Hyperosmolarity-induced Gene Stimulation Is Mediated by the Negative Calcium Responsive Element*
- Tomoki Okazaki‡§,
- Toshio Ishikawa‡,
- Shigeki Nishimori‡,
- Tetsuya Igarashi‡,
- Keishi Hata¶ and
- Toshiro Fujita‡
- From the ‡Endocrine Genetics and Hypertension Unit, 4th Department of Internal Medicine, University of Tokyo School of Medicine, Bunkyo-ku, Tokyo 112 and the ¶Mitsubishi Kagaku Bio-clinical Laboratory Inc., Itabashi-ku, Tokyo 174, Japan
Abstract
The negative calcium responsive elements of the parathyroid hormone gene bind to a specific set of nuclear proteins in an extracellular calcium (Ca2+ e)-dependent manner. We have found that one of the negative calcium responsive elements, named oligo B, is found in the 5′-flanking region of such vasoactive genes as the vasopressin and atrial natriuretic polypeptide genes. Furthermore, the oligo B-like sequence in the former gene is conserved throughout evolution. Because expression of some of these vasoactive genes is altered by external stimuli which change cell volume, we examined whether oligo B is involved in gene regulation by hyperosmolarity. Here, we demonstrate that the binding between oligo B and its binding nuclear proteins including a redox factor 1 was reduced by hyperosmolarity generated by sodium chloride but not by urea. Such attenuated binding was reversed by dephosphorylating nuclear proteins by a potato acid phosphatase, suggesting that NaCl treatment elicited phosphorylation of these nuclear proteins to weaken their binding activity to oligo B. Furthermore, these nuclear events led to hyperosmolarity-mediated transcriptional stimulation of the genes bearing this DNA element in the cultured cells.
Footnotes
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↵* This work was supported by grants-in-aid for scientific research from the Ministry of Education, Science and Culture of Japan and by grants from Araki Foundation and the Life Science Foundation of Japan.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵§ To whom correspondence should be addressed. Tel.: 81-3-3943-1151; Fax: 81-3-3943-3102; E-mail: okbgeni-tky@umin.u-tokyo.ac.
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↵1 The abbreviations used are: Ca2+ e, extracellular calcium; nCaRE(B), negative calcium responsive element (binding protein); PTH, parathyroid hormone; CAT, chloramphenicol acetyltransferase; Ref1, redox factor protein; EMSA, electrophoretic mobility shift assay; Tk, thymidine kinase; HEK cells, human embryonal kidney cells; ANP, atrial natriuretic polypeptide; CRE, cyclic AMP response element.
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- Received June 23, 1997.
- Revision received September 16, 1997.
