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This Article Accepted manuscript (PDF) All Versions of this Article: JOE-07-0292v1 199/2/267    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Tsutsumi, S. Articles by Mendelsohn, M. Search for Related Content PubMed PubMed Citation Articles by Tsutsumi, S. Articles by Mendelsohn, M.

S Tsutsumi, Department of Obstetrics and Gynecology, Yamagata University School of Medicine, Yamagata, Japan
X Zhang, Yamagata, Japan
K Takata, Department of Obstetrics and Gynecology, Yamagata University School of Medicine, Yamagata, Japan
K Takahashi, Department of Obstetrics and Gynecology, Yamagata University School of Medicine, Yamagata, Japan
R Karas, Molecular Cardiology Research Institute, Tufts Medical Center, Boston, United States
H Kurachi, Department of Obstetrics and Gynecology, Yamagata University School of Medicine, Yamagata, Japan
M Mendelsohn, Molecualr Cardiology Research Institute, Tufts-New England Medical Center, Boston, United States

Correspondence: Michael Mendelsohn, Email: mmendelsohn{at}tufts-nemc.org

Abstract

Estrogen has rapid and longer-term direct effects on cardiovascular tissues mediated by the two estrogen receptors, ERand ERβ. Estrogen regulates the expression of inducible nitric oxide synthase (iNOS) in vascular smooth muscle cells (VSMC) and ERβ knockout mice have vascular dysfunction and hypertension (Zhu et al, Science 2002;295:505-508). Here we report studies to examine the differential regulation of iNOS gene expression by ER and ERβ. Immunoblotting and RT-PCR studies revealed that different VSMC lines expressed different levels of ER and ERβ protein and mRNA. VSMC from different vascular beds were studied, including aortic VSMC expressing ER and radial VSMC expressing ERβ. E2 inhibited NO production and iNOS protein expression in aortic VSMC. Human iNOS promoter reporter studies revealed suppression of iNOS reporter activity by E2 in aortic VSMC, and stimulation of iNOS reporter activity by E2 in radial arterial VSMC. In studies of COS-7 cells, E2 treatment of COS-7 cells did not alter iNOS reporter activity in the presence of ER, while activity increased 2.3-fold in the presence of ERβ. Similar experiments using the SERM raloxifene showed that raloxifene caused reduced iNOS reporter activity with ER co-expression, and an increase with ER co-expression. Rat VSMC expressing ERβ but not ER also showed increased iNOS reporter activity with E2 treatment, an effect lost when ER was introduced into the cells. Taken together, these data support that hiNOS transcription is positively regulated by ERβ and negatively regulated by ER in VSMC, supporting differential actions of these two estrogen receptors on a physiologically relevant gene in vascular smooth muscle cells.