Findings indicate that zinc-mediated lysosomal activation by 1H10 enhances the autophagy-lysosomal pathway and attenuates tau pathology in AD models, suggesting that targeting lysosomal function may represent a potential therapeutic strategy for neurodegenerative disorders characterized by impaired proteostasis.
Abstract
Impaired autophagic flux and lysosomal dysfunction contribute critically to the accumulation of pathological protein aggregates in Alzheimer's disease (AD). Emerging evidence suggests that intracellular zinc dynamics regulate lysosomal function by modulating processes such as acidification and lysosomal biogenesis. We previously identified 1H10 as an AMP-activated protein kinase (AMPK) inhibitor and subsequently demonstrated its zinc-binding capacity and ability to regulate intracellular zinc homeostasis. Building on our prior findings that intra-lysosomal zinc promotes acidification and activates transcription factor EB (TFEB), we investigated whether 1H10 enhances lysosomal function through zinc mobilization in neurons, thereby improving autophagy and reducing pathological protein accumulation. In primary cortical neurons, 1H10 increased lysosomal abundance and enhanced lysosomal degradative capacity in a zinc-dependent manner, as demonstrated by increased cathepsin B activity and DQ-BSA degradation. It alleviated lysosomal dysfunction induced by v-ATPase inhibition and promoted autophagic flux, leading to reduced accumulation of amyloid-β (Aβ) and tau in neuronal models. In 5XFAD mice, 1H10 treatment showed trends toward improved spatial learning in the Morris water maze, reduced tau phosphorylation at Thr205 and Ser214, normalized LC3-II levels, and restored autophagic-lysosomal homeostasis, without significant changes in extracellular amyloid plaque burden. These findings indicate that zinc-mediated lysosomal activation by 1H10 enhances the autophagy-lysosomal pathway and attenuates tau pathology in AD models, suggesting that targeting lysosomal function may represent a potential therapeutic strategy for neurodegenerative disorders characterized by impaired proteostasis.
The autophagy–lysosomal pathway is key for the removal of harmful substances in cells. This article integrates evidence that highlights the role of lysosomal function and the autophagy–lysosomal pathway in maintaining intracellular homeostasis and the effects of their dysfunction on protein secretion and metabolic disorders, leading to the pathogenesis of Alzheimer's disease (AD) and other tau diseases. Dysfunction of the autophagy-lysosomal pathway is believed to be the main factor leading to the accumulation of amyloid-β and tau proteins, which are also pathological features of AD. This article also discusses why autophagy is indispensable in the early to mature stages of neuronal development and how damage to the function of autophagy can cause neurodevelopmental abnormalities and neurodegenerative diseases. We also summarized the potential role of oligodendrocytes. We believe that its relationship with lysosomes can provide a new perspective and research direction for future research on neurodegenerative diseases. Autophagy-lysosomal pathway damage is considered to be a key factor in the pathology and diagnosis of multiple sclerosis, but we believe that the challenge associated with its transformation into clinical treatment is enormous. These findings suggest that enhancing or improving autophagy function may be an effective treatment method to alleviate the condition of AD patients, which can provide new strategies for clinical treatment and intervention of AD in the future.
