEK and ERK inhibitors protected sGCα1 mRNA expression in TGFβ-1-treated CS54 cells. Nuclear ERK activity is sufficient for sGC regulation; heterologous expression of a nucleus-retained, constitutively active ERK2-MEK1 fusion protein decreased CS54 cell sGCα1 mRNA levels. The in vivo relevance of this TGFβ-MEK/ERK-sGC downregulation pathway is suggested by the detection of ERK activation and sGCα1 protein expression downregulation in TGFβ-associated mouse pup hyperoxic lung injury, and the determination that ERK decreases sGCα1 protein expression in TGFβ-1-treated primary PASMC obtained from mouse pups. These studies identify MEK/ERK signaling as an important pathway by which TGFβ regulates sGC expression in PASMC.

scholarly journals Transforming growth factor-β stimulates Smad1/5 signaling in pulmonary artery smooth muscle cells and fibroblasts of the newborn mouse through ALK1

2017 ◽  
Vol 313 (3) ◽  
pp. L615-L627 ◽  
Author(s):  
Huili Zhang ◽  
Lili Du ◽  
Ying Zhong ◽  
Kathleen C. Flanders ◽  
Jesse D. Roberts
Keyword(s):  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Nuclear Localization ◽  
Muscle Cells ◽  
Proximity Ligation Assay ◽  
Type I ◽  
Newborn Mouse ◽  
Pulmonary Artery Smooth Muscle ◽  
Mouse Pup

The intracellular signaling mechanisms through which TGF-β regulates pulmonary development are incompletely understood. Canonical TGF-β signaling involves Smad2/3 phosphorylation, Smad2/3·Smad4 complex formation and nuclear localization, and gene regulation. Here, we show that physiologically relevant TGF-β1 levels also stimulate Smad1/5 phosphorylation, which is typically a mediator of bone morphogenetic protein (BMP) signaling, in mouse pup pulmonary artery smooth muscle cells (mPASMC) and lung fibroblasts and other interstitial lung cell lines. This cross-talk mechanism likely has in vivo relevance because mixed Smad1/5/8·Smad2/3 complexes, which are indicative of TGF-β-stimulated Smad1/5 activation, were detected in the developing mouse lung using a proximity ligation assay. Although mixed Smad complexes have been shown not to transduce nuclear signaling, we determined that TGF-β stimulates nuclear localization of phosphorylated Smad1/5 and induces the expression of prototypical BMP-regulated genes in the mPASMC. Small-molecule kinase inhibitor studies suggested that TGF-β-regulated Smad1/5 phosphorylation in these cells is mediated by TGF-β-type I receptors, not BMP-type I receptors, but possibly the accessory activin-like kinase (ALK1) receptor. Although work by others suggested that ALK1 is expressed exclusively in endothelial cells in the vasculature, we detected ALK1 mRNA and protein expression in mPASMC in vitro and in mouse pup lungs. Moreover, using an antimurine ALK1 antibody and mPASMC, we determined that ALK1 regulates Smad1/5 phosphorylation by TGF-β. Together, these studies characterize an accessory TGF-β-stimulated BMP R-Smad signaling mechanism in interstitial cells of the developing lung. They also indicate the importance of considering alternate Smad pathways in studies directed at determining how TGF-β regulates newborn lung development.

scholarly journals Hypoxia Up-Regulates Hypoxia-Inducible Factor-1α Transcription by Involving Phosphatidylinositol 3-Kinase and Nuclear Factor κB in Pulmonary Artery Smooth Muscle Cells

2007 ◽  
Vol 18 (12) ◽  
pp. 4691-4697 ◽  
Author(s):  
Rachida S. BelAiba ◽  
Steve Bonello ◽  
Christian Zähringer ◽  
Stefanie Schmidt ◽  
John Hess ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Promoter Activity ◽  
Hypoxia Inducible Factor ◽  
Nuclear Factor Κb ◽  
Mrna Levels ◽  
Nuclear Factor ◽  
Phosphatidylinositol 3 Kinase ◽  
Pulmonary Artery Smooth Muscle

