CRISPR-based genome editing of zebrafish

Plxnd1-mediated mechanosensing of blood flow controls the caliber of the Dorsal Aorta via the transcription factor Klf2

The cardiovascular system generates and responds to mechanical forces. The heartbeat pumps blood through a network of vascular tubes, which adjust their caliber in response to the hemodynamic environment. However, how endothelial cells in the developing vascular system integrate inputs from circulatory forces into signaling pathways to define vessel caliber is poorly understood. Using vertebrate embryos and in vitro-assembled microvascular networks of human endothelial cells as models, flow and genetic manipulations, and custom software, we reveal that Plexin-D1, an endothelial Semaphorin receptor critical for angiogenic guidance, employs its mechanosensing activity to serve as a crucial positive regulator of the Dorsal Aorta's (DA) caliber. We also uncover that the flow-responsive transcription factor KLF2 acts as a paramount mechanosensitive effector of Plexin-D1 that enlarges endothelial cells to widen the vessel. These findings illuminate the molecular and cellular mechanisms orchestrating the interplay between cardiovascular development and hemodynamic forces.

Dendrobium offificinale polysaccharides prevents glucocorticoids-induced osteoporosis by destabilizing KEAP1-NRF2 interaction

Glucocorticoid-induced osteoporosis (GIOP) represents the foremost cause of secondary osteoporosis and fragility fractures. Novel therapeutic strategies for GIOP are needed, with improved safety profiles and reduced costs compared to current options. Dendrobium officinale (D. officinale) is a traditional Chinese medicine that has been reported to have beneficial effects on bone metabolism. Here, we sought to investigate the impacts of D. officinale polysaccharides (DOP), the main active constituents of D. officinale, on GIOP in vivo models and dexamethasone (DEX)-treated osteoblast lineage cells. We found that low concentrations of DOP are relatively safe in vitro and in vivo, respectively. Importantly, we found that DOP treatment significantly inhibited DEX-induced osteoporosis in two in vivo models, zebrafish and mice, while boosting osteogenic differentiation of hBMSCs exposed to DEX. Futhermore, our data reveal that DOP elevates nuclear Nrf2 levels under DEX treatment, by suppressing of Nrf2 ubiquitination. Leveraging Keap1b knockout zebrafish and RNAi approach, we demonstrated that DOP disrupts the association of Nrf2/Keap1, resulting in the inhibition of Nrf2 ubiquitination. Taken together, these results illuminate that DOP stimulates osteogenesis in the presence of DEX by destabilizing the Nrf2/Keap1 interaction. These findings suggest that DOP may serve as a novel drug against osteoporosis caused by glucocorticoids.

Zebrafish (Danio rerio) as a Model for the Study of Developmental and Cardiovascular Toxicity of Electronic Cigarettes

The increasing popularity of electronic cigarettes (e-cigarettes) as an alternative to conventional tobacco products has raised concerns regarding their potential adverse effects. The cardiovascular system undergoes intricate processes forming the heart and blood vessels during fetal development. However, the precise impact of e-cigarette smoke and aerosols on these delicate developmental processes remains elusive. Previous studies have revealed changes in gene expression patterns, disruptions in cellular signaling pathways, and increased oxidative stress resulting from e-cigarette exposure. These findings indicate the potential for e-cigarettes to cause developmental and cardiovascular harm. This comprehensive review article discusses various aspects of electronic cigarette use, emphasizing the relevance of cardiovascular studies in Zebrafish for understanding the risks to human health. It also highlights novel experimental approaches and technologies while addressing their inherent challenges and limitations.

