OBJECTIVES: The purinergic receptor P2X2 (P2RX2) encodes an ATP-gated ion channel permeable to Na⁺, K⁺, and especially Ca²⁺. Loss-of-function mutations in P2RX2 are known to cause autosomal dominant nonsyndromic deafness 41 (DFNA41), which manifests as high-frequency hearing loss, accelerated presbycusis, and increased susceptibility to noise-induced damage. Zebrafish, owing to their small size, rapid development, high fecundity, transparent embryos, and high gene conservation with humans, provide an ideal model for studying human diseases and developmental mechanisms. This study aims to generate a p2rx2 knockout zebrafish model using CRISPR/Cas9 gene editing system to investigate the effect of p2rx2 deficiency on the auditory system, providing a basis for understanding P2RX2-related hearing loss and developing gene therapy strategies. METHODS: Two CRISPR targets (sgRNA1 and sgRNA2) spaced 47 bp apart were designed within the zebrafish p2rx2 gene. Synthesized sgRNAs and Cas9 protein were microinjected into single-cell stage Tübingen (TU)-strain zebrafish embryos. PCR and gel electrophoresis verified editing efficiency at 36 hours post-fertilization (hpf). Surviving embryos were raised to adulthood (F0), tail-clipped, genotyped, and screened for positive mosaics. F1 heterozygotes were generated by outcrossing, and F2 homozygous mutants were obtained by intercrossing. Polymerase chain reaction (PCR) combined with sequencing verified mutation type and heritability. At 5 days post-fertilization (dpf), YO-PRO-1 staining was used to examine hair cell morphology and count in lateral line neuromasts and the otolith region. Auditory evoked potential (AEP) thresholds at 600, 800, 1 000, and 2 000 Hz were measured in nine 4-month-old wild type and mutant zebrafish per group. RESULTS: A stable p2rx2 knockout zebrafish line was successfully established. Sequencing revealed a 66 bp insertion at the first target site introducing a premature stop codon (TAA), leading to early termination of protein translation and loss of function. Embryos developed normally with no gross malformations. At 5 dpf, mutants exhibited significantly reduced hair cell density in the otolith region compared with wild type, although lateral line neuromasts were unaffected. AEP testing showed significantly elevated auditory thresholds at all 4 frequencies in homozygous mutants compared with wild type (all P<0.001), indicating reduced hearing sensitivity. CONCLUSIONS We successfully generated a p2rx2 loss-of-function zebrafish model using CRISPR/Cas9 technology. p2rx2 deficiency caused hair cell defects in the otolith region and increased auditory thresholds across frequencies, indicating its key role in maintaining zebrafish auditory hair cell function and hearing perception. The phenotype's restriction to the otolith region suggests tissue-specific roles of p2rx2 in sensory organs. This model provides a valuable tool for elucidating the molecular mechanisms of P2RX2-related hearing loss and for screening otoprotective drugs and developing gene therapies.
Animals ; Zebrafish/genetics* ; Receptors, Purinergic P2X2/deficiency* ; CRISPR-Cas Systems/genetics* ; Gene Knockout Techniques ; Phenotype ; Zebrafish Proteins/genetics* ; Disease Models, Animal

Acute mitochondrial damage and the energy crisis following axonal injury highlight mitochondrial transport as an important target for axonal regeneration. Syntaphilin (Snph), known for its potent mitochondrial anchoring action, has emerged as a significant inhibitor of both mitochondrial transport and axonal regeneration. Therefore, investigating the molecular mechanisms that influence the expression levels of the snph gene can provide a viable strategy to regulate mitochondrial trafficking and enhance axonal regeneration. Here, we reveal the inhibitory effect of microRNA-146b (miR-146b) on the expression of the homologous zebrafish gene syntaphilin b (snphb). Through CRISPR/Cas9 and single-cell electroporation, we elucidated the positive regulatory effect of the miR-146b-snphb axis on Mauthner cell (M-cell) axon regeneration at the global and single-cell levels. Through escape response tests, we show that miR-146b-snphb signaling positively regulates functional recovery after M-cell axon injury. In addition, continuous dynamic imaging in vivo showed that reprogramming miR-146b significantly promotes axonal mitochondrial trafficking in the pre-injury and early stages of regeneration. Our study reveals an intrinsic axonal regeneration regulatory axis that promotes axonal regeneration by reprogramming mitochondrial transport and anchoring. This regulation involves noncoding RNA, and mitochondria-associated genes may provide a potential opportunity for the repair of central nervous system injury.
Animals ; Zebrafish ; MicroRNAs/genetics* ; Nerve Regeneration/physiology* ; Mitochondria/metabolism* ; Zebrafish Proteins/genetics* ; Axons/metabolism* ; Signal Transduction/physiology* ; Axonal Transport/physiology* ; Nerve Tissue Proteins/genetics*

