scholarly journals Progesterone Inhibits the Estrogen-Induced Phosphoinositide 3-Kinase→AKT→GSK-3β→Cyclin D1→pRB Pathway to Block Uterine Epithelial Cell Proliferation

2005 ◽  
Vol 19 (8) ◽  
pp. 1978-1990 ◽  
Author(s):  
Bo Chen ◽  
Haiyan Pan ◽  
Liyin Zhu ◽  
Yan Deng ◽  
Jeffrey W. Pollard
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Epithelial Cell ◽  
Cyclin D1 ◽  
Nuclear Accumulation ◽  
Nuclear Antigen ◽  
Epithelial Cell Proliferation ◽  
Uterine Epithelial Cell ◽  
Gsk 3Β ◽  
Phosphoinositide 3 Kinase

Abstract The mammalian cell cycle is regulated by the cyclin/cyclin-dependent kinase (CDK) phosphorylation of the retinoblastoma (pRB) family of proteins. Cyclin D1 with its CDK4/6 partners initiates the cell cycle and acts as the link between extracellular signals and the cell cycle machinery. Estradiol-17β (E2) stimulates uterine epithelial cell proliferation, a process that is completely inhibited by pretreatment with progesterone (P4). Previously, we identified cyclin D1 localization as a key point of regulation in these cells with E2 causing its nuclear accumulation and P4 retaining it in the cytoplasm with the resultant inhibition of pRB phosphorylation. Here we show that E2 stimulates phosphoinositide 3-kinase to activate phosphokinase B/AKT to effect an inhibitory phosphorylation of glycogen synthase kinase (GSK-3β). This pathway is suppressed by P4. Inhibition of the GSK-3β activity in P4-treated uteri by the specific inhibitor, LiCl, reversed the nuclear accumulation of cyclin D1 and in doing so, caused pRB phosphorylation and the induction of downstream genes, proliferating cell nuclear antigen and Ki67. Conversely, inhibition of phosphoinositide 3 kinase by LY294002 or Wortmanin reversed the E2-induced GSK-3β Ser9 inhibitory phosphorylation and blocked nuclear accumulation of cyclin D1. These data show the reciprocal actions of E2 and P4 on the phosphoinositide 3-kinase through to the GSK-3β pathway that in turn regulates cyclin D1 localization and cell cycle progression. These data reveal a novel signaling pathway that links E2 and P4 action to growth factor-mediated signaling in the uterus.

scholarly journals The molecular basis of tamoxifen induction of mouse uterine epithelial cell proliferation

2005 ◽  
Vol 184 (1) ◽  
pp. 129-140 ◽  
Author(s):  
Haifan Zhang ◽  
Tim McElrath ◽  
Wei Tong ◽  
Jeffrey W Pollard
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Dna Synthesis ◽  
Cyclin D1 ◽  
Cyclin E ◽  
Cyclin A ◽  
Nuclear Accumulation ◽  
Maximal Response ◽  
Epithelial Cell Proliferation ◽  
Uterine Epithelial Cell

Tamoxifen, a selective estrogen modulator (SERM) that has found clinical utility in the treatment of breast cancer, is an antagonist in the breast and an agonist in the uterus. These agonist actions in the uterus lead to an increased risk of endometrial cancer. In this study in mice we have analyzed the mechanism of action of tamoxifen in inducing cell proliferation in the uterine luminal epithelia. Tamoxifen induces a wave of DNA synthesis in these epithelial cells with kinetics similar to those seen after 17β-estradiol (E2) treatment. However, by these criteria of mitogenicity, it is much less potent and never achieves full estrogenicity. This uterine epithelial cell proliferation is preceded by the mobilization of cyclin D1 from the cytoplasm to the nucleus which, together with CDK4, phosphorylates members of the Rb-retinoblastoma family of proteins, pRb and p107. Subsequent to this initial nuclear accumulation of cyclin D1, cyclin E and then cyclin A are induced that, together with the activation of CDK2, results in enhanced cyclin E- and cyclin A-dependent CDK2 kinase activity and further phosphorylation of pRb and p107. These actions of tamoxifen parallel those of E2. Tamoxifen also induced the classical estrogen water imbibition response. However, in this it was more potent, producing a maximal response at doses that do not affect DNA synthesis. This suggests that the uterotropic response is not an accurate predictor of the compound’s hyperplasia responses. We can conclude that, in its effects on proliferation, tamoxifen acts as a classical impeded estrogen and this suggests that the AF-1 transcription activation domain of the estrogen receptor that is activated upon both E2 and tamoxifen binding to this receptor regulates these responses in the uterus.