asb5a/asb5b Double Knockout Affects Zebrafish Cardiac Contractile Function

Ankyrin repeat and suppression-of-cytokine-signaling box (Asb) proteins, a subset of ubiquitin ligase E3, include Asb5 with six ankyrin-repeat domains. Zebrafish harbor two asb5 gene isoforms, asb5a and asb5b. Currently, the effects of asb5 gene inactivation on zebrafish embryonic development and heart function are unknown. Using CRISPR/Cas9, we generated asb5a-knockout zebrafish, revealing no abnormal phenotypes at 48 h post-fertilization (hpf). In situ hybridization showed similar asb5a and asb5b expression patterns, indicating the functional redundancy of these isoforms. Morpholino interference was used to target asb5b in wild-type and asb5a-knockout zebrafish. Knocking down asb5b in the wild-type had no phenotypic impact, but simultaneous asb5b knockdown in asb5a-knockout homozygotes led to severe pericardial cavity enlargement and atrial dilation. RNA-seq and cluster analyses identified significantly enriched cardiac muscle contraction genes in the double-knockout at 48 hpf. Moreover, semi-automatic heartbeat analysis demonstrated significant changes in various heart function indicators. STRING database/Cytoscape analyses confirmed that 11 cardiac-contraction-related hub genes exhibited disrupted expression, with three modules containing these genes potentially regulating cardiac contractile function through calcium ion channels. This study reveals functional redundancy in asb5a and asb5b, with simultaneous knockout significantly impacting zebrafish early heart development and contraction, providing key insights into asb5's mechanism.

CRISPR/Cas9-induced asap1a and asap1b co-knockout mutant zebrafish displayed abnormal embryonic development and impaired neutrophil migration

ASAP1 (Arf-GAP with SH3 domain, the ankyrin repeat and the PH domain) is the GTPase activating protein of the small G protein Arf. To understand more about the physiological functions of ASAP1 in vivo, we chose to use the zebrafish as an animal model, and analyzed the characterization of asap1 using loss-of-function studies. Here, two isoforms in zebrafish, asap1a and asap1b, were found to be homologous to human ASAP1, and the gene knockout zebrafish lines for asap1a and asap1b were established using the CRISPR/Cas9 technique with different insertions and deletions of bases. Zebrafish with asap1a and asap1b co-knockout showed a significant reduction in survival and hatching rates, as well as an increase in malformation rates during the early stages of development, while the asap1a or asap1b single knockout mutants did not affect the growth and development of individual zebrafish. Exploring the gene expression compensation between asap1a and asap1b using qRT-PCR, we found that asap1b had increased expression when asap1a was knocked out, showing a clear compensatory effect against asap1a knockout; In turn, asap1a did not have detectable compensating expression after asap1b knockout. Furthermore, the co-knockout homozygous mutants displayed impaired neutrophil migration to Mycobacterium marinum infection, and showed an increased bacterial load. Together, these are the first inherited asap1a and/or asap1b mutant zebrafish lines by the CRISPR/Cas9 gene editing approach, and by serving as useful models, they can significantly contribute to better annotation and follow-up physiological studies of human ASAP1.

Enhanced contrast synchrotron X-ray microtomography for describing skeleton-associated soft tissue defects in zebrafish mutants

Detailed histological analyses are desirable for zebrafish mutants that are models for human skeletal diseases, but traditional histological techniques are limited to two-dimensional thin sections with orientations highly dependent on careful sample preparation. On the other hand, techniques that provide three-dimensional (3D) datasets including µCT scanning are typically limited to visualizing the bony skeleton and lack histological resolution. We combined diffusible iodine-based contrast enhancement (DICE) and propagation phase-contrast synchrotron radiation micro-computed tomography (PPC-SRµCT) to image late larval and juvenile zebrafish, obtaining high-quality 3D virtual histology datasets of the mineralized skeleton and surrounding soft tissues. To demonstrate this technique, we used virtual histological thin sections and 3D segmentation to qualitatively and quantitatively compare wild-type zebrafish and nkx3.2 -/- mutants to characterize novel soft-tissue phenotypes in the muscles and tendons of the jaw and ligaments of the Weberian apparatus, as well as the sinus perilymphaticus associated with the inner ear. We could observe disrupted fiber organization and tendons of the adductor mandibulae and protractor hyoideus muscles associated with the jaws, and show that despite this, the overall muscle volumes appeared unaffected. Ligaments associated with the malformed Weberian ossicles were mostly absent in nkx3.2 -/- mutants, and the sinus perilymphaticus was severely constricted or absent as a result of the fused exoccipital and basioccipital elements. These soft-tissue phenotypes have implications for the physiology of nkx3.2 -/- zebrafish, and demonstrate the promise of DICE-PPC-SRµCT for histopathological investigations of bone-associated soft tissues in small-fish skeletal disease models and developmental studies more broadly.

