Moesin

Moesin (MSN) is an ezrin-radixin-moesin (ERM) family protein that serves as a critical linker between the actin cytoskeleton and plasma membrane (UniProt: P26038). Through phosphorylation-dependent activation, moesin oscillates between inactive and active states, enabling transient interactions with F-actin that drive cytoskeletal rearrangement. This function regulates diverse cellular processes including cell shape, membrane transport, and signal transduction, with particularly important roles in lymphocyte homeostasis, immune tolerance, and immunologic synapse formation (UniProt: P26038).

Moesin is broadly expressed and functions in immune cell biology; mutations in MSN cause immunodeficiency 50 (IMD50), a primary immunodeficiency disorder with early-onset infections and profound lymphopenia (UniProt: P26038).

In Alzheimer's disease, moesin shows disease-relevant upregulation in post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change of +0.97 across examined subcellular fractions (Chaparral AD proteomics). This elevation suggests a potential involvement in AD pathophysiology, possibly relating to cytoskeletal dysfunction or neuroinflammatory processes characteristic of the disease.