Regulation of Estrogen Receptors and MMP-2 Expression by Estrogens in Human Retinal Pigment Epithelium
Invest. Ophthalmol. Vis. Sci.. 2003-01-01; 44(1): 50
DOI: 10.1167/iovs.01-1276
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1. Invest Ophthalmol Vis Sci. 2003 Jan;44(1):50-9. doi: 10.1167/iovs.01-1276.
Regulation of estrogen receptors and MMP-2 expression by estrogens in human
retinal pigment epithelium.
Marin-Castaño ME(1), Elliot SJ, Potier M, Karl M, Striker LJ, Striker GE, Csaky
KG, Cousins SW.
Author information:
(1)Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami
School of Medicine, 1638 NW 10th Avenue, Miami, FL 33136, USA.
PURPOSE: Age-related macular degeneration (ARMD) is characterized by progressive
thickening and accumulation of various lipid-rich extracellular matrix (ECM)
deposits under the retinal pigment epithelium (RPE). ECM dysregulation probably
contributes to the pathologic course of ARMD. By activating estrogen receptors
(ERs), estrogens regulate the expression of genes relevant in the turnover of
ECM, among them matrix metalloproteinase (MMP)-2. Estrogen deficiency may
predispose to dysregulated synthesis and degradation of ECM, leading to
accumulation of collagens and other proteins between the RPE and its basement
membrane. The purposes in the current study were to confirm the expression of
ERs in human RPE, to elucidate whether these ERs are functional, and to test
whether 17beta-estradiol (E(2)) regulates expression of ERs and MMP-2.
METHODS: Expression of ERs was examined in freshly isolated human RPE monolayer
and in cultured human RPE cells, by using total RNA for RT-PCR and protein
extracts for Western blot analysis. Supernatants were collected from freshly
isolated human RPE and from cultured human RPE to assess MMP-2 activity by
zymography and protein expression by Western blot. The transcriptional activity
of ERs was studied in transfection experiments with an estrogen-responsive
reporter construct. All these studies were preformed in the presence or absence
of E(2) (10(-11) and 10(-7) M).
RESULTS: Human RPE isolated from female and male individuals expressed both ER
subtypes alpha and beta at the mRNA and protein levels. Treatment of cultured
RPE cells with 10(-10) M E(2) increased expression of mRNA and protein of both
receptor subtypes. E(2) (10(-10) M) also increased MMP-2 activity (approximately
2.2-fold) and protein expression (approximately 2.5-fold). In contrast, there
was no change in ER levels and MMP-2 activity at higher E(2) concentrations
(10(-8) M), compared with baseline. Preincubation of cells with 10(-7) M
pyrrolidinedithiocarbamate (PDTC), an inhibitor of nuclear factor (NF)-kappaB,
abolished the increase in MMP-2 activity and protein expression induced by E(2)
at 10(-10) M.
CONCLUSIONS: Both ER subtypes are expressed in RPE and regulated in a
dose-dependent fashion by E(2). Estrogens similarly regulate MMP-2. This
estrogen-induced effect is, at least in part, mediated through NF-kappaB. These
data support the hypothesis that estrogens may exert biological function in RPE
through ERs and that estrogen deficiency or excess may cause dysregulation of
molecules that influence the turnover of ECM in Bruch’s membrane associated with
ARMD.
DOI: 10.1167/iovs.01-1276
PMID: 12506055 [Indexed for MEDLINE]