The cell adhesion molecule DdCAD-1 regulates morphogenesis through differential spatiotemporal expression inDictyostelium discoideum

Abstract

SUMMARYDuring development of Dictyostelium, multiple cell types are formed and undergo a coordinated series of morphogenetic movements guided by their adhesive properties and other cellular factors. DdCAD-1 is a unique homophilic cell adhesion molecule encoded by the cadA gene. It is synthesized in the cytoplasm and transported to the plasma membrane by contractile vacuoles. In chimeras developed on soil plates, DdCAD-1-expressing cells showed greater propensity to develop into spores than did cadA-null cells. When development was performed on non-nutrient agar, wild-type cells sorted from the cadA-null cells and moved to the anterior zone. They differentiated mostly into stalk cells and eventually died, whereas the cadA-null cells survived as spores. To assess the role of DdCAD-1 in this novel behavior of wild-type and mutant cells, cadA-null cells were rescued by the ectopic expression of DdCAD-1-GFP. Morphological studies have revealed major spatiotemporal changes in the subcellular distribution of DdCAD-1 during development. Whereas DdCAD-1 became internalized in most cells in the post-aggregation stages, it was prominent in the contact regions of anterior cells. Cell sorting was also restored in cadA -slugs by exogenous recombinant DdCAD-1. Remarkably, DdCAD-1 remained on the surface of anterior cells, whereas it was internalized in the posterior cells. Additionally, DdCAD-1-expressing cells migrated slower than cadA -cells and sorted to the anterior region of chimeric slugs. These results show that DdCAD-1 influences the sorting behavior of cells in slugs by its differential distribution on the prestalk and prespore cells.

Ca2+-binding Motif of βγ-Crystallins

“…During its transport, the protein is internalized in vacuoles in a Ca 2ϩ -and conformation-dependent manner (92,93). The available functional information, although limited, suggests important roles played by this domain that remain yet to be explored.…”

New Insights into Roles of Acidocalcisomes and Contractile Vacuole Complex in Osmoregulation in Protists

“…Two soluble proteins, DdCAD-1 (Sesaki et al, 1997; Siu et al, 2011; Sriskanthadevan et al, 2009; Sriskanthadevan et al, 2011) and discoidin 1 (Sriskanthadevan et al, 2009) are transported to the cell surface previous residence in the lumen of the CVC. Polyphosphate (polyP) has also been detected by DAPI staining in the lumen of the CVC of C. reinhardtii (Ruiz et al, 2001a), and D. discoideum (Marchesini et al, 2002), while orthophosphate (Pi) was enriched in subcellular fractions of T. cruzi containing the CVC (Rohloff et al, 2004), suggesting hydrolysis of polyP during fractionation.…”

The G alpha subunit Gα8 inhibits proliferation, promotes adhesion and regulates cell differentiation

“…Cell-type specific alterations in adhesion have also been proposed in cell sorting. Cells with greater adhesiveness tend to differentiate into prestalk cells (Nicol et al, 1999; Sriskanthadevan et al, 2011). Our results are consistent with adhesion-dependent differentiation during development and suggest that cell adhesion likely precedes cell cycle position in determining cell differentiation.…”

“…The strong cell–substrate adhesion of cells expressing Gα8 might also reduce cAMP chemotactic speed, which causes cells to reach the aggregates later than wild-type cells. Previous studies have suggested that spatial position in aggregates affects cell type differentiation (Krefft et al, 1984; Sriskanthadevan et al, 2011). Cells in the periphery differentiate mostly into prestalk cells and our results are consistent with position-dependent differentiation during development.…”