All Publications

  • BMP restricts stemness of intestinal Lgr5+ stem cells by directly suppressing their signature genes. Nature communications Qi, Z., Li, Y., Zhao, B., Xu, C., Liu, Y., Li, H., Zhang, B., Wang, X., Yang, X., Xie, W., Li, B., Han, J. J., Chen, Y. G. 2017; 8: 13824


    The intestinal epithelium possesses a remarkable self-renewal ability, which is mediated by actively proliferating Lgr5+ stem cells. Bone morphogenetic protein (BMP) signalling represents one major counterforce that limits the hyperproliferation of intestinal epithelium, but the exact mechanism remains elusive. Here we demonstrate that epithelial BMP signalling plays an indispensable role in restricting Lgr5+ stem cell expansion to maintain intestinal homeostasis and prevent premalignant hyperproliferation on damage. Mechanistically, BMP inhibits stemness of Lgr5+ stem cells through Smad-mediated transcriptional repression of a large number of stem cell signature genes, including Lgr5, and this effect is independent of Wnt/β-catenin signalling. Smad1/Smad4 recruits histone deacetylase HDAC1 to the promoters to repress transcription, and knockout of Smad4 abolishes the negative effects of BMP on stem cells. Our findings therefore demonstrate that epithelial BMP constrains the Lgr5+ stem cell self-renewal via Smad-mediated repression of stem cell signature genes to ensure proper homeostatic renewal of intestinal epithelium.

    View details for DOI 10.1038/ncomms13824

    View details for PubMedID 28059064

    View details for PubMedCentralID PMC5227110

  • The non-muscle-myosin-II heavy chain Myh9 mediates colitis-induced epithelium injury by restricting Lgr5+ stem cells. Nature communications Zhao, B., Qi, Z., Li, Y., Wang, C., Fu, W., Chen, Y. G. 2015; 6: 7166


    Lgr5+ 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+ 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+ cells. These results establish a critical role of the Myh9-Rac1-PAK1-Akt pathway in the maintenance of Lgr5+ stem cells. As blebbistatin can mitigate DSS-induced colitis and preserve Lgr5+ colonic stem cells in vivo, our findings provide a potential therapeutic intervention of gastrointestinal epithelium injury and degenerative diseases.

    View details for DOI 10.1038/ncomms8166

    View details for PubMedID 25968904

  • Tankyrases maintain homeostasis of intestinal epithelium by preventing cell death. PLoS genetics Ye, P., Chiang, Y. J., Qi, Z., Li, Y., Wang, S., Liu, Y., Li, X., Chen, Y. G. 2018; 14 (9): e1007697


    Lgr5+ intestinal stem cells are crucial for fast homeostatic renewal of intestinal epithelium and Wnt/β-catenin signaling plays an essential role in this process by sustaining stem cell self-renewal. The poly(ADP-ribose) polymerases tankyrases (TNKSs) mediate protein poly-ADP-ribosylation and are involved in multiple cellular processes such as Wnt signaling regulation, mitotic progression and telomere maintenance. However, little is known about the physiological function of TNKSs in epithelium homeostasis regulation. Here, using Villin-creERT2;Tnks1-/-;Tnks2fl/fl (DKO) mice, we observed that loss of TNKSs causes a rapid decrease of Lgr5+ intestinal stem cells and magnified apoptosis in small intestinal crypts, leading to intestine degeneration and increased mouse mortality. Consistently, deletion of Tnks or blockage of TNKS activity with the inhibitor XAV939 significantly inhibits the growth of intestinal organoids. We further showed that the Wnt signaling agonist CHIR99021 sustains the growth of DKO organoids, and XAV939 does not cause growth retardation of Apc-/- organoids. Consistent with the promoting function of TNKSs in Wnt signaling, Wnt/β-catenin signaling is significantly decreased with stabilized Axin in DKO crypts. Together, our findings unravel the essential role of TNKSs-mediated protein parsylation in small intestinal homeostasis by modulating Wnt/β-catenin signaling.

    View details for DOI 10.1371/journal.pgen.1007697

    View details for PubMedID 30260955

    View details for PubMedCentralID PMC6177203

  • Monolayer culture of intestinal epithelium sustains Lgr5+ intestinal stem cells. Cell discovery Liu, Y., Qi, Z., Li, X., Du, Y., Chen, Y. G. 2018; 4: 32

    View details for DOI 10.1038/s41421-018-0036-z

    View details for PubMedID 29928510

    View details for PubMedCentralID PMC5997714

  • TGFβ induced factor homeobox 1 promotes colorectal cancer development through activating Wnt/β-catenin signaling. Oncotarget Wang, J. L., Qi, Z., Li, Y. H., Zhao, H. M., Chen, Y. G., Fu, W. 2017; 8 (41): 70214-70225


    Colorectal cancer (CRC) is one of the most common cancers, but the mechanisms underlying its initiation and progression are largely unknown. TGIF1 (TGFB induced factor homeobox 1) is a transcriptional corepressor that belongs to the three-amino acid loop extension (TALE) superclass of atypical homeodomains. It has been reported that TGIF1 is highly expressed in mammary cancer and non-small cell lung cancer and can enhance tumor progression. However, the role of TGIF1 in colorectal cancer remains unknown. Here, we report that TGIF1 is significantly upregulated in colorectal cancers, and its high expression predicts poor prognosis. Overexpression of TGIF1 markedly promotes the proliferation of colorectal cancer cells both in vivo and in vitro. In addition, TGIF1 activates Wnt/β-catenin signaling, and the homeodomain is indispensable for Wnt activation and β-catenin interaction. Taken together, our results suggest that TGIF1 is a novel colorectal tumor promoter and indicate that TGIF1 enhances colorectal cancer tumorigenesis through activating Wnt signaling.

