PRDX4 (Peroxiredoxin 4) is a member of the peroxiredoxin family of antioxidant enzymes that catalyze the reduction of hydrogen peroxide, organic hydroperoxides, and peroxynitrite[@rhee2020]. Unlike cytosolic peroxiredoxins, PRDX4 is localized primarily to the endoplasmic reticulum (ER) and is secreted via the conventional secretory pathway[@tavender2008]. This unique subcellular localization positions PRDX4 as a critical regulator of ER redox homeostasis and extracellular oxidative stress.
Function
PRDX4 functions as a thiol-dependent peroxidase using a conserved cysteine residue (Cys^157) at its active site to reduce peroxides[@park2000]. The enzyme exhibits the following key functions:
ER Redox Homeostasis: Maintains the ER lumen in a reduced state necessary for proper protein folding
Peroxide Detoxification: Catalyzes reduction of H₂O₂ to water, preventing oxidative damage to proteins and lipids
Chaperone Activity: Exhibits chaperone-like properties under oxidative stress conditions
Inflammatory Modulation: Regulates [NF-κB](/entities/nf-kb) signaling and inflammatory responses through peroxide scavenging[@jin2013]
Disease Associations
Alzheimer's Disease
PRDX4 is significantly downregulated in AD brains, particularly in the hippocampus and cerebral cortex[@kim2009]. Loss of PRDX4 leads to increased oxidative stress, protein oxidation, and acceleration of amyloid-β pathology. Studies show that PRDX4 overexpression protects against [Aβ](/proteins/amyloid-beta)-induced neurotoxicity in cellular models[@luo2016].
Parkinson's Disease
In PD models, PRDX4 protects dopaminergic [neurons](/entities/neurons) from oxidative stress-induced cell death[@zhang2020]. The enzyme is implicated in maintaining mitochondrial function and preventing mitochondrial permeability transition.
Amyotrophic Lateral Sclerosis
PRDX4 expression is altered in ALS and may play a protective role against oxidative damage in motor neurons[@arai2010].
Expression Pattern
PRDX4 shows high expression in:
Cerebral cortex
Hippocampus (CA1-CA3 regions)
Liver and kidney (highest expression)
Pancreas
Lower expression in cerebellum and brainstem
Therapeutic Implications
Recombinant PRDX4: Being explored as a neuroprotective agent
Small Molecule Activators: Compounds that upregulate PRDX4 expression