Deep learning image recognition enables efficient genome editing in zebrafish by automated injections

<div><p>One of the most popular techniques in zebrafish research is microinjection. This is a rapid and efficient way to genetically manipulate early developing embryos, and to introduce microbes, chemical compounds, nanoparticles or tracers at larval stages. Here we demonstrate the development of a machine learning software that allows for microinjection at a trained target site in zebrafish eggs at unprecedented speed. The software is based on the open-source deep-learning library Inception v3. In a first step, the software distinguishes wells containing embryos at one-cell stage from wells to be skipped with an accuracy of 93%. A second step was developed to pinpoint the injection site. Deep learning allows to predict this location on average within 42 μm to manually annotated sites. Using a Graphics Processing Unit (GPU), both steps together take less than 100 milliseconds. We first tested our system by injecting a morpholino into the middle of the yolk and found that the automated injection efficiency is as efficient as manual injection (~ 80%). Next, we tested both CRISPR/Cas9 and DNA construct injections into the zygote and obtained a comparable efficiency to that of an experienced experimentalist. Combined with a higher throughput, this results in a higher yield. Hence, the automated injection of CRISPR/Cas9 will allow high-throughput applications to knock out and knock in relevant genes to study their mechanisms or pathways of interest in diverse areas of biomedical research.</p></div

An archaeal compound as a driver of Parkinson’s disease pathogenesis

Patients with Parkinson’s disease (PD) exhibit differences in their gut microbiomes compared to healthy individuals. Although differences have most commonly been described in the abundances of bacterial taxa, changes to viral and archaeal populations have also been observed. Mechanistic links between gut microbes and PD pathogenesis remain elusive but could involve molecules that promote α-synuclein aggregation. Here, we show that 2-hydroxypyridine (2-HP) represents a key molecule for the pathogenesis of PD. We observe significantly elevated 2-HP levels in faecal samples from patients with PD or its prodrome, idiopathic REM sleep behaviour disorder (iRBD), compared to healthy controls. 2-HP is correlated with the archaeal species Methanobrevibacter smithii and with genes involved in methane metabolism, and it is detectable in isolate cultures of M. smithii. We demonstrate that 2-HP is selectively toxic to transgenic α-synuclein overexpressing yeast and increases α-synuclein aggregation in a yeast model as well as in human induced pluripotent stem cell derived enteric neurons. It also exacerbates PD-related motor symptoms, α-synuclein aggregation, and striatal degeneration when injected intrastriatally in transgenic mice overexpressing human α-synuclein. Our results highlight the effect of an archaeal molecule in relation to the gut-brain axis, which is critical for the diagnosis, prognosis, and treatment of PD.

Modeling CLN3 and ATP13A2 deficiency in yeast and zebrafish and use of the ATP13A2 models for drug repurposing

Neuronal ceroid lipofuscinoses (NCL) are a heterogeneous group of inherited recessive neurodegenerative disorders that appear during childhood and result in premature death. Nowadays, mutations in 14 genes are known to cause NCL and this project focused on CLN3 and ATP13A2 (CLN12), two genes linked to a juvenile form of NCL (JNCL). Mutations in CLN12 are known to cause two additional rare neurodegenerative disorders called Kufor-Rakeb syndrome and spastic paraplegia- 78. Since the number of people affected with a rare disease is relatively small and the cost of the drug development process is high, the chance for a patient to get therapeutic treatment is very low. Therefore, the aim of this PhD project was to develop a new drug screening pipeline for the identification of drug candidates that could be used for the treatment of some of these rare diseases. In this work, we successfully developed a phenotypic high-throughput assay based on a decreased zinc resistance phenotype in an ATP13A2-deficient yeast model and we screened more than 2500 compounds, resulting in the identification of 11 hits. Subsequently, we created a stable ATP13A2 knockout line in zebrafish and developed a validation platform based on decreased manganese resistance in this line. Using this approach, N-acetylcysteine and furaltadone emerged as promising compounds for follow-up studies. A similar strategy could not be implemented for CLN3, due to failure, despite extensive efforts, to find a suitable phenotype in yeast for a drug screening. Nevertheless, we successfully created two stable cln3 mutant lines in zebrafish. No overt phenotype was initially observed, but behavioral tests suggested that cln3 mutants display subtle neurological dysfunction, making them more susceptible to treatment with picrotoxin, a pro-convulsive drug. Further investigation is needed, but our preliminary data indicate that cln3 mutant larvae may recapitulate certain aspects of JNCL pathology. On the whole, this work provides a time- and cost-efficient pipeline for the discovery of drugs against ATP13A2 deficiencies, which can be applied for the screening of larger compound libraries in the future. In addition, we generated a new CLN3 disease model in zebrafish that will be instrumental for the development of drug screens and also may help to elucidate the molecular disease mechanism of JNCL

Phenotypic assays in yeast and zebrafish reveal drugs that rescue ATP13A2 deficiency

