A stress response kinase, KrsA, controls cAMP relay during the early development of Dictyostelium discoideum.
Solitary amoebae of Dictyostelium discoideum are frequently exposed to stressful conditions in nature, and their multicellular development is one response to environmental stress. Here we analyzed an aggregation stage abundant gene, krsA, homologous to human krs1 (kinase responsive to stress 1) to understand the mechanisms for the initiation of development and cell fate determination. The krsA- cells exhibited reduced viability under hyperosmotic conditions. They produced smaller aggregates on membrane filters and did not form aggregation streams on a plastic surface under submerged starvation conditions, but were normal in sexual development. During early asexual development, the expression of cAMP-related genes peaked earlier in the knockout mutants. Neither cAMP oscillation in starved cells nor an increase in the cAMP level following osmotic stress was observed in krsA-. The nuclear export signal, as well as the kinase domain, in KrsA was necessary for stream formation. These results strongly suggest that krsA is involved in cAMP relay, and that signaling pathways for multicellular development have evolved in unison with the stress response.
Muramoto
Tetsuya
T
Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8572, Japan.
Kuwayama
Hidekazu
H
Kobayashi
Kumiko
K
Urushihara
Hideko
H
D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism*; D017931:DNA Primers; D004023:Dictyostelium / Q000201:enzymology / Q000254:growth & development*; D040461:Gene Components; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000502:physiology*; D016297:Mutagenesis, Site-Directed; D009997:Osmotic Pressure; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D017931:DNA Primers; D015800:Protozoan Proteins; D000242:Cyclic AMP; C520080:Krs1 protein, Dictyostelium discoideum; D017346:Protein Serine-Threonine Kinases