PINK1 Deficiency Aggravates the β-amyloid-attenuated Mitophagy-lysosomal Degradation in PC12 Cells

Abstract

PTEN-induced putative kinase 1 (PINK1) is a mitochondrial kinase that regulates mitophagy. PINK1-deficient mAPP mice display low LC3B levels, and PINK1 overexpression enhances autophagy and increases the expression level of lysosome-associated membrane protein 1 (LAMP1). The present study evaluated whether altered PINK1 expression could modulate β-amyloid (Aβ)-treated mitophagy in PC12 cells, a simple cellular model to simulate pathological changes in neurodegenerative diseases in vitro.

PC12 cells were transfected with PINK1 siRNA for 48 h, and then incubated with 20 μM Aβ_25–35 for 24 h. The relevant protein expression was determined by immunofluorescence, immunoelectron microscopy, and Western blot. Mitochondrial membrane potential (MMP) was tested by JC-1-based confocal fluorescent imaging.

Following Aβ_25–35 treatment, PINK1 silencing significantly decreased the levels of LC3B, Parkin, and LAMP1 as well as Parkin in mitochondria, p62 degradation, but increased OPTN and Parkin expression in PC12 cells, relative to that of the control PC12 cells. Furthermore, PINK1 silencing decreased MMP in PC12 cells.

PINK1 deficiency deteriorated the blockade of the Aβ_25–35-induced mitophagy-lysosome pathway in PC12 cells. Aβ-treated PC12 cells might be a valuable cellular model to evaluate PINK1-mediated mitophagy and bioactive compound screening.