Fig. 1.

 IL-1α is a chromatin-associated cytokine. (A) Schematic representation of IL-1α GFP-conjugated proteins. The N-terminal domain containing the NLS in position 82–89 is denoted by a dark gray box. The C-terminal mature component (known as the IL-1R interacting domain) is represented by a clear box. (B) B16 melanoma cells were transfected with precIL-1α, ppIL-1α, and IL-1α mutants containing inactive NLS or GFP. Twenty-four hours later, nuclear localization and chromatin alignment were analyzed by confocal microscopy. (C) ChIP assays were performed using sheared chromatin from lysates of precIL-1α or GFP (as a control) transfected cells and were immunoprecipitated with anti-GFP antibody. An additional control assay was performed without the presence of antibody (beads only). The immunoprecipitates were separated over a 4–20% gradient SDS/PAGE gel and transferred to a nitrocellulose membrane. To verify chromatin presence, histone H3 antibody served as a molecular marker in Western blot analysis.