Protein misfolding, aggregation, and aberrant aggregate accumulation play a central role in neurodegenerative disease progression. The proteotoxic factors also govern the aging process to a large extent. Molecular chaperones modulate proteostasis and thereby impact aberrant-protein-induced proteotoxicity. These chaperones have a diverse functional spectrum, including nascent protein folding, misfolded protein sequestration, refolding, or degradation. Small heat shock proteins (sHsps) possess an ATP-independent chaperone-like activity that prevents protein aggregation by keeping target proteins in a folding-competent state to be refolded by ATP-dependent chaperones. Due to their near-universal upregulation and presence in sites of proteotoxic stress like diseased brains, sHsps were considered pathological. However, gene knockdown and overexpression studies have established their protective functions. This review provides an updated overview of the sHsp role in protein aggregation amelioration and highlights evidence for sHsp modulation of neurodegenerative disease-related protein aggregation and aging.

Heat stroke is among the most hazardous hyperthermia-related illnesses and an emerging threat to humans from climate change. Acute brain injury and long-lasting brain damage are the hallmarks of this condition. Hyperthermic neurological manifestations are remarkable for their damage correlation with stress amplitude and long-term persistence. Hyperthermia-induced protein unfolding, and nonspecific aggregation accumulation have neurotoxic effects and contribute to the pathogenesis of brain damage in heat stroke. Therefore, we generated heat-induced, dose-responsive extreme and mild proteotoxic stress models in medulloblastoma [Daoy] and neuroblastoma [SH-SY5Y] and differentiated SH-SY5Y neuronal cells. We show that heat-induced protein aggregation is associated with reduced cell proliferation and viability. Higher protein aggregation in differentiated neurons than in neuroblastoma precursors suggests a differential neuronal vulnerability to heat. We characterized the neuronal heat shock response through RT-PCR array analysis of eighty-four genes involved in protein folding and protein quality control (PQC). We identify seventeen significantly expressed genes, five of which are Hsp70 chaperones, and four of their known complementing function proteins. Protein expression analysis determined the individual differential contribution of the five Hsp70 chaperones to the proteotoxic stress response and the significance of only two members under mild conditions. The co-expression analysis reveals significantly high co-expression between the Hsp70 chaperones and their interacting partners. The findings of this study lend support to the hypothesis that hyperthermia-induced proteotoxicity may underlie the brain injury of heat stroke. Additionally, this study presents a comprehensive map of the Hsp70 network in these models with potential clinical and translational implications.

Artemisia sieberi Besser (A. sieberi) has shown promise as a natural source of safe cytotoxic agents for breast cancer therapy. However, its effects on triple-negative breast cancer (TNBC), a very aggressive subtype lacking targeted treatments, remain poorly studied. This study evaluates the anticancer activity of A. sieberi extracts against the MDA-MB-231 TNBC cell line, comparing results with hormone receptor-positive MCF-7 cells. Aerial parts of A. sieberi were extracted using ethanol and methanol and then chemically characterized via gas chromatography/mass spectrometry (GC/MS) to identify bioactive compounds. Cytotoxic effects were assessed using cell viability assays, while apoptosis induction was examined through flow cytometry (Annexin V/propidium iodide staining), caspase-3/-7 activation assays, and mitochondrial membrane permeabilization visualized using confocal microscopy. Western blotting analyzed the expression levels of apoptotic proteins. In silico molecular docking simulations explored the interactions between phytochemicals and apoptosis-regulating proteins. A. sieberi extracts exhibited higher cytotoxicity against MDA-MB-231 cells than against MCF-7 cells, with lower IC₅₀ values. Treatment of TNBC cells induced apoptosis, evidenced by increased caspase activity, mitochondrial membrane permeabilization, elevated Bax, and decreased Bcl-2 expression. Additionally, colony formation assays demonstrated a significant reduction in tumorigenic potential. Computational analyses indicate that β-sitosterol and stigmasterol, among the main compounds, exhibited strong interactions with apoptosis regulators by docking with Bcl-2, supporting their promising anticancer potential. A. sieberi extracts induce potent apoptosis and exert anti-tumour effects in TNBC cells, highlighting their potential as sources of novel anticancer agents. Further isolation and characterization of active constituents are warranted for therapeutic development. Graphical abstract