CCAAT/enhancer-binding protein α is required for hepatic outgrowth via the p53 pathway in zebrafish

Molecular Genealogy of Metabolic-associated Hepatocellular Carcinoma

This review examines the latest epidemiological and molecular pathogenic findings of metabolic-associated hepatocellular carcinoma (HCC). Its increasing prevalence is a significant concern and reflects the growing burden of obesity and metabolic diseases, including metabolic dysfunction-associated steatotic liver disease, formerly known as nonalcoholic fatty liver disease, and type 2 diabetes. Metabolic-associated HCC has unique molecular abnormality and distinctive gene expression patterns implicating aberrations in bile acid, fatty acid metabolism, oxidative stress, and proinflammatory pathways. Furthermore, a notable frequency of single nucleotide polymorphisms in genes such as patatin-like phospholipase domain-containing 3, transmembrane 6 superfamily member 2, glucokinase regulator, and membrane-bound O-acyltransferase domain-containing 7 has been observed. The tumor immune microenvironment of metabolic-associated HCC is characterized by unique phenotypes of macrophages, neutrophils, and T lymphocytes. Additionally, the pathogenesis of metabolic-associated HCC is influenced by abnormal lipid metabolism, insulin resistance, and dysbiosis. In conclusion, deciphering the intricate interactions among metabolic processes, genetic predispositions, inflammatory responses, immune regulation, and microbial ecology is imperative for the development of novel therapeutic and preventative measures against metabolic-associated HCC.

Aquaporin 8ab is required in zebrafish embryonic intestine development

The aquaporin 8 (AQP8) is a small integral membrane protein that selectively transports water and other small uncharged solutes across cell plasma membranes. It has been demonstrated that AQP8 is ubiquitously present in various tissues and organs of mammals, and participates in many physiological and pathological processes. Recent studies showed that AQP8 is highly expressed in the columnar epithelial cells of mammalian colonic mucosa facing lumen, indicating that AQP8 plays potential roles in the physiology and pathophysiology of gastrointestinal tract. However, the role of AQP8 during gastrointestinal tract development is unclear. In the present study, RT-PCR results reveal that the zebrafish genome encodes three kinds of aqp8s ( aqp8aa, aqp8ab, and aqp8b). We use whole mount in situ hybridization to describe aqp8 genes spatiotemporal expression pattern, and the results show that aqp8ab mRNA is detectable mainly in the zebrafish embryonic intestine. To reveal the details of aqp8ab distribution, histological sections are employed. Transverse sections indicate that aqp8ab mRNA expression is more intense in the layer lining the intestinal cavity. Knockout of aqp8ab using the CRISPR/Cas9 system induces intestine development defects and abnormal formation of intestinal lumen. In addition, aqp8ab mRNA significantly rescues the intestine defects in the aqp8ab mutant. These results indicate that aqp8ab is required in the intestine development of zebrafish.

Zebrafish Cancer Predisposition Models

Cancer predisposition syndromes are rare, typically monogenic disorders that result from germline mutations that increase the likelihood of developing cancer. Although these disorders are individually rare, resulting cancers collectively represent 5-10% of all malignancies. In addition to a greater incidence of cancer, affected individuals have an earlier tumor onset and are frequently subjected to long-term multi-modal cancer screening protocols for earlier detection and initiation of treatment. In vivo models are needed to better understand tumor-driving mechanisms, tailor patient screening approaches and develop targeted therapies to improve patient care and disease prognosis. The zebrafish (Danio rerio) has emerged as a robust model for cancer research due to its high fecundity, time- and cost-efficient genetic manipulation and real-time high-resolution imaging. Tumors developing in zebrafish cancer models are histologically and molecularly similar to their human counterparts, confirming the validity of these models. The zebrafish platform supports both large-scale random mutagenesis screens to identify potential candidate/modifier genes and recently optimized genome editing strategies. These techniques have greatly increased our ability to investigate the impact of certain mutations and how these lesions impact tumorigenesis and disease phenotype. These unique characteristics position the zebrafish as a powerful in vivo tool to model cancer predisposition syndromes and as such, several have already been created, including those recapitulating Li-Fraumeni syndrome, familial adenomatous polyposis, RASopathies, inherited bone marrow failure syndromes, and several other pathogenic mutations in cancer predisposition genes. In addition, the zebrafish platform supports medium- to high-throughput preclinical drug screening to identify compounds that may represent novel treatment paradigms or even prevent cancer evolution. This review will highlight and synthesize the findings from zebrafish cancer predisposition models created to date. We will discuss emerging trends in how these zebrafish cancer models can improve our understanding of the genetic mechanisms driving cancer predisposition and their potential to discover therapeutic and/or preventative compounds that change the natural history of disease for these vulnerable children, youth and adults.

