ErbB3 is required for hyperaminoacidemia-induced pancreatic α cell hyperplasia.

Blood amino acid levels are maintained in a narrow physiological range. The pancreatic α cells have emerged as the primary aminoacidemia regulator through glucagon secretion to promote hepatic amino acid catabolism. Interruption of glucagon signaling disrupts the liver - α cells axis leading to hyperaminoacidemia, which triggers a compensatory rise in glucagon secretion and α cell hyperplasia. The mechanisms of hyperaminoacidemia-induced α cell hyperplasia remain incompletely understood. Using a mouse α cell line and in vivo studies in zebrafish and mice, we found that hyperaminoacidemia-induced α cell hyperplasia requires ErbB3 signaling. In addition to mTORC1, another ErbB3 downstream effector STAT3 also plays a role in α cell hyperplasia. Mechanistically, ErbB3 may partner with ErbB2 to stimulate cyclin D2 and suppress p27 via mTORC1 and STAT3. Our study identifies ErbB3 as a new regulator for hyperaminoacidemia-induced α cell proliferation and a critical component of the liver-α cells axis that regulates aminoacidemia.

A Vegfc-Emilin2a-Cxcl8a Signaling Axis Required for Zebrafish Cardiac Regeneration.

BACKGROUND: Ischemic heart disease following the obstruction of coronary vessels leads to the death of cardiac tissue and the formation of a fibrotic scar. In contrast to adult mammals, zebrafish can regenerate their heart after injury, enabling the study of the underlying mechanisms. One of the earliest responses following cardiac injury in adult zebrafish is coronary revascularization. Defects in this process lead to impaired cardiomyocyte repopulation and scarring. Hence, identifying and investigating factors that promote coronary revascularization holds great therapeutic potential. METHODS: We used wholemount imaging, immunohistochemistry and histology to assess various aspects of zebrafish cardiac regeneration. Deep transcriptomic analysis allowed us to identify targets and potential effectors of Vegfc (vascular endothelial growth factor C) signaling. We used newly generated loss- and gain-of-function genetic tools to investigate the role of Emilin2a (elastin microfibril interfacer 2a) and Cxcl8a (chemokine (C-X-C) motif ligand 8a)-Cxcr1 (chemokine (C-X-C) motif receptor 1) signaling in cardiac regeneration. RESULTS: We first show that regenerating coronary endothelial cells upregulate vegfc upon cardiac injury in adult zebrafish and that Vegfc signaling is required for their proliferation during regeneration. Notably, blocking Vegfc signaling also significantly reduces cardiomyocyte dedifferentiation and proliferation. Using transcriptomic analyses, we identified emilin2a as a target of Vegfc signaling and found that manipulation of emilin2a expression can modulate coronary revascularization as well as cardiomyocyte proliferation. Mechanistically, Emilin2a induces the expression of the chemokine gene cxcl8a in epicardium-derived cells, while cxcr1, the Cxcl8a receptor gene, is expressed in coronary endothelial cells. We further show that Cxcl8a-Cxcr1 signaling is also required for coronary endothelial cell proliferation during cardiac regeneration. CONCLUSIONS: These data show that after cardiac injury, coronary endothelial cells upregulate vegfc to promote coronary network reestablishment and cardiac regeneration. Mechanistically, Vegfc signaling upregulates epicardial emilin2a and cxcl8a expression to promote cardiac regeneration. These studies aid in understanding the mechanisms underlying coronary revascularization in zebrafish, with potential therapeutic implications to enhance revascularization and regeneration in injured human hearts.

Plaat1l1 controls feeding induced NAPE biosynthesis and contributes to energy balance regulation in zebrafish.

