A heat-activated MAP kinase (HAMK) as a mediator of heat shock response in tobacco cells.
A heat-activated MAP kinase (HAMK), immunologically related to the extracellular signal-regulated kinase (ERK) super-family of protein kinases, has been identified in BY2 cells of tobacco. The activation of HAMK at 37 degrees C was transient and detected within 2 min and reached a maximum level within 5 min. Ca(2+) chelators and channel blockers, and the known inhibitors of MEK, a MAP kinase kinase, prevented the heat activation of HAMK. This suggests that HAMK activation is part of a heat-triggered MAP kinase cascade that requires Ca(2+) influx. The heat shock protein HSP70 accumulated at 37 degrees C, but not when HAMK activation was prevented with the inhibitors of MEK or with Ca(2+) chelators or channel blockers. As previously shown for heat activation of HAMK, heat-induced accumulation of HSP70 requires membrane fluidization and reorganization of cytoskeleton. We concluded that heat-triggered HAMK cascade might play an essential role in the launching of heat shock response and hsp gene expression in tobacco cells.
Suri
Sarabjeet S
SS
Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada.
Dhindsa
Rajinder S
RS
D002118:Calcium / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D018869:Heat-Shock Response / Q000187:drug effects; D006358:Hot Temperature; D008560:Membrane Fluidity / Q000187:drug effects; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D014026:Nicotiana / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
D004791:Enzyme Inhibitors; D018840:HSP70 Heat-Shock Proteins; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D002118:Calcium