The oxygen sensitive α-subunit of the hypoxia-inducible factor-1 (HIF-1) is a major trigger of the cellular response to hypoxia. Although the posttranslational regulation of HIF-1α by hypoxia is well known, its transcriptional regulation by hypoxia is still under debate. We, therefore, investigated the regulation of HIF-1α mRNA in response to hypoxia in pulmonary artery smooth muscle cells. Hypoxia rapidly enhanced HIF-1α mRNA levels and HIF-1α promoter activity. Furthermore, inhibition of the phosphatidylinositol 3-kinase (PI3K)/AKT but not extracellular signal-regulated kinase 1/2 pathway blocked the hypoxia-dependent induction of HIF-1α mRNA and HIF-1α promoter activity, suggesting involvement of a PI3K/AKT-regulated transcription factor. Interestingly, hypoxia also induced nuclear factor-κB (NFκB) nuclear translocation and activity. In line, expression of the NFκB subunits p50 and p65 enhanced HIF-1α mRNA levels, whereas blocking of NFκB by an inhibitor of nuclear factor-κB attenuated HIF-1α mRNA induction by hypoxia. Reporter gene assays revealed the presence of an NFκB site within the HIF-1α promoter, and mutation of this site abolished induction by hypoxia. In line, gel shift analysis and chromatin immunoprecipitation confirmed binding of p50 and p65 NFκB subunits to the HIF-1α promoter under hypoxia. Together, these findings provide a novel mechanism in which hypoxia induces HIF-1α mRNA expression via the PI3K/AKT pathway and activation of NFκB.

Regulation of serotonin-induced DNA synthesis of bovine pulmonary artery smooth muscle cells

1994 ◽  
Vol 266 (1) ◽  
pp. L53-L60 ◽  
Author(s):  
S. L. Lee ◽  
W. W. Wang ◽  
J. J. Lanzillo ◽  
B. L. Fanburg
Keyword(s):  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Dna Synthesis ◽  
Thymidine Incorporation ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Actin Mrna ◽  
Pulmonary Artery Smooth Muscle ◽  
Cellular Dna

We have previously reported that serotonin [5-hydroxytryptamine (5-HT)] stimulates DNA synthesis of bovine pulmonary artery smooth muscle cells (SMC) by its high-affinity uptake. Uptake inhibitors, but not selective 5-HT receptor antagonists, prevented the stimulatory effect (S.-L. Lee and B. L. Fanburg. J. Cell. Physiol. 150:396–405, 1992). We have now further evaluated the mechanism by which 5-HT enhances SMC DNA synthesis. Although some serotonergic agonists mimicked this stimulation, selective 5-HT receptor agonists produced no or only minor and variable stimulatory effects. The action of 5-HT was not inhibited by inhibitors of phospholipases C and A2, the protein kinase C (PKC) inhibitors dihydrosphingosine and 1-(-isoquinolinylsulfonyl)-2 methylpiperazine (H-7), or down-regulation of PKC with phorbol 12,13-dibutyrate. Staurosporine, a reputed PKC and tyrosine kinase (TK) inhibitor, and genistein, a selective TK inhibitor, reversed the stimulatory effect of 5-HT in a dose-dependent manner. Before stimulation of thymidine incorporation into cellular DNA, 5-HT elevated c-myc and actin mRNAs. Imipramine, fluoxetine, staurosporine, and cholera toxin inhibited the stimulations of both DNA synthesis and c-myc and actin mRNA expressions by 5-HT. Thus the data support a concept that 5-HT-induced thymidine incorporation by SMC involves membrane transport of 5-HT that initiates tyrosine phosphorylation.