Dysregulation of energy balance leading to obesity is a significant risk factor for cardiometabolic diseases such as diabetes, non-alcoholic fatty liver disease and atherosclerosis. In rodents and several other vertebrates, feeding has been shown to induce a rapid rise in the intestinal levels of N-acyl-ethanolamines (NAEs) and the chronic consumption of a high fat diet abolishes this rise. Administering NAEs to rodents consuming a high fat diet reduces their adiposity, in part by reducing food intake and enhancing fat oxidation, so that feeding-induced intestinal NAE biosynthesis appears to be critical to appropriate regulation of energy balance. However, the contribution of feeding-induced intestinal NAE biosynthesis to appropriate energy balance remains poorly understood in part because there are multiple enzymes that can contribute to NAE biosynthesis and the specific enzyme(s) that are responsible for feeding-induced intestinal NAE biosynthesis have not been identified. The rate-limiting step in the intestinal biosynthesis of NAEs is formation of their immediate precursors, the N-acyl-phosphatidylethanolamines (NAPEs), by phosphatidylethanolamine N-acyltransferases (NATs). At least six NATs are found in humans and multiple homologs of these NATs are found in most vertebrate species. In recent years, the fecundity and small size of zebrafish (Danio rerio), as well as their similarities in feeding behavior and energy balance regulation with mammals, have led to their use to model key features of cardiometabolic disease. We therefore searched the Danio rerio genome to identify all NAT homologs and found two additional NAT homologs besides the previously reported plaat1, rarres3, and rarres3l, and used CRISPR/cas9 to delete these two NAT homologs (plaat1l1 and plaat1l2). While wild-type fish markedly increased their intestinal NAPE levels in response to a meal after fasting, this response was completely ablated in plaat1l1-/-fish. Furthermore, plaat1l1-/- fish fed a standard flake diet had increased weight gain and glucose intolerance compared to wild-type fish. The results support a critical role for feeding-induced NAPE and NAE biosynthesis in regulating energy balance and suggest that restoring this response in obese animals could potentially be used to treat obesity and cardiometabolic disease.

Systematically analyzed molecular characteristics of lung adenocarcinoma using metabolism-related genes classification.

High heterogeneity of lung adenocarcinoma (LUAD) is a major clinical challenge. This study aims to characterize the molecular features of LUAD through classification based on metabolism-related genes. A total of 500 LUAD samples from The Cancer Genome Atlas (TCGA) and 612 from Gene Expression Omnibus (GEO) were integrated with 2,753 metabolism-related genes to determine the molecular classification. Systematic bioinformatics analysis was used to conduct correlation analysis between metabolism-related classification and molecular characteristics of LUAD. LUAD patients were divided into three molecular clusters (C1-C3). Survival analysis revealed that C1 and C2 showed good and poor prognoses, respectively. Associational analysis of classification and molecular characteristics revealed that C1 was associated with low pathological stage, metabolic pathways, high metabolic process, active immune process and checkpoint, sensitive drug response, as well as a low genetic mutation. Nevertheless, C2 was associated with high pathological stage, carcinogenic pathways, low metabolic process, inactive immune signatures, resistant drug response, and frequent genetic mutation. Eventually, a classifier with 60 metabolic genes was constructed, confirming the robustness of molecular classification on LUAD. Our findings promote the understanding of LUAD molecular characteristics, and the research data may be used for providing information be helpful for clinical diagnosis and treatment.

Taste buds are not derived from neural crest in mouse, chicken, and zebrafish.

Our lineage tracing studies using multiple Cre mouse lines showed a concurrent labeling of abundant taste bud cells and the underlying connective tissue with a neural crest (NC) origin, warranting a further examination on the issue of whether there is an NC derivation of taste bud cells. In this study, we mapped NC cell lineages in three different models, Sox10-iCreERT2/tdT mouse, GFP+ neural fold transplantation to GFP- chickens, and Sox10-Cre/GFP-RFP zebrafish model. We found that in mice, Sox10-iCreERT2 specifically labels NC cell lineages with a single dose of tamoxifen at E7.5 and that the labeled cells were widely distributed in the connective tissue of the tongue. No labeled cells were found in taste buds or the surrounding epithelium in the postnatal mice. In the GFP+/GFP- chicken chimera model, GFP+ cells migrated extensively to the cranial region of chicken embryos ipsilateral to the surgery side but were absent in taste buds in the base of oral cavity and palate. In zebrafish, Sox10-Cre/GFP-RFP faithfully labeled known NC-derived tissues but did not label taste buds in lower jaw or the barbel. Our data, together with previous findings in axolotl, indicate that taste buds are not derived from NC cells in rodents, birds, amphibians or teleost fish.

