RAPID COMMUNICATION
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Abstract |
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Abstract
Introduction
Materials & Methods
Results
Discussion
References
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We have demonstrated that extracellular signal-regulated kinases (ERKs) and cyclin D1 are required for bovine tracheal myocyte DNA synthesis. We hypothesized that catalytic activation by ERKs may regulate cyclin D1 expression in these cells. To test this hypothesis, we examined the effects of two inhibitors of ERKs and two reagents that increase the level of activated ERKs on cyclin D1 protein abundance and promoter activity. ERK activity was inhibited either by PD98059, a synthetic inhibitor of mitogen-activated protein kinase (MAPK)/ERK kinase (MEK), the upstream signaling intermediate required and sufficient for ERK activation, or by transient transfection with a dominant-negative mutant of MEK1 (MEK-2A). The level of activated ERKs was increased by transient transfection with either a constitutively active form of MEK1 (MEK-2E) or wild-type ERK2 (MAPKwt). Cyclin D1 expression was assessed either by immunoblot or cotransfection with the full-length cyclin D1 promoter subcloned into a luciferase reporter. We found that pretreatment of bovine tracheal myocytes with PD98059 significantly attenuated platelet- derived growth factor (PDGF)-induced cyclin D1 protein abundance. Furthermore, transfection with MEK-2A reduced PDGF-induced cyclin D1 promoter activity. Finally, transfection with either MEK-2E or MAPKwt induced cyclin D1 promoter activity in the absence of growth factor treatment. We conclude that catalytic activation of ERKs regulates cyclin D1 expression in airway smooth-muscle cells.
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Introduction |
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Abstract
Introduction
Materials & Methods
Results
Discussion
References
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Extracellular signal-regulated kinases (ERKs) are cytosolic serine/threonine kinases of the mitogen-activated protein kinase superfamily. Two ERK isoforms, p44ERK1 and p42ERK2, require concurrent tyrosine and threonine phosphorylation for maximal activation (1). Activated ERKs, which may translocate from the cytoplasm to the nucleus after mitogenic stimulation (2, 3), have been demonstrated to induce phosphorylation or associate with numerous nuclear transcription factors (4). Thus, ERKs have the potential for directly regulating gene expression.
We (15) and others (16, 17) have demonstrated that ERK activation requires the catalytic activation of mitogen-activated protein kinase (MAPK)/ERK kinase-1 (MEK1), a 45-kD dual-specificity kinase capable of phosphorylating tyrosine and serine/threonine residues. Activation of MEK1 also appears to be sufficient for ERK activity (15). We have demonstrated that inhibition of MEK1 and ERK activity attenuates platelet-derived growth factor (PDGF)- induced DNA synthesis in bovine tracheal myocytes, strongly suggesting that activation of MEK1 and ERKs is required S-phase traversal in these cells (15).
The D-type cyclins (cyclins D1, D2, and D3) are thought to be key regulators of G1 progression in mammalian cells. Cyclin D1 and its protein partner, the serine/threonine kinase cyclin-dependent kinase-4 (cdk4), are induced as part of the delayed early response to mitogenic stimulation (18). Once activated, cdk4 phosphorylates the 110-kD retinoblastoma protein (21). Rb phosphorylation, in turn, releases the transcription factors E2F1 through 3, which induce the expression of genes required for DNA synthesis (22). We have shown in bovine tracheal myocytes that mitogenic stimulation with PDGF induces cyclin D1 transcriptional activation and protein synthesis, as well as phosphorylation of Rb (23). Furthermore, microinjection of cells with a neutralizing antibody against cyclin D1 inhibits serum-induced S-phase traversal, suggesting that cyclin D1 is required for DNA synthesis in these cells. The association of sustained ERK activation and cyclin D1 expression following PDGF stimulation, as well as the requirement of both ERKs and cyclin D1 for S-phase traversal, suggest that cyclin D1 is a key downstream target of ERKs, and that downstream transcription factor targets of ERKs regulate cyclin D1 promoter transcriptional activity.
