Emergence and subsequent functional specialization of kindlins during evolution of cell adhesiveness.
Bottom Line: Kindlin appears to originate from a duplication of the sequence encoding the N-terminal fragment of talin (the talin head domain) with a subsequent insertion of the PH domain of separate origin.The presence of this segment enables K2 but not K3 to localize to focal adhesions.Thus emergence and subsequent functional specialization of kindlins allowed multicellular organisms to develop additional tissue-specific adaptations of cell adhesiveness.
Affiliation: Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.Show MeSH
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Mentions: There is accumulating evidence that some premetazoan organisms possess homologues of metazoan integrins. Thus four β-integrin–encoding genes have been found in the genome of Capsaspora owczarzaki (Sebe-Pedros et al., 2010; Sebe-Pedros and Ruiz-Trillo, 2010), one β-integrin in Thecamonas trahens (Sebe-Pedros et al., 2011), and one in Sphaeroforma arctica (Figure 1B). The functions of integrins in these organisms are not clear; however, it was hypothesized that together with intracellular components of the cell adhesion complex (α-actinin, vinculin, and talin), these were forerunners of integrin signaling in unicellular protists (Sebe-Pedros and Ruiz-Trillo, 2010). Although it is not known how the integrin functions evolved from unicellular to multicellular organisms, it is likely that this transition required an upgrade of intracellular integrin adhesion machinery.
Affiliation: Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.