Nodal promotes mir206 expression to control convergence and extension movements during zebrafish gastrulation

DNA methylation and histone modifications are essential for regulation of stem cell formation and differentiation in zebrafish development

The complex processes necessary for embryogenesis require a gene regulatory network that is complex and systematic. Gene expression regulates development and organogenesis, but this process is altered and fine-tuned by epigenetic regulators that facilitate changes in the chromatin landscape. Epigenetic regulation of embryogenesis adjusts the chromatin structure by modifying both DNA through methylation and nucleosomes through posttranslational modifications of histone tails. The zebrafish is a well-characterized model organism that is a quintessential tool for studying developmental biology. With external fertilization, low cost and high fecundity, the zebrafish are an efficient tool for studying early developmental stages. Genetic manipulation can be performed in vivo resulting in quick identification of gene function. Large-scale genome analyses including RNA sequencing, chromatin immunoprecipitation and chromatin structure all are feasible in the zebrafish. In this review, we highlight the key events in zebrafish development where epigenetic regulation plays a critical role from the early stem cell stages through differentiation and organogenesis.

Targeting Nodal and Cripto-1: Perspectives Inside Dual Potential Theranostic Cancer Biomarkers

BACKGROUND

Elucidating the mechanisms of recurrence of embryonic signaling pathways in tumorigenesis has led to the discovery of onco-fetal players which have physiological roles during normal development but result aberrantly re-activated in tumors. In this context, Nodal and Cripto-1 are recognized as onco-developmental factors, which are absent in normal tissues but are overexpressed in several solid tumors where they can serve as theranostic agents.

OBJECTIVE

To collect, review and discuss the most relevant papers related to the involvement of Nodal and Cripto-1 in the development, progression, recurrence and metastasis of several tumors where they are over-expressed, with a particular attention to their occurrence on the surface of the corresponding sub-populations of cancer stem cells (CSC).

RESULTS

We have gathered, rationalized and discussed the most interesting findings extracted from some 370 papers related to the involvement of Cripto-1 and Nodal in all tumor types where they have been detected. Data demonstrate the clear connection between Nodal and Cripto-1 presence and their multiple oncogenic activities across different tumors. We have also reviewed and highlighted the potential of targeting Nodal, Cripto-1 and the complexes that they form on the surface of tumor cells, especially of CSC, as an innovative approach to detect and suppress tumors with molecules that block one or more mechanisms that they regulate.

CONCLUSION

Overall, Nodal and Cripto-1 represent two innovative and effective biomarkers for developing potential theranostic anti-tumor agents that target normal as well as CSC subpopulations and overcome both pharmacological resistance and tumor relapse.

TGF-β Family Signaling in Early Vertebrate Development

TGF-β family ligands function in inducing and patterning many tissues of the early vertebrate embryonic body plan. Nodal signaling is essential for the specification of mesendodermal tissues and the concurrent cellular movements of gastrulation. Bone morphogenetic protein (BMP) signaling patterns tissues along the dorsal-ventral axis and simultaneously directs the cell movements of convergence and extension. After gastrulation, a second wave of Nodal signaling breaks the symmetry between the left and right sides of the embryo. During these processes, elaborate regulatory feedback between TGF-β ligands and their antagonists direct the proper specification and patterning of embryonic tissues. In this review, we summarize the current knowledge of the function and regulation of TGF-β family signaling in these processes. Although we cover principles that are involved in the development of all vertebrate embryos, we focus specifically on three popular model organisms: the mouse Mus musculus, the African clawed frog of the genus Xenopus, and the zebrafish Danio rerio, highlighting the similarities and differences between these species.

