Effect of BMP–Wnt–Nodal signal on stem cell differentiation

Summary The generation of germ cells from embryonic stem cells in vitro has current historical significance. Western blot, qPCR, immunofluorescence and flow cytometry assays were used to investigate the differences in expression levels of totipotency and specific markers for Wnt regulation and the related signalling pathways during primordial germ cell-like cell (PGCLC) induction and differentiation. During PGCLC induction, activation of WNT3a increased the expression of NANOG, SOX2 and OCT4, but Mvh, DAZL, Blimp1, TFAP2C, Gata4, SOX17, EOMES, Brachyury and PRDM1 expression levels were significantly reduced. Inhibition of the WNT signal demonstrated the opposite effect. Similarly, inhibitors of BMP and the Nodal/Activin signal were used to determine the effect of signal pathways on differentiation. CER1 affected the Wnt signal and differentiation, but the inhibitor SB only regulated differentiation. BMP–WNT–NODAL were mainly responsible for regulating differentiation. Our results provide a reliable theoretical basis and feasibility for further clinical medical research.

Notch-Wnt signal crosstalk regulates proliferation and differentiation of osteoprogenitor cells during intramembranous bone healing

Adult bone regeneration is orchestrated by the precise actions of osteoprogenitor cells (OPCs). However, the mechanisms by which OPC proliferation and differentiation are linked and thereby regulated are yet to be defined. Here, we present evidence that during intramembranous bone formation OPC proliferation is controlled by Notch signaling, while differentiation is initiated by activation of canonical Wnt signaling. The temporospatial separation of Notch and Wnt signal activation during the early stages of bone regeneration suggests crosstalk between the two pathways. In vitro and in vivo manipulation of the two essential pathways demonstrate that Wnt activation leads to initiation of osteogenic differentiation and at the same time inhibits Notch signaling, which results in termination of the proliferative phase. Here, we establish canonical Wnt signaling as a key regulator that facilitates the crosstalk between OPC proliferation and differentiation during intramembranous, primary bone healing.

Antibacterial and Zebrafish-based Screening for Wnt Signal Inhibitory Activities of Syzygium polycephaloides (C.B. Robb. Merr.) Bark Extracts

Syzygium polycephaloides, a plant native to Southeast Asia, is used to cure common illnesses. In this study, the methanolic bark extracts of S. polycephaloides was evaluated for their antibacterial activity and screened for their Wnt signal inhibitory activity using zebrafish-based assay. In the antibacterial assay, the extracts were tested against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeroginosa, and Escherichia coli using disk diffusion assay. On the other hand, zebrafish-based screening was used to determine the inhibitory potential of S. polycephaloides against the Wnt signal. Zebrafish embryos were treated with LiCl to upregulate the Wnt signal which produces eyeless phenotype. The methanolic extracts had antibacterial activity against the test microorganisms except P. aeruginosa. After fractionation, ethyl acetate (EtOAc) and aqueous fractions exhibited wide-spectrum antibacterial activity. For the Wnt signal inhibitory activity screening, the LiCl-treated embryos were rescued to their normal eye development after treatment with the S. polycephaloides bark extracts (100 g/mL). The results suggest that the extracts may have inhibited the Wnt signal. This study shows that the S. polycephaloides is a potent source of antibacterial compounds and Wnt inhibitors.

P085 Expression profiling of Wnt pathway genes in colon biopsies of patients with Ulcerative Colitis

Background There is an increasing demand of agents that can promote mucosal healing in Inflammatory Bowel Disease (IBD). Wnt/β-catenin signaling plays a critical role in epithelial regeneration and repair, and stimulating regeneration in the damaged epithelium by modulating Wnt signaling has been suggested as a potential treatment option for IBD. To guide development of Wnt modulating therapeutic molecules for IBD, an understanding of how Wnt signaling may be altered in IBD tissues is required. While earlier work showed altered Wnt pathway gene expression in UC tissues, these studies failed to consider disease conditions (moderate vs severe) and patient treatment history on expression of the Wnt family genes. These previous studies utilized RT-qPCR or microarray and did not reveal how Wnt pathway gene expression might be affected specifically in the epithelium and in the adjacent stromal stem cell niche. Here we report our work investigating expression patterns of Wnt pathway genes in UC biopsies from 12 patients with moderate and severe disease. Patients had either received no anti-TNF treatment or had gone through anti-TNF treatment and partially responded to the treatment. Methods Expression of a set of Wnt pathway genes was assessed in UC colon and rectum biopsies by RNAscope in situ hybridization and compared to expression patterns in normal control colon. The genes included the Wnt target genes AXIN2, LGR5 and RNF43, Wnt ligands and the FZD5 and LRP6 receptors enriched in the intestinal epithelium as well as key Wnt signal modulators RSPO1-4. Results Expression of Wnt target genes were mildly reduced in the UC colon epithelium, while their expression in some crypts appeared much lower. Overall expression levels of Wnt pathway genes did not differ between moderate and severe UC colon and Wnt target gene expression was more affected in the anti-TNF treated colons, which may reflect more refractory disease. Expression of FZD5, LRP6 and the key niche factor RSPO2, was reduced in the UC colon. RSPOs are normally expressed in the stromal cells next to the crypt bottom stem cell compartment but this expression pattern was disrupted in the UC colon as a result of immune cell infiltration. Although expression of Wnts was induced in the UC colon tissues, the location of expression was altered due to tissue damage, potentially making the Wnts less accessible to the intestinal stem cells. Conclusion Reduced expression of Wnt receptors, RSPOs and Wnt target genes indicate insufficient Wnt signal induction in the damaged colon epithelium of UC patients. This suggests that repair of the damaged epithelium by Wnt agonist treatment may constitute a new mechanism of action and benefit patients with UC.