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A gene encoding, prespore-cell-inducing factor in Dictyostelium discoideum
Takefumi Kawata1, Manabu Nakagawa, Nao Shimada
1Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan.
Development, Growth & Differentiation
|September 16, 2004
Summary
A novel growth factor, psi factor, from Dictyostelium discoideum amoebae induces prespore cell differentiation and division. This discovery expands the known families of growth factors in animals.
Area of Science:
- Cellular and Molecular Biology
- Developmental Biology
- Biochemistry
Background:
- Conditioned medium (CM) of Dictyostelium discoideum contains factors inducing prespore cell differentiation.
- A glycoprotein, psi factor, was previously purified and identified as a key inducer.
Purpose of the Study:
- To characterize the novel psi factor protein and its role in Dictyostelium discoideum development.
- To investigate the function of psi factor in prespore cell differentiation and proliferation.
Main Methods:
- Isolation and sequencing of the psi factor cDNA clone.
- Creation of knockout mutant strains (psiA(-)) using targeted integration.
- Analysis of CM from wild-type, mutant, and rescued strains for prespore-inducing activity.
Main Results:
- The psi factor cDNA encodes a novel 60 kDa secreted protein, maximally expressed at the loose mound stage.
- psiA(-) mutants exhibited reduced prespore-cell-inducing activity in their CM.
- Rescued strains overproducing psi factor showed a 20-fold increase in inducing activity and restored cell division induction.
Conclusions:
- Psi factor is a novel type of growth factor, distinct from known animal growth factor families.
- Psi factor plays a critical role in regulating Dictyostelium discoideum prespore cell differentiation and proliferation.