In vivo labeling of endogenous genomic loci in C. elegans using CRISPR/dCas9

Visualization of genomic loci with open chromatin state has been reported in mammalian tissue culture cells using a CRISPR/Cas9-based system that utilizes an EGFP-tagged endonuclease-deficient Cas9 protein (dCas9::EGFP) (Chen et al. 2013). Here, we adapted this approach for use in Caenorhabditis elegans . We generated a C. elegans strain that expresses the dCas9 protein fused to two nuclear-localized EGFP molecules (dCas9::NLS::2xEGFP::NLS) in an inducible manner. Using this strain, we report the visualization in live C. elegans embryos of two endogenous repetitive loci, rrn-4 and rrn-1 , from which 5S and 18S ribosomal RNAs are constitutively generated.

Aquatic Freshwater Vertebrate Models of Epilepsy Pathology: Past Discoveries and Future Directions for Therapeutic Discovery

Epilepsy is an international public health concern that greatly affects patients’ health and lifestyle. About 30% of patients do not respond to available therapies, making new research models important for further drug discovery. Aquatic vertebrates present a promising avenue for improved seizure drug screening and discovery. Zebrafish (Danio rerio) and African clawed frogs (Xenopus laevis and tropicalis) are increasing in popularity for seizure research due to their cost-effective housing and rearing, similar genome to humans, ease of genetic manipulation, and simplicity of drug dosing. These organisms have demonstrated utility in a variety of seizure-induction models including chemical and genetic methods. Past studies with these methods have produced promising data and generated questions for further applications of these models to promote discovery of drug-resistant seizure pathology and lead to effective treatments for these patients.

Establishment and application of a human osteosarcoma U-2OS cell line that can stably express Cas9 protein

Osteosarcoma is the most common primary malignant bone tumor, and U-2OS is a common osteosarcoma cell model. The study obtained a human osteosarcoma U-2OS tool cell line which could stably express Cas9 protein, and we reported its production method and application. Firstly, we introduced a Cas9 protein expression gene and an antibiotic screening marker gene through CRISPR/Cas9 system to construct a human osteosarcoma U-2OS tool cell line which could stably express Cas9 protein. Secondly, as the cell line could stably express Cas9 protein, it was only transfected alone a small sgRNA fragment for related gene editing, we then transfected, respectively, a small ETV4 and MALAT1 sgRNA fragment to U-2OS tool cell line for gene editing. Lastly, the Q-PCR results showed that the transcription levels of ETV4 and MALAT1 were significantly decreased, and western blotting result showed that the translation level of ETV4 was significantly decreased, these results indicated that the constructed U-2OS tool cell line could effectively edit protein-coding gene (ETV4) and long non-coding RNA gene (MALAT1). The results of this study also indicated that the constructed U-2OS tool cell line could greatly improve the efficiency of gene editing. Therefore, the genetic engineering cell line provided by the study is of great significance for studying the pathogenesis and regulatory network of osteosarcoma, and for preventing and treating bone tumor as soon as possible.

Visualization Analysis of CRISPR Gene-editing Knowledge Map based on Citespace

CRISPR is an adaptive immune defense system found in bacteria and archaea that is resistant to heterologous invasive genetic material. Later studies showed that the CRISPR system can be used for gene-editing. This study used the Web of Science database as a search object, then visually analyzed the literature related to CRISPR gene-editing technology with CiteSpace IV. The results show that publications had increased year by year. USA ranked first in terms of publications. China is second, but the centrality is very low. Doudna JA and Zhang F have made outstanding contributions. There are close connections between the internal institutions of the various states, but there are few links between the states. The hot spot and frontier are the application of CRISPR in animals, plants, detection, diagnosis, and clinical treatment.