Nonspecific cytotoxic cell antimicrobial protein (NCAMP-1): a novel alarmin ligand identified in zebrafish

Vital Dye Uptake of YO-PRO-1 and DASPEI Depends Upon Mechanoelectrical Transduction Function in Zebrafish Hair Cells

PURPOSE

Vital dyes allow the visualization of cells in vivo without causing tissue damage, making them a useful tool for studying lateral line and inner ear hair cells in living zebrafish and other vertebrates. FM1-43, YO-PRO-1, and DASPEI are three vital dyes commonly used for hair cell visualization. While it has been established that FM1-43 enters hair cells of zebrafish and other organisms through the mechanoelectrical transduction (MET) channel, the mechanism of entry into hair cells for YO-PRO-1 and DASPEI has not been established despite widespread use. We hypothesize that YO-PRO-1 and DASPEI entry into zebrafish hair cells is MET channel uptake dependent similar to FM1-43.

METHODS

To test this hypothesis, we used both genetic and pharmacologic means to block MET channel function. Genetic based MET channel assays were conducted with two different mechanotransduction defective zebrafish lines, specifically the myo7aa-/- loss of function mutant tc320b (p.Y846X) and cdh23-/- loss of function mutant (c.570-571del). Pharmacologic assays were performed with Gadolinium(III) Chloride (Gad(III)), a compound that can temporarily block mechanotransduction activity.

RESULTS

Five-day post fertilization (5dpf) myo7aa-/- and cdh23-/- larvae incubated with FM1-43, YO-PRO-1, and DASPEI all showed nearly absent uptake of each vital dye. Treatment of wildtype zebrafish larvae with Gad(III) significantly reduces uptake of FM1-43, YO-PRO-1, and DASPEI vital dyes.

CONCLUSION

These results indicate that YO-PRO-1 and DASPEI entry into zebrafish hair cells is MET channel dependent similar to FM1-43. This knowledge expands the repertoire of vital dyes that can be used to assess mechanotransduction and MET channel function in zebrafish and other vertebrate models of hair cell function.

Animal Models for the Investigation of P2X7 Receptors

The P2X7 receptor is a trimeric ligand-gated cation channel activated by extracellular adenosine 5'-triphosphate. The study of animals has greatly advanced the investigation of P2X7 and helped to establish the numerous physiological and pathophysiological roles of this receptor in human health and disease. Following a short overview of the P2X7 distribution, roles and functional properties, this article discusses how animal models have contributed to the generation of P2X7-specific antibodies and nanobodies (including biologics), recombinant receptors and radioligands to study P2X7 as well as to the pharmacokinetic testing of P2X7 antagonists. This article then outlines how mouse and rat models have been used to study P2X7. These sections include discussions on preclinical disease models, polymorphic P2X7 variants, P2X7 knockout mice (including bone marrow chimeras and conditional knockouts), P2X7 reporter mice, humanized P2X7 mice and P2X7 knockout rats. Finally, this article reviews the limited number of studies involving guinea pigs, rabbits, monkeys (rhesus macaques), dogs, cats, zebrafish, and other fish species (seabream, ayu sweetfish, rainbow trout and Japanese flounder) to study P2X7.

Intraocular delivery of ZIF-90-RhB-GW2580 nanoparticles prevents the progression of photoreceptor degeneration

Photoreceptor degeneration is one of the major causes of progressive blindness which lacks of curative treatment. GW2580, a highly selective inhibitor of colony-stimulating factor 1 receptor, has the protective potential on neurons; however, little was known about the application of GW2580 on photoreceptor degeneration. In this study, BV-2 and 661W cells coculture system was constructed to investigate the interaction between microglia and photoreceptors. GW2580 was loaded into zeolitic imidazolate framework-90-rhodamine B (ZIF-90-RhB) to synthesize a novel kind of nanoparticles, namely, ZIF-90-RhB-GW2580, through a one-step self-assembly approach. A photoreceptor degeneration model was generated by intense light exposure in zebrafish and ZIF-90-RhB-GW2580 nanoparticles were delivered by the intraocular injection. The results showed that in vitro GW2580 treatment promoted phenotypic transformation in microglia and led to the blockade of photoreceptor apoptosis. Following the intraocular delivery of ZIF-90-RhB-GW2580 nanoparticles, the microglial proliferation and inflammatory response were significantly inhibited; moreover, the photoreceptors underwent alleviated injury with a recovery of retinal structure and visual function. In conclusion, the intraocular injection of ZIF-90-RhB-GW2580 at the early stage enables the precise delivery and sustained release of the GW2580, thus preventing the progression of photoreceptor degeneration.

Molecular Actors of Inflammation and Their Signaling Pathways: Mechanistic Insights from Zebrafish

Inflammation is a hallmark of the physiological response to aggressions. It is orchestrated by a plethora of molecules that detect the danger, signal intracellularly, and activate immune mechanisms to fight the threat. Understanding these processes at a level that allows to modulate their fate in a pathological context strongly relies on in vivo studies, as these can capture the complexity of the whole process and integrate the intricate interplay between the cellular and molecular actors of inflammation. Over the years, zebrafish has proven to be a well-recognized model to study immune responses linked to human physiopathology. We here provide a systematic review of the molecular effectors of inflammation known in this vertebrate and recapitulate their modes of action, as inferred from sterile or infection-based inflammatory models. We present a comprehensive analysis of their sequence, expression, and tissue distribution and summarize the tools that have been developed to study their function. We further highlight how these tools helped gain insights into the mechanisms of immune cell activation, induction, or resolution of inflammation, by uncovering downstream receptors and signaling pathways. These progresses pave the way for more refined models of inflammation, mimicking human diseases and enabling drug development using zebrafish models.