In the present study, we tested the hypothesis that ERKs regulate cyclin D1 expression. To accomplish this, we examined the effects of two inhibitors of ERKs and two reagents that increase the level of activated ERKs on cyclin D1 transcriptional activation and synthesis. First, we inhibited ERK activity using a synthetic inhibitor of MEKs, PD98059 [2-(2'-amino-3'-methoxyphenol)-oxanaphthalen-4-one]. PD98059 has been shown to inhibit the activation of ERK1 by MEK1 in vitro (24) and to inhibit ERK activity in vivo (24, 25). We have shown that PD98059 inhibits PDGF-induced activation of endogenous MEK1 and ERKs in bovine tracheal myocytes. PD98059 had no discernible effect on the activation of two additional protein kinases, Src and Raf-1, suggesting that it is a specific inhibitor in this cell system (15). Second, we inhibited or activated ERK by transient transfection with expression vectors encoding either a dominant-negative mutant or constitutively active form of MEK1. The dominant-negative MEK1 (MEK-2A) is a MEK1 protein in which alanine has been substituted for serine at the Ser218 and Ser222 sites; the constitutively active MEK1 (MEK-2E) is a MEK1 protein in which glutamic acid has been substituted for serine at the 218 and 222 sites (17). Because these serine phosphorylation sites are required for activation of MEK1, alanine substitution prevents activation; whereas glutamate substitution, which mimics phosphorylation, confers constitutive activation. We have demonstrated that these expression vectors are functional in bovine tracheal myocytes, and that the dominant-negative and constitutively active forms of MEK1 inhibit and activate ERK activity, respectively (15). Finally, we transiently transfected cells with an expression vector that overexpresses wild-type ERK2 (MAPKwt). Our data indicate that catalytic activation of ERKs regulates cyclin D1 expression in airway smooth-muscle cells.
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Materials and Methods |
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Abstract
Introduction
Materials & Methods
Results
Discussion
References
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Cell Culture
Bovine tracheal smooth-muscle cells were isolated as described previously (26). Myocytes of passage number 5 or
less were studied. Confluent cultures exhibited the typical
"hill and valley" appearance under phase contrast microscopy and showed specific immunostaining with anti-
-smooth-muscle actin.
Preparation of Cell Extracts for Western Analyses of Cyclin D1 Protein Levels
Cell cultures in six-well plates were serum-starved by incubation in Dulbecco's modified Eagle's medium (DMEM)
for 24 h. At 16 h after treatment with the relevant stimulus, cells were washed with cold phosphate-buffered saline
(0.1 M phosphate, pH 7.5) and incubated with 100 ml of a
homogenization solution consisting of 50 mM 
-glycerophosphate (pH 7.4), 1 mM ethyleneglycol-bis-(-aminoethyl ether)-N,N'-tetraacetic acid, 1 mM dithiothreitol, 2 mM
phenylmethylsulfonyl fluoride, and 0.1 mM sodium orthovanadate. Homogenates were centrifuged (14,000 rpm for
10 min at 4°C), and the supernatant was transferred to a
microcentrifuge tube. To determine the requirement of
MEK1 and ERKs for cyclin D1 protein synthesis, cells were
treated with PDGF (30 ng/ml) and, when appropriate, PD98059 (3 to 100 µM).
Western Blotting
Extracts were resolved on a 10% sodium dodecyl sulfate-polyacrylamide gel and transferred to nitrocellulose by semidry transfer (Hoefer, San Francisco, CA). After incubation with polyclonal antibodies against cyclin D1 (Santa Cruz Biotechnology, Santa Cruz, CA), signals were amplified and visualized using antirabbit IgG (Sigma Chemical, St. Louis, MO) and enhanced chemiluminescence (Amersham Life Science, Arlington Heights, IL). Cyclin D1 signals were quantified by optical scanning.
