Overlapping Functions of the Two Talin Homologues inDictyostelium

• DOI: 10.1128/ec.00464-07
• Publication Date: 2008-03-29T12:03:48Z
• Authors: Masatsune Tsujioka; Kunito Yoshida; Akira Nagasaki; Shigenobu Yonemura; Annette Müller-T...; Taro Q. P. Uyeda
• Keywords: Talin; 0301 basic medicine; Focal Adhesions; Life Cycle Stages; Recombinant Fusion Proteins; Cell Cycle; Green Fluorescent Proteins; 03 medical and health sciences; Cell Movement; Animals; Protein Isoforms; Dictyostelium; Peptides; Oligopeptides; Cytokinesis

ABSTRACTTalin is a cytoskeletal protein involved in constructing and regulating focal adhesions in animal cells. The cellular slime moldDictyostelium discoideumhas two talin homologues,talAandtalB, and earlier studies have characterized the single knockout mutants.talA−cells show reduced adhesion to the substrates and slightly impaired cytokinesis leading to a high proportion of multinucleated cells in the vegetative stage, while the development is normal. In contrast,talB−cells are characterized by reduced motility in the developmental stage, and they are arrested at the tight-mound stage. Here, we created and analyzed a double mutant with a disruption of bothtalAandtalB. Defects in adhesion to the substrates, cytokinesis, and development were more severe in cells with a disruption of bothtalAandtalB. ThetalA−talB−cells failed to attach to the substrates in the vegetative stage, exhibited a higher proportion of multinucleated cells thantalA−cells, and showed more-reduced motility during the development and an earlier developmental arrest thantalB−cells at the loose-mound stage. Moreover, overexpression of eithertalAortalBcompensated for the loss of the other talin, respectively. The analysis oftalA−talB−cells also revealed that talin was required for the formation of paxillin-rich adhesion sites and that there was another adhesion mechanism which is independent of talin in the developmental stage. This is the first study demonstrating overlapping functions of two talin homologues, and our data further indicate the importance of talin.