Thermoprotection of synaptic transmission in a Drosophila heat shock factor mutant is accompanied by increased expression of Hsp83 and DnaJ-1.
In Drosophila larvae, acquired synaptic thermotolerance after heat shock has previously been shown to correlate with the induction of heat shock proteins (Hsps) including HSP70. We tested the hypothesis that synaptic thermotolerance would be significantly diminished in a temperature-sensitive strain (Drosophila heat shock factor mutant hsf4), which has been reported not to be able to produce inducible Hsps in response to heat shock. Contrary to our hypothesis, considerable thermoprotection was still observed at hsf4 larval synapses after heat shock. To investigate the cause of this thermoprotection, we conducted DNA microarray experiments to identify heat-induced transcript changes in these organisms. Transcripts of the hsp83, dnaJ-1 (hsp40), and glutathione-S-transferase gstE1 genes were significantly upregulated in hsf4 larvae after heat shock. In addition, increases in the levels of Hsp83 and DnaJ-1 proteins but not in the inducible form of Hsp70 were detected by Western blot analysis. The mode of heat shock administration differentially affected the relative transcript and translational changes for these chaperones. These results indicate that the compensatory upregulation of constitutively expressed Hsps, in the absence of the synthesis of the major inducible Hsp, Hsp70, could still provide substantial thermoprotection to both synapses and the whole organism.
Neal
Scott J
SJ
Department of Biology, University of Toronto, Mississauga, Ontario, Canada.
Karunanithi
Shanker
S
Best
Adrienne
A
So
Anthony Ken-Choy
AK
Tanguay
Robert M
RM
Atwood
Harold L
HL
Westwood
J Timothy
JT
D000064:Acclimatization; D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D050956:HSP40 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response / Q000235:genetics; D006358:Hot Temperature; D007814:Larva / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000378:metabolism; D015203:Reproducibility of Results; D009435:Synaptic Transmission / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
D004268:DNA-Binding Proteins; C494637:DnaJ-1 protein, Drosophila; D029721:Drosophila Proteins; D050956:HSP40 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C053134:Hsf protein, Drosophila; C089272:Hsp83 protein, Drosophila; D012333:RNA, Messenger; D014157:Transcription Factors