Determination of Cyclin D1 Promoter Transcriptional Activity
Cells were transiently transfected with a plasmid encoding
the human cyclin D1 promoter subcloned into a luciferase
reporter. To construct this plasmid, a 1,882-base pair PvuII
fragment of the human cyclin D1 genomic clone was subcloned into the vector pA3 to form the reporter 
1745CD1LUC (27). Cells were seeded into 60-mm dishes at 50 to
80% confluence and incubated in 10% fetal bovine serum
(FBS)/DMEM overnight. After rinsing, cells were incubated
with a liposome solution consisting of serum- and antibiotic-free medium, plasmid DNA (total of 3.6 µg/plate), and Lipofectamine (12 µl/plate; Life Technologies, Gaithersburg, MD). After 4 h, the liposome solution was replaced
with 10% FBS/DMEM. The next day, cells were serum-starved in DMEM. At 8 h later, cells were treated with the
appropriate stimulus. Finally, 16 h after treatment, cells
were harvested for analysis of luciferase activity using lysis
buffer provided with the Promega Luciferase Assay system (Promega, Madison, WI). Luciferase activity was measured at room temperature using a luminometer (Turner
Designs, Sunnyvale, CA). Luciferase content was assessed
by measuring the light emitted during the initial 30 s of the
reaction, and the values were expressed in arbitrary light
units. The background activity from cell extracts was typically less than 0.02 units.
Cotransfection with cDNAs Encoding MEK1 Mutants and Wild-type ERK2
To determine the requirement and sufficiency of MEK1 and ERKs for cyclin D1 transcriptional activation, cells were cotransfected with CMV-driven expression vectors encoding mutant forms of MEK1 (MEK-2A and MEK-2E) and wild-type ERK2 (MAPKwt). These vectors were obtained from Dr. Dennis Templeton (17) and Dr. Roger Davis (28). Because cotransfection with the CMV promoter tends to reduce expression of the cotransfected vector (15), a concentration-response curve was generated for each MEK expression vector and the effect of the expression vectors on cyclin D1 promoter activity was compared with that of an equal amount of parental empty vector (either EE-CMV or pcDNA3). For MEK-2A, concentrations of 600 to 1,200 ng/plate were employed. For MEK-2E, concentrations of 30 to 50 ng/plate were used. For MAPKwt, concentrations of 50 to 200 ng/plate were used.
In previous experiments, we transiently cotransfected
cells with a plasmid encoding -galactosidase (pCMV-LacZ) to normalize cyclin D1 promoter activity for transfection efficiency (23). However, as noted previously, cotransfection with plasmids driven by the CMV promoter
tended to reduce cyclin D1 transcription. We have had
similar experiences with other viral promoters, including MLV, MSV, and SV40 (data not shown). Therefore, like
Albanese and colleagues (27), we compared the effect of
MEK expression vectors on cyclin D1 promoter activity
with that of an equal amount of parental empty vector,
and elected to omit normalization by -galactosidase.
Statistical Analysis
For individual experiments, all data were normalized to the control value. The effects of PD98059, MEK-2A, MEK-2E, and MAPKwt on cyclin D1 expression were assessed by one-way analysis of variance (ANOVA) with repeated measures. Differences identified by ANOVA were pinpointed by a Student-Newman-Keuls multiple-range test.
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Results |
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Abstract
Introduction
Materials & Methods
Results
Discussion
References
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A Synthetic MEK Inhibitor Attenuates PDGF-induced Cyclin D1 Protein Synthesis
As shown previously (23), immunoblots employing a polyclonal antibody against cyclin D1 demonstrated the appearance of cyclin D1 16 h after treatment with PDGF (30 ng/ml), a potent mitogen for these cells. Pretreatment with PD98059 attenuated cyclin D1 expression in a concentration-dependent fashion (Figure 1, top panel). A total of 30 µM PD98059 significantly reduced PDGF-induced cyclin D1 expression (Figure 1, bottom panel; P < 0.05).