Igf2bp1 is required for hepatic outgrowth during early liver development in zebrafish

IGF2BPs, a subclass of RNA-binding proteins, regulate cellular differentiation, proliferation and migration during multiple organs development, but their functions in liver development still remain unclear. Here, in this study, whole-mount in situ hybridization showed that igf2bp1 was constantly and stably expressed at early stages of embryo development in zebrafish. Both the morpholino-induced knockdown and CRISPR/Cas9-mediated knockout of igf2bp1 led to a reduced-size liver phenotype. Further analysis revealed that igf2bp1 is required for hepatic outgrowth, but not for hepatoblast specification and budding. Deficiency of igf2bp1 resulted in reduced cell proliferation, but had no effect on apoptosis. Therefore, we concluded that igf2bp1 is a critical factor to regulate hepatic outgrowth via cell proliferation during early liver development in zebrafish.

PIWIL3/OIP5-AS1/miR-367-3p/CEBPA feedback loop regulates the biological behavior of glioma cells

Rationale: PIWI-interacting RNAs (piRNAs), a class of newly discovered small RNA molecules that function by binding to the Argonaute protein family (i.e., the PIWIL protein subfamily), and long noncoding RNAs (lncRNA) are implicated in several cancers. However, the detailed roles of ncRNAs in glioma remain unclear.

Methods: The expression of PIWIL3, piR-30188, OIP5-AS1, miR-367, CEBPA and TRAF4 were measured in glioma tissues and cells. The role of PIWIL3/OIP5-AS1/miR-367-3p/CEBPA feedback loop was evaluated in cell and animal models. The association of the above molecules was analyzed.

Results: Over-expression of PIWIL3, piR-30188 and miR-367-3p or knockdown of OIP5-AS1 resulted in inhibition of glioma cells progression. Binding sites between piR-30188 and OIP5-AS1 as well as between OIP5-AS1 and miR-367-3p were confirmed by RNA immunoprecipitation and luciferase assays. OIP5-AS1 knockdown or miR-367-3p over-expression contributed to a decrease in CEBPA (CCAAT/enhancer binding protein alpha) protein. Furthermore, CEBPA was detected as a target of miR-367-3p and played an oncogenic role in glioma. Treatment with CEBPA and miR-367-3p resulted in the modulation of downstream TRAF4 (TNF receptor-associated factor 4). PIWIL3 was also a target of CEBPA, forming a positive feedback loop in the growth regulation of glioma cells. Significantly, knockdown of OIP5-AS1 combined with over-expression of PIWIL3 and miR-367-3p resulted in tumor regression and extended survival in vivo.

Conclusion: These results identified a novel molecular pathway in glioma cells that may provide a potential innovative approach for tumor therapy.

Dose-dependent effects of gamma radiation on the early zebrafish development and gene expression

