Protective role of Bre1 in mitochondrial function and energy metabolism in Drosophila models of Parkinson's disease

Abstract

Background

The second most common cause of autosomal recessive early-onset Parkinson's disease (PD) can be attributed to mutations in the PINK1 gene, malfunction of the mitochondria is the key pathological mechanism. Bre1 encodes an E3 ubiquitin ligase, with the discovery of Bre1's role in repairing mitochondrial damage, further investigation into its implications for PD is warranted.

Methods

We used the PINK1^B9 drosophila melanogaster as the PD model. The effects of Bre1 on PD phenotypes were evaluated based on the morphology of the wings and dorsal region, as well as flight ability. Immunostaining of dopaminergic neurons was used to examine neurodegeneration. Transcriptomes were used to detect the pathway directly involved. Mitochondrial structure and function were observed using electron microscopy, ATP detection, and an oxygen consumption assay. The detection of SOD activity and ROS were used to explicit the effects of Bre1 on oxidative stress. To identify the effects of Bre1 on glycolysis and tricarboxylic acid (TCA) cycle, we performed Western Blot and RT-PCR.

Results

We discovered that Bre1 overexpression significantly improved the phenotype of PD flies and protected their dopaminergic neurons from degeneration. More significantly, we observed that the overexpression of Bre1 markedly enhanced the respiratory capacity of mitochondrial Complex I and Complex II, elevated ATP levels, reduced ROS levels, and improved mitochondrial structural integrity. The Western Blot results demonstrate a significant increase in the critical glycolysis enzymes, Pfk and Pyk proteins. Moreover, qRT-PCR results showed a remarkably upregulation in the transcriptional level of OGDH, a critical rate-limiting enzyme in the TCA cycle. Therefore, our study suggests that Bre1 improves the phenotypes of PD model flies by attenuating mitochondrial damage and enhancing energy metabolism, offering a potential drug target for ameliorating the symptoms of PINK1 mutant autosomal recessive PD patients.