The non-muscle-myosin-II heavy chain Myh9 mediates colitis-induced epithelium injury by restricting Lgr5+ stem cells

Abstract

Lgr5 þ stem cells are crucial to gut epithelium homeostasis, and therapies targeting these cells hold promise for treatment of gastrointestinal diseases. Here we report that the non-muscle-myosin-II (NMII) heavy chain Myh9 accumulates at epithelial injury sites in mice distal colon treated with dextran sulphate sodium (DSS). Gut-epithelium-specific Myh9 monoallelic deletion alleviates DSS-induced colonic crypt damage and acute colitis. Consistently, the NMII inhibitor blebbistatin can improve the survival of Lgr5 þ stem cells and the growth of Lgr5 organoids. Mechanistically, inhibition of NMII by blebbistatin or Myh9 monoallelic deletion activates Akt through Rac1 and PAK1, which is essential for the survival and pluripotency of Lgr5 þ cells. These results establish a critical role of the Myh9-Rac1-PAK1-Akt pathway in the maintenance of Lgr5 þ stem cells. As blebbistatin can mitigate DSS-induced colitis and preserve Lgr5 þ colonic stem cells in vivo, our findings provide a potential therapeutic intervention of gastrointestinal epithelium injury and degenerative diseases.

A growth factor-free culture system underscores the coordination between Wnt and BMP signaling in Lgr5+ intestinal stem cell maintenance

“…We have previously shown that blebbistatin could promote survival of crypts 22 , and Yin et al demonstrated that valproic acid (VPA) increased Lgr5 + ISCs in ENR-cultured organoids 14 . We then examined their effect in the 2ki culture system and found that blebbistatin markedly increased the organoid number (Supplementary Fig.…”

“…Intestinal crypts were isolated and cultured as previously described 22 . Briefly, mouse intestine was cut longitudinally and washed three times with cold PBS.…”

“…Protein lysates were prepared from organoids, and immunoblotting was performed as previously described 22 . The following primary antibodies were used: mouse anti-β-catenin (Sata Cruz, sc-7963, 1:1000), rabbit anti-Smad1 (CST, 6944, 1:2000), rabbit anti-p-Smad1/5/8 (CST, 9511, 1:2000), rabbit anti-p-AKT 473 (CST, 4060, 1:2000), rabbit anti-AKT (CST, 9272, 1:2000), mouse anti-YAP (Sata Cruz, sc-101199, 1:1000), rabbit anti-p-p38 (CST, 9215L, 1:2000), mouse anti-P38 (Sata Cruz, sc-7972, 1:1000), and mouse anti-tubulin (Proteintech, 66031–1-Ig, 1:20,000).…”

MYH9 binds to lncRNA gene PTCSC2 and regulates FOXE1 in the 9q22 thyroid cancer risk locus

“…Recently, additional functions of MYH9 have been reported. For example, MYH9 affects the expression of PAX5 by interacting with Thy28 (27), and it can activate AKT through RAC1 and PAK1 (28), suggesting a role in gene regulation. In 2014, a role for MYH9 as a tumor suppressor gene was discovered in squamous cell carcinomas (SCCs).…”

BMP restricts stemness of intestinal Lgr5+ stem cells by directly suppressing their signature genes

“…Intestinal crypts were isolated and cultured as previously described63. Briefly, mouse intestine was cut longitudinally and washed three times with cold PBS.…”