Urokinase potentiates PDGF-induced chemotaxis of human airway smooth muscle cells

We investigated the chemotactic action of PDGF and urokinase on human airway smooth muscle (HASM) cells in culture. Cells were put in collagen-coated transwells with 8-μm perforations, incubated for 4 h with test compounds, then fixed, stained, and counted as migrated nuclei by microscopy. Cells from all culture conditions showed some basal migration (migration in the absence of stimuli during the assay), but cells preincubated for 24 h in 10% FBS or 20 ng/ml PDGF showed higher basal migration than cells quiesced in 1% FBS. PDGFBB, PDGFAA, and PDGFABwere all chemotactic when added during the assay. PDGF chemotaxis was blocked by the phosphatidyl 3′-kinase inhibitor LY-294002, the MEK inhibitor U-0126, PGE2, formoterol, pertussis toxin, and the Rho kinase inhibitor Y-27632. Urokinase alone had no stimulatory effect on migration of quiescent cells but caused a dose-dependent potentiation of chemotaxis toward PDGF. Urokinase also potentiated the elevated basal migration of cells pretreated in 10% FBS or PDGF. This potentiating effect of urokinase appears to be novel. We conclude that PDGF and similar cytokines may be important factors in airway remodeling by redistribution of smooth muscle cells during inflammation and that urokinase may be important in potentiating the response.

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Role of the JAK-STAT pathway in PDGF-stimulated proliferation of human airway smooth muscle cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00315.2001 ◽

2002 ◽

Vol 282 (6) ◽

pp. L1296-L1304 ◽

Cited By ~ 68

Author(s):

Amy R. Simon ◽

Satoe Takahashi ◽

Mariano Severgnini ◽

Barry L. Fanburg ◽

Brent H. Cochran

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Airway Smooth Muscle ◽

Airway Remodeling ◽

Muscle Cells ◽

Airway Smooth Muscle Cells ◽

Human Airway Smooth Muscle ◽

Asthmatic Patients ◽

Human Airway ◽

Stat Pathway

Airway remodeling, as manifested by an increase in airway smooth muscle mass, mucous gland hyperplasia, and subepithelial fibrosis, contributes to the airway hyperresponsiveness and fixed obstruction seen in some asthmatic patients. Here we investigated whether the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway contributes to platelet-derived growth factor (PDGF)-stimulated mitogenesis of human airway smooth muscle cells (HASMC). PDGF treatment of quiescent HASMC resulted in the rapid tyrosine phosphorylation and DNA binding of STAT1 and STAT3. This phosphorylation was blocked by inhibition of Src and JAK2 kinases. In addition, STAT activation by PDGF was found to be redox dependent. Moreover, PDGF-induced thymidine uptake was completely blocked by pretreatment of HASMC with the STAT kinase inhibitors AG-490, SU-6656, and PP2. Interestingly, the JAK pathway was required for HASMC mitogenesis independently of mitogen-activated protein kinase activation. Inhibition of the Src and JAK kinases blocked PDGF-stimulated gene expression of the STAT target genes cyclin D1 and c- myc. These results indicate that the JAK-STAT pathway contributes to PDGF-induced mitogenesis, and thus this pathway may be important in the airway remodeling seen in some asthmatic patients.

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Induction of early growth-response factor 1 by platelet-derived growth factor in human airway smooth muscle

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00190.2003 ◽

2004 ◽

Vol 286 (4) ◽

pp. L817-L825 ◽

Cited By ~ 17

Author(s):

Josephine Hjoberg ◽

Louis Le ◽

Amy Imrich ◽

Venkat Subramaniam ◽

Sheeba I. Mathew ◽

...

Keyword(s):

Transcription Factor ◽

Smooth Muscle ◽

Smooth Muscle Cells ◽

Airway Smooth Muscle ◽

Airway Remodeling ◽

Muscle Cells ◽

Airway Smooth Muscle Cells ◽

Human Airway Smooth Muscle ◽

Asthmatic Patients ◽

Human Airway

Platelet-derived growth factors (PDGF) may contribute to the activation and growth of smooth muscle that is characteristic of airway remodeling in asthmatic patients. Early growth response 1 (EGR-1) is a transcription factor that is induced in several cell types by PDGF and may mediate some of the effects of PDGF. We show that human airway smooth muscle cells in cell culture express EGR-1 ∼1 h after addition of PDGF. Analysis of the EGR-1 promoter indicates that a serum response element located between 663 and 654 bp 5′ to the ATG start site is essential for this induction. Serum response factor, E26 transcription factor-like protein 1, and serum protein 1 bind to this region. PDGF causes phosphorylation of ERK1/2 and is temporally associated with E26 transcription factor-like protein 1 phosphorylation. Finally, the specific ERK1/2 inhibitor U-0126 abolishes PDGF-induced expression of EGR-1 in these cells. On the basis of these data, we speculated that EGR-1 would be increased in airway smooth muscle of asthmatic patients compared with nonasthmatic controls. Using immunohistochemistry, we found that EGR-1 protein was expressed in airway smooth muscle cells and epithelial cells of asthmatic patients and nonasthmatic controls; however, there was no significant difference in the intensity of staining between groups. EGR-1 was similarly expressed in the lungs of mice with and without ovalbumin-induced airway inflammation; however, there was no difference between groups by immunohistochemistry and quantitative PCR. Although EGR-1 is induced by PDGF in human airway smooth muscle cells in cell culture, the role of EGR-1 in airway remodeling and asthma remains to be established.

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