title: Novel development rescuing factors (DRFs) secreted by the developing Dictyostelium cells, that are involved in the restoration of a mutant lacking MAP-kinase ERK2.
abstract: We found novel development rescuing factors (DRFs) secreted from developing Dictyostelium cells, by using a mutant (erkB-) which is missing MAP-kinase ERK2 as a test strain for bioassay. The mutant erkB- fails to undergo multicellular morphogenesis due to impaired cAMP signaling. However, such developmental defect can be restored by the presence of low-molecular weight DRFs that are secreted from developing wild-type cells. We previously showed that DIF-1 (Differentiation-Inducing Factor 1 for stalk cells) possesses this activity, indicating a newly discovered role of DIF-1. Surprisingly, however, the mutant dmtA-, which is incapable of DIF-1 synthesis still exerts a strong inducing activity of the multicellular morphogenesis of erkB-. After analysis of HPLC fractions of conditioned media prepared from both wild type Ax2 and dmtA- strains revealed that both strains secrete at least two novel DRF activities with DIF-like mobility. However, these activities were not derived from other DIFs such as DIF-2 and DIF-3. Identification of these DRFs found in this study would provide insight into the mechanism by which the development of the erkB- mutant is restored and how these factors act in the normal development of Dictyostelium.
authors.affiliation: Department of Biology, Osaka University, Machikaneyama-cho 101, Tyonaka, Osaka 560-0043, Japan.
authors.forename: Masatsune
authors.initials: M
authors.lastname: Tsujioka
authors.forename: Tatsuyoshi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Thompson
authors.forename: Robert R
authors.initials: RR
authors.lastname: Kay
authors.forename: Mineko
authors.initials: M
authors.lastname: Maeda
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D004023:Dictyostelium / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006588:Hexanones / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D009024:Morphogenesis; D010422:Pentanones / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D006588:Hexanones; D010422:Pentanones; C053433:1-((3,5-dichloro)-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone; C055365:1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl-)-1-pentanone; C055364:1-(3-chloro-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone; D019950:Mitogen-Activated Protein Kinase 1