Opalin

Opalin (OPALIN) is a central nervous system-specific myelin protein that promotes oligodendrocyte differentiation and increases expression of myelin genes during terminal differentiation of oligodendrocytes (UniProt: Q96PE5). The protein is involved in myelin formation and maintenance, representing a key factor in the myelination process essential for proper neuronal function.

In Alzheimer's Disease, opalin shows reduced abundance in post-mortem AD brain tissue compared to age-matched controls across human brain subcellular fractions (Chaparral AD proteomics). The mean log2 fold-change is −0.5735, indicating consistent downregulation. This reduction was measured in TMT-labeled, data-dependent acquisition proteomics across four subcellular fractions from AD and control samples.

The downregulation of opalin in AD brain suggests impaired oligodendrocyte function or myelin integrity in the disease state. Since opalin is critical for promoting oligodendrocyte differentiation and myelin gene expression, its decreased levels may contribute to white matter changes and myelin dysfunction observed in Alzheimer's pathology.