Kun Lu, Yirui Lu, Runyu Tang et al.· Journal of Alzheimer's Disea...· 0 citations
Astrocytes are among the earliest cells to exhibit dysfunction in Alzheimer’s disease (AD), developing profound calcium signalling deficits before amyloid plaques have formed, yet the underlying mechanisms remain unknown. Lysosomal dysfunction is a hallmark of AD, but whether it initiates this early functional impairment or arises as a consequence of established pathology remains unresolved. Here, we find that astrocytic cytosolic calcium activity is suppressed prior to amyloid plaque deposition and is accompanied by reduced lysosomal acidification in vivo. Using a lysosome-targeted calcium indicator selectively expressed in astrocytes, we directly visualise lysosomal calcium dynamics in vivo and reveal a profound early loss of lysosomal calcium release, identifying lysosomal failure as an initiating event in astrocyte dysfunction in AD. Reduced expression of the lysosomal calcium channel TRPML1 provides the mechanistic basis for this deficit. Astrocyte-specific restoration of TRPML1 expression rescues lysosomal homeostasis and cytosolic calcium signalling and prevents astrocyte reactivity and morphological hypertrophy. Strikingly, early TRPML1 restoration prevents both the initial calcium hypoactivity observed before plaque formation and the later hyperactivity that characterises post-plaque disease, demonstrating that lysosomal calcium homeostasis stabilises astrocyte function across the disease trajectory. TRPML1 restoration also reduces amyloid plaque burden, indicating that astrocytic lysosomal competence directly shapes disease pathology. These findings identify lysosomal calcium failure as an early organelle-level mechanism linking amyloid stress to astrocyte dysfunction in AD, and position TRPML1-mediated lysosomal calcium signalling as a tractable target for limiting disease progression.
D. shah, P. Desai, C. Chertavian et al.· bioRxiv· 0 citations
Chloride is the most abundant anion within lysosomes and plays a pivotal role in regulating lysosomal physiology and function. However, the mechanisms governing lysosomal chloride homeostasis remain largely elusive. Here, we identified TTYH3 as a regulator of lysosomal chloride permeability. TTYH3 mediates chloride efflux from the lysosomal lumen and enhances TRPML1-mediated lysosomal calcium release. Overexpression of TTYH3 results in markedly enlarged lysosomes by promoting lysosomal fusion via the Ca2+/CaM and HSP90 pathways. Moreover, TTYH3 enhances autophagy by inhibiting the AKT/mTOR signaling pathway and alleviates cellular senescence via activation of the ERK pathway. Notably, TTYH3 expression mitigates cellular phenotypes associated with lysosomal storage diseases caused by deficiencies in another lysosomal chloride channel CLN7. Collectively, our findings demonstrate that TTYH3 mediates a lysosomal chloride conductance and regulates lysosomal physiology and autophagy, and may serve as a potential therapeutic target for interventions in aging and lysosome-related diseases.
Huntington disease (HD) is a progressive neurodegenerative disease caused by an expanded CAG repeat in the HTT (huntingtin) gene, leading to the accumulation of mutant HTT (mHTT). IL17A (interleukin 17A), a proinflammatory cytokine primarily secreted by Th17 and γδ T cells, has been implicated in immune-mediated neurodegeneration. However, the role of IL17A in the pathogenesis of HD remains poorly understood. Here, we identify IL17A as a critical pathogenic factor in HD that promotes neuroinflammation, mHTT aggregation, and autophagy-lysosomal dysfunction. IL17A disrupts autophagic flux by downregulating CTSB and CTSD, inducing SQSTM1/p62 and MAP1LC3B-II/LC3-II accumulation, and impairing lysosomal reformation. Mechanistically, IL17A suppresses lysosomal biogenesis by inhibiting the nuclear translocation of TFE3. This regulation occurs via a novel GSK3B/GSK-3β-TFE3 signaling pathway. Therapeutic neutralization of IL17A with a monoclonal antibody (IL17A mAb) ameliorates disease phenotypes in R6/2 HD mice, improving motor performance, extending survival, and reducing gliosis. IL17A mAb also attenuates mHTT aggregation and enhances neuroprotective signaling, as evidenced by increased expression of DLG4/PSD-95, phosphorylated CREB1, and BDNF. Moreover, IL17A mAb restores autophagy-lysosomal function by facilitating the clearance of protein aggregates and upregulating lysosomal enzymes and biogenesis markers, including CTSB, CTSD, PIP5K1A, and LAMP2. These findings establish IL17A as a key modulator of HD pathophysiology and highlight IL17A inhibition as a promising therapeutic strategy for targeting autophagy-lysosomal dysfunction in HD.