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Expression of a Dominant-negative MEK1 Inhibits Cyclin D1 Transcriptional Activation
To determine whether catalytic activation of MEK1 and ERKs is required for cyclin D1 promoter transcriptional activity, cells were transiently cotransfected with plasmids encoding the full-length human cyclin D1 promoter subcloned into a luciferase reporter, as well as an expression vector encoding a dominant-negative MEK1 (MEK-2A). Control cells were cotransfected with the cyclin D1 promoter and empty vector (EE-CMV). Treatment with PDGF increased cyclin D1 promoter transcriptional activity almost 3-fold (Figure 2). Cotransfection with MEK-2A decreased PDGF-induced cyclin D1 promoter activity by approximately 70% (P < 0.05).
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Expression of Either a Constitutively Active MEK1 or a Wild-type ERK2 Induces Cyclin D1 Transcriptional Activation
To determine whether catalytic activation of MEK1 and ERKs is sufficient for cyclin D1 promoter transcriptional activity, cells were transiently cotransfected with plasmids encoding the full-length human cyclin D1 promoter subcloned into a luciferase reporter, and either an expression vector encoding a constitutively active MEK1 (MEK-2E) or wild-type ERK2 (MAPKwt). Control cells were cotransfected with the cyclin D1 promoter and empty vector (EE-CMV or pcDNA3). Cotransfection with either MEK-2E or MAPKwt significantly increased cyclin D1 promoter activation relative to control cells (Figure 3; P < 0.05). However, cyclin D1 transcriptional activation following cotransfection with MEK-2E or MAPKwt was significantly less than that obtained following PDGF treatment.
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Discussion |
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Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
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We have shown that two inhibitors of ERKs
PD98059, a
synthetic inhibitor of MEKs, and MEK-2A, a dominant-negative MEK1attenuate cyclin D1 expression in primary bovine tracheal myocytes. In addition, transfection
of cells with either a constitutively active form of MEK1 or
wild-type ERK2 each increased cyclin D1 transcriptional activation. Together, these results suggest that ERKs are
required and sufficient for cyclin D1 expression in airway
smooth muscle. Although similar results have been found
in immortalized cell lines (see subsequent discussion), this
is the first demonstration that catalytic activation of ERKs
regulates cyclin D1 expression in primary cells. We believe
this distinction to be an important one because many
transformed cells do not require exogenous signals for
growth, and therefore key regulatory pathways may be altered. Thus, it is conceivable that signaling intermediates
that are sufficient for particular outcomes in transformed
cells may not be so in primary cells.
The requirement and sufficiency of ERK activation for
cyclin D1 transcriptional activation has been shown previously in the trophoblast cell line JEG-3 (27, 29), the mink
lung epithelial cell line Mv1.Lu (27), and the Chinese hamster lung fibroblast cell line CCL39 (30). Albanese and colleagues (27) and Watanabe and coworkers (29) cotransfected cells with the full-length cyclin D1 promoter and
either a dominant-negative ERK2, wild-type ERK2, or
catalytically active MEK1. Expression of the mutant ERK decreased epidermal growth factor (EGF)-induced cyclin
D1 promoter activity by 40%, whereas expression of the
constitutively active MEK mutants or wild-type ERK increased cyclin D1 promoter activity 4- to 8-fold. By comparison, treatment with EGF (20 ng/ml) increased cyclin transcriptional activity 15- to 20-fold. Lavoie and colleagues (30) cotransfected cells with the 944 to +139 fragment of
the cyclin D1 promoter and a dominant-negative MEK1,
dominant-negative ERK1, or constitutively active MEK1.
