Tight Junctions and the Regulation of Epithelial Cell Proliferation and Gene Expression

Explanted bladder epithelial cells from patients with interstitial cystitis (IC) have been shown to differ from explanted control cells in several ways, including production of an antiproliferative factor (APF), altered production of certain epithelial growth factors, and rate of proliferation. To better understand the role of the APF in abnormal bladder epithelial cell proliferation in IC, we studied gene expression patterns in normal bladder epithelial cells treated with APF vs. mock APF and compared them to expression patterns in IC vs. normal cells using microarray analysis. Oligo-dT-primed total cellular RNA was labeled with [33P]dCTP and hybridized to GeneFilter GF211 microarray membranes (Research Genetics) containing cDNA for 3,964 human genes. Thirteen genes that function in epithelial cell proliferation or differentiation were consistently differentially expressed in both IC (compared with control) and APF-treated (compared with mock APF-treated) normal bladder epithelial cells. The general pattern of gene expression in IC and APF-treated cells suggested a less proliferative phenotype, with increased expression of E-cadherin, phosphoribosylpyrophosphate synthetase-associated protein 39, and SWI/SNF complex 170-kDa subunit, and decreased expression of vimentin, α2-integrin, α1-catenin, cyclin D1, and jun N-terminal kinase 1; these findings were confirmed for the structural gene products (E-cadherin, vimentin, α2-integrin, and α-catenin) by immunohistochemistry. These results are compatible with the previously noted decreased proliferation rate of IC and APF-treated normal cells, and indicate that the mechanism whereby APF inhibits cell proliferation may involve both downregulation of genes that stimulate cell proliferation along with upregulation of genes that inhibit cell growth.

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Estrogen-dependent responses of the mammary fat pad in prepubertal dairy heifers

Journal of Endocrinology ◽

10.1677/joe.1.06883 ◽

2006 ◽

Vol 190 (3) ◽

pp. 819-827 ◽

Cited By ~ 18

Author(s):

M J Meyer ◽

A V Capuco ◽

Y R Boisclair ◽

M E Van Amburgh

Keyword(s):

Gene Expression ◽

Cell Proliferation ◽

Epithelial Cell ◽

Epithelial Cells ◽

Epithelial Cell Proliferation ◽

Fat Pad ◽

Dairy Heifers ◽

Ovarian Status ◽

Mammary Fat Pad ◽

Igf I

Ovaries are absolutely required for development of the mammary parenchyma (PAR) in cattle, reflecting estrogen-dependent epithelial cell proliferation. However, the estrogen receptor (ER) that mediates the mammary estrogen effects, ERα, is absent in proliferating epithelial cells. In the mouse, this discrepancy is explained in part by the ability of the mammary fat pad (MFP) to synthesize epithelial cell mitogens such as IGF-I in response to estrogen. Consistent with a similar role for the bovine MFP, 30% of its fibroblasts and adipocytes were immunoreactive for ERα in prepubertal dairy heifers. To assess estrogen-dependent gene expression in the MFP, 16 prepubertal dairy heifers were randomly assigned to a 2×2 factorial. The first factor was ovarian status, with heifers undergoing bilateral ovariectomy or left intact at 4.6 months of age. The second factor was applied 30 days after surgery and consisted of injection of estrogen or excipient. After 3 days of injection, heifers were administered an intrajugular bolus of bromodeoxyuridine (BrdU) and slaughtered 2 h later. The estrogen injection, but not ovarian status, caused significant increases in the fraction of epithelial cells labeled with BrdU and produced tissue-specific effects on gene expression. In the PAR, estrogen injection increased IGF-I gene expression by twofold despite reductions of 50% or more in ERα mRNA abundance and the fraction of epithelial cells immunoreactive for ERα. The estrogen-dependent increase in IGF-I mRNA was greater in the MFP, presumably because estrogen failed to downregulate ERα expression in this mammary compartment. Finally, estrogen-responsiveness of the MFP appears unique among the bovine fat depots as estrogen injection did not induce IGF-I expression in its s.c. counterpart. Our data demonstrate that the bovine MFP is highly responsive to exogenous estrogen, consistent with a role for this tissue compartment in communicating its effects on epithelial cell proliferation.

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

The Journal of Cell Biology ◽

10.1083/jcb.200210020 ◽

2003 ◽

Vol 160 (3) ◽

pp. 423-432 ◽

Cited By ~ 243

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.

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