Figure 4: RNaseH1 depletion leads to RPA activation at ALT telomeres.
From: RNaseH1 regulates TERRA-telomeric DNA hybrids and telomere maintenance in ALT tumour cells
(a) HeLa and U2OS cells were transfected with the indicated siRNAs and 48 and 72 h later protein extracts were prepared. Western blot analysis was performed using antibodies against RNaseH1, RPA32 phosphorylated at Serine 33 (pSer33), total RPA32 and KAP1 (loading control). The asterisk indicates a cross-reacting band. Cells treated for 6 h with 5 mM hydroxyurea (HU) were used as controls for pSer33 activation. (b) SiRNA transfected cells were subjected to indirect immunofluorescence using antibodies against TRF2 (to visualize telomeres; red) and pSer33 (green). DNA was counterstained with DAPI (blue). Arrows point to examples of pSer33 foci co-localizing with TRF2 (TIFs). Scale bar, 9 μm. Cells treated for 6 h with 5 mM HU were used as controls for pSer33 activation.