Expression of the dominant-negatives reduced serum-
induced cyclin D1 promoter activity by 30 to 80%, whereas
expression of the constitutively active increased cyclin D1
transcriptional activity 6- to 10-fold. Addition of 10% serum further increased cyclin D1 promoter activity to a
level approximately 15-fold higher than that in untreated
control cells. In bovine tracheal myocytes, cotransfection
with the dominant-negative MEK decreased cyclin D1 expression by 70%, whereas transfection with the constitutively active MEK1 or wild-type ERK2 increased cyclin D1
transcriptional activity 2- to 3-fold. Consistent with previous studies, treatment with PDGF increased cyclin D1 promoter activity 3- to 4-fold. This additional increase in cyclin D1 promoter activity after growth factor treatment
suggests that although ERKs are required and sufficient
for cyclin D1 transcriptional activation, growth factors stimulate additional signaling pathways with distinct transcription factor targets and response elements in the cyclin D1
promoter. Indeed, it has been demonstrated that two alternative MAPKs, Jun amino-terminal kinase and the p38
high osmolarity glycerol kinase, may also regulate cyclin
D1 transcriptional activation (27, 30).
As noted previously, we and Albanese and colleagues (27) demonstrated increased cyclin D1 promoter activity after cotransfection with wild-type ERK2. The precise mechanism by which overexpression of an inactive, wild-type ERK increases transcriptional activation over control values is unclear, but may relate to residual MEK1 activity (perhaps due to growth factors in the culture medium). This "baseline" MEK1 activity may be sufficient to activate a subset of the overexpressed protein, leading to increased cyclin D1 promoter activity while still maintaining the capacity for further activity from added PDGF.
Activated ERKs have been shown to induce phosphorylation and increase the trans-activating functions of a
number of nuclear transcription factors, including transcription factors constituting the AP-1 complex (Jun, Fos,
Fra-1, and Fra-2), the Ets family transcription factors
(Elk-1, SAP1a, Ets-1, and Ets-2), ATF-2, C/EBP, and
Myc (4, 31). In previous studies, Albanese and colleagues (27) found that c-Jun and members of the Fos
family induced cyclin D1 promoter activity in JEG-3 trophoblasts and COS cells, suggesting that transcription factors constituting the AP-1 complex regulate cyclin D1 expression. In addition, transient cotransfection of JEG-3
trophoblasts with a complementary DNA (cDNA) encoding an activating c-Ets-2 expression vector induced cyclin
D1 promoter activity, whereas a dominant-negative Ets-2 decreased activity, suggesting that Ets transcription factors play a role in regulating cyclin D1 transcriptional activity. Thus, several different target transcription factors may be
involved in the induction of cyclin D1 transcriptional activation by ERKs.
We have previously demonstrated that MEK1, ERKs, and cyclin D1 are required for DNA synthesis in bovine airway smooth-muscle cells (15, 23). The requirement of ERKs and cyclin D1 for S-phase traversal in these primary cells is analogous to that described for various mammalian fibroblast cell lines (24, 32). In addition, it has recently been shown that inhibition of MEK1 and ERK activation with PD98059 inhibits DNA synthesis in rat airway smooth-muscle cells (35). These reports, together with our data suggesting that MEK1 and ERKs are required and sufficient for cyclin D1 expression in airway smooth muscle, strongly support the notion that ERK activation and cyclin D1 expression are elements of a distinct pathway required for DNA synthesis. However, the sufficiency of these molecules for inducing DNA synthesis in airway smooth muscle has not been tested.
It is important to recognize one limitation to our study. We did not demonstrate expression of the MEK1 mutants or wild-type ERK2 in transfected cells. However, we have already demonstrated successfully that the two MEK mutants appropriately inhibit and activate ERK2 in our system (15). Also, we are unable to think of a mechanism by which cotransfection of near-identical cDNAs encoding dominant-negative and constitutively active MEKs could alter cyclin D1 promoter activity in the appropriate directions without being expressed. We therefore believe that the data are reliable.