OBJECTIVE: To investigate the hemostatic effect of modified Sijunzi Granules (MSG) in primary immune thrombocytopenia (ITP) zebrafish model and explore the potential mechanism. METHODS: AB strain wild type zebrafish were treated with simvastatin (6 µmol/L) for 24 h to establish the hemorrhage model (model control group). The zebrafish were treated with MSG at different doses (55.6, 167, and 500 µg/mL), respectively. The hemostatic effect was assessed by examining the intestinal bleeding and hemostatic rate. 5-Hydroxytryptamine (5-HT) content was determined using enzyme-linked immunosorbent assay (ELISA) assay. The expressions of 5-HT2aR, 5-HT2bR, and SERT genes were detected by quantitative real-time polymerase chain reaction(PCR). The protein expressions of protein kinase B (Akt), p-Akt, extracellular regulated protein kinases (Erk), and p-Erk were examined using Western blot analysis. RESULTS: The intestinal bleeding rate was 37%, 40%, and 80% in the 55.6, 167, and 500 µg/mL dose of MSG, respectively, in which 55.6 and 167 µg/mL MSG dose groups were associated with significantly decreased intestinal bleeding rate when compared with the model control group (70%, P<0.05). Significantly higher hemostatic rates were also observed in the 55.6 (54%) and 167 (52%) µg/mL MSG dose groups (P<0.05). MSG increased the 5-HT content and mRNA expression levels of 5-HT2aR, 5-HT2bR, and SERT (P<0.05). In addition, caspase3/7 activity was inhibited (P<0.05). Significant increase in p-Akt and p-Erk was also detected after treatment with MSG (P<0.05). CONCLUSIONS MSG could reduce the incidence and severity of intestinal bleeding in zebrafish by activating MAPK/Erk and PI3K/Akt signal pathways through regulating the levels of 5-HT and its receptors, which may provide evidence for the treatment of ITP.
Animals ; Zebrafish ; Serotonin/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Drugs, Chinese Herbal/pharmacology* ; Hemostatics/pharmacology* ; MAP Kinase Signaling System/drug effects* ; Receptors, Serotonin/genetics* ; Extracellular Signal-Regulated MAP Kinases/metabolism* ; Signal Transduction/drug effects* ; Hemostasis/drug effects*

In order to develop a transgenic zebrafish line with green fluorescent protein (enhanced green fluorescent protein, EGFP) expressed specifically in muscle and heart, the recombinant expression vector constructed using the zebrafish ttn.2 gene promoter fragment and EGFP gene coding sequence and the capped mRNA of Tol2 transposase were co-injected into the zebrafish 1-cell stage embryos. The stable genetic Tg (ttn.2: EGFP) transgenic zebrafish line was successfully developed by fluorescence detection, followed by genetic hybridization screening and molecular identification. Fluorescence signals and whole-mount in situ hybridization showed that EGFP expression was located in muscle and heart, the specificity of which was consistent with the expression of ttn.2 mRNA. Inverse PCR showed that EGFP was integrated into chromosomes 4 and 11 of zebrafish in No. 33 transgenic line, while integrated into chromosome 1 in No. 34 transgenic line. The successful construction of this fluorescent transgenic zebrafish line, Tg (ttn.2: EGFP), laid a foundation for the research of muscle and heart development and related diseases. In addition, the transgenic zebrafish lines with strong green fluorescence can also be used as a new ornamental fish.
Animals ; Zebrafish/genetics* ; Animals, Genetically Modified/genetics* ; Green Fluorescent Proteins/metabolism* ; Zebrafish Proteins/genetics* ; Promoter Regions, Genetic

Motor neurons are an important type of neurons that control movement. The transgenic fluorescent protein (FP)-labeled motor neurons of zebrafish line is disadvantageous for studying the morphogenesis of motor neurons. For example, the individual motor neuron is indistinguishable in this transgenic line due to the high density of the motor neurons and the interlaced synapses. In order to optimize the in vivo imaging methods for the analysis of motor neurons, the present study was aimed to establish a microtubule-fluorescent fusion protein mosaic system that can label motor neurons in zebrafish. Firstly, the promotor of mnx1, which was highly expressed in the spinal cord motor neurons, was subcloned into pDestTol2pA2 construct combined with the GFP-α-Tubulin fusion protein sequence by Gateway cloning technique. Then the recombinant constructs were co-injected with transposase mRNA into the 4-8 cell zebrafish embryos. Confocal imaging analysis was performed at 72 hours post fertilization (hpf). The results showed that the GFP fusion protein was expressed in three different types of motor neurons, and individual motor neurons were mosaically labeled. Further, the present study analyzed the correlation between the injection dose and the number and distribution of the mosaically labeled neurons. Fifteen nanograms of the recombinant constructs were suggested as an appropriate injection dose. Also, the defects of the motor neuron caused by the down-regulation of insm1a and kif15 were verified with this system. These results indicate that our novel microtubule-fluorescent fusion protein mosaic system can efficiently label motor neurons in zebrafish, which provides a more effective model for exploring the development and morphogenesis of motor neurons. It may also help to decipher the mechanisms underlying motor neuron disease and can be potentially utilized in drug screening.
Animals ; Animals, Genetically Modified ; Green Fluorescent Proteins/pharmacology* ; Microtubules/metabolism* ; Motor Neurons ; Zebrafish/genetics* ; Zebrafish Proteins/genetics*

