FIG. 6.

Enhancement of nuclear entry by addition of NLS rescues the transcriptional repression activity defect of PERΔ. This much-improved repression activity of PERΔ-NLS remains sensitive to down-regulation of DBT and CKII similar to wild-type PER, albeit to lesser extent, suggesting that these kinases could be involved in both nuclear localization and repression activity potentiation of PER. (a) Immunocytochemistry of PERΔ (top) and PERΔ-NLS (bottom). (Left) Staining of PER using anti-V5 antibody; (middle) nuclear staining using DAPI (4′,6′-diamidino-2-phenylindole); (right) merged image showing subcellular localization of PERΔ and PERΔ-NLS. (b) PERΔ-NLS regains active repression activity (bottom left and top right; unfilled bars); reduction of DBT and of CKIIα activity by RNAi reduces the repression activity (bottom left and top right, respectively; filled bars). The graph depicts normalized luciferase activity from S2 cell repression activity assay using increasing amounts of PERΔ-NLS; wild-type PER was used as a control (second column). (Bottom right) RNAi of both kinases shows stronger effect but to an extent noticeably less than that for wild-type PER.