Figure 5. Succinate-induced tuft cell hyperplasia protects DDX5^ΔIEC mice against exacerbated ileitis and restores tumorigenic potential in the DDX5^ΔIEC colon.

A. Survival plot of mice treated with succinate-NaCl (Succ., WT^IEC, n=6; DDX5^ΔIEC, n=7) or equal molar of NaCl (Veh., WT^IEC, n=4; DDX5^ΔIEC, n=6) in drinking water for 2 weeks and subsequently challenged by by 15μg of anti-CD3ɛ per mouse for 5 days. * p<0.05 (Mantel-Cox test).

B. Normalized mRNA expression of Tnf in small intestinal lamina propria (LP) mononuclear cells isolated from mice from A on day 19. Each dot represents the result of one mouse. n.s. not significant, * p<0.05 (paired t-test).

C. Normalized mRNA expression of Dclk1 in the small intestinal IECs isolated from mice from A on day 19. One dot represents the result of one mouse. * p<0.05 (unpaired t-test).

D. Representative images of DCLK1 staining in colon from mice treated with NaCl (Veh.) or succinate-NaCl in drinking water for 30 days. Scale bar represents 100μm.

E. Left: Representative images of colonic tumors from 120 days old APC^ΔIEC DDX5^WT and APC^ΔIEC DDX5^ΔIEC mice treated with succinate-NaCl or equal molar of NaCl in drinking water on day 90 for 30 days. Right: Summary of colonic tumor counts from treated APC^ΔIEC DDX5^WT and APC^ΔIEC DDX5^ΔIEC mice. Each dot represents the result from one mouse. * p<0.05 (unpaired t-test). Scale bar represents 1cm.

F. Working model. Left: DDX5-CDC42-POU2f3 axis regulating progenitor commitment toward the tuft cell lineage. Right: DDX5-dependent gene programs in differentiated tuft cells.