Ectopic expression of cyclase associated protein CAP restores the streaming and aggregation defects of adenylyl cyclase a deficient Dictyostelium discoideum cells

Here, we have investigated the role of cyclase-associated protein (CAP), an important regulator of cell polarity and F-actin/G-actin ratio in the aca- mutant. We show that ectopic expression of GFP-CAP improves cell polarization, streaming and aggregation in aca- cells, but it fails to completely restore development. Our studies indicate a requirement of CAP in the ACA dependent signal transduction for progression of the development of unicellular amoebae into multicellular structures. The reduced expression of the cell adhesion molecule DdCAD1 together with csA is responsible for the defects in aca- cells to initiate multicellular development. Early development was restored by the expression of GFP-CAP that enhanced the DdCAD1 transcript levels and to a lesser extent the csA mRNA levels.Collectively, our data shows a novel role of CAP in regulating cell adhesion mechanisms during development that might be envisioned to unravel the functions of mammalian CAP during animal embryogenesis.The amoeba Dictyostelium discoideum has adopted a unique strategy for multicellular development, as in their vegetative stage, single-celled amoebae feed on bacteria and multiply by binary fission. Upon starvation, they embark on a developmental cycle where individual cells come together in response to the chemoattractant cAMP finally forming fruiting bodies that are highly differentiated multicellular structures [1,2]. These features of D. discoideum make it a valuable and convenient experimental model for studies related to signal transduction, cell migration, chemotaxis, cell adhesion, differentiation and development. Its development displays many features that are characteristics of mammalian embryogenesis including the tightly regulated cell-cell adhesion. Cell adhesion, an integral part of D. discoideum development, is important for morphogenesis and regulated gene expression in the multicellular context and is required to trigger cell-differentiation [3-5].Specific cell-cell ad