Generation of Mice with Hepatocyte-Specific Conditional Deletion of Notum

Abstract

BackgroundFine tuning of the Wnt/β-catenin signaling pathway is essential for the proper development and function of the liver. Aberrant activation of this pathway is observed in 20%-40% of hepatocellular carcinomas (HCC). Notum encodes a secreted Wnt deacylase that inhibits Wnt activity and thereby restricts the zone of activation of Wnt/β-catenin signaling. An important role of NOTUM has been described in development in drosophila, planaria and zebrafish, but its role in the mammalian liver is unknown. Notum is required for spatial control of the Wnt/β-catenin signaling in several animal models and the Wnt/β-catenin pathway contributes to liver patterning involved in metabolic zonation. Therefore, Notum may be involved in the liver patterning induced by the Wnt/β-catenin signaling during the adult stage.Methodology/principal findingsWe generated a conditional Notum knockout mouse mutant to study the effect of the deletion of Notum in the liver. We show that Notum is a direct target of the Wnt/β-catenin signaling in the liver. Liver-specific deletion of Notum did not modify liver zonation, but Notum deletion had a long-term effect on mouse physiology. In particular, male mutant mice developed metabolic disorders.ConclusionWe show that Notum is not a key actor of Wnt/β-catenin-dependent liver patterning of adult mice, but has role in liver glucose homeostasis. Male mice deficient in Notum specifically in the liver develop metabolic dysfunctions implicating Notum in the development of Type 2 diabetes.

Fgf and Wnt signaling interaction in the mesenchymal niche regulates the murine hair cycle clock

“…The absence of Fgf signaling in the DP of the dMF1/2 mutant at P16 prevents the elevation of both Dkk2 and Notum, suggesting that Dkk2 and Notum are transcriptionally activated by Fgf signaling in the DP. However, Dkk2 and Notum were previously shown to be target genes of Wnt signaling as part of a negative feedback loop [45][46][47] . To explore whether Dkk2 and Notum are target genes of Wnt signaling in the DP, in situ hybridization was performed to compare their expression between wild-type and Ctnnb1 mutant littermates.…”

Osteoblast‐derived NOTUM reduces cortical bone mass in mice and the NOTUM locus is associated with bone mineral density in humans

“…The global Notum −/− and Notum +/− mice were generated by breeding male Notum flox/flox mice (kindly provided by Prof. Christine Perret, INSERM, Institut Cochin) (16), with female mice expressing Cre recombinase ubiquitously and from an early embryonic stage under the control of the phosphoglycerate kinase-1 promoter (PGKcre) (17). In PGKcre-expressing female mice, the Cre activity starts in the diploid phase of oogenesis, and thereby a complete recombination of LoxP sites occurs also in Cre − offspring.…”

“…In PGKcre-expressing female mice, the Cre activity starts in the diploid phase of oogenesis, and thereby a complete recombination of LoxP sites occurs also in Cre − offspring. In the Notum flox mice, LoxP sites are introduced upstream from Notum exon 2 and downstream from Notum exon 8 and in the presence of an active Cre recombinase, the DNA fragment from exon 2 to exon 8 of the Notum gene is excised (16). Presence or absence of the Notum flox allele was determined by use of multiplex real-time PCR analysis (StepOnePlus Real-Time PCR System, Thermo Fisher Scientific, Waltham, MA, USA).…”

Progenitors oppositely polarize WNT activators and inhibitors to orchestrate tissue development

“…Rosa26Flox-Stop-Flox-tdTom (The Jackson Laboratory), Apcfl/fl was a kind gift from Kucherlapati Lab(Kuraguchi et al 2006), Fucci (595, Riken,(Sakaue-Sawano et al 2008)), Lhx2-EGFP (The Gene Expression Nervous System Atlas (GENSAT) Project, NINDS Contracts N01NS02331 & HHSN271200723701C to The Rockefeller University, New York, NY, USA), Wif1-KO was a kind gift from Igor Dawid (NIH), Notum-KO embryos and Notumfl/fl mice were kind gifts from the Jean Paul-VincentLab(Canal et al 2016).…”