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Embryonic and post-embryonic utilization and subcellular localization of the nuclear receptor SpSHR2 in the sea urchin

Kontrogianni-Konstantopoulos, Aikaterini and Leahy, Patrick S. and Flytzanis, Constantin N. (1998) Embryonic and post-embryonic utilization and subcellular localization of the nuclear receptor SpSHR2 in the sea urchin. Journal of Cell Science, 111 (15). pp. 2159-2169. ISSN 0021-9533.

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SpSHR2 (Strongylocentrotus purpuratus steroid hormone receptor 2) is a nuclear receptor, encoded by a maternal RNA in the sea urchin embryo. These maternal SpSHR2 transcripts, which are present in all cells, persist until the blastula stage and then are rapidly turned over. A small fraction of the embryonic SpSHR2 protein is maternal, but the majority of this nuclear receptor in the embryo is the product of new synthesis, presumably from the maternal RNA after fertilization. In agreement with the mRNA distribution, the SpSHR2 protein is also detected in all embryonic cells. Contrary to the RNA though, the SpSHR2 protein persists throughout embryonic development to the pluteus stage, long after the mRNA is depleted. Following fertilization and as soon as the 2-cell stage, the cytoplasmic SpSHR2 protein enters rapidly into the embryonic nuclei where it appears in the form of speckles. During subsequent stages (from fourth cleavage onward), SpSHR2 resides in speckled form in both the nucleus and the cytoplasm of the embryonic cells. The cytoplasmic localization of SpSHR2 differs between polarized and non-polarized cells, maintaining an apical position in the ectoderm and endoderm versus a uniform distribution in mesenchyme cells. Following the end of embryonic development (pluteus stage), the SpSHR2 protein is depleted from all tissues. During the ensuing four weeks of larval development, the SpSHR2 is not detected in either the larval or the rudiment cells which will give rise to the adult. Just prior to metamorphosis, at about 35 days post-fertilization, the protein is detected again but in contrast to the uniform distribution in the early embryo, the larval SpSHR2 is specifically expressed in cells of the mouth epithelium and the epaulettes. In adult ovaries and testes, SpSHR2 is specifically detected in the myoepithelial cells surrounding the ovarioles and the testicular acini. Nuclear SpSHR2 in blastula extracts binds to the C1R hormone response element in the upstream promoter region of the CyIIIb actin gene indicating that the latter may be a target of this nuclear receptor in the sea urchin embryo.

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Additional Information:© 1998 The Company of Biologists Ltd. Accepted 26 May; published on WWW 15 July 1998. We thank Drs Jon Holy and Gary Wessel for their generous gifts of the lamin and myosin antibodies, respectively. We are grateful to Drs Michael Mancini and Jeff Rosen for critical review of the manuscript. We also thank Maria Gonzalez-Rimbau, Liz Hopkins and Christopher P. Schultz for expert technical assistance. This work was supported by a grant from the National Institutes of Health (GM 53727) to C.N.F.
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National Institutes of HealthGM 53727
Subject Keywords:sea urchin embryonic development; SpSHR2 orphan; nuclear receptor; maternal RNA; subcellular protein localization; tissue specific larval expression
Issue or Number:15
Record Number:CaltechAUTHORS:KONjcs98
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12392
Deposited By: Tony Diaz
Deposited On:03 Dec 2008 23:33
Last Modified:03 Oct 2019 00:28

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