Nuclear Apoptosis Inducing Factor 1 (NAIF1)

The deduced 327-amino acid protein contains 2 N-terminal nuclear localization signals, a glycine-rich region, and a homeodomain-like region. Northern blot analysis detected multiple NAIF1 transcripts in nearly all tissues examined, consistent with the existence of alternative RNA splicing forms. Immunofluorescence studies of NAIF1 expressed in HeLa and other cell lines localized NAIF1 to the nucleus. Overexpression of NAIF1 induced apoptosis characterized by chromatin condensation and margination that began later than BAX-induced apoptosis, and NAIF1-induced apoptosis was accompanied by a decrease in mitochondrial transmembrane potential, measured by DiOC6(3) staining, and activation of caspase-3 (CASP3). NAIF1 amino acids 1-70 were required for NAIF1 nuclear localization and induction of apoptosis.