Table 1.

Cell-specific normal and impaired functions of autophagy in the colonic epithelial cells.

Cell Type	Autophagy
	Normal Function	Effects of Functional Impairments
Absorptive cell (colonocyte)	cell differentiation cell survival ↑ cell metabolism ↔	dysbiosis ○ immune cell function ↓ ○ inflammation ↑ ○ autophagy Ʇ ATG genes/proteins ↓ ○ autophagy Ʇ ■ dysbiosis ■ cell permeability ↑ ■ cell proliferation ↑↑ ■ T cell infiltration ↑ autophagy ↑ ○ cell proliferation ↓
Goblet cell	mucin accumulation and secretion normal gut flora ↔ antimicrobial peptide production protection against colitis (ATG7) role in GAPs	autophagy ↓ ○ abnormal microflora ↑ ○ antimicrobial peptide ↓ ○ MUC-2 production ↓ ○ mucus ↓ ○ colitis sensitivity ↑
Intestinal (colonic) stem cell	cell maintenance controlling cell proliferation regulating cell differentiation regulating cell reprogramming generating PSCs	mitophagy ↑ (NOD2, ATG16L1) colitis ↑ (Slit2/Robo1 pathway) colonic SC proliferation ○ epithelial stress and cell hyperplasia Ʇ autophagy → EGFR/pMAPK/ERK ↑
Paneth-like cell	facilitating secretory function secretion of antibacterial products (e.g., lysozyme) preventing bacterial adhesion encoding niche factors supporting ISCs nutritional status detector	secretory autophagy ↑ ATG gene mutations (e.g., ATG16L1, ATG5, ATG7) ○ autophagy Ʇ ■ abnormal/reduced granules ↑ ■ abnormal exocytosis of granules ■ bacterial clearance ↓

Legend: ↑/↓: increase/decrease; stimulation/inhibition; ↔: maintenance; Ʇ: suppression; →: lead to; ATG: autophagy-related; EGFR: epidermal growth factor receptor; ERK: extracellular signal-regulated kinase; GAPs: goblet-cell-associated antigen passages; GLP-2: Glucagon-like peptide 2; IGF: insulin-like growth factor; (I)SCs: (intestinal) stem cells; (p)MAPK: (phosphorylated) mitogen-activated protein kinase; NOD2: the nucleotide-binding oligomerization domain-containing protein 2; PSCs: pluripotent stem cells.