Nuclear localization of propiece IL-1 alpha in HeLa cells

Purpose: The study aimed to examine the nuclear localization of propiece interleukin (IL)-1 alpha (ppIL-1 alpha) and extracellular release rates of ppIL-1 alpha, pIL-1 alpha, and mIL-1 alpha. Methods: The subcellular localization of IL-1 alpha molecules was observed in HeLa cells transfected with green fluorescent protein (GFP)-tagged IL-1 alpha. Extracellular release efficiency was examined using N-terminal HiBiT-tagged IL-1 alpha. The nuclear localization status of ppIL-1 alpha was examined by incubating ppIL-1 alpha transfectants with 0.1% Triton X-100 solution or with complete medium on ice. Results: The results indicated the diffuse cytoplasmic and nuclear localization for m and p and ppIL-1, respectively. All IL-1 alpha forms were released from the cells even in the steady state, and the release efficiency was 25%, 13%, and 8% for mIL-1 alpha, pIL-1 alpha, and ppIL-1 alpha, respectively. Under oxidative stress condition, GFP-mIL-1 alpha was totally diminished, but weak staining of GFP-pIL-1 alpha and GFP-ppIL-1 alpha was detected; nuclear localization of GFP-ppIL-1 alpha was completely abolished by 0.1% Triton X-100 treatment, however, it remained in the nucleus after culture in complete medium on ice. Conclusion: The results of this study showed that ppIL-1 alpha was localized in the nucleus and released extracellularly even in the steady state. Moreover, its cellular localization is not firm, and it is presumed to be floating in the nucleoplasm.