Cardiomyocyte regeneration following cardiac damage is challenging to study because of the inflammatory process, the multiplication of cells in the stroma, and the creation of scar tissue. In addition to the initial damage, the subsequent decrease in cardiac myocytes adds to heart failure. Piezo1 is remarkably understudied in the heart, which may be related to its recent discovery. Despite this, Piezo1 is expressed in a variety of cardiovascular cell populations, notably epithelial cells (EC), cardiac fibroblasts (CF), and cardiac myocytes (CM), in both animal and human samples, with fibroblasts expressing more than myocytes. Researchers have recently shown that disrupting Piezo1 signaling causes defects in zebrafish developing the outflow tract (OFT) and aortic valves. Platelet plasma membranes may provide lipid substrates, such as phosphatidylinositol bisphosphate, that aid in activating the piezo 1 ion channel in the cardiovascular system. In addition, CXC chemokine ligand 8/CXC chemokine receptor 1/2 (CXCL8-CXCR1/2) signaling was identified to establish the proliferation of coronary endothelial cells during cardiac regeneration. Notably, all these pathways are calcium-dependent, and cell proliferation and angiogenesis were necessary to recover myocardial cells. This review will examine the most current findings to understand further how platelet-rich plasma (PRP) and the piezo 1 channel might aid in cardiomyocyte regeneration.

Gene expression is regulated at many levels including co- or post-transcriptionally, where chemical modifications are added to RNA on riboses and bases. Expression control via RNA modifications has been termed \'epitranscriptomics\' to keep with the related \'epigenomics\' for DNA modification. One such RNA modification is the N6-methylation found on adenosine (m6A) and 2\'-O-methyladenosine (m6Am) in most types of RNA. The N6-methylation can affect the fold, stability, degradation and cellular interaction(s) of the modified RNA, implicating it in processes such as splicing, translation, export and decay. The multiple roles played by this modification explains why m6A misregulation is connected to multiple human cancers. The m6A/m6Am writer enzymes are RNA methyltransferases (MTases). Structures are available for functionally characterized m6A RNA MTases from human (m6A mRNA, m6A snRNA, m6A rRNA and m6Am mRNA MTases), zebrafish (m6Am mRNA MTase) and bacteria (m6A rRNA MTase). For each of these MTases, we describe their overall domain organization, the active site architecture and the substrate binding. We identify areas that remain to be investigated, propose yet unexplored routes for structural characterization of MTase:substrate complexes, and highlight common structural elements that should be described for future m6A/m6Am RNA MTase structures.

Glucocorticoids (GCs) are steroid hormones that contribute to the regulation of many physiological processes, such as inflammation, metabolism and stress response, mainly through binding to their cognate receptor, GR, which works as a ligand-activated transcription factor. Due to their pleiotropy and the common medical use of these steroids to treat patients affected by different pathologies, the investigation of their mechanisms of action is extremely important in biology and clinical research. The evolutionary conservation of GC physiological function, biosynthesis pathways, as well as the sequence and structure of the GC nuclear receptors has stimulated, in the last 20 years, the use of zebrafish (a teleost of Cyprinidae family) as a reliable model organism to investigate this topic. In this review, we wanted to collect many of the most significant findings obtained by the the scientific community using zebrafish to study GCs and their receptors. The paper begins by describing the experiments with transient knockdown of zebrafish gr to gain insights, mainly during development, and continues with the discoveries provided by the generation of transgenic reporter lines. Finally, we discuss how the generation of mutant lines for either gr or the enzymes involved in GC synthesis has significantly advanced our knowledge on GC biology.

Over the last 2 decades, the zebrafish (Danio rerio) has emerged as a stellar model for unraveling molecular signaling events mediated by the aryl hydrocarbon receptor (AHR), an important ligand-activated receptor found in all eumetazoan animals. Zebrafish have 3 AHRs-AHR1a, AHR1b, and AHR2, and studies have demonstrated the diversity of both the endogenous and toxicological functions of the zebrafish AHRs. In this contemporary review, we first highlight the evolution of the zebrafish ahr genes, and the characteristics of the receptors including developmental and adult expression, their endogenous and inducible roles, and the predicted ligands from homology modeling studies. We then review the toxicity of a broad spectrum of AHR ligands across multiple life stages (early stage, and adult), discuss their transcriptomic and epigenetic mechanisms of action, and report on any known interactions between the AHRs and other signaling pathways. Through this article, we summarize the promising research that furthers our understanding of the complex AHR pathway through the extensive use of zebrafish as a model, coupled with a large array of molecular techniques. As much of the research has focused on the functions of AHR2 during development and the mechanism of TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) toxicity, we illustrate the need to address the considerable knowledge gap in our understanding of both the mechanistic roles of AHR1a and AHR1b, and the diverse modes of toxicity of the various AHR ligands.

Teleost fish, as with other vertebrates, rely on their innate immune system as a first line of defense against invading pathogens. A very important characteristic of the innate immune response is its ability to recognize conserved molecular structures, such as viral dsRNA and ssRNA. Mda5 is one of the three pattern recognition receptors (PRRs) that recognize cytoplasmic viral ligands. Teleost Mda5 is widely conserved among several fish species and possesses the same structural domains as those seen in their mammalian counterparts. Fish Mda5 has been shown to be capable of initiating an inflammatory response both in vitro (in different fish cell lines) and in vivo using synthetic viral analogs or virus. The interferon (IFN) pathway is triggered as a result of Mda5 activation, leading to the expression of type I IFNs, IFN- stimulated genes and pro-inflammatory cytokines. Although it is known that Mda5 acts as a receptor for virally-produced ligands, it has been shown more recently that it can also initiate an immune response against bacterial challenges. This review discusses recent advances in the characterization of teleost Mda5 and its potential role in antiviral and antibacterial immunity in teleost fish.