Abstract P063: BMP-2 Upregulates PTEN Expression and Induces Apoptosis of Pulmonary Artery Smooth Muscle Cells Under Hypoxia

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Weifeng Pi ◽  
LiPing Su ◽  
Jian Zhu ◽  
Weiguo Xu
Keyword(s):  
Gene Expression ◽  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Protein Expression ◽  
Smooth Muscle Cells ◽  
Caspase 3 ◽  
Dose Dependence ◽  
Pten Expression ◽  
Pten Protein ◽  
Pulmonary Artery Smooth Muscle

Background: Primary pulmonary hypertension is mainly caused by increased proliferation and decreased apoptosis in pulmonary artery smooth muscle cells (PASMCs). Aim: To investigate the role of BMP-2 in regulation of PTEN and apoptosis of PASMCs under hypoxia. Methods: Normal human PASMCs were cultured in basal medium (BM) or growth medium (GM) and treated with BMP-2 from 5–80 ng/ml under hypoxia (5% CO 2 + 94% N 2 +1% O 2 ) for 72 hours. Gene expression of PTEN, caspase−3, −8, and −9, AKT-1 and -2 were determined by quantitative RT-PCR (QRT-PCR). Protein expression levels of PTEN, AKT and phosph-AKT (pAKT) were determined. Apoptosis of PASMCs were determined by measuring activities of caspases-3, -8 and -9. siRNA-smad-4 was used to determine whether Smad signaling pathway was involved in the regulation of PTEN expression by BMP-2. bpV(HOpic) (PTEN inhibitor) and GW9662 (PPAR-r antagonist) were also used. Results: Proliferation of PASMCs showed dose dependence of BMP-2, the lowest proliferative rate was achieved at 40–60ng/ml under hypoxia (BM=77.2±4%, GM=80±2.8%). Increased gene expression levels of PTEN, caspases−3, −8 and −9 were found, while AKT-1, and -2 did not change. Consistently, the PTEN protein expression also showed dose dependence of BMP-2. Though AKT was unchanged in all treated samples, reduced pAKT was found in BMP-2 treated PASMCs. Increased activities of caspase-3, -8 and -9 of PASMCs were found after cultured with BMP-2 in both mediums. PTEN expression was unchanged when Smad-4 expression was inhibited. However pre-treat PASMCs with bpV(HOpic) and GW9662 (PPAR-r inhibitor) inhibited PTEN protein expression and recovered PASMCs proliferation rate. Conclusion: BMP-2 can increase PTEN expression under hypoxia in a dose dependent pattern. BMP-2 can increase apoptosis of PASMCs under hypoxia. The increased PTEN expression may be mediated through PPAR-r signalling pathway, instead of BMP/Smad signalling pathway.

Tetrahydrobiopterin synthesis and inducible nitric oxide production in pulmonary artery smooth muscle

1994 ◽  
Vol 266 (4) ◽  
pp. L455-L460 ◽  
Author(s):  
D. K. Nakayama ◽  
D. A. Geller ◽  
M. Di Silvio ◽  
G. Bloomgarden ◽  
P. Davies ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Pulmonary Artery ◽  
De Novo ◽  
Interleukin 1 ◽  
No Production ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Pulmonary Artery Smooth Muscle ◽  
Inducible Nitric Oxide

