Relationships between cell-cell interactions, cAMP, and gene expression in a developmental mutant of Dictyostelium discoideum.
Previous work has led us to propose that close cell-cell associations during D. discoideum development serve as a signal to deactivate expression of discoidin I mRNA, and that intracellular cAMP serves as a mediator of this regulatory pathway. This model is based in part on the failure of a morphogenetic mutant, EB-21, to deactivate discoidin I expression under conditions where these cells fail to acquire cell-cell cohesiveness and hence remain as single cells, unlike the wild type strain which forms multicellular aggregates. Here we show that the failure of EB-21 to express specific cohesiveness depends on developmental conditions, and that under conditions where close cell-cell associations are allowed to form, discoidin I mRNA expression is deactivated normally. Furthermore, in both wild type and EB-21 there is a close correlation between formation close cell-cell associations and elevation of intracellular cAMP under different developmental conditions. Additional analyses of the biological behavior of EB-21 indicate that it acquires a normal cAMP chemotactic signal-response system, and that the morphogenetic defect cannot be corrected by co-development with wild type cells. The results are discussed in terms of possible relationships between cell-cell interactions, cAMP metabolism, and developmental gene expression in this organism.
Bozzone
D M
DM
Cell Biology Group, Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 91545.
Kohnken
R E
RE
Berger
E A
EA
D002633:Chemotaxis; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology*; D004023:Dictyostelium / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D000070821:Discoidins; D005656:Fungal Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D037102:Lectins; D009154:Mutation; D015800:Protozoan Proteins; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics
D000070821:Discoidins; D005656:Fungal Proteins; D037102:Lectins; D015800:Protozoan Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D000242:Cyclic AMP