Journal: Molecular and Cellular Biology
Article Title: Protein Kinase Cδ Blocks Immediate-Early Gene Expression in Senescent Cells by Inactivating Serum Response Factor
doi: 10.1128/mcb.24.16.7298-7311.2004
Figure Lengend Snippet: FIG. 7. PKC phosphorylates both native and recombinant SRF on T160, and mutation of this site blocks SRF inactivation. (A) The mutant form of SRF, A160, and wild-type SRF were subjected to PKC and casein kinase II treatment for 90 min. Kinase reactions with [-32P]ATP, SRF (wild type or A160), and PKC or casein kinase II were performed, and the results are shown in the top panel. Parallel reactions without radiolabel were analyzed by Western blotting with the Phe 1 or Arg 3 phosphorylation-specific antibodies and are shown in the bottom panels. (B) Parallel unlabeled reactions were also used in SRF-SRE EMSAs. Control (C) reactions in the EMSA used SRF T160 or A160 but were not treated with kinase. (C) Native SRF phospho-analysis was performed with young- and senescent-cell extracts treated with dimethyl sulfoxide (DMSO), rottlerin (Rot), or bistratene A (BisA) before harvesting. An immunoprecipitation with the SRF polyclonal was followed by resolution by SDS–10% PAGE and transfer. Western blots of native SRF used anti-SRF (SRF), phospho-S/T Phe 1 (anti-Phe 1), or phospho-S/T Arg 3 (anti-Arg-3) antibodies. (D) Small peptides of SRF which are generated by Glu-C digestion and contain the consensus sequence for the anti-phospho-Phe 1 antibody (S/T-F, boxed) or anti-phospho-Arg 3 antibody (RxxS/T, bold). (E) Peptide analysis was carried out by immunoprecipitating SRF from young (Y) and senescent (O) cell extracts after vehicle, bistratene A (BisA), or rottlerin (Rot) treatment, silver staining, isolation from gels, and digestion with Glu-C. The resulting peptides were resolved on a 15% Tricine gel and Western blotted with phospho-S/T Phe 1 (Phe 1) or phospho-S/T Arg 3 (Arg-3) antibodies.
Article Snippet: Incubation with 20 ng of PKC polyclonal antibody (Santa Cruz sc-937) or 0.5 l of SRF rabbit antiserum was carried out with 500 g of total cellular protein for 4 h at 4°C.
Techniques: Recombinant, Mutagenesis, Western Blot, Phospho-proteomics, Control, Immunoprecipitation, Generated, Sequencing, Silver Staining, Isolation