Mitochondrial RNA in Alzheimer's Disease Circulating Extracellular Vesicles

Area of Science:

• Neuroscience
• Biochemistry
• Genetics

Background:

• Alzheimer's disease (AD) is a leading cause of dementia, characterized by amyloid plaques, neurofibrillary tangles, and neuronal loss.
• Early diagnosis and prognostic biomarkers are crucial for effective AD management.
• Circulating extracellular vesicles (EVs) offer a promising avenue for non-invasive "liquid biopsy" biomarkers.

Purpose of the Study:

• To investigate the RNA content of plasma EVs in individuals with varying cognitive statuses.
• To identify potential RNA biomarkers for Alzheimer's disease and mild cognitive impairment.

Main Methods:

• Plasma EVs were isolated from cognitively normal individuals (healthy controls, HC), those with mild cognitive impairment (MCI), and mild AD dementia (AD).
• RNA sequencing was performed to analyze the RNA content of these EVs.
• EVs from cultured neurons, astrocytes, and microglia exposed to AD-relevant toxins were analyzed for mitochondrial components.

Main Results:

• Mitochondrial (mt)-RNAs, including specific mRNAs and non-coding mt-RNAs, were significantly elevated in plasma EVs of MCI and AD individuals compared to HC.
• EVs derived from stressed neuronal, glial, and astrocyte cultures contained mitochondrial structures and RNA/proteins.
• This suggests that mitochondrial damage in the AD brain leads to the release of mt-RNAs via EVs.

Conclusions:

• Elevated mt-RNAs in plasma EVs may serve as diagnostic and prognostic biomarkers for MCI and AD.
• This finding opens new possibilities for non-invasive detection and monitoring of Alzheimer's disease progression.