Mutations in ATP13A2 (PARK9) are causally linked to the rare neurodegenerative disorders Kufor-Rakeb syndrome, hereditary spastic paraplegia and neuronal ceroid lipofuscinosis. This suggests that ATP13A2, a lysosomal cation-transporting ATPase, plays a crucial role in neuronal cells. The heterogeneity of the clinical spectrum of ATP13A2-associated disorders is not yet well understood and currently these diseases remain without effective treatment. Interestingly, ATP13A2 is widely conserved among eukaryotes, and the yeast model for ATP13A2 deficiency was the first to indicate a role in heavy metal homeostasis, which was later confirmed in human cells. Here we show that deletion of YPK9 (the yeast ortholog of ATP13A2) in Saccharomyces cerevisiae leads to growth impairment in the presence of Zn2+, Mn2+, Co2+ and Ni2+, with the strongest phenotype being observed in the presence of zinc. Using the ypk9 mutant, we developed a high-throughput growth rescue screen based on the Zn2+ sensitivity phenotype. Screening of two drug libraries identified 11 compounds that rescued growth. Subsequently, we generated a zebrafish model for ATP13A2 deficiency and found that both partial and complete loss of atp13a2 function led to increased sensitivity to Mn2+. Based on this phenotype, we validated two of the FDA-approved drugs found in the yeast screen to also exert a rescue effect in zebrafish – N-acetylcysteine, a potent antioxidant, and furaltadone, a nitrofuran antibiotic. This study further supports that combining the high-throughput screening capacity of yeast with rapid in vivo drug testing in zebrafish can represent an efficient drug repurposing strategy in the context of rare inherited disorders involving conserved genes. This work also deepens the understanding of the role of ATP13A2 in heavy metal detoxification and provides a new in vivo model for investigating ATP13A2 deficiency

CLN3 deficiency leads to neurological and metabolic perturbations during early development.

peer reviewedJuvenile neuronal ceroid lipofuscinosis (or Batten disease) is an autosomal recessive, rare neurodegenerative disorder that affects mainly children above the age of 5 yr and is most commonly caused by mutations in the highly conserved CLN3 gene. Here, we generated cln3 morphants and stable mutant lines in zebrafish. Although neither morphant nor mutant cln3 larvae showed any obvious developmental or morphological defects, behavioral phenotyping of the mutant larvae revealed hyposensitivity to abrupt light changes and hypersensitivity to pro-convulsive drugs. Importantly, in-depth metabolomics and lipidomics analyses revealed significant accumulation of several glycerophosphodiesters (GPDs) and cholesteryl esters, and a global decrease in bis(monoacylglycero)phosphate species, two of which (GPDs and bis(monoacylglycero)phosphates) were previously proposed as potential biomarkers for CLN3 disease based on independent studies in other organisms. We could also demonstrate GPD accumulation in human-induced pluripotent stem cell-derived cerebral organoids carrying a pathogenic variant for CLN3 Our models revealed that GPDs accumulate at very early stages of life in the absence of functional CLN3 and highlight glycerophosphoinositol and BMP as promising biomarker candidates for pre-symptomatic CLN3 disease

CLN3 deficiency leads to neurological and metabolic perturbations during early development

AbstractJuvenile Neuronal Ceroid Lipofuscinosis (or Batten disease) is an autosomal recessive, rare neurodegenerative disorder that affects mainly children above the age of 5 years and is most commonly caused by mutations in the highly conservedCLN3gene. Here, we generatedcln3morphants and stable mutant lines in zebrafish. Although neither morphant nor mutantcln3larvae showed any obvious developmental or morphological defects, behavioral phenotyping of the mutant larvae revealed higher basal activity, hyposensitivity to abrupt light changes and hypersensitivity to pro-convulsive drugs. Importantly, in-depth metabolomics and lipidomics analyses revealed significant accumulation of several glycerophosphodiesters (GPDs) and a global decrease of bis(monoacylglycero)phosphate (BMP) species, two classes of molecules previously proposed as potential biomarkers forCLN3disease based on independent studies in other organisms. We could also demonstrate GPD accumulation in human-induced pluripotent stem cell-derived cerebral organoids carrying a pathogenic variant forCLN3. Our models revealed that GPDs accumulate at very early stages of life in the absence of functional CLN3 and highlight glycerophosphoinositol and BMP as promising biomarker candidates for pre-symptomaticCLN3disease

An archaeal compound as a driver of Parkinson’s disease pathogenesis

Patients with Parkinson’s disease (PD) exhibit differences in their gut microbiomes compared to healthy individuals. Although differences have most commonly been described in the abundances of bacterial taxa, changes to viral and archaeal populations have also been observed. Mechanistic links between gut microbes and PD pathogenesis remain elusive but could involve molecules that promote α-synuclein aggregation. Here, we show that 2-hydroxypyridine (2-HP) represents a key molecule for the pathogenesis of PD. We observe significantly elevated 2-HP levels in faecal samples from patients with PD or its prodrome, idiopathic REM sleep behaviour disorder (iRBD), compared to healthy controls. 2-HP is correlated with the archaeal species Methanobrevibacter smithii and with genes involved in methane metabolism, and it is detectable in isolate cultures of M. smithii. We demonstrate that 2-HP is selectively toxic to transgenic α-synuclein overexpressing yeast and increases α-synuclein aggregation in a yeast model as well as in human induced pluripotent stem cell derived enteric neurons. It also exacerbates PD-related motor symptoms, α-synuclein aggregation, and striatal degeneration when injected intrastriatally in transgenic mice overexpressing human α-synuclein. Our results highlight the effect of an archaeal molecule in relation to the gut-brain axis, which is critical for the diagnosis, prognosis, and treatment of PD