Glucocorticoids regulate small extracellular vesicle (sEV) release via activation of nSMase2

Chronic stress, marked by prolonged elevation of glucocorticoid (GC) stress hormones, is a major risk factor for Alzheimers disease (AD) and accelerates AD pathology in mouse models. A key mechanism contributing to AD progression is the release of small extracellular vesicles (sEVs) carrying pathogenic proteins (e.g., tau, amyloid-beta) between brain regions, but the role of GCs in sEV biogenesis and release is unknown. Using total internal reflection fluorescence (TIRF) microscopy and the pH-sensitive marker mCh-CD63-pHluorin to visualize sEV release, we show that GCs stimulate sEV secretion in a neuronal cell line. This process requires the GTPase Rab27a and the enzyme neutral sphingomyelinase 2 (nSMase2), which catalyzes ceramide production and drives sEV formation. We further demonstrate that GCs promote sEV release by activating nSMase2 downstream of mitochondrial reactive oxygen species production and opening of the mitochondrial permeability transition pore (mPTP). These findings link GC-induced mitochondrial damage, specifically mPTP opening, to nSMase2 activation and enhanced sEV release by neuronal cells. SummaryThis study reveals a mechanism by which glucocorticoid stress hormones promote extracellular vesicle release from neuronal cells by activating the enzyme neutral sphingomyelinase 2. These findings provide a possible explanation for how stress accelerates the spread of Alzheimers pathology in the brain. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/680983v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1056e33org.highwire.dtl.DTLVardef@185dbecorg.highwire.dtl.DTLVardef@1296bf0org.highwire.dtl.DTLVardef@6d9086_HPS_FORMAT_FIGEXP M_FIG C_FIG