Fig 2: JAG1 heterozygous mutations in CHH probands.(A) Schematic illustration of JAG1 mutations in nCHH and KS probands. The signal peptide (SP), the Delta:Serrate:LAG-2 (DSL) domain, the EGF-like repeats, the cysteine-rich region (CR), and the transmembrane domain (TM) are represented. The relative position of the variants is indicated on the illustration. (B) Alignment of partial protein sequences of JAG1 orthologs showing in blue the amino acid residues evolutionarily conserved.

Fig 3: Mechanisms of regulation of JAG1 expression based on in vitro study. (a) The effect of inhibition of RAS‐MEK‐MAP kinase pathway on JAG1 expression and induction of EMT‐like phenotype was examined using the MEK inhibitor PD325901 in the colon cancer cell line HCT‐116. In the left panel, blue staining indicates the nucleus and green staining indicates JAG1 protein. In the middle panel, blue staining indicates the nucleus and red staining indicates E‐cadherin protein. In the right panel, blue, green, and red staining indicate the nucleus, SNAIL, and JAG1 protein, respectively. Scale bars represent 50 µm. (b) Fluorescence intensity of JAG1, Snail, and E‐cadherin was analyzed. Data are presented as mean ± SD of 20 fields of view. *, P < 0.05, Student's t‐test. (c) Effects of GSK3β inhibitor on JAG1 protein expression and EMT‐like phenotype. JAG1, E‐cadherin, and SNAIL protein expression was analyzed by western blotting.

Fig 4: Hypothesized mechanisms of cancer recurrence or death induced by JAG1‐Notch pathway activation following increased JAG1 expression regulated by various factors.

Fig 5: NOTCH1 signalling mediates non-cell autonomous regulation of chromatin structure at the microscopic and nucleosome scale. Lateral induction of NOTCH1 activity in a signal-receiving cell by JAG1 on the surface of an adjacent cell (including cancer cells) can drive NIS. NIS cells form unique chromatin-accessible regions and microscopically ‘smoothened’ chromatin. In the context of RIS, non-cell autonomous activation of NOTCH1 signalling can repress the formation of AT-rich RAS-driven accessible regions at the nucleosome level and SAHF formation at the microscopic level. Mechanistically, N1ICD represses HMGA1, which is responsible for SAHF formation and at least partially for the formation of ectopic-accessible chromatin in RIS cells