Ameliorating role of microRNA-378 carried by umbilical cord mesenchymal stem cells-released extracellular vesicles in mesangial proliferative glomerulonephritis.

BACKGROUND: Mesenchymal stem cells (MSCs) and their released extracellular vesicles (Evs) have shown protective effects against kidney diseases. This study aims to study the functions of umbilical cord MSCs-released Evs (ucMSC-Evs) and their implicated molecules in mesangial proliferative glomerulonephritis (MsPGN). METHODS: A rat model of MsPGN was induced by anti-Thy-1.1, and rat mesangial cells (rMCs) HBZY-1 were treated with PDGF-BB/DD to mimic MsPGN condition in vitro. Rats and cells were treated with different doses of ucMSC-Evs, and then the pathological changes in renal tissues and proliferation of rMCs were determined. Differentially expressed microRNAs (miRNAs) after Evs treatment were screened by microarray analysis. The interactions among miR-378, PSMD14, and TGFBR1 were analyzed. Gain- and loss-of function studies of miR-378 and PSMD14 were performed to explore their effects on tissue hyperplasia and rMC proliferation and their interactions with the TGF-ß1/Smad2/3 signaling pathway. RESULTS: The ucMSC-Evs treatment ameliorated mesangial hyperplasia and fibrosis in rat renal tissues and suppressed the aberrant proliferation of rMCs in a dose-dependent manner. miR-378 was the most upregulated miRNA in tissues and cells after ucMSC-Evs treatment. miR-378 directly targeted PSMD14, and PSMD14 maintained the stability of TGFBR1 through deubiquitination modification, which led to TGF-ß1/Smad2/3 activation. Either miR-378 knockdown or PSMD14 overexpression diminished the protective functions of ucMSC-Evs by activating the TGF-ß1/Smad2/3 signaling pathway. CONCLUSION: UcMSC-Evs ameliorate pathological process in MsPGN through the delivery of miR-378, which suppresses PSMD14-mediated TGFBR1 stability and inactivates the TGF-ß1/Smad2/3 signaling pathway to reduce tissue hyperplasia and rMC proliferation. Video abstract.

Active medulloblastoma enhancers reveal subgroup-specific cellular origins.

Medulloblastoma is a highly malignant paediatric brain tumour, often inflicting devastating consequences on the developing child. Genomic studies have revealed four distinct molecular subgroups with divergent biology and clinical behaviour. An understanding of the regulatory circuitry governing the transcriptional landscapes of medulloblastoma subgroups, and how this relates to their respective developmental origins, is lacking. Here, using H3K27ac and BRD4 chromatin immunoprecipitation followed by sequencing (ChIP-seq) coupled with tissue-matched DNA methylation and transcriptome data, we describe the active cis-regulatory landscape across 28 primary medulloblastoma specimens. Analysis of differentially regulated enhancers and super-enhancers reinforced inter-subgroup heterogeneity and revealed novel, clinically relevant insights into medulloblastoma biology. Computational reconstruction of core regulatory circuitry identified a master set of transcription factors, validated by ChIP-seq, that is responsible for subgroup divergence, and implicates candidate cells of origin for Group 4. Our integrated analysis of enhancer elements in a large series of primary tumour samples reveals insights into cis-regulatory architecture, unrecognized dependencies, and cellular origins.

Prospective Analysis of Proteins Carried in Extracellular Vesicles with Clinical Outcome in Hepatocellular Carcinoma.

