PDIA6 (Protein Disulfide Isomerase Family A Member 6), also known as P5 or ERP5, is a chaperone protein residing primarily in the endoplasmic reticulum (ER). PDIA6 plays crucial roles in protein folding, ER redox homeostasis, and the unfolded protein response (UPR). Given the central role of ER stress in neurodegenerative diseases, PDIA6 has emerged as a significant player in Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS).
PDIA6 contains thioredoxin-like domains that facilitate disulfide bond formation and isomerization during protein folding. Unlike other PDI family members, PDIA6 has a flexible substrate-binding pocket and exhibits broad specificity. [1]
In AD, PDIA6 exerts protective effects through 1: [2]
ER Chaperone Function: PDIA6 helps fold amyloid precursor protein (APP) and potentially reduces amyloid-beta (Aβ) aggregation.
Redox Homeostasis: By maintaining ER redox balance, PDIA6 protects neurons from oxidative stress, a key contributor to AD pathogenesis.
UPR Modulation: PDIA6 regulates the PERK-eIF2α pathway, influencing tau (tau protein) phosphorylation.
PDIA6 is implicated in PD through 2: [3]
Alpha-Synuclein Folding: PDIA6 may assist in proper folding of alpha-synuclein (α-syn), reducing aggregation.
ER Stress Response: PDIA6 levels increase in PD brains, reflecting adaptive UPR activation.
Mitochondrial Function: PDIA6 interacts with mitochondrial proteins, protecting dopaminergic neurons.
In ALS, PDIA6 3:
PDIA6 is ubiquitously expressed with high levels in:
PDIA6 is a promising therapeutic target: