期刊
DEVELOPMENTAL BIOLOGY
卷 218, 期 2, 页码 284-298出版社
ACADEMIC PRESS INC
DOI: 10.1006/dbio.1999.9456
关键词
COUP-TF; sea urchin; embryonic development; cell cycle; maternal transcription factor; orphan nuclear receptor; chromosomal localization; subcellular trafficking
资金
- NIGMS NIH HHS [GM 53727] Funding Source: Medline
The nuclear receptor SpCOUP-TF is the highly conserved sea urchin homologue of the COUP family of transcription factors. Previous results from our laboratory demonstrated that SpCOUP-TF transcripts are localized in the egg and asymmetrically distributed in the early embryonic blastomeres (A. Vlahou ct al., 1996, Development 122, 521-526). To examine the subcellular localization of SpCOUP-TF protein, polyclonal antibodies were separately raised against the divergent N-terminus as well as the conserved DNA-binding and ligand-binding domains. Immunohistochemical analyses suggest that SpCOUP-TF is a maternal protein residing in the cytoplasm of the unfertilized egg. After fertilization, and as soon as the two-cell-stage embryo, most of the receptor translocates from the cytoplasm to the cell nuclei. During the rapid embryonic cell division, SpCOUP-TF was found to shuttle from the interphase nuclear periphery to the condensed chromosomes in mitosis, in a cell-cycle-dependent manner, In an attempt to confirm these observations, the subcellular localization of myc-tagged human COUP-TF I introduced into the sea urchin embryo by RNA injection of fertilized eggs was examined. The pattern of human COUP-TF I subcellular localization, detected with a monoclonal myc antibody, recapitulated the essential features described for the endogenous SpCOUP-TF trafficking. Replacement of the N-terminus of the human receptor with the unique sea urchin N-terminus enhanced its localization to the nuclear rim during interphase. Deletion of the DNA-binding domain of human COUP-TF I resulted in loss of all aspects of nuclear periphery and chromosomal localization. Taken together these data suggest that SpCOUP-TF transcriptional activity is keyed on a cell-cycle-dependent mechanism that regulates chromosomal protein traffic. (C) 2000 Academic Press.
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