We recently reported (Am. J. Respir. Cell Mol. Biol. 7: 471-476, 1992) that a mixture of lipopolysaccharide (LPS) and cytokines produced a time-dependent increase in mRNA and protein expression of inducible nitric oxide synthase (iNOS) in cultured rat pulmonary artery smooth muscle cells (RPASM). In the current study we extend observations on regulation of iNOS in RPASM by showing that de novo synthesis of tetrahydrobiopterin (BH4) is critical for LPS and cytokine-induced NO production. A mixture of LPS and the cytokines gamma-interferon, interleukin-1 beta, and tumor necrosis factor-alpha increased steady-state levels of mRNA of GTP-cyclohydrolase-I (GTP-CH), the rate-limiting enzyme in BH4 biosynthesis. Levels of mRNA to GTP-CH became detectable by 4 h, with further increases at 24 h by Northern blot analysis and reverse-transcriptase polymerase chain reaction. Total intracellular biopterin levels, undetectable under basal conditions, increased after 24 h exposure to LPS and cytokines (to 32.3 +/- 0.8 pmol/mg protein). LPS and cytokine-induced NO production, determined by nitrite concentrations in the medium, was decreased in a concentration-dependent manner by the GTP-CH inhibitor, 2,4-diamino-6-hydroxypyrimidine (DAHP) at 24 h. DAHP also inhibited completely the LPS- and cytokine-induced accumulation of intracellular biopterins. Sepiapterin, which supplies BH4 through a salvage pathway independent of GTP-CH, reversed the effect of DAHP on LPS and cytokine-induced NO production.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic mechanical stretch induces VEGF and FGF-2 expression in pulmonary vascular smooth muscle cells

2002 ◽  
Vol 282 (5) ◽  
pp. L897-L903 ◽  
Author(s):  
Timothy P. Quinn ◽  
Marielle Schlueter ◽  
Scott J. Soifer ◽  
Jorge A. Gutierrez
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Vascular Development ◽  
Muscle Cells ◽  
Mechanical Stretch ◽  
Cyclic Stretch ◽  
Dependent Manner ◽  
Pulmonary Artery Smooth Muscle

Vascular endothelial growth factor (VEGF) and basic (b) fibroblast growth factor (FGF-2/bFGF) are involved in vascular development and angiogenesis. Pulmonary artery smooth muscle cells express VEGF and FGF-2 and are subjected to mechanical forces during pulsatile blood flow. The effect of stretch on growth factor expression in these cells is not well characterized. We investigated the effect of cyclic stretch on the expression of VEGF and FGF-2 in ovine pulmonary artery smooth muscle cells. Primary confluent cells from 6-wk-old lambs were cultured on flexible silicon membranes and subjected to cyclic biaxial stretch (1 Hz; 5–25% stretch; 4–48 h). Nonstretched cells served as controls. Expression of VEGF and FGF-2 was determined by Northern blot analysis. Cyclic stretch induced expression of both VEGF and FGF-2 mRNA in a time- and amplitude-dependent manner. Maximum expression was found at 24 h and 15% stretch (VEGF: 1.8-fold; FGF-2: 1.9-fold). These results demonstrate that mechanical stretch regulates VEGF and FGF-2 gene expression, which could play a role in pulmonary vascular development or in postnatal pulmonary artery function or disease.

scholarly journals PDGF induces SphK1 expression via Egr-1 to promote pulmonary artery smooth muscle cell proliferation

2016 ◽  
Vol 310 (11) ◽  
pp. C983-C992 ◽  
Author(s):  
Justin R. Sysol ◽  
Viswanathan Natarajan ◽  
Roberto F. Machado
Keyword(s):  
Cell Proliferation ◽  
Transcription Factor ◽  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Protein Expression ◽  
Selective Inhibition ◽  
Pulmonary Vasculature ◽  
Sphingosine 1 Phosphate ◽  
Life Threatening ◽  
Pulmonary Artery Smooth Muscle

