Reticulon-3

Reticulon-3 (RTN3) is a 1,032-amino-acid endoplasmic reticulum (ER)-resident protein involved in membrane trafficking and ER tubule biogenesis (UniProt: O95197). The protein inhibits BACE1 activity and amyloid precursor protein processing, suggesting a protective role against amyloidogenic pathways. RTN3 also functions as an inflammation-resolving regulator by suppressing RIG-I signaling, thereby limiting IRF3 and NF-κB activation during innate immune responses.

In the brain, RTN3 participates in ER stress responses and apoptotic regulation, including caspase-8 cascade activation and BCL2 translocation to mitochondria. These functions position RTN3 within neuroprotective ER quality-control and cell-death pathways relevant to neurodegenerative processes.

RTN3 shows decreased abundance in Alzheimer's disease brain tissue compared to age-matched controls (mean log2 fold-change: −0.49; Chaparral AD proteomics). This downregulation in post-mortem AD brain tissue suggests that loss of RTN3-mediated BACE1 inhibition and inflammation resolution may contribute to AD pathology, though the modest magnitude of change indicates context-dependent or region-specific effects across the measured subcellular fractions.