Overexpression of hCLP46 enhances Notch activation and regulates cell proliferation in a cell type-dependent manner.

Human CAP10-like protein 46 kDa (hCLP46), also known as Poglut1, has been shown to be an essential regulator of Notch signalling. hCLP46 is overexpressed in primary acute myelogenous leukaemia, T-acute lymphoblastic leukaemia samples and other leukaemia cell lines. However, effects of hCLP46 overexpression, up to now, have remained unknown. In this study, we established stable 293TRex cell lines inducibly overexpressing hCLP46, and knocked down hCLP6 with a specific small interfering RNA to explore function of the protein in Notch signalling and cell proliferation. hCLP46 overexpression enhanced Notch1 activation in 293Trex cells in a ligand-dependent manner, with increased Notch signalling enhancing Hes1 expression. We further verified that overexpression of hCLP46 inhibited proliferation of 293TRexs and was correlated with increases in cyclin dependent kinase inhibitors p21 and p27, whereas reduced hCLP46 expression moderately increased cell proliferation. In addition, p21 and p27 protein levels were higher when Notch signalling was activated by EDTA treatment. Taken together, hCLP46 enhanced Notch activation and inhibited 293TRex cell proliferation through CDKI signalling.