Pulmonary arterial hypertension (PAH) is a progressive, life-threatening disease for which there is currently no curative treatment available. Pathologic changes in this disease involve remodeling of the pulmonary vasculature, including marked proliferation of pulmonary artery smooth muscle cells (PASMCs). Recently, the bioactive lipid sphingosine-1-phosphate (S1P) and its activating kinase, sphingosine kinase 1 (SphK1), have been shown to be upregulated in PAH and promote PASMC proliferation. The mechanisms regulating the transcriptional upregulation of SphK1 in PASMCs are unknown. In this study, we investigated the role of platelet-derived growth factor (PDGF), a PAH-relevant stimuli associated with enhanced PASMC proliferation, on SphK1 expression regulation. In human PASMCs (hPASMCs), PDGF significantly increased SphK1 mRNA and protein expression and induced cell proliferation. Selective inhibition of SphK1 attenuated PDGF-induced hPASMC proliferation. In silico promoter analysis for SphK1 identified several binding sites for early growth response protein 1 (Egr-1), a PDGF-associated transcription factor. Luciferase assays demonstrated that PDGF activates the SphK1 promoter in hPASMCs, and truncation of the 5′-promoter reduced PDGF-induced SphK1 expression. Stimulation of hPASMCs with PDGF induced Egr-1 protein expression, and direct binding of Egr-1 to the SphK1 promoter was confirmed by chromatin immunoprecipitation analysis. Inhibition of ERK signaling prevented induction of Egr-1 by PDGF. Silencing of Egr-1 attenuated PDGF-induced SphK1 expression and hPASMC proliferation. These studies demonstrate that SphK1 is regulated by PDGF in hPASMCs via the transcription factor Egr-1, promoting cell proliferation. This novel mechanism of SphK1 regulation may be a therapeutic target in pulmonary vascular remodeling in PAH.

Propofol Attenuates Capacitative Calcium Entry in Pulmonary Artery Smooth Muscle Cells

2001 ◽  
Vol 95 (3) ◽  
pp. 681-688 ◽  
Author(s):  
Mayumi Horibe ◽  
Izumi Kondo ◽  
Derek S. Damron ◽  
Paul A. Murray
Keyword(s):  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Tyrosine Kinases ◽  
Muscle Tone ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Fura 2 ◽  
Anesthetic Agents ◽  
Pulmonary Artery Smooth Muscle

Background Depletion of intracellular Ca2+ stores results in capacitative Ca2+ entry (CCE) in pulmonary artery smooth muscle cells (PASMCs). The authors aimed to investigate the effects of propofol on CCE and to assess the extent to which protein kinase C (PKC) and tyrosine kinases mediate propofol-induced changes in CCE. Methods Pulmonary artery smooth muscle cells were cultured from explants of canine intrapulmonary artery. Fura 2-loaded PASMCs were placed in a dish (37 degrees C) on an inverted fluorescence microscope. Intracellular Ca2+ concentration was measured using fura 2 in PASMCs using a dual-wavelength spectrofluorometer. Thapsigargin (1 microM), a sarcoplasmic reticulum Ca2+-adenosine triphosphatase inhibitor, was used to deplete intracellular Ca2+ stores after removing extracellular Ca2+. CCE was activated when extracellular Ca2+ (2.2 mM) was restored. Results Thapsigargin caused a transient increase in intracellular Ca2+ concentration (182+/-11%). Restoring extracellular calcium (to induce CCE) resulted in a peak (246+/-12% of baseline) and a sustained (187+/-7% of baseline) increase in intracellular Ca2+ concentration. Propofol (1, 10, 100 microM) attenuated CCE in a dose-dependent manner (peak: 85+/-3, 70+/-4, 62+/-4%; sustained: 94+/-5, 80+/-5, 72+/-5% of control respectively). Tyrosine kinase inhibition (tyrphostin 23) attenuated CCE (peak: 67+/-4%; sustained: 74+/-5% of control), but the propofol-induced decrease in CCE was still apparent after tyrosine kinases inhibition. PKC activation (phorbol 12-myristate 13-acetate) attenuated CCE (peak: 48+/-1%; sustained: 53+/-3% of control), whereas PKC inhibition (bisindolylmaleimide) potentiated CCE (peak: 132+/-11%; sustained: 120+/-4% of control). Moreover, PKC inhibition abolished the propofol-induced attenuation of CCE. Conclusion Tyrosine kinases activate and PKC inhibits CCE in PASMCs. Propofol attenuates CCE primarily via a PKC-dependent pathway. CCE should be considered a possible cellular target for anesthetic agents that alter vascular smooth muscle tone.

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