Unfolded proteins and aggregates: The role of proteostasis in pseudoexfoliation pathology

Proteostasis impairment is central to cellular dysfunction in protein aggregation disorders such as Alzheimer disease, Parkinson disease, and age-related macular degeneration. Pseudoexfoliation (PEX), a systemic age-related disorder and a leading cause of secondary glaucoma, is increasingly recognized as a protein aggregation disease. It is characterized by the deposition of pseudoexfoliative material (PEXM) in ocular tissues, leading to elevated intraocular pressure and optic neuropathy.

This review synthesizes current evidence on the role of proteostasis failure in PEX pathogenesis, with a focus on molecular mechanisms, stress response pathways, and potential therapeutic interventions.

We conducted a comprehensive literature review of studies examining proteostasis mechanisms in PEX. Emphasis was placed on cellular pathways regulating protein synthesis, folding, and degradation, including the unfolded protein response (UPR), ubiquitin-proteasome system (UPS), and autophagy, as well as environmental and aging-related triggers of proteotoxic stress.

Evidence indicates that chronic proteotoxic stress, arising from aging, oxidative damage, and environmental influences, disrupts the proteostasis network (PN). Dysregulation of ER stress signaling, cytosolic stress responses, and protein degradation pathways contributes to the accumulation of misfolded proteins and extracellular matrix deposits in ocular tissues. These molecular alterations underlie disease onset and progression in PEX syndrome (PEXS) and PEX glaucoma (PEXG).

Proteostasis dysfunction plays a pivotal role in PEX pathogenesis by promoting protein misfolding, aggregation, and extracellular deposition. Targeting the proteostasis network, through modulation of stress responses and enhancement of degradation pathways, represents a promising therapeutic strategy for PEXS and PEXG.