The gpd1 + gene of Schizosaccharomyces pombe encodes an isozyme of NADH-dependent glycerol-3-phosphate dehydrogenases that is involved in glycerol synthesis, whose expression is induced upon an upshift of the medium osmolarity. We provide evidence that this osmotic induction of gpd1 + in S. pombe is under the control of a MAP-signaling pathway involving the wis1 + gene-product, which is a homologue of MAP-kinase kinases. The results suggested that the gpd1 + gene is a downstream target of the osmosensing signaling that is transmitted through Wis1, thereby defects of either of these genes result in the similar phenotype, namely, osmosensitive for growth, because of the failure in accumulation of the intracellular osmoprotectant, glycerol.
