miRNA family miR-29 inhibits PINK1-PRKN dependent mitophagy via ATG9A

Area of Science:

• Cellular biology
• Neuroscience
• Genetics

Background:

• Loss-of-function mutations in PINK1 and PRKN cause early-onset Parkinson disease (EOPD).
• The PINK1-PRKN pathway is crucial for eliminating damaged mitochondria via mitophagy, a vital neuroprotective process.
• Identifying novel regulators of this pathway is essential for understanding EOPD pathogenesis.

Purpose of the Study:

• To identify novel regulators of the PINK1-PRKN mitophagy pathway.
• To investigate the role of microRNA 29 (miR-29) family members in mitophagy.
• To explore the functional impact of identified EOPD-associated variants in ATG9A.

Main Methods:

• Genome-wide high-content imaging miRNA screen to identify mitophagy inhibitors.
• RNA sequencing (RNAseq) to identify miR-29 target genes.
• siRNA-mediated knockdown and expression of wild-type and variant ATG9A in cellular models.
• Analysis of rare missense variants in an EOPD cohort.

Main Results:

• The miR-29 family was identified as inhibitors of the PINK1-PRKN mitophagy pathway.
• ATG9A was identified as a direct target of miR-29, and its knockdown phenocopied miR-29 effects on mitophagy.
• Two rare, potentially deleterious missense variants (p.R631W and p.S828L) in ATG9A were found in EOPD patients and behaved as loss-of-function mutations.
• Wild-type ATG9A expression rescued miR-29a-induced mitophagy defects, while EOPD variants did not.

Conclusions:

• miR-29 and its target ATG9A are novel regulators of mitophagy initiation.
• The study provides proof-of-concept for identifying EOPD-linked variants in mitophagy genes.
• Findings are significant for patient stratification and potential therapeutic strategies in EOPD.