Rare cases of Ewing\'s sarcoma/primitive neuroectodermal tumors (EWS/PNETs) arising from mesenteric tissue have been reported. This report describes an EWS/PNET in a 25-year-old woman who presented with abdominal pain lasting 3 days. Radiologic evaluation revealed a 9 cm × 6 cm homogeneous mass in the lower abdomen with homogeneous enhancement and invasion of the ileum. Surgical resection was completed during exploratory laparotomy. Immunohistochemically, the tumor cells revealed CD99, friend leukemia virus integration-1 and NKX2.2 (NK2 Homeobox 2, a protein coding gene) and subsequently showed EWSR1 rearrangement. The histological feature, immunohistochemical results and genetic fluorescence in situ hybridization analysis of this case were confirming the diagnosis of EWS/PNET. Adjuvant chemotherapy was suggested, but the patient was lost to follow-up.

This short review provides a current synopsis of caudal fin regeneration in zebrafish with an emphasis on the molecular signaling networks that dictate epimorphic regeneration. At the outset, the fundamentals of caudal fin architecture and the stages of epimorphic regeneration are described. This is followed by a detailed look at the main networks implicated in fin regeneration, namely the Wnt, fibroblast growth factor, activin-betaA, retinoic acid and hedgehog signaling pathways. Throughout this mini-review, these molecular networks are examined through the lens of wound healing, blastema formation or regenerative outgrowth, three of the main stages of epimorphic regeneration. Next, the emerging role of noncoding RNAs as regulators of regeneration and mechanisms of regenerative termination are discussed. Finally, the implications for future research and the broader field of regenerative medicine are examined.

Zebrafish is one of several important teleost models for understanding principles of vertebrate developmental, molecular, organismal, genetic, evolutionary, and genomic biology. Efficient investigation of the molecular genetic basis of induced mutations depends on knowledge of the zebrafish genome. Principles of zebrafish genomic analysis, including gene mapping, ortholog identification, conservation of syntenies, genome duplication, and evolution of duplicate gene function are discussed here using as a case study the zebrafish msxa, msxb, msxc, msxd, and msxe genes, which together constitute zebrafish orthologs of tetrapod Msx1, Msx2, and Msx3. Genomic analysis suggests orthologs for this difficult to understand group of paralogs.

NT2/NTera2 cells, derived from human embryonal tumor, differentiate into neuronal cells after treatment with all-trans-retinoic acid (ATRA). We have cloned and characterized 13 out of 19 human WNT genes, and also 9 out of 10 human Frizzled (FZD) genes encoding seven-transmembrane-type WNT receptors, which are potent targets for pharmacogenomics in the post-genomic era, especially in the field of regenerative medicine and clinical oncology. Because WNT signals are implicated in morphogenesis of neural tissues, regulation of 19 WNT genes and 10 FZD genes during the early phase of neuronal differentiation in NT2 cells is reviewed. Multiple WNTs and FZDs are expressed in NT2 cells. WNT2B/WNT13 gene encode 2 isoforms due to alternative splicing of alternative promoter type, and WNT2B isoform 2 (WNT2B2) rather than WNT2B isoform 1 (WNT2B1) is expressed in NT2 cells. WNT3A, WNT8A, WNT8B, WNT10B and WNT11 are down-regulated in NT2 cells after ATRA treatment, while WNT2, WNT7B and WNT14B are up-regulated. FZD4 and FZD10 are up-regulated in NT2 cells after ATRA treatment. Expression of multiple WNT signaling molecules are dramatically changed during the early phase of neuronal differentiation in NT2 cells. Each WNT activates the beta-catenin - TCF pathway, the JNK pathway or the Ca2+-releasing pathway in NT2 cells, and summed effects of multiple WNTs might determine the fate of NT2 cells (self-renewal or differentiation) through switching intracellular WNT signaling pathways. The author proposes the threshold model of WNT action.

Gene-finding methods are classified into homology-based bench-top approach (degenerate cDNA-PCR and cDNA selection), ab initio bench-top approach (cDNA subtraction, two-hybrid system, and exon trapping), homology-based desk-top approach (BLAST search), ab initio desk-top approach (Fgenesh and GENSCAN programs), and hybrid desk-top approach (GenomeScan program). cDNA-library screening, cDNA-PCR, and RACE are used to isolate cDNAs for complete coding sequences. Because WNT signaling molecules are potent targets for oncology, regenerative medicine, and other fields of medical science, we have cloned and characterized many human genes encoding WNT signaling molecules, including 13 out of 19 human WNT genes, and 9 out of 10 human FZD genes. We used degenerate cDNA-PCR and cDNA-library screening in the 20th century, while we use BLAST program and cDNA-PCR in the 21st century. The interval between gene-finding and manuscript-publication in my laboratory was 17.2+/-7.5 (mean +/- SD) months in the 20th century (n=13), 11.5+/-7.8 months in 2001 (n=19), and 5.5+/-1.6 months in 2002 (n=13). The interval using desk-top gene-finding approach (7.2+/-2.6 months, n=30) was significantly shorter than that using bench-top approach (19.8+/-8.0 months, n=15) (p=0.003). Gene-finding has been significantly accelerated due to paradigm shift from bench-top approach to desk-top approach. Dramatic increase of information about human genome, transcriptome and proteome accompanied by improvements of genomics, proteonics and bioinformatics technologies will accelerate paradigm shift from bench-top science to desk-top science.