We conclude that catalytic activation of MEK1 and ERKs regulates cyclin D1 expression in airway smooth-muscle cells. Because abnormal airway smooth muscle proliferation may play a role in the pathogenesis of chronic, severe asthma (36), further studies examining the precise roles of these molecules in airway smooth muscle proliferation are warranted.
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Footnotes |
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Address correspondence to: Marc B. Hershenson, M.D., University of Chicago Children's Hospital, 5841 S. Maryland Ave., MC 4064, Chicago, IL 60637-1470. E-mail: mhershen{at}midway.uchicago.edu
(Received in original form August 25, 1997 and in revised form November 19, 1997).
Acknowledgments: The authors thank Dr. Marsha Rosner for her thoughtful advice and assistance during the course of this study. This work was supported by National Institutes of Health grants HL54685, HL56399 (M.B.H.), HL07605 (N.L.M.), CA13330, CA70897, and CA75503 (R.G.P.).
Abbreviations DMEM, Dulbecco's modified Eagle's medium; ERK(s), extracellular signal-regulated kinase(s); MAPK, mitogen-activated protein kinase; MEK, MAPK/ERK kinase; PDGF, platelet-derived growth factor.
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References |
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Abstract
Introduction
Materials & Methods
Results
Discussion
References
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  B. N. Kang, J. A. Jude, R. A. Panettieri Jr., T. F. Walseth, and M. S. Kannan Glucocorticoid regulation of CD38 expression in human airway smooth muscle cells: role of dual specificity phosphatase 1 Am J Physiol Lung Cell Mol Physiol, July 1, 2008; 295(1): L186 - L193. [Abstract] [Full Text] [PDF]
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 K.-K. Ho, A. A. Anderson, E. Rosivatz, E. W.-F. Lam, R. Woscholski, and D. J. Mann Identification of Cyclin A2 as the Downstream Effector of the Nuclear Phosphatidylinositol 4,5-Bisphosphate Signaling Network J. Biol. Chem., February 29, 2008; 283(9): 5477 - 5485. [Abstract] [Full Text] [PDF]
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 J. K. Bentley and M. B. Hershenson Airway Smooth Muscle Growth in Asthma: Proliferation, Hypertrophy, and Migration Proceedings of the ATS, January 1, 2008; 5(1): 89 - 96. [Abstract] [Full Text] [PDF]
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S. Xie, M. B. Sukkar, R. Issa, N. M. Khorasani, and K. F. Chung Mechanisms of induction of airway smooth muscle hyperplasia by transforming growth factor-beta Am J Physiol Lung Cell Mol Physiol, July 1, 2007; 293(1): L245 - L253. [Abstract] [Full Text] [PDF]
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K. G. Tirumurugaan, J. A. Jude, B. N. Kang, R. A. Panettieri, T. F. Walseth, and M. S. Kannan TNF-{alpha} induced CD38 expression in human airway smooth muscle cells: role of MAP kinases and transcription factors NF-{kappa}B and AP-1 Am J Physiol Lung Cell Mol Physiol, June 1, 2007; 292(6): L1385 - L1395. [Abstract] [Full Text] [PDF]
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Y. Osawa, D. Xu, D. Sternberg, J. R. Sonett, J. D'Armiento, R. A. Panettieri, and C. W. Emala Functional expression of the GABAB receptor in human airway smooth muscle Am J Physiol Lung Cell Mol Physiol, November 1, 2006; 291(5): L923 - L931. [Abstract] [Full Text] [PDF]