Background: Extracellular vehicles (EVs) contain different proteins that relay information between tumor cells, thus promoting tumorigenesis. Therefore, EVs can serve as an ideal marker for tumor pathogenesis and clinical application. Objective: Here, we characterised EV-specific proteins in hepatocellular carcinoma (HCC) samples and established their potential protein-protein interaction (PPI) networks. Materials and Methods: We used multi-dimensional bioinformatics methods to mine a network module to use as a prognostic signature and validated the model's prediction using additional datasets. The relationship between the prognostic model and tumor immune cells or the tumor microenvironment status was also examined. Results: 1134 proteins from 316 HCC samples were mapped to the exoRBase database. HCC-specific EVs specifically expressed a total of 437 proteins. The PPI network revealed 321 proteins and 938 interaction pathways, which were mined to identify a three network module (3NM) with significant prognostic prediction ability. Validation of the 3NM in two more datasets demonstrated that the model outperformed the other signatures in prognostic prediction ability. Functional analysis revealed that the network proteins were involved in various tumor-related pathways. Additionally, these findings demonstrated a favorable association between the 3NM signature and macrophages, dendritic, and mast cells. Besides, the 3NM revealed the tumor microenvironment status, including hypoxia and inflammation. Conclusion: These findings demonstrate that the 3NM signature reliably predicts HCC pathogenesis. Therefore, the model may be used as an effective prognostic biomarker in managing patients with HCC.

Predicting susceptibility to SARS-CoV-2 infection based on structural differences in ACE2 across species.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the global pandemic of coronavirus disease-2019 (COVID-19). SARS-CoV-2 is a zoonotic disease, but little is known about variations in species susceptibility that could identify potential reservoir species, animal models, and the risk to pets, wildlife, and livestock. Certain species, such as domestic cats and tigers, are susceptible to SARS-CoV-2 infection, while other species such as mice and chickens are not. Most animal species, including those in close contact with humans, have unknown susceptibility. Hence, methods to predict the infection risk of animal species are urgently needed. SARS-CoV-2 spike protein binding to angiotensin-converting enzyme 2 (ACE2) is critical for viral cell entry and infection. Here we integrate species differences in susceptibility with multiple in-depth structural analyses to identify key ACE2 amino acid positions including 30, 83, 90, 322, and 354 that distinguish susceptible from resistant species. Using differences in these residues across species, we developed a susceptibility score that predicts an elevated risk of SARS-CoV-2 infection for multiple species including horses and camels. We also demonstrate that SARS-CoV-2 is nearly optimal for binding ACE2 of humans compared to other animals, which may underlie the highly contagious transmissibility of this virus among humans. Taken together, our findings define potential ACE2 and SARS-CoV-2 residues for therapeutic targeting and identification of animal species on which to focus research and protection measures for environmental and public health.

Preselection TCR repertoire predicts CD4+ and CD8+ T-cell differentiation state.

T cells must display diversity regarding both the cell state and T-cell receptor (TCR) repertoire to provide effective immunity against pathogens; however, the generation and evolution of cellular T-cell heterogeneity in the adaptive immune system remains unclear. In the present study, a combination of multiplex PCR and immune repertoire sequencing (IR-seq) was used for a standardized analysis of the TCR ß-chain repertoire of CD4+ naive, CD4+ memory, CD8+ naive and CD8+ memory T cells. We showed that the T-cell subsets could be distinguished from each another with regard to the TCR ß-chain (TCR-ß) diversity, CDR3 length distribution and TRBV usage, which could be observed both in the preselection and in the post-selection repertoire. Moreover, the Dß-Jß and Vß-Dß combination patterns at the initial recombination step, template-independent insertion of nucleotides and inter-subset overlap were consistent between the pre- and post-selection repertoires, with a remarkably positive correlation. Taken together, these results support differentiation of the CD4+ and CD8+ T-cell subsets prior to thymic selection, and these differences survived both positive and negative selection. In conclusion, these findings provide deeper insight into the generation and evolution of TCR repertoire generation.

