期刊
INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY
卷 41, 期 11, 页码 843-851出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ibmb.2011.06.006
关键词
Heat shock transcription factor; Heat shock element; 5 degrees C-acclimation; Up-regulation; Heat shock protein 70a; Samui; Embryonic diapause; Bombyx mori
资金
- Japan Society for the Promotion of Science (JSPS)
- Ministry of Agriculture, Forestry and Fisheries
- Grants-in-Aid for Scientific Research [21248007] Funding Source: KAKEN
To understand the molecular mechanisms of how 5 degrees C-incubation activates mRNA expression of Hsp70a and Samui genes in Bombyx mod diapause eggs, we first searched the 5'-upstream regions of the Hsp70a and Samui genes for heat shock elements (HSEs) and found two regions [Hsp70aHSE-1 (-95 to -58) and -2 (-145 to 121), and SamuiHSE-1 (-84 to 55) and -2 (-304 to 290)] corresponding to HSEs (repeats of nGAAn and/or nTTCn). We cloned four cDNAs encoding heat shock factor (HSF)-a2 (627 amino acids), -b (685 aa), -c (682 aa) and -d (705 aa), which were produced by alternative splicing. When we exposed diapause eggs to 5 degrees C beginning at 2 day post-oviposition to break diapause, HSFd mRNA only increased after chilling for 6-8 days, a pattern very similar to those of Hsp70a and Samui mRNAs. To examine further whether HSFd binds to the respective HSEs, we carried out a gel shift assay using HSFd protein expressed in a cell-free system and the isolated HSEs; migration of the respective digoxigenin(DIG)-labeled HSE-1 and -2 of Hsp70a and Samui was retarded by addition of HSFd; the retarded bands disappeared after addition of the corresponding unlabeled HSE-1 and -2 as competitors, but were not affected by addition of the respective mutated unlabeled HSE-1 and -2. These results indicated that HSFd protein binds to the respective HSEs and may activate mRNA expression of Hsp70a and Samui genes upon exposure of diapause eggs to 5 degrees C (C). 2011 Elsevier Ltd. All rights reserved.
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