p21-activated kinase regulates Rab3a vesicles to repair plasma membrane damage caused by Amyloid-β oligomers

The interaction of amyloid-β (Aβ) peptides with the plasma membrane (PM) is a potential trigger that initiates the formation of higher-order aggregates, membrane alterations/damage, and progressive neurotoxicity in Alzheimer’s disease (AD). In a previous study, we showed that oligomers of Aβ _1-42 (oAβ _1-42 ) induced PM damage, resulting in PM repair cascade via lysosomal exocytosis coupled with endocytosis, and facilitation of tunneling nanotubes (TNTs)-like membrane protrusions to promote direct cell-to-cell transfer of aggregates. In this study, we demonstrated that PM damage induced by oligomers of the aggregation-prone peptide Aβ _1-42 significantly facilitates PM repair by enhancing phosphorylated p21-activated kinase 1 (pPAK1)-dependent endocytosis and Rab3a-dependent exocytosis in SH-SY5Y and SK-N-SH neuronal cells compared to control and oAβ _1-40 treated cells. We studied the kinetics of pPAK1-dependent endocytosis and the fusion of EGFP-Rab3a vesicles near the PM using total internal reflection fluorescence (TIRF) microscopy. IPA-3, a selective non-ATP competitive inhibitor of PAK1, inhibits endocytosis of oAβ peptides and Rab3a-dependent PM repair. Further, shRNA-mediated knockdown of the Rab3a gene inhibits pPAK1 and disrupts PM repair. Repair of damaged PM is a vital protective mechanism for non-proliferative cells like neurons, as disruption in PM repair leads to gradual neuronal cell death. However, there was no explicit understanding of PM repair in response to Aβ oligomers. This study revealed the interconnected action of Rab3a and pPAK1 in PM repair in response to oAβ-mediated damage, and its potential correlation in AD pathogenesis.