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Comments on Jeanna M Wheeler et al. (2005) International Worm Meeting "Identification of a novel gene family involved in the response to osmotic stress" (0)
Overview
Jeanna M Wheeler, & James H Thomas (2005). Identification of a novel gene family involved in the response to osmotic stress presented in International Worm Meeting. Unpublished information; cite only with author permission.
Exposure to high osmolarity can be extremely damaging to living cells, and thus organisms ranging from bacteria to mammals employ mechanisms designed to protect against this damage. One common strategy is the accumulation of a physiologically compatible solute to increase the osmolarity of the cytoplasm. Though mammalian cells use several different compatible solutes (betaine, taurine, inositol, etc.), yeast accumulates glycerol in response to osmotic stress, activated primarily by the MAP kinase Hog1 signaling pathway. In addition, a pathway regulated by protein kinase C (PKC1) is activated by changes in osmolarity as well as by cell wall damage and high temperature. It has been shown that C. elegans also accumulates glycerol in response to high osmolarity, but the molecular pathways responsible for this are not yet well understood.We report the molecular identification of two genes, osm-7 (p.k.a. dec-2) and osm-11, which are related members of a novel gene family in C. elegans. Loss-of-function mutations in either gene lead to high internal levels of glycerol, which in turn causes an osmotic resistance phenotype (Osr). We also find that these mutants have altered defecation behavior. The mutant phenotype of osm-7 can be partially suppressed by defects in unc-43, a kinase reported to be upstream of both MAPK and PKC pathways in C. elegans. osm-7 is expressed exclusively in the hypodermis, and its sequence suggests that it may be extracellular. We hypothesize that osm-7 and osm-11 are components of the cuticle, and that disruption of cuticle function causes activation of unc-43 and an increase in internal glycerol. These results suggest that the response to high osmolarity is similar in yeast and worms, and that Osr mutants provide a model for studying the response to high osmolarity in a multicellular organism.
Affiliation:
- Department of Genome Sciences, University of Washington, Seattle, WA.