期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 320, 期 4, 页码 697-704出版社
ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD
DOI: 10.1016/S0022-2836(02)00555-7
关键词
C. elegans; pharynx; pha-4/peb-1; gene regulation
资金
- NIGMS NIH HHS [GM 53966, GM 20606, R01 GM053996, R01 GM053996-09] Funding Source: Medline
PHA-4 is a forkhead/winged helix transcription factor that acts as an organ identity factor in the development of the Caenorhabditis elegans pharynx. PEB-1 is a novel DNA-binding protein also involved in pharyngeal morphogenesis. PHA-4 and PEB-1 bind at overlapping sites on the C183 sequence element that controls pharynx-specific expression of the C. elegans myo-2 gene. It has been suggested that PHA-4 and PEB-1 act cooperatively on the C183 sequence. In this study, we test this model and assess the C183-dependent transcriptional activity of PHA-4 and PEB-1, both individually and in combination. We show that PHA-4 and PEB-1 are both modest transcriptional activators in yeast but that co-expression of the two factors does not result in significantly increased expression of a C183-regulated reporter gene. Electrophoretic mobility-shift assays provide no evidence for the formation of a PHA-4/PEB-1 complex in vitro but rather show that PHA-4 and PEB-1 cannot bind C183 simultaneously. As we have reported previously, ectopic expression of PHA-4 in C. elegans causes ectopic expression of a C183-regulated reporter gene. We show that ectopic expression of PEB-1 cannot cause ectopic expression of the same reporter but rather ectopic PEB-1 inhibits reporter gene activation by PHA-4. Overall, our results do not support a model in which PHA-4 and PEB-1 synergize in vivo but rather support a model in which PEB-1 may negatively modulate PHA-4's ability to activate, transcription through C183 during formation of the C. elegans pharynx. (C) 2002 Elsevier Science Ltd. All rights reserved.
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