کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2198291 1551010 2006 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A candidate juvenoid hormone receptor cis-element in the Daphnia magna hb2 hemoglobin gene promoter
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی بیولوژی سلول
پیش نمایش صفحه اول مقاله
A candidate juvenoid hormone receptor cis-element in the Daphnia magna hb2 hemoglobin gene promoter
چکیده انگلیسی

Hemoglobin levels are significantly elevated in the crustacean Daphnia magna by juvenoid hormones. The present study was undertaken to identify the specific globin (hb) genes that are induced by juvenoids and to identify putative juvenoid response elements (JREs) that may mediate this induction. Gene product of globin 2 (hb2), but not globin 1 and globin 3, was robustly elevated following juvenoid treatment of daphnids. A candidate JRE, located in the promoter of hb2, bound activated factor(s) in response to juvenoid treatment of daphnids. This hormone-induced protein:JRE interaction was robust when daphnids were reared at high oxygen tension but was inhibited when daphnids were reared under low pO2, implying that hypoxia might act to disrupt juvenoid-mediated endocrine signaling. The candidate JRE consists of a steroid/retinoid-response element-like core adjacent to a 5′ AT-rich extension and thus bears resemblance to response elements that bind monomeric nuclear receptors. The induction of hb2 mRNA levels by juvenoid treatment occurred rapidly (within 4 h of exposure) and was not attenuated by treatment of daphnids with cycloheximide. In contrast, cycloheximide treatment did block hormone-mediated elevations in hemoglobin protein levels. Thus, induction of hb2 by juvenoids was not dependent upon the synthesis of secondary transcription factors that bound the JRE but was likely due to activation of the gene directly by the juvenoid-receptor complex. Affinity pull-down experiments with nuclear proteins extracted from juvenoid-treated daphnids using the JRE as bait yielded a 52 kDa candidate for a monomeric nuclear receptor in D. magna that may mediate the regulatory activity of juvenoids.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Molecular and Cellular Endocrinology - Volume 247, Issues 1–2, 9 March 2006, Pages 91–102
نویسندگان
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