Introduction

Protein phosphatases (PP) and kinases are known to regulate the cell cycle dynamics. Although kinases have been studied extensively, most of the phosphatases are still unexplored. Therefore, the present study aimed to investigate the association of an isoform of PP1 family protein phosphatases 1 gamma 2 (PP12) in the regulation of cervical cancer HeLa cell proliferation.

Material and methods

Expression of PP12 transcript and protein was assessed in the cervical cancer cell line of HeLa cells through RT-PCR and western blotting. Flow cytometry was employed to confirm its expression quantitatively, and Immuno-fluorescence was done to evaluate the distribution of PP12 in the dividing mononuclear and Taxol-induced multipolar HeLa cells. PP12-specific siRNA-mediated silencing was done to understand downstream pathways. The effect of the hypoxic tumour microenvironment on PP12 expression was also evaluated.

Results

RT-PCR and western blotting confirmed the expression of PP12 in HeLa cells, and flow cytometry analysis established intracellular expression of PP12. Immunofluorescence is localized PP12 in the nucleus of mononuclear cells during interphase, whereas it is transiently redistributed to spindle poles throughout the cell division and localized back to the nucleus after complete karyokinesis. Taxol-induced multipolar HeLa cells also showed a temporal redistribution of PP12 on the spindle poles. Hypoxic conditions upregulated PP12 expression, but downregulated PP12 levels through siRNA increased GSK3phosphorylation.

Conclusions

Collectively, data suggests that PP12 is modulated during HeLa cell division and regulates GSK3phosphorylation, which may regulate downstream signalling of cell division.