Transient knockdown of LIS1 results in seizures, differential gene expression and a neuronal migration disorder in developing zebrafish
ABSTRACT: Mutation or deletion of LIS1 (Lissencephaly-1) underlies classical lissencephaly, a migration disorder resulting in brain malformation, epilepsy and mental retardation. Orthologues for LIS1 genes (lis1a and lis1b) are ubiquitously expressed in developing zebrafish larvae, but the functional consequences of Lis1 knockdown are unknown. Here we used lis1-specific morpholino oligonucleotides (MOs, targeting protein translation or mRNA splicing, respectively) to transiently knockdown Lis1 expression in zebrafish. Injection of lis1 MOs resulted in morphological changes including microcephaly. At four days post-fertilization, lis1 morphants exhibited spontaneous convulsive behavior and abnormal large-amplitude electrographic discharge resembling that seen in acute and genetic zebrafish models of epilepsy. Abnormal brain development and neuronal migration defects were observed when lis1 MO injections were made into fluorescent reporter lines demarcating interneuron distribution (Dlx5a/6a:GFP) and brain structure (GBT0133:mRFP). Microarray analysis for ~44,000 Danio rerio transcripts identified 215 up-regulated and 160 down-regulated genes. Quantitative PCR and whole-mount in situ hybridization were used to validate these results for twenty and seven genes, respectively. These findings in a simple vertebrate model reproducing neuroanatomical and epileptic hallmarks of the human condition represent a novel approach to the study of childhood seizure disorders associated with a single gene mutation 4 WT samples (sample= 10 pooled larvae) and 4 Lis1Morphants slight phenotype (sample= 10 pooled larvae) were collected at 4dpf (days post fertilization). The morphants were selected based on phenotype and seizure behavior. Both groups of fish derived from same pools of eggs
Project description:Inosine 5'-phosphate dehydrogenase (impdh) has been well known as a key enzyme in GTP biosynthesis pathway. We found that three isoforms of impdh in zebrafish, namely impdh1a, impdh1b and impdh2, all show robust circadian expression.To examine the molecular functions of three impdh isoforms in zebrafish on the genome scale, we measured the global expression changes of impdh1a, impdh1b and impdh2 morpholino injected larvae (morphants) respectively using RNA-seq. Wild type (WT), control and three impdh morphants were collected at 32 hpf. In our RNA-seq result, we identified 468, 331 and 1166 significant genes affected by impdh1a, impdh1b and impdh2 morpholino (MO) knock-down respectively. Among them, there are limited overlaps between genes affected by different MOs and only 36 genes in common among all three MOs. This indicates that the three impdh isoforms have distinct molecular functions. Overall design: To knock down the target genes, three impdh MOs and control MO were pressure-injected into 1- to 2-cell stage embryos. WT, control and three impdh morphants were raised at 28°C under 14h: 10h light/dark cycle from birth and sampled simultaneously at 32 hpf. Each group has at least 40 embryos.
Project description:Inosine 5'-phosphate dehydrogenase (impdh) has been well known as a key enzyme in GTP biosynthesis pathway. We found that three isoforms of impdh in zebrafish, namely impdh1a, impdh1b and impdh2, all show robust circadian expression.To examine the molecular functions of three impdh isoforms in zebrafish on the genome scale, we measured the global expression changes of impdh1a, impdh1b and impdh2 morpholino injected larvae (morphants) respectively using RNA-seq. Wild type (WT), control and three impdh morphants were collected at 32 hpf. In our RNA-seq result, we identified 468, 331 and 1166 significant genes affected by impdh1a, impdh1b and impdh2 morpholino (MO) knock-down respectively. Among them, there are limited overlaps between genes affected by different MOs and only 36 genes in common among all three MOs. This indicates that the three impdh isoforms have distinct molecular functions. To knock down the target genes, three impdh MOs and control MO were pressure-injected into 1- to 2-cell stage embryos. WT, control and three impdh morphants were raised at 28°C under 14h: 10h light/dark cycle from birth and sampled simultaneously at 32 hpf. Each group has at least 40 embryos.
Project description:Severe myoclonic epilepsy of infancy (SMEI), or Dravet syndrome (DS), is a catastrophic pediatric epilepsy with severe intellectual disability, impaired social development, and persistent drug-resistant seizures. One of its primary monogenic causes is a mutation in SCN1A (Nav1.1), a type I voltage-gated sodium channel. In mice, Nav1.1 mutation is associated with reduced sodium current, altered interneuron firing, cognitive deficits, autistic-like traits and seizures. Here we describe a larval zebrafish Nav1.1 mutant that recapitulates salient features of the human SCN1A mutation phenotype. Between three and seven days post-fertilization, Nav1.1 mutants exhibit spontaneous abnormal electrographic activity, hyperactivity and convulsive behaviors. Transcriptomic analysis of Nav1.1 mutants was remarkable for the relatively small fraction of genes that were differentially expressed (~2%) and the lack of compensatory changes in expression for other SCN subunits. Pharmacological studies confirmed an antiepileptic action for the ketogenic diet, benzodiazepine, valproate, potassium bromide and stiripentol in Nav1.1 mutants; acetazolamide, phenytoin, ethosuximide had no effect, carbamazepine and vigabatrin made seizures worse. Using this mutant, we screened a chemical library of 320 compounds and identified four compounds that reduced spontaneous seizure-like behavior and one compound (clemizole) that inhibited convulsive behavior and electrographic seizures. Drug-resistant scn1a zebrafish mutants described here represent a new direction in modeling pediatric epilepsy and could be used to identify novel lead compounds for DS patients 4 Control sibling samples (sample= 10 pooled larvae) and 4 Nav1.1 mutants (sample= 10 pooled larvae) were collected at 6 dpf (days post fertilization). The Nav1.1 mutants were selected based on phenotype (dark color).
