Abstract
Elevated levels of the cold shock protein Y-Box binding protein 1 (YB-1) are associated with poor prognosis and a reduction in disease-free survival in many cancers including breast cancer. Recently, mass spectrometry data from our laboratory revealed that YB-1 potentially binds to the cytoskeletal protein Septin 2 (SEPT2). This novel interaction is further investigated in this research project.
Using co-immunoprecipitation (co-IP), I show that YB-1 and SEPT2 bind through concomitant binding with β-Actin which acts as an intermediary protein. Using immunofluorescence, I go on to show that YB-1, SEPT2, and Actin colocalise during telophase and also during cell migration. Knockdown of YBX1 (the gene encoding YB-1) by siRNA reduces the amount of co-localisation between SEPT2 and Actin during cell migration. Western blot labelling of lysates from cells following YBX1 knockdown revealed that YB-1 is not transcriptionally regulating levels of SEPT2, indicating that the interaction between YB-1 and SEPT2 occurs post-transcriptionally via protein-protein interaction. Further analysis of cell motility in both 2D and 3D revealed a reduction in both speed and distance travelled by single cells following YBX1 knockdown as well as reduced cellular adhesion and reduced spheroid size and cohesiveness. Together, these findings show that YB-1 is important with regards to cancer cell migration.