Endoplasmic Reticulum Proteins Impact Penetrance in a <i>Pink1</i>-Mutant <i>Drosophila</i> Model

Parkinson&rsquo;s disease (PD) is a neurodegenerative disorder with a high variability of age at onset, disease severity, and progression. This suggests that other factors, including genetic, environ-mental, or biological factors, are at play in PD. Loss of PINK1 causes a recessive form of PD and is typically fully penetrant; however, it features a wide range in disease onset, further supporting the existence of protective factors, endogenous or exogenous, to play a role. Loss of Pink1 in Drosophila melanogaster results in locomotion deficits, which are also observed in PINK1-related PD in humans. In flies, Pink1 deficiency induces defects in the ability to fly; none-theless, around ten percent of the mutant flies are still capable of flying, indicating that advanta-geous factors affecting penetrance also exist in flies. Here, we aimed to identify the mechanisms underlying this reduced penetrance in Pink1-deficient flies. We performed genetic screening in pink1-mutant flies to identify RNA expression alterations affecting the flying ability. The most important biological processes involved were transcription-al and translational activities, endoplasmic reticulum (ER) regulation, and flagellated movement and microtubule organization. We validated 2 ER-related proteins, zonda and windbeutel, to positively affect the flying ability of Pink1-deficient flies. Thus, our data suggest that these pro-cesses are involved in the reduced penetrance and that influencing them may be beneficial for Pink1 deficiency.