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 S. Mizuno, M. Kadowaki, Y. Demura, S. Ameshima, I. Miyamori, and T. Ishizaki p42/44 Mitogen-Activated Protein Kinase Regulated by p53 and Nitric Oxide in Human Pulmonary Arterial Smooth Muscle Cells Am. J. Respir. Cell Mol. Biol., August 1, 2004; 31(2): 184 - 192. [Abstract] [Full Text] [PDF]
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L. Zhou, A. Tan, S. Iasvovskaia, J. Li, A. Lin, and M. B. Hershenson Ras and Mitogen-Activated Protein Kinase Kinase Kinase-1 Coregulate Activator Protein-1- and Nuclear Factor-{kappa}B-Mediated Gene Expression in Airway Epithelial Cells Am. J. Respir. Cell Mol. Biol., June 1, 2003; 28(6): 762 - 769. [Abstract] [Full Text] [PDF]
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 K. Page, J. Li, L. Zhou, S. Iasvoyskaia, K. C. Corbit, J.-W. Soh, I. B. Weinstein, A. R. Brasier, A. Lin, and M. B. Hershenson Regulation of Airway Epithelial Cell NF-{kappa}B-Dependent Gene Expression by Protein Kinase C{delta} J. Immunol., June 1, 2003; 170(11): 5681 - 5689. [Abstract] [Full Text] [PDF]
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J. Li, X. D. Johnson, S. Iazvovskaia, A. Tan, A. Lin, and M. B. Hershenson Signaling intermediates required for NF-kappa B activation and IL-8 expression in CF bronchial epithelial cells Am J Physiol Lung Cell Mol Physiol, February 1, 2003; 284(2): L307 - L315. [Abstract] [Full Text] [PDF]
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J. Li, S. Kartha, S. Iasvovskaia, A. Tan, R. K. Bhat, J. M. Manaligod, K. Page, A. R. Brasier, and M. B. Hershenson Regulation of human airway epithelial cell IL-8 expression by MAP kinases Am J Physiol Lung Cell Mol Physiol, October 1, 2002; 283(4): L690 - L699. [Abstract] [Full Text] [PDF]
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K. Page, J. Li, K. C. Corbit, K. M. Rumilla, J.-W. Soh, I. B. Weinstein, C. Albanese, R. G. Pestell, M. R. Rosner, and M. B. Hershenson Regulation of Airway Smooth Muscle Cyclin D1 Transcription by Protein Kinase C-{delta} Am. J. Respir. Cell Mol. Biol., August 1, 2002; 27(2): 204 - 213. [Abstract] [Full Text] [PDF]
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 A. J. Ammit and R. A. Panettieri Jr. Signal Transduction in Smooth Muscle: Invited Review: The circle of life: cell cycle regulation in airway smooth muscle J Appl Physiol, September 1, 2001; 91(3): 1431 - 1437. [Abstract] [Full Text] [PDF]
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K. Page, J. Li, and M. B. Hershenson p38 MAP kinase negatively regulates cyclin D1 expression in airway smooth muscle cells Am J Physiol Lung Cell Mol Physiol, May 1, 2001; 280(5): L955 - L964. [Abstract] [Full Text] [PDF]
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C. P. Bauerfeld, M. B. Hershenson, and K. Page Cdc42, but not RhoA, regulates cyclin D1 expression in bovine tracheal myocytes Am J Physiol Lung Cell Mol Physiol, May 1, 2001; 280(5): L974 - L982. [Abstract] [Full Text] [PDF]
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J.-H. Lee, P. R. A. Johnson, M. Roth, N. H. Hunt, and J. L. Black ERK activation and mitogenesis in human airway smooth muscle cells Am J Physiol Lung Cell Mol Physiol, May 1, 2001; 280(5): L1019 - L1029. [Abstract] [Full Text] [PDF]
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K. Page, J. Li, Y. Wang, S. Kartha, R. G. Pestell, and M. B. Hershenson Regulation of Cyclin D1 Expression and DNA Synthesis by Phosphatidylinositol 3-Kinase in Airway Smooth Muscle Cells Am. J. Respir. Cell Mol. Biol., October 1, 2000; 23(4): 436 - 443. [Abstract] [Full Text]