Identification and functional analysis of histone 1.2-like in red sea bream (Pagrus major)

Histone H1 acts as an essential chromatin component and participates in the formation of higher chromatin structures together with core histones. In addition, H1 also has important functions in physiological processes such as gene expression regulation, DNA repair, and the immune response. In this study, the histone homologous protein Pm-H1.2-like was identified from the transcriptome database of Pagrus major we studied previously. Conservatism of evolution was investigated by sequence alignment and phylogenetic analysis. Transcripts of Pm-H1.2-like were detected in P. major tissues. The highest expression level was found in gill and skin tissues. Consistent with the data from the transcriptome database, we observed that the expression of Pm-H1.2-like was rapidly induced in nonspecific cytotoxic cells (NCCs) infected with inactivated Vibrio anguillarum. Gene silencing of Pm-H1.2-like by RNAi significantly suppressed the expression of NK-lysin and GZMB in NCCs at 12 h after pathogen stimulation, but had no significant effect on IFN-γ expression. Next, we obtained the fusion proteins rPm-H1.2-like and rPm-H1.2-like (36-80) through prokaryotic expression. ELISA showed that rPm-H1.2-like bound to oligonucleotide (ODN) in a concentration-dependent manner, while no binding activity of rPm-H1.2-like (36-80) with ODN was observed. This study confirmed that Pm-H1.2-like actively participates in the immune response of NCCs to bacterial infection, deepening the understanding of the immune features of histone H1 in fish.

Folic acid-nanoscale gadolinium-porphyrin metal-organic frameworks: fluorescence and magnetic resonance dual-modality imaging and photodynamic therapy in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and severely threatens human health. Since the prognosis of advanced HCC remains poor, there is an urgent need to develop new therapeutic approaches. Porphyrin metal-organic frameworks are a class of porous organic-inorganic hybrid functional materials with good biocompatibility.

Methods

Gadolinium-porphyrin metal-organic frameworks were used as a skeleton for folic acid (FA) conjugation to synthesize a novel type of nanoparticle, denoted as folic acid-nanoscale gadolinium-porphyrin metal-organic frameworks (FA-NPMOFs). The FA-NPMOFs were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric-differential thermal analysis. The biotoxicity and imaging capability of the FA-NPMOFs were determined using HepG2 cells and embryonic and larval zebrafish. The delivery and photodynamic therapeutic effect of FA-NPMOFs were explored in transgenic zebrafish with doxycycline-induced HCC.

Results

FA-NPMOFs were spherical in structure with good dispersion and water solubility. They showed low biotoxicity, emitted bright red fluorescence, and exhibited an excellent magnetic resonance imaging capability, both in vitro and in vivo. Meanwhile, the FA-NPMOFs exhibited a strong affinity for folate receptor (FR)-expressing cells and were delivered to the tumor site in a targeted manner. Moreover, HCC tumor cells were eliminated following laser irradiation.

Conclusion

FA-NPMOFs can be used for dual-modality imaging and photodynamic therapy in HCC and show promise for use as a carrier in new therapies for HCC and other FR-positive tumors.

Zebrafish methanol exposure causes patterning defects and suppressive cell proliferation in retina

PURPOSE

Methanol exposure have been shown to produce retinal abnormalities and visual dysfunctions in rodents and other mammals developing in utero. In this study, we characterized how methanol affects the retinal development in an ex utero embryonic system, the zebrafish.

METHODS

Zebrafish embryos were raised for 24 hours in fish water supplemented with various concentrations of methanol at 6 hours after fertilisation. The effects of methanol on retinal morphology were assessed by histologic and immunohistochemical analyses.

RESULTS

Zebrafish embryos exposed to moderate (3%) and high (4%) levels of methanol during early embryonic development had a small eye phenotype. Embryos exposed to high (4%) level of methanol had morphological abnormalities of the retinal pigment epithelia and the photoreceptors. Methanol exposure also caused inhibition of cell differentiation and proliferation in the retina at the early developmental stage.

CONCLUSIONS

Low concentrations of methanol affect photoreceptor function but do not disturb retinal morphology. Higher levels of methanol exposure cause retinal patterning defects and a small eye phenotype.

Effects of copper oxide nanoparticles on developing zebrafish embryos and larvae

Copper oxide nanoparticles (CuO NPs) are used for a variety of purposes in a wide range of commercially available products. Some CuO NPs probably end up in the aquatic systems, thus raising concerns about aqueous exposure toxicity, and the impact of CuO NPs on liver development and neuronal differentiation remains unclear. In this study, particles were characterized using Fourier transform infrared spectra, scanning electron microscopy, and transmission electron microscopy. Zebrafish embryos were continuously exposed to CuO NPs from 4 hours postfertilization at concentrations of 50, 25, 12.5, 6.25, or 1 mg/L. The expression of gstp1 and cyp1a was examined by quantitative reverse transcription polymerase chain reaction. The expression of tumor necrosis factor alpha and superoxide dismutase 1 was examined by quantitative reverse transcription polymerase chain reaction and Western blotting. Liver development and retinal neurodifferentiation were analyzed by whole-mount in situ hybridization, hematoxylin–eosin staining, and immunohistochemistry, and a behavioral test was performed to track the movement of larvae. We show that exposure of CuO NPs at low doses has little effect on embryonic development. However, exposure to CuO NPs at concentrations of 12.5 mg/L or higher leads to abnormal phenotypes and induces an inflammatory response in a dose-dependent pattern. Moreover, exposure to CuO NPs at high doses results in an underdeveloped liver and a delay in retinal neurodifferentiation accompanied by reduced locomotor ability. Our data demonstrate that short-term exposure to CuO NPs at high doses shows hepatotoxicity and neurotoxicity in zebrafish embryos and larvae.