PMC

Close contact between telocyte (TC) and enterochromaffin cells (EC). Inset: electron-dense reinforcements in telocyte membrane (arrows). Note the enterochromaffin cell with large amounts of pleomorphic secretory granules. MEC: mucosal epithelial cell; m: mitochondria.

Bile acid signaling in the intestine (adapted from Ticho et al.). Note. 5-HT, 5-hydroxytryptamine; BA, bile acid; EC, enterochromaffin cell; IEC, intestinal epithelial cell; TGR5, Takeda G protein-coupled receptor 5.

Schematic description of the biosynthetic pathway of melatonin in enterochromaffin cells of mammals. ANAAT: arylalkylamine-N-acetyl transferase; HIOMT: hydroxindole-O-methyltransferase; EC: enterochromaffin cell; black arrows indicate the reactions. Modified from Pal et al., 2019 [].

Distribution and reserve stem cell potential of HopX-expressing Tph1⁺ EC cells. A: representative images of HopX-expressing EC cells. HopX-tdTomato, ChgA (Alexa-647) and Tph1-CFP appear in yellow, red, and blue, respectively. A non-EC-enteroendocrine (HopX⁻/Tph1⁻/ChgA⁺) cell and a HopX⁺ EC cell (HopX ⁺/TPH1⁺/ChgA⁺, white arrow) were found at p2’ and p4, respectively. B: distribution of HopX ⁺/ChgA⁺/Tph1⁺, HopX ⁺/ChgA⁺/Tph1^-, HopX ⁻/ChgA⁺/Tph1⁺ and HopX⁻/ChgA⁺/Tph1⁻ cells along the crypt axis at 17-h post-TAM induction. The x- and y-axes indicate cell position along the crypt axis and number of cells per 100 crypts, respectively. Note that the count for positions higher than p10 (>p10) was from p11 to the top edge of isolated crypts. C: organoid formation from FACS-sorted HopX ⁺/Tph1⁺ EC cells. Left: representative images of a FACS-sorted HopX ⁺/Tph1⁺ EC cell that was identified by expression of HopX-tdTomato (yellow) and Tph1-CFP (blue). Right: representative images of an organoid that developed from a single HopX ⁺/Tph1⁺ EC cell and thus appears entirely tdTomato-positive (yellow). D: organoid formation potential of EC cells in relation to HopX-expression and radiation exposure. The graph shows percent organoid formation per seeded FACS-sorted cell type for HopX ⁺/Tph1⁺ and HopX⁻/Tph1⁺ cells from control (white bars) and irradiated mice (black bars) on day 4 after a single 14 Gy exposure (mean ±, *P < 0.05, **P < 0.01). EC, enterochromaffin cell.