The potential role of tRNAs and small RNAs derived from tRNAs in the occurrence and development of systemic lupus erythematosus.

BACKGROUND: Emerging evidence has shown the involvement of dysregulated transfer RNAs (tRNAs) and small RNAs derived from transfer RNAs (tsRNAs) in the pathophysiology of human diseases. The role of tRNAs and tsRNAs in systemic lupus erythematosus (SLE) remains unclear. Therefore, this study aims to investigate the possible regulatory roles of tRNAs and tsRNAs in the pathological mechanism of SLE. METHODS: Total RNA was extracted from peripheral blood mononuclear cells (PBMCs) of 20 SLE patients and 20 normal controls (NCs) to obtain tRNAs and tsRNAs, followed by tRNA and tsRNA expression profiling by the NextSeq system. Target genes were predicted by informatics analysis. Subsequently, to explore the function of messenger RNA (mRNA) in these target genes, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed using the Cytoscape plug-in BinGo, the DAVID database, and Cytoscape software. RESULTS: A total of 101 tRNAs and 355 tsRNAs were found to be differentially expressed in SLE patients versus NCs by RNA microarray. GO analysis revealed that the altered target genes of the selected tRNAs and tsRNAs were most enriched similarly in immune response and the immune system process. Moreover, KEGG pathway analysis demonstrated that altered target genes of tRNAs were most enriched in systemic lupus erythematosus, while the altered target genes of tsRNAs were most enriched in the T cell receptor signalling pathway, Th1 and Th2 cell differentiation and primary immunodeficiency. These pathways may be related to the initiation of SLE. CONCLUSION: Our results provide a novel perspective for studying the tRNA-related and tsRNA-related pathogenesis of SLE.

Global Transcriptomic Analysis of Zebrafish Glucagon Receptor Mutant Reveals Its Regulated Metabolic Network.

The glucagon receptor (GCGR) is a G-protein-coupled receptor (GPCR) that mediates the activity of glucagon. Disruption of GCGR results in many metabolic alterations, including increased glucose tolerance, decreased adiposity, hypoglycemia, and pancreatic α-cell hyperplasia. To better understand the global transcriptomic changes resulting from GCGR deficiency, we performed whole-organism RNA sequencing analysis in wild type and gcgr-deficient zebrafish. We found that the expression of 1645 genes changes more than two-fold among mutants. Most of these genes are related to metabolism of carbohydrates, lipids, and amino acids. Genes related to fatty acid ß-oxidation, amino acid catabolism, and ureagenesis are often downregulated. Among gcrgr-deficient zebrafish, we experimentally confirmed increases in lipid accumulation in the liver and whole-body glucose uptake, as well as a modest decrease in total amino acid content. These results provide new information about the global metabolic network that GCGR signaling regulates in addition to a better understanding of the receptor's physiological functions.

Zebrafish Genome Engineering Using the CRISPR-Cas9 System.

Geneticists have long sought the ability to manipulate vertebrate genomes by directly altering the information encoded in specific genes. The recently discovered clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 endonuclease has the ability to bind single loci within vertebrate genomes and generate double-strand breaks (DSBs) at those sites. These DSBs induce an endogenous DSB repair response that results in small insertions or deletions at the targeted site. Alternatively, a template can be supplied, in which case homology-directed repair results in the generation of engineered alleles at the break site. These changes alter the function of the targeted gene facilitating the analysis of gene function. This tool has been widely adopted in the zebrafish model; we discuss the development of this system in the zebrafish and how it can be manipulated to facilitate genome engineering.

DNA methylation-based classification and identification of renal cell carcinoma prognosis-subgroups.

