Cyclic AMP response element binding protein (CREB) participates in the heat-inducible expression of humanhsp90β gene

Ex vivo promoter analysis of antiviral heat shock cognate 70B gene in Anopheles gambiae

Background

The Anopheles gambiae heat shock cognate gene (hsc70B) encodes a constitutively expressed protein in the hsp70 family and it functions as a molecular chaperone for protein folding. However, the expression of hsc70B can be further induced by certain stimuli such as heat shock and infection. We previously demonstrated that the An. gambiae hsc70B is induced during o'nyong-nyong virus (ONNV) infection and subsequently suppresses ONNV replication in the mosquito. To further characterize the inducibility of hsc70B by ONNV infection in An. gambiae, we cloned a 2.6-kb region immediately 5' upstream of the starting codon of hsc70B into a luciferase reporter vector (pGL3-Basic), and studied its promoter activity in transfected Vero cells during infection with o'nyong-nyong, West Nile and La Crosse viruses.

Results

Serial deletion analysis of the hsc70B upstream sequence revealed that the putative promoter is likely located in a region 1615–2150 bp upstream of the hsc70B starting codon. Sequence analysis of this region revealed transcriptional regulatory elements for heat shock element-binding protein (HSE-bind), nuclear factor κB (NF-κB), dorsal (Dl) and fushi-tarazu (Ftz). Arbovirus infection, regardless of virus type, significantly increased the hsc70B promoter activity in transfected Vero cells.

Conclusion

Our results further validate the transcriptional activation of hsc70B during arbovirus infection and support the role of specific putative regulatory elements. Induction by three taxonomically distinct arboviruses suggests that the HSC70B protein may be expressed to cope with cellular stress imposed during infection.

Differential hypersensitivity to DNase I in the regulatory region of human hsp90 beta gene in heat shock and constitutive expression

DNase I hypersensitivity analysis is a useful tool to investigate impact of structure changes in chromatin on the expression of a gene. In order to unravel chromatin regulation on human hsp90 beta gene, differential sensitivity to DNase I in non-treated and heat-shocked Jurkat cells are examined. Four major hypersensitive sites at -120/-20 bp (HS1), +360 bp (HS2), +630/+780 bp (HS4) and around +1020 bp (HS5) with respect to the transcription start site of hsp90 beta gene have been identified. The HS1 is shared by both constitutive and heat shock, while the intronic sites of HS4 and HS5 are elicited by heat shock and HS2 is illustrated only in constitutive expression. In addition, distal HSs at around 8.7 kb upstream and 6.8 kb downstream are found in both constitutive and heat shock expression, which indicate that the boundaries of the hsp90 beta gene extend for some 16 kb. The HS patterns confirm chromatin regulation in the expression of hsp90 beta gene under various treatments.