Calmodulin is involved in heat shock signal transduction in wheat.
The involvement of calcium and calcium-activated calmodulin (Ca(2+)-CaM) in heat shock (HS) signal transduction in wheat (Triticum aestivum) was investigated. Using Fluo-3/acetoxymethyl esters and laser scanning confocal microscopy, it was found that the increase of intracellular free calcium ion concentration started within 1 min after a 37 degrees C HS. The levels of CaM mRNA and protein increased during HS at 37 degrees C in the presence of Ca(2+). The expression of hsp26 and hsp70 genes was up-regulated by the addition of CaCl(2) and down-regulated by the calcium ion chelator EGTA, the calcium ion channel blockers LaCl(3) and verapamil, or the CaM antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide and chlorpromazine. Treatment with Ca(2+) also increased, and with EGTA, verapamil, chlorpromazine, or trifluoperazine decreased, synthesis of HS proteins. The temporal expression of the CaM1-2 gene and the hsp26 and hsp70 genes demonstrated that up-regulation of the CaM1-2 gene occurred at 10 min after HS at 37 degrees C, whereas that of hsp26 and hsp70 appeared at 20 min after HS. A 5-min HS induced expression of hsp26 after a period of recovery at 22 degrees C after HS at 37 degrees C. Taken together, these results indicate that Ca(2+)-CaM is directly involved in the HS signal transduction pathway. A working hypothesis about the relationship between upstream and downstream of HS signal transduction is presented.
Liu
Hong-Tao
HT
Institute of Molecular Cell Biology, Hebei Normal University, Shijiazhuang 050016, People's Republic of China.
Li
Bing
B
Shang
Zhong-Lin
ZL
Li
Xiao-Zhi
XZ
Mu
Rui-Ling
RL
Sun
Da-Ye
DY
Zhou
Ren-Gang
RG
D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D018869:Heat-Shock Response / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014908:Triticum / Q000187:drug effects / Q000235:genetics / Q000502:physiology*
D002147:Calmodulin; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D002118:Calcium