BACKGROUND: Renal cell carcinoma (RCC) is the most common kidney cancer and includes several molecular and histological subtypes with different clinical characteristics. The combination of DNA methylation and gene expression data can improve the classification of tumor heterogeneity, by incorporating differences at the epigenetic level and clinical features. METHODS: In this study, we identified the prognostic methylation and constructed specific prognosis-subgroups based on the DNA methylation spectrum of RCC from the TCGA database. RESULTS: Significant differences in DNA methylation profiles among the seven subgroups were revealed by consistent clustering using 3389 CpGs that indicated that were significant differences in prognosis. The specific DNA methylation patterns reflected differentially in the clinical index, including TNM classification, pathological grade, clinical stage, and age. In addition, 437 CpGs corresponding to 477 genes of 151 samples were identified as specific hyper/hypomethylation sites for each specific subgroup. A total of 277 and 212 genes corresponding to DNA methylation at promoter sites were enriched in transcription factor of GKLF and RREB-1, respectively. Finally, Bayesian network classifier with specific methylation sites was constructed and was used to verify the test set of prognoses into DNA methylation subgroups, which was found to be consistent with the classification results of the train set. DNA methylation-based classification can be used to identify the distinct subtypes of renal cell carcinoma. CONCLUSIONS: This study shows that DNA methylation-based classification is highly relevant for future diagnosis and treatment of renal cell carcinoma as it identifies the prognostic value of each epigenetic subtype.

Analysis of autophagy-related genes and associated noncoding RNAs and transcription factors in digestive system tumors.

Aim: To investigate the autophagy-related gene (ATG) expression and the associated noncoding RNAs (ncRNA) and transcription factors (TF) in digestive system tumors (DST). Methods: We systematically investigated the ATG expression in DST by weighted gene correlation network analysis, crosstalk connection, functional analysis and Pivot analysis. Results: ATGs were clustered into six modules with co-expression in DST. Functional analysis revealed that six ATG-related modules were enriched in biological pathways involved in tumorigenesis. Pivot analysis identified key ncRNAs and TFs, which are essential for the pathogenesis, clinical diagnosis and treatment of DST. Conclusion: Our study highlights the crucial roles of ncRNA and TFs in the identification of potential biomarkers or therapeutic targets for DST.

Comprehensive Analysis of the mRNA-lncRNA Co-expression Profile and ceRNA Networks Patterns in Chronic Hepatitis B.

BACKGROUND: Long non-coding RNAs (lncRNAs) are emerging as important regulators in the modulation of virus infection by targeting mRNA transcription. However, their roles in chronic hepatitis B (CHB) remain to be elucidated. OBJECTIVE: The study aimed to explore the lncRNAs and mRNA expression profiles in CHB and asymp-tomatic HBsAg carriers (ASC) and construct mRNA-lncRNA co-expression profile and ceRNA net-works to identify the potential targets of diagnosis and treatment in CHB. METHODS: We determined the expression profiles of lncRNAs and mRNAs in CHB and ASC using mi-croarray analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) path-way enrichment analyses were performed to explore their function. We also constructed co-expression, cis-regulatory, and competing endogenous RNA (ceRNA) networks with bioinformatics methods. RESULTS: We identified 1634 mRNAs and 5550 lncRNAs that were differentially expressed between CHB and ASC. Significantly enriched GO terms and pathways were identified, many of which were linked to immune processes and inflammatory responses. Co-expression analysis showed 1196 relation-ships between the top 20 up/downregulated lncRNAs and mRNA, especially 213 lncRNAs interacted with ZFP57. The ZFP57-specific ceRNA network covered 3 lncRNAs, 5 miRNAs, and 17 edges. Cis-correlation analysis showed that lncRNA T039096 was paired with the most differentially expressed gene, ZFP57. Moreover, by expending the clinical samples size, the qRT-PCR results showed that the expression of ZFP57 and T039096 increased in CHB compared to ASC. CONCLUSION: Our study provides insights into the roles of mRNA and lncRNA networks in CHB, high-lighting potential applications of lncRNA-T039096 and mRNA-ZFP57 for diagnosis and treatment.

Leptin signaling regulates glucose homeostasis, but not adipostasis, in the zebrafish.

