Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.12.2 (MEK)
 18,161 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

For the fission yeast Schizosaccharomyces pombe, adaptation to high-osmolarity medium is mediated by a mitogen-activated protein (MAP) kinase cascade, involving the Wis1 MAP kinase kinase and the Sty1 MAP kinase. The MAP kinase pathway transduces an osmotic signal and accordingly regulates the expression of the downstream target gene (gpd1(+)) that encodes NADH-dependent glycerol-3-phosphate dehydrogenase, in order to adaptively accumulate glycerol inside the cells as an osmoprotectant. We previously characterized a set of high-osmolarity-sensitive S. pombe mutants, including wis1, sty1, and gpd1. In this study, we attempted to further isolate novel osmolarity-sensitive mutants. For some of the mutants isolated, profiles of glycerol production in response to the osmolarity of the growth medium were indistinguishable from that of the wild-type cells, suggesting that they are novel types. They were classified into three distinct types genetically and, thus, were designated hos1, hos2, and hos3 (high osmolarity sensitive) mutants. One of them, the hos1 mutant, was characterized in detail. The hos1 mutant was demonstrated to have a mutational lesion in the known ryh1(+) gene, which encodes a small GTP-binding protein. Disruption of the ryh1(+) gene results not only in osmosensitivity but also in temperature sensitivity for growth. It was also found that the delta ryh1 mutant is severely sterile. These results are discussed with special reference to the osmoadaptation of S. pombe.
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PMID:Isolation and characterization of high-osmolarity-sensitive mutants of fission yeast. 974 34

The salt-tolerant yeast Zygosaccharomyces rouxii can adjust its osmotic balance when responding to osmotic shock by accumulating glycerol as the compatible osmolyte. However, the mechanism of glycerol production in Z. rouxii cells and its genetic regulation remain to be elucidated. Two putative mitogen-activated protein (MAP) kinase genes, ZrHOG1 and ZrHOG2, were cloned from Z. rouxii by their homology with HOG1 from Saccharomyces cerevisiae. The deduced amino acid sequences of ZrHog1p and ZrHog2p indicated close homology to that of Hog1p and contained a TGY motif for phosphorylation by MAP kinase kinase. When ZrHOG1 or ZrHOG2 was expressed in an S. cerevisiae hog1delta null mutant, the salt tolerance and osmotic tolerance characteristics of wild-type S. cerevisiae were restored. In addition, the aberrant cell morphology and low glycerol content of the hog1delta null mutant were corrected, indicating that ZrHog1p and ZrHog2p have functions similar to Hog1p. While the transcription of the glycerol-3-phosphate dehydrogenase gene (GPD1) of the ZrHOG1-harbouring S. cerevisiae mutant was similar to that of wild-type S. cerevisiae, the ZrHOG2-harbouring strain showed prolonged GPD1 transcription. Both Zrhog1delta and Zrhog2delta Z. rouxii null mutants showed a decrease in salt tolerance compared to the wild-type strain. The present study suggested the presence of a high-osmolarity glycerol response (HOG) pathway in Z. rouxii similar to that elucidated in S. cerevisiae. Two putative MAP kinase genes in Z. rouxii appeared to be significant in either osmotic regulation or ion homeostasis.
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PMID:Two putative MAP kinase genes, ZrHOG1 and ZrHOG2, cloned from the salt-tolerant yeast Zygosaccharomyces rouxii are functionally homologous to the Saccharomyces cerevisiae HOG1 gene. 1020 4

Two-component signal transduction comprising of OS-1 (histidine kinase), OS-4 (MAPKK kinase), OS-5 (MAPK kinase), and OS-2 (MAP kinase) plays an important role in osmotic regulation in Neurospora crassa. To identify the genes regulated downstream of OS-2 MAP kinase, quantitative real-time RT-PCR analysis was conducted in selected genes based on Hog1 MAP kinase regulated genes in yeast. In response to osmotic stress and fludioxonil, expression of six genes that for glycerol synthesis (gcy-1, gcy-3, and dak-1), gluconeogenesis (fbp-1 and pck-1), and catalase (ctt-1) was activated in the wild-type strain, but not in the os-2 mutant. A heat shock treatment also induced their expression in the same way. Consisting with the gene expression, the enzyme activity of glycerol dehydrogenase, but not glycerol-3-phosphate dehydrogenase, was increased in response to osmotic stress and fludioxonil in the wild-type strain. OS-2 was phosphorylated by the OS-1 cascade in response to relatively low osmotic stress and fludioxonil. However, OS-2 phosphorylation by heat shock and a higher osmotic stress was found in the os-1 mutant normally but not in the os-4 and os-5 mutants. These results suggested that non-OS-1 signaling activates OS-2 in an OS-4-dependent manner in such conditions.
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PMID:Identification of OS-2 MAP kinase-dependent genes induced in response to osmotic stress, antifungal agent fludioxonil, and heat shock in Neurospora crassa. 1699 38