Cyclin kinase inhibitor p21CIP1/WAF1 limits interstitial cell proliferation following ureteric obstruction

1999 ◽  
Vol 277 (6) ◽  
pp. F948-F956 ◽  
Author(s):  
Jeremy Hughes ◽  
Paul Brown ◽  
Stuart J. Shankland
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Interstitial Cell ◽  
Tubular Epithelial Cell ◽  
Collagen I ◽  
Macrophage Infiltration ◽  
Nuclear Antigen ◽  
Epithelial Cell Proliferation ◽  
Ureteric Obstruction ◽  
Proliferation And Apoptosis

Tubulointerstitial renal injury induced by unilateral ureteric obstruction (UUO) is characterized by marked cell proliferation and apoptosis. Proliferation requires cell cycle transit that is positively regulated by cyclins and cyclin-dependent kinases (CDKs) and inhibited by the CIP/KIP family of cyclin-dependent kinase inhibitors (CKIs: p21, p27, and p57). We have shown that the absence of p27 results in markedly increased tubular epithelial cell proliferation and apoptosis following UUO (V. Ophascharoensuk, M. L. Fero, J. Hughes, J. M. Roberts, and S. J. Shankland. Nat. Med.4: 575–580, 1998). Since p21 mRNA is upregulated following UUO, we hypothesized that p21 would also serve to limit cell proliferation and apoptosis. We performed UUO in p21 +/+ and p21 −/− mice. Cell proliferation [bromodeoxyuridine (BrdU), proliferating cell nuclear antigen (PCNA)], apoptosis [terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method], interstitial myofibroblast accumulation (actin), macrophage infiltration (F4/80), and collagen I expression were quantified at days 3, 7, and 14. In contrast to p27 −/− mice, there was no difference in tubular epithelial cell proliferation or apoptosis between p21 −/− and p21 +/+ mice at any time point. However, interstitial cell proliferation at day 3 was significantly increased in p21 −/− mice [BrdU, 40.7 ± 1.9 cells/high-power field (cells/hpf) vs. 28.8 ± 2, P< 0.005], although, interestingly, no difference was seen in interstitial cell apoptosis. Actin/BrdU double staining demonstrated increased interstitial myofibroblast proliferation at day 3 in p21 −/− animals (10 ± 0.12 vs. 5.8 ± 0.11 cells/hpf, P < 0.05), which was followed by increased myofibroblast accumulation at day 7 in p21 −/− mice. No differences were detected in interstitial macrophage infiltration, collagen I deposition or transforming growth factor-β1 mRNA (in situ hybridization) expression. In conclusion p21, unlike p27, is not essential for the regulation of tubular epithelial cell proliferation and apoptosis following UUO, but p21 levels do serve to limit the magnitude of the early myofibroblast proliferation. This study demonstrates a differential role for the CKI p21 and p27 in this model.

Proliferation and repair of guinea pig tracheal epithelium after neuropeptide depletion and injury in vivo

1997 ◽  
Vol 273 (6) ◽  
pp. L1235-L1241 ◽  
Author(s):  
John S. Kim ◽  
Valerie S. McKinnis ◽  
Kimberly Adams ◽  
Steven R. White
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Mucosal Injury ◽  
Nuclear Antigen ◽  
Airway Epithelial ◽  
Epithelial Cell Proliferation ◽  
Injury Site ◽  
And Migration

Neuropeptides stimulate airway epithelial cell proliferation and migration in vitro, but the role of neuropeptides in the repair of the epithelium after injury in vivo is not clear. We studied epithelial proliferation and repair in 83 male Hartley guinea pigs. Animals received capsaicin weekly for 3 wk to deplete airway neuropeptides. One week later, the dorsal aspect of the trachea was injured with a metal stylette. Animals were killed 1 h to 1 wk later, after which epithelial cell proliferation was assessed for the presence of proliferating cell nuclear antigen (PCNA). PCNA labeling was <3% in noninjured animals. PCNA labeling increased substantially in the first 72 h after injury in control animals but was significantly decreased in capsaicin-treated animals within and adjacent to the site of injury. PCNA labeling increased opposite to the injury site in both control and capsaicin animals over the first 72 h. We conclude that neuropeptide depletion significantly attenuates both epithelial cell proliferation and repair in the first 72 h after mechanical injury to the trachea. However, neuropeptide depletion did not slow the ultimate repair of tracheal mucosal injury. Proliferation of epithelial cells in response to injury occurs throughout the airway, even away from the injury site.

