Tubulin binding protein, CacyBP/SIP, induces actin polymerization and may link actin and tubulin cytoskeletons

Cytoskeleton, which is built by three types of structural elements: microtubules, intermediate filaments and actin filaments, provides mechanical strength to a cell and plays an active role in many processes, including cell motility, intracellular transport and signal transduction. Impaired organization of the actin cytoskeleton may be the cause of many diseases. For example, in cancerous cells perturbations in actin polymerization/depolymerization result in higher cell motility and invasiveness. In neural diseases such as epilepsy, autism or Alzheimer’s disease, impaired organization and dynamics of the actin cytoskeleton contribute to neuronal dysfunction. Recently, our research has been focused on elucidating the role of a novel protein identified in our laboratory and named CacyBP/SIP. In 2007 we presented results showing that CacyBP/SIP interacts with tubulin and our current study shows that this protein also interacts with actin. We have identified this interaction using different techniques such as immunofluorescence microcopy, chemical crosslinking and co-sedimentation. We have also shown that CacyBP/SIP can bind actin and tubulin simultaneously. Furthermore, we observed that an increased level of CacyBP/SIP affected cell morphology, motility and adhesion. Our results show that CacyBP/SIP can have an important effect on the function of cytoskeleton.

11 October 2010