BMAL1 in Astrocytes: A Protective Role in Alzheimer’s and Parkinson’s Disease

Abstract

Astrocyte activation is a critical aspect of brain health and disease, and the central circadian clock protein BMAL1 has emerged as a regulator of astrogliosis and inflammatory gene expression. Bmal1 deletion in astrocytes reprograms endolysosomal transcriptional pathways, inducing endocytosis, lysosomal degradation, and autophagic activity. This regulation of proteostasis by BMAL1 implicates circadian clock proteins in neurodegenerative diseases. Studies suggest that astrocyte activation is a complex process with diverse phenotypes beyond classic markers such as GFAP, exhibiting neurotoxic and neuroprotective effects. Deletion of Bmal1 in astrocytes has shown protective effects in models of Alzheimer’s disease (AD) and Parkinson’s disease (PD), influencing Aβ accumulation and α-syn pathology, respectively, through a state of protective astrocyte activation that mitigates tauopathy and α-syn pathology, possibly through the induction of the chaperone protein BAG3. These findings suggest that BMAL1 is crucial in regulating astrocytic function and neuroprotection in neurodegenerative diseases. This review explores the relationship between circadian dysfunction and the development/progression of AD and PD. Furthermore, it recapitulates the most recent findings on manipulating the clock protein BMAL1 and its potential protective effects in astrocytes.