IWP2 impairs the development of porcine somatic cell nuclear transfer embryos via Wnt signaling pathway inactivation

Abstract

Abstract. Wnt signaling is critical in embryonic development and post-embryonic tissue homeostasis. The aim of the present study was to evaluate the expression levels of canonical Wnt signaling genes in porcine somatic cell nuclear transfer (SCNT) embryos. Quantitative polymerase chain reaction analysis was performed in porcine SCNT embryos, and the results indicated that the temporal expression patterns of canonical signaling genes were similar between in vivo and SCNT embryos from the 2-cell to the blastocyst stage. In addition, aberrant expression in a small number of Wnt signaling genes in SCNT embryos was identified. IWP2, an inhibitor of Wnt processing, was applied to the culture of SCNT embryos. The Wnt signaling pathway in the SCNT blastocysts may be inactivated via IWP2 treatment, reflecting the low expression levels of c-Myc and peroxisome proliferator-activated receptor δ. Furthermore, blastocyst hatching was damaged by IWP2 treatment. These findings indicate that the canonical Wnt signaling pathway is important for SCNT embryo development. IntroductionSomatic cell nuclear transfer (SCNT) is an effective method of reprogramming differentiated nuclei and has many potential applications (1). Owing to incomplete or faulty reprogramming, however, the cloning efficiency of SCNT embryos remains low (2,3). Aberrant reprogramming leads to changes in the expression levels of certain genes important for embryonic development. Studies on the expression of development-associated genes may be valuable for improving the developmental competence of SCNT embryos.Wnt signaling is a critical regulator of many cellular and physiological processes. Wnt signaling regulates cell proliferation and differentiation, controls migration and patterning during embryonic development, and maintains tissue homeostasis in adults (4,5). Depending on the involvement of β-catenin, these signaling pathways have been classified as canonical (β-catenin-dependent) or non-canonical (β-catenin-independent) (6). In the canonical Wnt signaling pathway, which has been better examined (7), β-catenin accumulates in the cytoplasm and eventually translocates to the nucleus where it acts as a transcriptional co-activator of transcription factors belonging to the T-cell factor/lymphoid enhancer factor-1(TCF/LEF) family. β-catenin that accumulates in the cytoplasm is degraded, however, by a protein complex that includes axin, glycogen synthase kinase-3 (GSK-3), protein phosphatase 2A (PP2A), casein kinase 1 (CK1) and adenomatous polyposis coli (APC) (6,8). This degradation complex becomes disrupted as soon as the Wnt protein binds to receptors of frizzled (Fz) and low-density lipoprotein receptor-related protein (LRP5/6), which activates multiple signaling cascades.Dysfunctions in Wnt signaling result in severe complications of embryonic development. For example, abnormalities were observed in the size and shape of mouse embryos lacking intact maternal/zygotic β-catenin during pre-and post-implantation development (5). By contrast, transient expression...

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“…Such findings are similar to those of hair follicle organoids as regenerated by droplet cultures [16, 17]. Illustrating the importance of the Wnt pathway, we show here that the addition of WNT3a protein to the growth medium enhanced the formation of type I aggregates, and conversely, treatment with IWP2 to inhibit WNT processing and secretion [48], blocked their formation (Fig. 5b, c).…”

β-catenin-promoted cholesterol metabolism protects against cellular senescence in naked mole-rat cells

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The DEAD-box protein p68 and β-catenin: the crucial regulators of FOXM1 gene expression in arbitrating colorectal cancer

“…3f) suggesting the suspected involvement of Wnt signaling in regulating FoxM1. Secondly, IWP2, a small molecule inhibitor of Porcupine production, can inhibit the canonical and non-canonical Wnt signaling pathways 32 . So, HCT 116 and HT-29 cells were treated with 20uM IWP2 inhibitor and a significant decrease in the expression profiles of FoxM1 and Cyclin D1 was obtained (Fig.…”

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