Zebrafish (Danio rerio) as a model for Glucocerebrosidase 1 (GBA1) deficiency (S7.004)

Objectives: To establish and characterise glucocerebrosidase 1 (GBA1) mutant zebrafish line. Background: Homozygous GBA1 mutations (GBA1-/-) cause Gaucher disease (GD), heterozygote GBA1 mutations (GBA+/-) are the most common risk factor for Parkinson’s disease (PD). We previously demonstrated the usefulness of zebrafish (Danio rerio) as a new animal model to study Parkin or PINK1 deficiency. The aim of this project was to now develop a zebrafish model of GBA1 deficiency and study PD-relevant mechanisms. Methods: Genome editing, RT PCR, behavioural analysis, Immunohistochemistry, H/E staining, whole mount in situ hybridisation, biochemical assays. Results: Using TALEN mutagenesis, we successfully generated a mutant zebrafish allele containing a 23 bp deletion. Homozygous mutants (GBA1-/-) developed normally and did not experience dopaminergic (DA) cell loss during development. From 8 week onwards, juvenile GBA1-/- zebrafish became underweight and had impaired balance, leading to “corkscrew” motions. Video tracking revealed a large decrease in spontaneous movements in GBA1-/- compared to WT and an intermediate motor phenotype in GBA1+/-. All homozygous mutants had to be culled at 3 months of age due to the severity of the phenotype. GBA1-/- zebrafish brains accumulated ‘Gaucher like’ cells at 9 weeks post fertilisation, with a further worsening of the pathology by 12 weeks as well as some mild accumulation of “Gaucher-like” cells in GBA+/- zebrafish brains at 12 weeks. There was also loss of DA neurons in GBA-/- at 12 weeks. Established GD biomarkers such as hexosaminidase or chitotriosidase activity were markedly abnormal (p<0.0001). Furthermore, there was marked impairment of mitochondrial respiratory chain activity in GBA-/-. Conclusions: GBA1-/- zebrafish share key biochemical and morphological features with GBA1 knockout mice or indeed human GD. This new vertebrate model system for GBA1 deficiency will be useful to study the interaction between GBA1 haploinsufficiency, alpha-synuclein and exogenous toxins. Study supported by: Parkinson’s UK. Disclosure: Dr. Bandmann has nothing to disclose. Dr. Keatinge has nothing to disclose. Dr. Da Costa has nothing to disclose. Dr. Menke has nothing to disclose. Dr. Chen has nothing to disclose. Dr. Panula has nothing to disclose.