The presenilin-associated rhomboid-like (
PARL) gene was found to contribute to mitochondrial morphology and function and was linked to familial Parkinson’s disease (PD). The 
PARL gene product is a mitochondrial intramembrane cleaving protease that acts on a number of mitochondrial proteins involved
            
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            The presenilin-associated rhomboid-like (
PARL) gene was found to contribute to mitochondrial morphology and function and was linked to familial Parkinson’s disease (PD). The 
PARL gene product is a mitochondrial intramembrane cleaving protease that acts on a number of mitochondrial proteins involved in mitochondrial morphology, apoptosis, and mitophagy. To date, functional and genetic studies of 
PARL have been mainly performed in mammals. However, little is known about 
PARL function and its role in dopaminergic (DA) neuron development in vertebrates. The zebrafish genome comprises two 
PARL paralogs: 
parla and 
parlb. Here, we established a loss-of-function mutation in 
parla via CRISPR/Cas9-mediated mutagenesis. We examined DA neuron numbers in the adult brain and expression of genes associated with DA neuron function in larvae and adults. We show that loss of 
parla function results in loss of DA neurons, mainly in the olfactory bulb. Changes in the levels of 
tyrosine hydroxylase transcripts supported this neuronal loss. Expression of 
fis1, a gene involved in mitochondrial fission, was increased in 
parla mutants. Finally, we showed that loss of 
parla function translates into impaired olfaction and altered locomotion parameters. These results suggest a role for 
parla in the development and/or maintenance of DA neuron function in zebrafish.
            
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