Pre-existent Hsp72 contributes to glutamine-induced hepatic hsp72 gene activation during heat shock recovery period in rat.
METHODS
Functional maintenance of liver is very important at all times for personal health. Hsp induction is associated with the protection of the organ. Glutamine, a nutrient inducer of Hsps, enhances cellular survival via Hsp72 induction in several organs, but not in the liver. The present study showed a novel approach to facilitate glutamine-induced hepatic Hsp72 synthesis and its possible mechanisms were discussed.


RESULTS
Sprague-Dawley rats were used as the experimental animals and the livers were the targets. Glutamine was administered via tail-vein injection, and its effects on hsp72 gene activation, including Hsp72 expression, heat shock factor-1 (HSF-1) phosphorylation and DNA-binding activation, were evaluated. The results showed that Hsp72 itself played a critical role in glutamine-induced hepatic Hsp72 synthesis during HS recovery period in a dose-dependent manner of preexistent Hsp72. The peak value of HSF-1 phosphorylation, HSF-1 DNA-binding activity, hsp72 mRNA accumulation, and Hsp72 synthesis was detected at 8 h after glutamine administration.


CONCLUSIONS
Glutamine switched on alteration pathway in inducing hsp72 gene activation. The existence of Hsp72 plays a critical role in the reactivation of hsp72 gene. Glutamine sustained the induction of intracellular Hsp72, which could be beneficial in protecting the liver from various injuries.
Department of Physiology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Shu-Jung
SJ
Wang
Hsiang-Wen
HW
Chen
Rei-Cheng
RC
Yang
D000818:Animals; D015153:Blotting, Western; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D005973:Glutamine / Q000494:pharmacology*; D050884:HSP72 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000187:drug effects*; D008099:Liver / Q000378:metabolism; D008297:Male; D010766:Phosphorylation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D050884:HSP72 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D012333:RNA, Messenger; D014157:Transcription Factors; D005973:Glutamine