Unknown,Transcriptomics,Genomics,Proteomics

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In vitro expansion of single adult Lgr5+ liver cells induced by Wnt-driven regeneration

ABSTRACT: The Wnt target gene Lgr5 marks actively dividing stem cells in Wnt-driven, self-renewing tissues such as small intestine and colon, stomach and hair follicles. A 3D culture system allows long-term clonal expansion of single Lgr5+ stem cells into transplantable organoids that retain many characteristics of the original epithelial architecture. A crucial component of the culture medium is the Wnt agonist Rspo, the recently discovered ligand of Lgr5. Here we show that Lgr5-LacZ is not expressed in healthy adult liver, yet that small Lgr5-LacZ+ cells appear near bile ducts upon damage, coinciding with robust activation of Wnt signaling. As shown by lineage tracing using a novel Lgr5-ires-CreERT2 knock-in allele, damage-induced Lgr5+ cells generate hepatocytes and bile ducts in vivo. Single Lgr5+ cells from damaged liver can be clonally expanded as organoids in Rspo1-based culture medium over multiple months. Such clonal organoids can be induced to differentiate in vitro and to generate functional hepatocytes upon transplantation into FAH-/- mice. These findings imply that previous findings on Lgr5+ stem cells in actively self-renewing tissues extend to damage-induced stem cells in a tissue with a low rate of spontaneous self-renewal. We first generated arrays from multiple wildtype tissues including muscle, white adipose tissues, brown adipose tissues, liver and pancreas. Then we generated arrays from liver derived cultures maintained in different conditions, and compared the expression profile with the corresponding parental tissues and other non-related tissues.

ORGANISM(S): Mus musculus

SUBMITTER: Vivian Li

PROVIDER: E-GEOD-32210 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background & Aims: Hierarchical organization of intestine relies on their stem cells by self-renew and producing committed progenitors. Although signals like Wnt are known to animate the continued renewal by maintaining intestinal stem cells (ISCs) activity, molecular mechanisms especially E3 ubiquitin ligases that modulate ISCs ‘stemness’ and supportive niche have not been well understood. Here, we investigated the role of Cullin 4B (Cul4b) in regulating ISC functions. Methods: We generated mice with intestinal epithelial-specific disruption of Cul4b (pVillin-cre; Cul4bfn/Y), inducible disruption of Cul4b (Lgr5-creERT2; Cul4bfn/Y, CAG-creERT2; Cul4bfn/Y) and their control (Cul4bfn/Y). Intestinal tissues were analyzed by histology, immunofluorescence, RNA sequencing and mass spectrum. Intestinal organoids deprived from mice with pVillin-Cre; Cul4bfn/Y, Lgr5-Cre; Cul4bfn/Y, Tg-Cul4b and their controls were used in assays to measure intestinal self-renewal, proliferation and differentiation. Wnt signaling and intestinal markers were analyzed by immunofluorescence and immunoblot assays. Differential proteins upon Cul4b ablation or Cul4b-interacting proteins were identified by mass spectrometry. Results: Cul4b specifically located at ISCs zone. Block of Cul4b impaired intestinal homeostasis maintenance by reduced self-renewal and proliferation. Transcriptome analysis revealed that Cul4b-null intestine lose ISC characterization and showed disturbed ISC niche. Mechanistically, reactivated Wnt pathway could recover intestinal dysfunction of Cul4b knockout mice. Analysis of differential total and ubiquitylated proteins uncovered the novel targeting substrate of Cullin-Ring ubiquitin ligase 4b (CRL4b), immunity-related GTPase family M member 1 (Irgm1) in intestine. Decreased Irgm1 rescued abnormally interferon signaling, overemphasized autophagy and downstream phosphate proteins in Cul4b knockout mice. Conclusion: We conclude that Cul4b is essential for ISC self-renewal and Paneth cell function by targeting Irgm1 and modulating Wnt signaling. Our results demonstrate that Cul4b is a novel ISC stemness and niche regulator.

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In vitro expansion of single adult Lgr5+ liver cells induced by Wnt-driven regeneration

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