TGF-β Signaling from Receptors to Smads

Transforming growth factor β (TGF-β) and related growth factors are secreted pleiotropic factors that play critical roles in embryogenesis and adult tissue homeostasis by regulating cell proliferation, differentiation, death, and migration. The TGF-β family members signal via heteromeric complexes of type I and type II receptors, which activate members of the Smad family of signal transducers. The main attribute of the TGF-β signaling pathway is context-dependence. Depending on the concentration and type of ligand, target tissue, and developmental stage, TGF-β family members transmit distinct signals. Deregulation of TGF-β signaling contributes to developmental defects and human diseases. More than a decade of studies have revealed the framework by which TGF-βs encode a context-dependent signal, which includes various positive and negative modifiers of the principal elements of the signaling pathway, the receptors, and the Smad proteins. In this review, we first introduce some basic components of the TGF-β signaling pathways and their actions, and then discuss posttranslational modifications and modulatory partners that modify the outcome of the signaling and contribute to its context-dependence, including small noncoding RNAs.

Temperature during early development has long-term effects on microRNA expression in Atlantic cod

Background

Environmental temperature has serious implications in life cycle of aquatic ectotherms. Understanding the molecular mechanisms of temperature acclimation and adaptation of marine organisms is of the uttermost importance for ecology, fisheries, and aquaculture, as it allows modeling the effects of global warming on population dynamics. Regulatory molecules are major modulators of acclimation and adaptation; among them, microRNAs (miRNAs) are versatile and substantial contributors to regulatory networks of development and adaptive plasticity. However, their role in thermal plasticity is poorly known. We have asked whether the temperature and its shift during the early ontogeny (embryonic and larval development) affect the miRNA repertoire of Atlantic cod (Gadus morhua), and if thermal experience has long-term consequences in the miRNA profile.

Results

We characterized miRNA during different developmental stages and in juvenile tissues using next generation sequencing. We identified 389 putative miRNA precursor loci, 120 novel precursor miRNAs, and 281 mature miRNAs. Some miRNAs showed stage- or tissue-enriched expression and miRNAs, such as the miR-17 ~ 92 cluster, myomiRs (miR-206), neuromiRs (miR-9, miR-124), miR-130b, and miR-430 showed differential expression in different temperature regimes. Long-term effect of embryonic incubation temperature was revealed on expression of some miRNAs in juvenile pituitary (miR-449), gonad (miR-27c, miR-30c, and miR-200a), and liver (let-7 h, miR-7a, miR-22, miR-34c, miR-132a, miR-192, miR-221, miR-451, miR-2188, and miR-7550), but not in brain. Some of differentially expressed miRNAs in the liver were confirmed using LNA-based rt-qPCR. The effect of temperature on methylation status of selected miRNA promoter regions was mostly inconclusive.

Conclusions

Temperature elevation by several degrees during embryonic and larval developmental stages significantly alters the miRNA profile, both short-term and long-term. Our results suggest that a further rise in seas temperature might affect life history of Atlantic cod.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1503-7) contains supplementary material, which is available to authorized users.

Down-regulation of miR-206 is associated with Hirschsprung disease and suppresses cell migration and proliferation in cell models

Hirschsprung disease (HSCR) is a well-known congenital digestive disease that originates due to the developmental disorder of neural crest cells. MiR-206 is kown to have a relationship with digestive malfunctions. Therefore, we investigated whether or not miR-206 was involved in the pathogenesis of HSCR. qRT-PCR and Western blot assays were used to detect the expression levels of miRNA and mRNAs, and proteins in case and control tissue samples and two cell lines (293T and SH-SY5Y). The functions of miR-206 in vitro were measured by transwell assay, CCK8 assay and flow cytometry. Finally, we conducted dual-luciferase reporter assay to verify the connections between miR-206 and the target mRNA SDPR. Down-regulation of miR-206 was found in HSCR case tissue samples compared with controls, which was validated to be connected with the increased level of mRNA and protein of SDPR by qRT-PCR and dual-luciferase reporter assay. Moreover, miR-206 suppressed the cell migration and proliferation and silencing of SDPR could rescue the extent of the suppressing effects by miR-206 inhibitor. The findings suggest that miR-206 may play a significant role in the pathogenesis of HSCR, as well as inhibiting the cell migration and proliferation by targeting SDPR in disease models.