Figure 5.

Overexpression in TO cells or knockdown of the HSF1 protein in OT cells can either rescue or aggravate the B12-associated ER stress. (a) Whereas transfecting TO cells with siRNA against HSF1 results in no significant changes to either the ER stress or the apoptosis, the same transfection in OT cells leads to lowered HSPs expressions (all P<0.05) and consequently higher ER stress and apoptosis (all P<0.05), as well as lowed proliferation (P<0.001). (b) Transfection with either a constitutively activated Hsf1 (Hsf1-act) or a dominant negative Hsf1 (Hsf1-inactive) construct shows similar results. In TO cells, positive effects are seen with the transfection of the Hsf1-act on HSPs expressions, ER stress reductions, apoptosis and proliferation, whereas no effect can be discerned when Hsf1-inactive construct is transfected into the same cells. In OT cells, adverse effects are seen only when the Hsf1-inactive construct is transfected into the cells and no difference can be detected with the transfection of the Hsf1-act construct. (c) Equally, the positive effects of celastrol, an activator for HSF1, on HSPs expression, ER stress and apoptosis can only be seen in TO cells, but not in OT cells