Project description:Neuronal migration disorders such as lissencephaly and subcortical band heterotopia (SBH) are associated with epilepsy and intellectual disability. Doublecortin (DCX), LIS1 and alpha1-tubulin (TUBA1A), are mutated in these disorders, however corresponding mouse mutants do not show heterotopic neurons in the neocortex. On the other hand, the spontaneously arisen HeCo mouse mutant displays this phenotype. The study of this model reveals novel mechanisms of heterotopia formation. While, HeCo neurons migrate at the same speed as WT, abnormally distributed dividing progenitors were found throughout the cortical wall from E13. Through genetic studies we identified Eml1 as the mutant gene in HeCo mice. No full length transcripts of Eml1 were identified due to a retrotransposon insertion in an intron. Re-expression of Eml1, coding for a microtubule-associated protein, rescues the HeCo progenitor phenotype. We further show that EML1 is mutated in giant ribbon-like heterotopia in human. Our data link abnormal spindle orientations, ectopic progenitors and severe heterotopia in mouse and human. 16 samples analyzed corresponding to 8 wild type brain and 8 HeCo mutant brain
Project description:Acute exposure to acrylamide (ACR), a type-2 alkene, may lead to a ataxia, skeletal muscles weakness and numbness of the extremities in exposed human and laboratory animals. Recently, a zebrafish model for ACR neurotoxicity mimicking most of the pathophysiological processes described in mammalian models, was generated in 8 days post-fertilization larvae. In order to better understand the predictive value of the zebrafish larvae model of acute ACR neurotoxicity, in the present manuscript the ACR acute neurotoxicity has been characterized in the brain of adult zebrafish, and the results compared with those obtained with the whole-larvae. Although qualitative and quantitative analysis of the data shows important differences in the ACR effects between the adult brain and the whole-larvae, the overall effects of ACR in adult zebrafish, including a significant decrease in locomotor activity, altered expression of transcriptional markers of proteins involved in synaptic vesicle cycle, presence of ACR-adducts on cysteine residues of some synaptic proteins, and changes in the profile of some neurotransmitter systems, are similar to those described in the larvae. Thus, these results support the suitability of the zebrafish ACR acute neurotoxicity recently developed in larvae for screening of molecules with therapeutic value to treat this toxic neuropathy.
Project description:Four independent pools of zebrafish embryo were injected with prp2 morphants and after 24 hours post fertilization, gene expression profiles were compared to their respective controls, using microarray. A dye swap design experiment using four microarray slides were conducted.
Project description:For analysis of gene expression changes in the zebrafish larvae heart in response to TCDD exposure, three replicate samples of heart tissue were collected at 73, 74, 76 and 84 hours post fertilization from larvae exposed to 1 ng/ml TCDD or vehicle from 72 - 73 hours post fertilization. For analysis of gene expression changes in the extracardiac tissue in response to TCDD exposure, three replicate samples of zebrafish larvae bodies with the heart tissue removed were collected at 73, 74, 76 and 84 hours post fertilization from larvae exposed to 1 ng/ml TCDD or vehicle from 72 - 73 hours post fertilization.
Project description:Proper cortical development relies on the balance of neuronal migration and proliferation. We investigated the gene expression differences of mouse knock-outs for Lissencephaly in humans. Our analysis suggests that gene expression and pathway analysis in mouse models of a similar disorder or within a common pathway can be used to define novel candidates for related human diseases. We investigated the developing brain of four mutants and wild-type mice using expression microarrays, bioinformatic analyses, and in vivo/in vitro experiments to address whether mutations in different members of the LIS1 neuronal migration complex lead to similar and/or distinct global gene expression alterations.
Project description:This dataset describe the transcriptomic profiling of adult brain, gonades (testis and ovaries) of adult zebrafish exposed to 20µg/L of depleted uranium for 10 days. The progeny of the exposed fishes were also analysed at two-cells stage and 96 hours post fertilization Overall design: Biological samples (adult dissected tissues and whole embryos and larvae) were tested by RNASeq in duplicates
Project description:Proprotein convertase subtilisin/kexin (PCSK) enzymes convert proproteins into bioactive end products. Although other PCSK enzymes are known to be essential for biological processes ranging from cholesterol metabolism to host defense, the in vivo importance of the evolutionarily ancient PCSK7 has remained enigmatic. Here, we quantified the expressions of all pcsk genes during the 1st week of fish development and in several tissues. pcsk7 expression was ubiquitous and evident already during the early development. To compare mammalian and zebrafish PCSK7, we prepared homology models, which demonstrated remarkable structural conservation. When the PCSK7 function in developing larvae was inhibited, we found that PCSK7-deficient fish have defects in various organs, including the brain, eye, and otic vesicle, and these result in mortality within 7 days postfertilization. A genome-wide analysis of PCSK7-dependent gene expression showed that, in addition to developmental processes, several immune system-related pathways are also regulated by PCSK7. Specifically, the PCSK7 contributed to the mRNA expression and proteolytic cleavage of the cytokine TGFβ1a. Consequently, tgfβ1a morphant fish displayed phenotypical similarities with pcsk7 morphants, underscoring the importance of this cytokine in the zebrafish development. Targeting PCSK activity has emerged as a strategy for treating human diseases. Our results suggest that inhibiting PCSK7 might interfere with normal vertebrate development. Gene expressions of zebrafish were measured at 6 and 24 hours post fertilization of the fish samples with PCSK7 blocked with morpholino technology. For each time point, triplicate samples pooled from 18-35 zebrafish embryos were used. Also gene expressions from triplicate control samples were measured.