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V. P. Krymskaya, M. J. Orsini, A. J. Eszterhas, K. C. Brodbeck, J. L. Benovic, R. A. Panettieri Jr., and R. B. Penn Mechanisms of Proliferation Synergy by Receptor Tyrosine Kinase and G Protein-Coupled Receptor Activation in Human Airway Smooth Muscle Am. J. Respir. Cell Mol. Biol., October 1, 2000; 23(4): 546 - 554. [Abstract] [Full Text]
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M. B. Hershenson and M. K. Abe Mitogen-Activated Signaling in Airway Smooth Muscle . A Central Role for Ras Am. J. Respir. Cell Mol. Biol., December 1, 1999; 21(6): 651 - 654. [Full Text]
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 E. T. NAURECKAS, I. MAURICE NDUKWU, A. J. HALAYKO, C. MAXWELL, M. B. HERSHENSON, and J. SOLWAY Bronchoalveolar Lavage Fluid from Asthmatic Subjects Is Mitogenic for Human Airway Smooth Muscle Am. J. Respir. Crit. Care Med., December 1, 1999; 160(6): 2062 - 2066. [Abstract] [Full Text]
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 A. G. Stewart, T. Harris, D. J. Fernandes, L. C. Schachte, V. Koutsoubos, E. Guida, C. E. Ravenhall, P. Vadiveloo, and J. W. Wilson beta 2-Adrenergic Receptor Agonists and cAMP Arrest Human Cultured Airway Smooth Muscle Cells in the G1 Phase of the Cell Cycle: Role of Proteasome Degradation of Cyclin D1 Mol. Pharmacol., November 1, 1999; 56(5): 1079 - 1086. [Abstract] [Full Text]
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 R. G. Pestell, C. Albanese, A. T. Reutens, J. E. Segall, R. J. Lee, and A. Arnold The Cyclins and Cyclin-Dependent Kinase Inhibitors in Hormonal Regulation of Proliferation and Differentiation Endocr. Rev., August 1, 1999; 20(4): 501 - 534. [Abstract] [Full Text] [PDF]
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K. Page, J. Li, J. A. Hodge, P. T. Liu, T. L. Vanden Hoek, L. B. Becker, R. G. Pestell, M. R. Rosner, and M. B. Hershenson Characterization of a Rac1 Signaling Pathway to Cyclin D1 Expression in Airway Smooth Muscle Cells J. Biol. Chem., July 30, 1999; 274(31): 22065 - 22071. [Abstract] [Full Text] [PDF]
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K. Page, J. Li, and M. B. Hershenson Platelet-Derived Growth Factor Stimulation of Mitogen-Activated Protein Kinases and Cyclin D1 Promoter Activity in Cultured Airway Smooth-Muscle Cells . Role of Ras Am. J. Respir. Cell Mol. Biol., June 1, 1999; 20(6): 1294 - 1302. [Abstract] [Full Text]
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R. J. Lee, C. Albanese, R. J. Stenger, G. Watanabe, G. Inghirami, G. K. Haines III, M. Webster, W. J. Muller, J. S. Brugge, R. J. Davis, et al. pp60v-src Induction of Cyclin D1 Requires Collaborative Interactions between the Extracellular Signal-regulated Kinase, p38, and Jun Kinase Pathways. A ROLE FOR cAMP RESPONSE ELEMENT-BINDING PROTEIN AND ACTIVATING TRANSCRIPTION FACTOR-2 IN pp60v-src SIGNALING IN BREAST CANCER CELLS J. Biol. Chem., March 12, 1999; 274(11): 7341 - 7350. [Abstract] [Full Text] [PDF]
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J. Glassford, M. Holman, L. Banerji, E. Clayton, G. G. B. Klaus, M. Turner, and E. W.-F. Lam Vav Is Required for Cyclin D2 Induction and Proliferation of Mouse B Lymphocytes Activated via the Antigen Receptor J. Biol. Chem., October 26, 2001; 276(44): 41040 - 41048. [Abstract] [Full Text] [PDF]
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