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To clarify, they didn't "find a special protein called AP-1". AP-1 is a well known, well studied family of transcription factors. From snippet in background for https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6678392/: "The Activator protein-1 (AP-1), is a group of transcription factors consisted of four sub-families: the Jun (c-Jun, JunB, JunD), Fos (c-Fos, FosB, Fra1, Fra2), Maf (musculoaponeurotic fibrosarcoma) (c-Maf, MafB, MafA. Mafg/f/k, Nrl), and the ATF-activating transcription factor (ATF2, LRF1/ATF3, BATF, JDP1, JDP2) protein families [21], characterized by pleiotropic effects and a central role in different aspects of the immune system such as T-cell activation, Th differentiation, T-cell anergy and exhaustion [22,23]. " They found a correlation between AP-1 binding sites/motifs and genes with age related changes in expression through their analysis (https://www.sciencedirect.com/science/article/pii/S155041312...): "This revealed that age-opening DARs had the highest enrichment for a subset of bZIP motifs, including AP-1 subunits FRA2, FRA, JUN, JUNB, FOS, ATF3, and BATF, compared with the other peak categories (Figures 4C and S5B). Conversely, age-closing DARs had the lowest AP-1 enrichment (Figures 4C and S5B). As broadly expressed pioneer factors,39,40 AP-1 family members are responsive to a variety of stimuli41 and have been linked to potentiating age-related pathologies and phenotypes.12,13,42,43,44,45 This makes them strong candidates for driving age-related chromatin opening. Highly stable cCREs showed intermediate enrichment levels for these AP-1 motifs (Figures 4C and S5B). However, a distinct feature of highly stable cCREs was very high CTCF motif enrichment levels and binding relative to all other peak categories (Figures 4D, S5B, and S5C)." |