The g-tubulin meshwork assists to the transport of cytosolic PCNA to chromatin in mammalian cells

Changes in the location of g-tubulin ensure cell survival and preserve genome integrity. We investigated whether the nuclear accumulation of g-tubulin facilitates the transport of proliferating cell nuclear antigen (PCNA) between the cytosolic and the nuclear compartment in mammalian cells. We found that the g-tubulin meshwork assists to the recruitment of PCNA to chromatin. Also, decreased levels of g-tubulin affected the nuclear pool of PCNA. In addition, the g-tubulin C terminus encodes a PCNA-interacting peptide (PIP) motif, and a g-tubulin–PIP-mutant affects the nuclear accumulation of PCNA. In a cell-free system, PCNA and g-tubulin formed a complex. In tumors, there is a significant positive correlation between TUBG1 and PCNA expression. Thus, we report a novel mechanism that constitutes the basis for tumor growth by which the g-tubulin meshwork maintains indefinite proliferation by acting as an opportune scaffold for the transport of PCNA from the cytosol to the chromatin. The experiment was performed in two cell lines and a total number of 64 samples were included.There are two samples for each antibody (gamma tubulin, PCNA, FoxM1 and Mcm5 in U2OS cells, and gamma tubulin, and PCNA for shTUBG U2OS cells) and timepoint (three, seven and nine hours, and Non-synchronous) per cell line and a whole cell lysate (WCE) is included as a control for each sample.