scholarly journals Tight function zonula occludens-3 regulates cyclin D1–dependent cell proliferation

2011 ◽  
Vol 22 (10) ◽  
pp. 1677-1685 ◽  
Author(s):  
Christopher T. Capaldo ◽  
Stefan Koch ◽  
Michael Kwon ◽  
Oskar Laur ◽  
Charles A. Parkos ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cyclin D1 ◽  
Epithelial Tissue ◽  
Binding Motif ◽  
Epithelial Cell Proliferation ◽  
Zonula Occludens ◽  
Evolutionarily Conserved ◽  
Dependent Cell ◽  
Regulatory Functions

Coordinated regulation of cell proliferation is vital for epithelial tissue homeostasis, and uncontrolled proliferation is a hallmark of carcinogenesis. A growing body of evidence indicates that epithelial tight junctions (TJs) play a role in these processes, although the mechanisms involved are poorly understood. In this study, we identify and characterize a novel plasma membrane pool of cyclin D1 with cell-cycle regulatory functions. We have determined that the zonula occludens (ZO) family of TJ plaque proteins sequesters cyclin D1 at TJs during mitosis, through an evolutionarily conserved class II PSD-95, Dlg, and ZO-1 (PDZ)-binding motif within cyclin D1. Disruption of the cyclin D1/ZO complex through mutagenesis or siRNA-mediated suppression of ZO-3 resulted in increased cyclin D1 proteolysis and G0/G1 cell-cycle retention. This study highlights an important new role for ZO family TJ proteins in regulating epithelial cell proliferation through stabilization of cyclin D1 during mitosis.

scholarly journals The ZO-1–associated Y-box factor ZONAB regulates epithelial cell proliferation and cell density

2003 ◽  
Vol 160 (3) ◽  
pp. 423-432 ◽  
Author(s):  
Maria S. Balda ◽  
Michelle D. Garrett ◽  
Karl Matter
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Tight Junctions ◽  
Cell Density ◽  
Mdck Cells ◽  
Nuclear Accumulation ◽  
Regulation Of Transcription ◽  
Epithelial Cell Proliferation ◽  
Nucleic Acid Binding ◽  
Nucleic Acid Binding Proteins

Epithelial tight junctions regulate paracellular permeability, restrict apical/basolateral intramembrane diffusion of lipids, and have been proposed to participate in the control of epithelial cell proliferation and differentiation. Previously, we have identified ZO-1–associated nucleic acid binding proteins (ZONAB), a Y-box transcription factor whose nuclear localization and transcriptional activity is regulated by the tight junction–associated candidate tumor suppressor ZO-1. Now, we found that reduction of ZONAB expression using an antisense approach or by RNA interference strongly reduced proliferation of MDCK cells. Transfection of wild-type or ZONAB-binding fragments of ZO-1 reduced proliferation as well as nuclear ZONAB pools, indicating that promotion of proliferation by ZONAB requires its nuclear accumulation. Overexpression of ZONAB resulted in increased cell density in mature monolayers, and depletion of ZONAB or overexpression of ZO-1 reduced cell density. ZONAB was found to associate with cell division kinase (CDK) 4, and reduction of nuclear ZONAB levels resulted in reduced nuclear CDK4. Thus, our data indicate that tight junctions can regulate epithelial cell proliferation and cell density via a ZONAB/ZO-1–based pathway. Although this regulatory process may also involve regulation of transcription by ZONAB, our data suggest that one mechanism by which ZONAB and ZO-1 influence proliferation is by regulating the nuclear accumulation of CDK4.

scholarly journals Intracellular Role for Sphingosine Kinase 1 in Intestinal Adenoma Cell Proliferation