Tripterygium wilfordii multiglycoside (GTW) is a commonly used compound for the treatment of rheumatoid arthritis (RA) and immune diseases in clinical practice. However, it can induce liver injury and the mechanism of hepatotoxicity is still not clear. This study was designed to investigate GTW-induced hepatotoxicity in zebrafish larvae and explore the mechanism involved. The 72 hpf (hours post fertilization) zebrafish larvae were administered with different concentrations of GTW for three days and their mortality, malformation rate, morphological changes in the liver, transaminase levels, and histopathological changes in the liver of zebrafish larvae were detected. The reverse transcription-polymerase chain reaction (RT-PCR) was used to examine the levels of microRNA-122 (miR-122) and genes related to inflammation, apoptosis, cell proliferation and liver function. The results showed that GTW increased the mortality of zebrafish larvae, while significant malformations and liver damage occurred. The main manifestations were elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), significant liver atrophy, vacuoles in liver tissue, sparse cytoplasm, and unclear hepatocyte contours. RT-PCR results showed that the expression of miR-122 significantly decreased by GTW; the mRNA levels of inflammation-related genes il1β, il6, tnfα, il10, cox2 and ptges significantly increased; the mRNA level of tgfβ significantly decreased; the mRNA levels of apoptosis-related genes, caspase-8 and caspase-9, significantly increased; the mRNA level of bcl2 significantly decreased; the mRNA levels of cell proliferation-related genes, top2α and uhrf1, significantly reduced; the mRNA levels of liver function-related genes, alr and cyp3c1, significantly increased; and the mRNA level of cyp3a65 significantly decreased. In zebrafish, GTW can cause increased inflammation, enhanced apoptosis, decreased cell proliferation, and abnormal expression of liver function-related genes, leading to abnormal liver structure and function and resulting in hepatotoxicity.
Animals ; Apoptosis ; Chemical and Drug Induced Liver Injury/genetics* ; Inflammation/genetics* ; Trans-Activators ; Tripterygium ; Zebrafish/genetics* ; Zebrafish Proteins

Heparin and heparan sulfate are a class of glycosaminoglycans for clinical anticoagulation. Heparosan N-sulfate-glucuronate 5-epimerase (C5, EC 5.1.3.17) is a critical modifying enzyme in the synthesis of heparin and heparan sulfate, and catalyzes the inversion of carboxyl group at position 5 on D-glucuronic acid (D-GlcA) of N-sulfoheparosan to form L-iduronic acid (L-IdoA). In this study, the heparin C5 epimerase gene Glce from zebrafish was expressed and molecularly modified in Escherichia coli. After comparing three expression vectors of pET-20b (+), pET-28a (+) and pCold Ⅲ, C5 activity reached the highest ((1 873.61±5.42) U/L) with the vector pCold Ⅲ. Then we fused the solution-promoting label SET2 at the N-terminal for increasing the soluble expression of C5. As a result, the soluble protein expression was increased by 50% compared with the control, and the enzyme activity reached (2 409±6.43) U/L. Based on this, site-directed mutations near the substrate binding pocket were performed through rational design, the optimal mutant (V153R) enzyme activity and specific enzyme activity were (5 804±5.63) U/L and (145.1±2.33) U/mg, respectively 2.41-fold and 2.28-fold of the original enzyme. Modification and expression optimization of heparin C5 epimerase has laid the foundation for heparin enzymatic catalytic biosynthesis.
Animals ; Carbohydrate Epimerases ; biosynthesis ; chemistry ; genetics ; Escherichia coli ; Gene Expression ; Heparin ; metabolism ; Heparitin Sulfate ; metabolism ; Iduronic Acid ; metabolism ; Zebrafish Proteins ; biosynthesis ; chemistry ; genetics

