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A gene encoding, prespore‐cell‐inducing factor in Dictyostelium discoideum
Author(s) -
Kawata Takefumi,
Nakagawa Manabu,
Shimada Nao,
Fujii Shigeru,
Oohata Akiko A.
Publication year - 2004
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.2004.00749.x
Subject(s) - dictyostelium discoideum , biology , mutant , complementary dna , microbiology and biotechnology , gene , cell division , growth factor , cell culture , null cell , cell , clone (java method) , molecular mass , genetics , biochemistry , receptor , enzyme
Two factors that exist in conditioned medium (CM) of Dictyostelium discoideum induce amoebae to differentiate into prespore cells when they are incubated at a very low cell density in submerged monolayer culture. Previously, we purified one of them, a glycoprotein factor with an apparent molecular mass of 106 kDa, and we named it ψ factor (psi, prespore‐inducing factor). Based on the partial amino acid sequence of the purified ψ factor, we have isolated the corresponding cDNA clone, which is expressed maximally at the loose mound stage. The cDNA encodes a novel protein and the predicted molecular mass of the mature secreted protein is 60 kDa. Knockout mutant strains of the ψ factor gene, psiA – , were created by targeted integration. Although these mutant strains appear to develop normally, CM from these mutants showed reduced prespore‐cell‐inducing activity. Rescuing the mutant strains by expression of ψ factor under control of a constitutive promoter causes overproduction of ψ factor protein and CM from such cells showed a 20‐fold higher level of prespore‐cell‐inducing activity than that from wild‐type cells. Further, CM from parental cells induced prespore cell division, while that from psiA null strains showed no cell division inducing activity. Our results indicate that ψ factor protein is a novel type of growth factor that does not belong to any of the families of growth factor so far identified in animals.