Ionizing radiation from natural sources or anthropogenic activity has the potential to cause oxidative stress or genetic damage in living organisms, through the ionization and excitation of molecules and the subsequent production of free radicals and reactive oxygen species (ROS). The present work focuses on radiation-induced biological effects using the zebrafish (Danio rerio) vertebrate model. Changes in developmental traits and gene expression in zebrafish were assessed after continuous external gamma irradiation (0.4, 3.9, 15 and 38 mGy/h) with corresponding controls, starting at 2.5 hours post fertilization (hpf) and lasting through embryogenesis and the early larval stage. The lowest dose rate corresponded to recommended benchmarks at which adverse effects are not expected to occur in aquatic ecosystems (2-10 mGy/day). The survival observed at 96 hours post fertilization (hpf) in the 38 mGy/h group was significantly lower, while other groups showed no significant difference compared to controls. The total hatching was significantly lower from controls in the 15 mGy/h group and a delay in hatching onset in the 0.4 mGy/h group was observed. The deformity frequency was significantly increased by prolonged exposure duration at dose rates ≥ 0.4 mGy/h. Molecular responses analyzed by RNA-seq at gastrulation (5.5 hpf transcriptome) indicate that the radiation induced adverse effects occurred during the earliest stages of development. A dose-response relationship was found in the numbers of differentially regulated genes in exposure groups compared to controls at a total dose as low as 1.62 mGy. Ingenuity Pathway Analysis identified retinoic acid receptor activation, apoptosis, and glutathione mediated detoxification signaling as the most affected pathways in the lower dose rate (0.54 mGy/h), while eif2 and mTOR, i.e., involved in the modulation of angiogenesis, were most affected in higher dose rates (5.4 and 10.9 mGy/h). By comparing gene expression data, myc was found to be the most significant upstream regulator, followed by tp53, TNF, hnf4a, TGFb1 and cebpa, while crabp2b and vegfab were identified as most frequent downstream target genes. These genes are associated with various developmental processes. The present findings show that continuous gamma irradiation (≥ 0.54 mGy/h) during early gastrula causes gene expression changes that are linked to developmental defects in zebrafish embryos.

Making It New Again: Insight Into Liver Development, Regeneration, and Disease From Zebrafish Research

The adult liver of most vertebrates is predominantly comprised of hepatocytes. However, these cells must work in concert with biliary, stellate, vascular, and immune cells to accomplish the vast array of hepatic functions required for physiological homeostasis. Our understanding of liver development was accelerated as zebrafish emerged as an ideal vertebrate system to study embryogenesis. Through work in zebrafish and other models, it is now clear that the cells in the liver develop in a coordinated fashion during embryogenesis through a complex yet incompletely understood set of molecular guidelines. Zebrafish research has uncovered many key players that govern the acquisition of hepatic potential, cell fate, and plasticity. Although rare, some hepatobiliary diseases-especially biliary atresia-are caused by developmental defects; we discuss how research using zebrafish to study liver development has informed our understanding of and approaches to liver disease. The liver can be injured in response to an array of stressors including viral, mechanical/surgical, toxin-induced, immune-mediated, or inborn defects in metabolism. The liver has thus evolved the capacity to efficiently repair and regenerate. We discuss the emerging field of using zebrafish to study liver regeneration and highlight recent advances where zebrafish genetics and imaging approaches have provided novel insights into how cell plasticity contributes to liver regeneration.

Role of C/EBP-α in Adriamycin-induced podocyte injury

Podocytes are terminally differentiated epithelial cells in the kidney glomeruli that act as a key component of the glomerular filtration barrier. Although the inciting injury to the podocyte may vary between various glomerular diseases, the inevitable consequence of podocyte injury results in their loss, leading to progressive kidney disease. Here, we report that the expression of CCAAT/enhancer binding protein-α (C/EBP-α), a transcription factor known to interact with and activate PPAR-γ and NF-κB, is suppressed in the glomerular cells, particularly in podocytes, in human kidneys with focal segmental glomerulosclerosis. Genetic ablation of C/EBP-α in podocytes resulted in increased proteinuria, increased podocyte foot process effacement, and to decreased podocyte number in the setting of Adriamycin (ADR)-induced nephropathy. Overexpression of C/EBP-α in human podocytes in vitro led to an inhibition of MCP-1 and IL-6 expression in response to TNF-α and IL-1β treatments. Conversely, augmented production of MCP-1 and IL-6 was observed in the glomeruli of C/EBP-α knockout mice and was associated increased infiltration of macrophages in vivo. Together, our data suggest that C/EBP-α mediates anti-inflammatory effects in podocytes to confer protection against podocyte injury and loss that may contribute to worsening glomerulosclerosis.