Searching for centaurin-α2 interacting proteins: evidence of interaction with tubulin-β

Centaurin-α2 belongs to the centaurin family and is characterized by a zinc binding domain similar to Arf-GAP and by two PH domains. Its expression pattern and function have not yet been extensively investigated. Centaurin-α2 was shown to bind PIP2 and PIP3 and to localize at plasma membrane, promoting the release of GTP and the consequent inactivation of Arf-6, a protein involved in the regulation of intracellular vesicular trafficking and in cytoskeletal rearrangement. We recently studied the expression profile of CENTA2 mRNA by in situ hybridization, during mouse embryo development and we found it is expressed in early developmental stages of encephalon and heart. With the final aim of elucidating the centaurin-α2 molecular pathways and its biological role/s, we searched for interactors by means of the yeast two-hybrid assay. An interaction with the C-terminal region of tubulin-β has been observed and confirmed by co-immunoprecipitation. This portion of tubulin- β is involved in the binding of MAPs and motor proteins. Considering that tubulin-β was found to bind phospholipase Cγ1 through its PH domains, we hypothesized an interaction between centaurin-α2 mediated by this domain. The yeast two-hybrid assay allowed us also to detect an interaction with nucleoporin NUP53, a component of the nuclear pore complex, that will be confirmed by co-immunoprecipitation. According to our evidence, that will be further investigated, we propose that centaurin-α2 can be localized at the plasma membrane, the cytoplasm and the perinuclear region, and can translocate through microtubules anchoring, according to its hypothesized role in vesicular trafficking.