To explore the effects of KIAA0196 gene on cardiac development and the establishment of zebrafish strain.
 Methods: Peripheral blood and gDNA from patients were extracted. Copy number variation analysis and target sequencing were conducted to screen candidate genes. The KIAA0196 knockout zebrafish was generated by CRISPR/Cas9 to detect whether KIAA0196 deficiency could affect cardiac development. Finally, the wild-type and mutant zebrafish were anatomized and histologically stained to observe the phenotype of heart defects.
 Results: The KIAA0196 knockout zebrafish strain was successfully constructed using CRISPR/Cas9 technology. After 60 hours fertilization, microscopic examination of KIAA0196 knockout zebrafish (heterozygote + homozygote) showed pericardial effusion, cardiac compression and severely curly tail. Compared with wild-type zebrafish, the hearts of mutant KIAA0196 zebrafish had cardiac defects including smaller atrium and larger ventricle, and the myocardial cells were looser.
 Conclusion: KIAA0196 gene plays an important regulatory role in the development of heart. It might be a candidate gene for congenital heart disease.
Animals ; DNA Copy Number Variations ; Heart ; Heart Defects, Congenital ; genetics ; Humans ; Myocytes, Cardiac ; Phenotype ; Proteins ; Zebrafish ; genetics ; Zebrafish Proteins ; genetics

PURPOSE: microRNAs (miRNAs) are non-coding RNAs composed of 20 to 22 nucleotides that regulate development and differentiation in various organs by silencing specific RNAs and regulating gene expression. In the present study, we show that the microRNA (miR)-183 cluster is upregulated during hair cell regeneration and that its inhibition reduces hair cell regeneration following neomycin-induced ototoxicity in zebrafish. MATERIALS AND METHODS: miRNA expression patterns after neomycin exposure were analyzed using microarray chips. Quantitative polymerase chain reaction was performed to validate miR-183 cluster expression patterns following neomycin exposure (500 µM for 2 h). After injection of an antisense morpholino (MO) to miR-183 (MO-183) immediately after fertilization, hair cell regeneration after neomycin exposure in neuromast cells was evaluated by fluorescent staining (YO-PRO1). The MO-183 effect also was assessed in transgenic zebrafish larvae expressing green fluorescent protein (GFP) in inner ear hair cells. RESULTS: Microarray analysis clearly showed that the miR-183 cluster (miR-96, miR-182, and miR-183) was upregulated after neomycin treatment. We also confirmed upregulated expression of the miR-183 cluster during hair cell regeneration after neomycin-induced ototoxicity. miR-183 inhibition using MO-183 reduced hair cell regeneration in both wild-type and GFP transgenic zebrafish larvae. CONCLUSION: Our work demonstrates that the miR-183 cluster is essential for the regeneration of hair cells following ototoxic injury in zebrafish larvae. Therefore, regulation of the miR-183 cluster can be a novel target for stimulation of hair cell regeneration.
Animals ; Animals, Genetically Modified ; Cell Count ; Gene Expression Profiling ; Gene Expression Regulation/drug effects ; Gene Knockdown Techniques ; Green Fluorescent Proteins/metabolism ; Hair Cells, Auditory/drug effects ; Hair Cells, Auditory/physiology ; Larva/drug effects ; Larva/genetics ; MicroRNAs/genetics ; MicroRNAs/metabolism ; Morpholinos/pharmacology ; Neomycin/toxicity ; Regeneration/drug effects ; Regeneration/genetics ; Zebrafish/genetics

Obesity has become a severe public health problem across the world, and seriously affects the health and life quality of human beings. Here we generated lepr and mc4r mutant zebrafish via the CRISPR/Cas9 technique, and performed morphological and functional characterizations of those mutants. We observed that there was no significant phenotypic difference between homozygous mutants and wild-type controls before 2.5 months post-fertilization (mpf). However, the adult leprand mc4rindividuals displayed increased food intake, heavier weight, and higher body fat percentage, the characteristics of obesity phenotypes. Blood glucose test showed that overfeeding induced significantly impaired glucose tolerance in adult leprand mc4rzebrafish. Furthermore, we analyzed 76 energy metabolism-related transcripts in leprand mc4rzebrafish livers by using real-time RT-PCR, and compared the results with the published microarray data of Lepmouse livers, and found that the changes in the expression of insulin/IGF signaling (IIS) pathway genes in leprzebrafish and Lepmouse were positively correlated, suggesting that the IIS pathway maintains functional conservation between zebrafish and mammals during the evolution of the obesity-regulating molecule network.
Animals ; CRISPR-Cas Systems ; Gene Knockout Techniques ; Insulin ; metabolism ; Leptin ; Mutation ; Obesity ; genetics ; Receptor, Melanocortin, Type 4 ; genetics ; Receptors, Leptin ; genetics ; Signal Transduction ; Zebrafish ; Zebrafish Proteins ; genetics