    View details for DOI 10.18632/oncotarget.19603

    View details for PubMedID 29050273

    View details for PubMedCentralID PMC5642548

  • Regulation of intestinal stem cell fate specification. Science China. Life sciences Qi, Z., Chen, Y. G. 2015; 58 (6): 570-8


    The remarkable ability of rapid self-renewal makes the intestinal epithelium an ideal model for the study of adult stem cells. The intestinal epithelium is organized into villus and crypt, and a group of intestinal stem cells located at the base of crypt are responsible for this constant self-renewal throughout the life. Identification of the intestinal stem cell marker Lgr5, isolation and in vitro culture of Lgr5+ intestinal stem cells and the use of transgenic mouse models have significantly facilitated the studies of intestinal stem cell homeostasis and differentiation, therefore greatly expanding our knowledge of the regulatory mechanisms underlying the intestinal stem cell fate determination. In this review, we summarize the current understanding of how signals of Wnt, BMP, Notch and EGF in the stem cell niche modulate the intestinal stem cell fate.

    View details for DOI 10.1007/s11427-015-4859-7

    View details for PubMedID 25951932

  • The Wnt Signaling Antagonist Dapper1 Accelerates Dishevelled2 Degradation via Promoting Its Ubiquitination and Aggregate-induced Autophagy. The Journal of biological chemistry Ma, B., Liu, B., Cao, W., Gao, C., Qi, Z., Ning, Y., Chen, Y. G. 2015; 290 (19): 12346-54


    Autophagy is a regulated process that sequesters and transports cytoplasmic materials such as protein aggregates via autophagosomes to lysosomes for degradation. Dapper1 (Dpr1), an interacting protein of Dishevelled (Dvl), antagonizes Wnt signaling by promoting Dishevelled degradation via lysosomes. However, the mechanism is unclear. Here, we show that Dpr1 promotes the von Hippel-Lindau tumor suppressor (VHL)-mediated ubiquitination of Dvl2 and its autophagic degradation. Knockdown of Dpr1 decreases the interaction between Dvl2 and pVHL, resulting in reduced ubiquitination of Dvl2. Dpr1-mediated autophagic degradation of Dvl2 depends on Dvl2 aggregation. Moreover, the aggregate-prone proteins Dvl2, p62, and the huntingtin mutant Htt103Q promote autophagy in a Dpr1-dependent manner. These protein aggregates enhance the Beclin1-Vps34 interaction and Atg14L puncta formation, indicating that aggregated proteins stimulate autophagy initiation. Ubiquitination is not essential for the aggregate-induced autophagy initiation as inhibition of the ubiquitin-activation E1 enzyme activity did not block the aggregate-induced Atg14L puncta formation. Our findings suggest that Dpr1 promotes the ubiquitination of Dvl2 by pVHL and mediates the protein aggregate-elicited autophagy initiation.

    View details for DOI 10.1074/jbc.M115.654590

    View details for PubMedID 25825496

    View details for PubMedCentralID PMC4424364

  • Dapper1 promotes autophagy by enhancing the Beclin1-Vps34-Atg14L complex formation. Cell research Ma, B., Cao, W., Li, W., Gao, C., Qi, Z., Zhao, Y., Du, J., Xue, H., Peng, J., Wen, J., Chen, H., Ning, Y., Huang, L., Zhang, H., Gao, X., Yu, L., Chen, Y. G. 2014; 24 (8): 912-24


    Autophagy is an intracellular degradation process to clear up aggregated proteins or aged and damaged organelles. The Beclin1-Vps34-Atg14L complex is essential for autophagosome formation. However, how the complex formation is regulated is unclear. Here, we show that Dapper1 (Dpr1) acts as a critical regulator of the Beclin1-Vps34-Atg14L complex to promote autophagy. Dpr1 ablation in the central nervous system results in motor coordination defect and accumulation of p62 and ubiquitinated proteins. Dpr1 increases autophagosome formation as indicated by elevated puncta formation of LC3, Atg14L and DFCP1 (Double FYVE-containing protein 1). Conversely, loss of Dpr1 impairs LC3 lipidation and causes p62/SQSTM1 accumulation. Dpr1 directly interacts with Beclin1 and Atg14L and enhances the Beclin1-Vps34 interaction and Vps34 activity. Together, our findings suggest that Dpr1 enhances the Atg14L-Beclin1-Vps34 complex formation to drive autophagy.

    View details for DOI 10.1038/cr.2014.84

    View details for PubMedID 24980960

    View details for PubMedCentralID PMC4123296