A Secreted Cell Number Counting Factor Represses Intracellular Glucose Levels to Regulate Group Size inDictyostelium

Wonhee Jang, Binh Chiem, Richard H. Gomer
2002 Journal of Biological Chemistry  
Developing Dictyostelium cells form evenly sized groups of ϳ2 ؋ 10 4 cells. A secreted 450-kDa protein complex called counting factor (CF) regulates group size by repressing cell-cell adhesion and myosin polymerization and by increasing cAMP-stimulated cAMP production, actin polymerization, and cell motility. We find that CF regulates group size in part by repressing internal glucose levels. Transformants lacking bioactive CF and wild-type cells with extracellular CF depleted by antibodies have
more » ... high glucose levels, whereas transformants oversecreting CF have low glucose levels. A component of CF, countin, affects group size in a manner similar to CF, and a 1-min exposure of cells to countin decreases glucose levels. Adding 1 mM exogenous glucose negates the effect of high levels of extracellular CF on group size and mimics the effect of depleting CF on glucose levels, cell-cell adhesion, cAMP pulse size, actin polymerization, myosin assembly, and motility. These results suggest that glucose is a downstream component in part of the CF signaling pathway and may be relevant to the observed role of the insulin pathway in tissue size regulation in higher eukaryotes.
doi:10.1074/jbc.m205635200 pmid:12161440 fatcat:dixzdl63sbbvpgcqpeoa5lhofe