2006 ◽  
Vol 26 (19) ◽  
pp. 7211-7223 ◽  
Author(s):  
Masataka Kohno ◽  
Michiko Momoi ◽  
Myat Lin Oo ◽  
Ji-Hye Paik ◽  
Yong-Moon Lee ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Epithelial Cell ◽  
Tumor Cell ◽  
Sphingosine Kinase ◽  
Sphingolipid Metabolism ◽  
Intestinal Tumor ◽  
Epithelial Cell Proliferation ◽  
Tumor Cell Proliferation ◽  
Adenoma Cell

ABSTRACT Sphingosine kinase (Sphk) enzymes are important in intracellular sphingolipid metabolism as well as in the biosynthesis of sphingosine 1-phosphate (S1P), an extracellular lipid mediator. Here, we show that Sphk1 is expressed and is required for small intestinal tumor cell proliferation in Apc Min/+ mice. Adenoma size but not incidence was dramatically reduced in Apc Min/+ Sphk −/ − mice. Concomitantly, epithelial cell proliferation in the polyps was significantly attenuated, suggesting that Sphk1 regulates adenoma progression. Although the S1P receptors (S1P1R, S1P2R, and S1P3R) are expressed, polyp incidence or size was unaltered in Apc Min/+ S1p2r −/ −, Apc Min/+ S1p3r −/ −, and Apc Min/+ S1p1r +/ − bigenic mice. These data suggest that extracellular S1P signaling via its receptors is not involved in adenoma cell proliferation. Interestingly, tissue sphingosine content was elevated in the adenomas of Apc Min/ + Sphk1 −/ − mice, whereas S1P levels were not significantly altered. Concomitantly, epithelial cell proliferation and the expression of the G1/S cell cycle regulator CDK4 and c-myc were diminished in the polyps of Apc Min/ + Sphk1 −/ − mice. In rat intestinal epithelial (RIE) cells in vitro, Sphk1 overexpression enhanced cell cycle traverse at the G1/S boundary. In addition, RIE cells treated with sphingosine but not C6-ceramide exhibited reduced cell proliferation, reduced retinoblastoma protein phosphorylation, and cyclin-dependent kinase 4 (Cdk4) expression. Our findings suggest that Sphk1 plays a critical role in intestinal tumor cell proliferation and that inhibitors of Sphk1 may be useful in the control of intestinal cancer.

412. The role of macrophages in regulating uterine epithelial cell proliferation

2008 ◽  
Vol 20 (9) ◽  
pp. 92
Author(s):  
A. S. Care ◽  
W. V. Ingman ◽  
M. J. Jasper ◽  
SA Robertson
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Diphtheria Toxin ◽  
Functional Markers ◽  
Epithelial Cell Proliferation ◽  
Uterine Epithelial Cells ◽  
Uterine Epithelial Cell ◽  
Macrophage Depletion ◽  
Embryo Attachment

During the oestrous cycle, uterine epithelial cells respond to ovarian steroid hormones by producing an array of cytokines and chemokines that cause macrophage recruitment into the uterus and regulate macrophage activation phenotype. In turn, growth factors and cytokines synthesised by macrophages potentially impact epithelial cell proliferation, secretory function and receptivity to embryo attachment. To investigate the hypothesis that uterine macrophages are essential contributors to the proliferation of uterine epithelial cells, we have used an ovariectomy and steroid replacement model in CD11b-DTR ‘Mac-terminator' mice. These mice are engineered for CD11b promoter-driven expression of the monkey diphtheria toxin (DT) receptor, allowing acute systemic ablation of macrophages by administration of human diphtheria toxin (DT). CD11b-DTR mice were ovariectomised, then 2–4 weeks later were primed with E 2, followed by administration of DT (25 ng/g, ip) to effect macrophage depletion, and BrDU to label proliferating cells. Control mice were given PBS instead of DT. Uterine tissues were stained with F4/80 to detect macrophages, and anti-BrDU to detect BrDU+ epithelial cell nuclei. DT treatment was associated with a depletion of >90% of F4/80+ uterine macrophages. However, the numbers of BrDU+ epithelial cells and the architecture of the luminal epithelial surface and abundance of epithelial glands were similar in control and DT-treated uterine tissues. These data suggest that resident macrophages may not be essential for oestrogen-driven uterine epithelial cell proliferation. In ongoing experiments we are assessing the effect of macrophage depletion on epithelial cell expression of functional markers including those involved in regulation of embryo attachment.

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