Curcumin Modulates Molecular Chaperones and Autophagy-Lysosomal Pathways In Vitro after Exposure to Aβ42

Abstract

Accumulation of misfolded amyloid beta proteins (Aβ) and hyper phosphorylated-tau are the key players in the pathologenesis of Alzheimer’s disease (AD). Molecular chaperones (heat shock proteins, HSPs), autophagylysosomal pathways (ALPs), and chaperone-mediated autophagy (CMA) are actively involved in degradation of these aggregates. Dysregulation of these systems has been observed in the AD brain, which demands the maintenance or restoration of these systems. In this context, as an anti-amyloid, curcumin (Cur) has potential role for AD therapy. Becuase of its solubility and bioavailability issues, recently we have used solid lipid curucmin particles (SLCP), which showed great permeability and neuroprotection. In this context, the present study was designed to investigate the role of Cur on HSPs and ALPs, In vitro, after exposure to Aβ42. Human cortical neurons (SH-SY5Y) and mouse neuroblastoma (N2a) cells were exposed with Aβ42 (10 μM) for 24 h and incubated with or without different concentrations of dietary Cur and or SLCP and several markers for HSPs and ALPs were investigated. We found that the most HSPs (HSP90, HSP70, HSP60, HSP40) were downregulated after exposure to Aβ42 and Cur treatment restored their levels. Similarly, markers for CMA, such as HSC70, LAMP2A, CHIP were downregulated by the Aβ42 exposure and Cur and or SLCP treatment restored their levels. In contrast, macroautophagy markers, such as LC3A/B-II and beclin-1 were upregulated after exposure to Aβ42, while Cur and or SLCP treatment further increased their levels. Therefore, maintenance or restoration of HSPs and regulation of ALPs by Cur may provide a promising strategy to degrade Aβ-aggregates from neurons in the AD brain.