A retinoblastoma ortholog controls stalk/spore preference in Dictyostelium.
We describe rblA, the Dictyostelium ortholog of the retinoblastoma susceptibility gene Rb. In the growth phase, rblA expression is correlated with several factors that lead to 'preference' for the spore pathway. During multicellular development, expression increases 200-fold in differentiating spores. rblA-null strains differentiate stalk cells and spores normally, but in chimeras with wild type, the mutant shows a strong preference for the stalk pathway. rblA-null cells are hypersensitive to the stalk morphogen DIF, suggesting that rblA normally suppresses the DIF response in cells destined for the spore pathway. rblA overexpression during growth leads to G1 arrest, but as growing Dictyostelium are overwhelmingly in G2 phase, rblA does not seem to be important in the normal cell cycle. rblA-null cells show reduced cell size and a premature growth-development transition; the latter appears anomalous but may reflect selection pressures acting on social ameba.
MacWilliams
Harry
H
Biozentrum der Ludwig-Maximilians-Universität, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany. macw@zi.bologie.uni-muenchen.de
Doquang
Kimchi
K
Pedrola
Roberto
R
Dollman
Gytha
G
Grassi
Daniela
D
Peis
Thomas
T
Tsang
Adrian
A
Ceccarelli
Adriano
A
D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000737:chemistry; D048429:Cell Size; D017124:Conserved Sequence; D016054:DNA, Protozoan / Q000032:analysis; D004023:Dictyostelium / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D019143:Evolution, Molecular; D005456:Fluorescent Dyes; D005786:Gene Expression Regulation / Q000187:drug effects; D017125:Genes, Protozoan; D016161:Genes, Retinoblastoma; D005947:Glucose / Q000494:pharmacology; D006588:Hexanones / Q000494:pharmacology; D007211:Indoles; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000235:genetics / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D033761:Spores, Protozoan
D016054:DNA, Protozoan; D005456:Fluorescent Dyes; D006588:Hexanones; D007211:Indoles; D015800:Protozoan Proteins; C053433:1-((3,5-dichloro)-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone; C007293:DAPI; D005947:Glucose