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Mol. Cell. Biol., Jun 1996, 2870-2877, Vol 16, No. 6
G Degols, K Shiozaki and P Russell
Spc1, an osmotic-stress-stimulated mitogen-activated protein kinase (MAPK)
homolog in the fission yeast Schizosaccharomyces pombe, is required for the
induction of mitosis and survival in high-osmolarity conditions. Spc1, also
known as Sty1, is activated by Wis1 MAPK kinase and inhibited by Pyp1
tyrosine phosphatase. Spc1 is most closely related to Saccharomyces
cerevisiae Hog1 and mammalian p38 kinases. Whereas Hog1 is specifically
responsive to osmotic stress, we report here that Spc1 is activated by
multiple forms of stress, including high temperature and oxidative stress.
In this regard Spc1 is more similar to mammalian p38. Activation of Spc1 is
crucial for survival of various forms of stress. Spc1 regulates expression
of genes encoding stress- related proteins such as glycerol-3-phosphate
dehydrogenase (gpd1+) and trehalose-6-phosphate synthase (tps1+). Spc1 also
promotes expression of pyp2+, which encodes a tyrosine phosphatase
postulated as a negative regulator of Spc1. This proposal is supported by
the finding that Spc1 associates with Pyp2 in vivo and that the amount of
Spc1 tyrosine phosphorylation is lower in a Pyp2-overproducing strain than
in the wild type. Moreover, the level of stress-stimulated gpd1+ expression
is higher in delta pyp2 mutants than in the wild type. These findings
demonstrate that Spc1 promotes expression of genes involved in stress
survival and that of regulation may be commonly employed to modulate MAPK
signal transduction pathways in eukaryotic species.
Copyright © 1996, American Society for Microbiology
Activation and regulation of the Spc1 stress-activated protein kinase in Schizosaccharomyces pombe
Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037, USA.
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