Leptin is the primary adipostatic factor in mammals. Produced largely by adipocytes in proportion to total adipose mass, the hormone informs the brain regarding total energy stored as triglycerides in fat cells. The hormone acts on multiple circuits in the brain to regulate food intake, autonomic outflow, and endocrine function to maintain energy balance. In addition to regulating adipose mass, mammalian leptin also plays a role in the regulation of glucose homeostasis and as a gating factor in reproductive competence. Leptin-deficient mice and people exhibit early onset profound hyperphagia and obesity, diabetes, and infertility. Although leptin and the leptin receptor are found in fish, the hormone is not expressed in adipose tissue, but is found in liver and other tissues. Here, we show that adult zebrafish lacking a functional leptin receptor do not exhibit hyperphagia or increased adiposity, and exhibit normal fertility. However, leptin receptor-deficient larvae have increased numbers of ß-cells and increased levels of insulin mRNA. Furthermore, larval zebrafish have been shown to exhibit ß-cell hyperplasia in response to high fat feeding or peripheral insulin resistance, and we show here that leptin receptor is required for this response. Adult zebrafish also have increased levels of insulin mRNA and other alterations in glucose homeostasis. Thus, a role for leptin in the regulation of ß-cell mass and glucose homeostasis appears to be conserved across vertebrates, whereas its role as an adipostatic factor is likely to be a secondary role acquired during the evolution of mammals.

High-throughput gene targeting and phenotyping in zebrafish using CRISPR/Cas9.

The use of CRISPR/Cas9 as a genome-editing tool in various model organisms has radically changed targeted mutagenesis. Here, we present a high-throughput targeted mutagenesis pipeline using CRISPR/Cas9 technology in zebrafish that will make possible both saturation mutagenesis of the genome and large-scale phenotyping efforts. We describe a cloning-free single-guide RNA (sgRNA) synthesis, coupled with streamlined mutant identification methods utilizing fluorescent PCR and multiplexed, high-throughput sequencing. We report germline transmission data from 162 loci targeting 83 genes in the zebrafish genome, in which we obtained a 99% success rate for generating mutations and an average germline transmission rate of 28%. We verified 678 unique alleles from 58 genes by high-throughput sequencing. We demonstrate that our method can be used for efficient multiplexed gene targeting. We also demonstrate that phenotyping can be done in the F1 generation by inbreeding two injected founder fish, significantly reducing animal husbandry and time. This study compares germline transmission data from CRISPR/Cas9 with those of TALENs and ZFNs and shows that efficiency of CRISPR/Cas9 is sixfold more efficient than other techniques. We show that the majority of published "rules" for efficient sgRNA design do not effectively predict germline transmission rates in zebrafish, with the exception of a GG or GA dinucleotide genomic match at the 5' end of the sgRNA. Finally, we show that predicted off-target mutagenesis is of low concern for in vivo genetic studies.

Circadian modulation of dopamine levels and dopaminergic neuron development contributes to attention deficiency and hyperactive behavior.

Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent psychiatric disorders in children and adults. While ADHD patients often display circadian abnormalities, the underlying mechanisms are unclear. Here we found that the zebrafish mutant for the circadian gene period1b (per1b) displays hyperactive, impulsive-like, and attention deficit-like behaviors and low levels of dopamine, reminiscent of human ADHD patients. We found that the circadian clock directly regulates dopamine-related genes monoamine oxidase and dopamine ß hydroxylase, and acts via genes important for the development or maintenance of dopaminergic neurons to regulate their number and organization in the ventral diencephalic posterior tuberculum. We then found that Per1 knock-out mice also display ADHD-like symptoms and reduced levels of dopamine, thereby showing highly conserved roles of the circadian clock in ADHD. Our studies demonstrate that disruption of a circadian clock gene elicits ADHD-like syndrome. The circadian model for attention deficiency and hyperactive behavior sheds light on ADHD pathogenesis and opens avenues for exploring novel targets for diagnosis and therapy for this common psychiatric disorder.