Functional assessment of the V390F mutation in the CCTδ subunit of chaperonin containing tailless complex polypeptide 1.

The chaperonin containing tailless complex polypeptide 1 (CCT) is a multi-subunit molecular chaperone. It is found in the cytoplasm of all eukaryotic cells, where the oligomeric form plays an essential role in the folding of predominantly the cytoskeletal proteins actin and tubulin. Both the CCT oligomer and monomeric subunits also display functions that extend beyond folding, which are often associated with microtubules and actin filaments. Here, we assess the functional significance of the CCTδ V390F mutation, reported in several cancer cell lines. Upon transfection into B16F1 mouse melanoma cells, GFP-CCTδ incorporates into the CCT oligomer more readily than GFP-CCTδ. Furthermore, unlike GFP-CCTδ, GFP-CCTδ does not interact with the dynactin complex component, p150. As CCTδ has previously been implicated in altered migration in wound healing assays, we assessed the behaviour of GFP-CCTδ and other mutants of CCTδ, previously used to assess functional interactions with p150, in chemotaxis assays. We developed the assay system to incorporate a layer of the inert hydrogel GrowDex® to provide a 3D matrix for chemotaxis assessment and found subtle differences in the migration of B16F1 cells, depending on the presence of the hydrogel.