Insights Into the Role of Heat Shock Protein 27 in the Development of Neurodegeneration

Targeting WDPF domain of Hsp27 achieves a broad spectrum of antiviral

Enterovirus A71 (EV-A71) is a positive-sense single-stranded RNA virus, which hijacks host proteins to benefit viral internal ribosome entry site (IRES)-dependent protein translation and further propagation. We demonstrated that serine 78 (S78) phosphorylation of Hsp27 is critical for Hsp27/hnRNP A1 relocalization upon EV-A71 infection. Here, we report that the deletion of WDPF and ACD domains disturbs subcellular localization of Hsp27, resulting in partial nuclear translocation. The domain deletion-induced Hsp27 nuclear translocation fails to direct hnRNP A1 translocation. The 2Apro-induced IRES activity and viral replication are suppressed by the deletion of WDPF or ACD domain. Surprisingly, a peptide (WDPF) dramatically inhibits S78 phosphorylation. Therefore, hnRNP A1 translocation, viral IRES activity, and viral protein translation and propagation are all strongly suppressed by the WDPF peptide, but not by peptide without WDPFR sequence (ΔWDPF). Moreover, the WDPF peptide also has potent antiviral activity on other RNA virus (e.g., coronavirus HCoV-OC43) and DNA virus (e.g., HSV-1 and HBV). Peptide treatment with kinase inhibitor Sorafenib brings an additional inhibitory effect on HCoV-OC43 and HSV-1. Taken together, we uncover a crucial role of WDPF domain in S78 phosphorylation for EV-A71-induced hnRNP A1 nuclear translocation, IRES-dependent viral protein translation, and EV-A71 propagation. Our results explore a new path for target-based pan-antiviral strategy.

Human Plasma‐Derived Extracellular Vesicles Protect Against Cerebral Ischemia‐Reperfusion Injury via HSP27 Phosphorylation

Ischemic stroke (IS) has become a serious public health problem, with patients undergoing endovascular treatment experiencing ischemia‐reperfusion (I/R) injury, which exacerbates cerebrovascular diseases. Circulating extracellular vesicles (EVs) have shown potential for treating cerebral I/R injury. In this study, the therapeutic effect of human plasma‐derived EVs and protective mechanisms in cerebral I/R injury is explored. An oxygen‐glucose deprivation/reperfusion (OGD/R) model is used to treat SH‐SY5Y cells in vitro, and an I/R injury model is constructed by transient middle cerebral artery occlusion (tMCAO) in mice. Human plasma‐derived EVs are extracted by size exclusion chromatography. Western blot, Immunofluorescence Staining, and 2,3,5‐Triphenyltetrazolium Chloride (TTC) Staining are employed to observe the effects of EVs on the neuroinflammatory response and infarct volumes in tMCAO mice, while TUNEL Staining, Flow Cytometry, and Western Blot are employed to assess cell apoptosis. Human plasma‐derived EVs alleviated apoptosis in SH‐SY5Y cells under OGD/R stress and exerted a protective effect against brain I/R injury in tMCAO mice. Mechanistically, EVs protected against cerebral I/R injury via HSP27 phosphorylation, and the HSP27 phosphorylation inhibitor KRIBB3 attenuated the anti‐apoptotic effects of EVs. Human plasma‐derived EVs activated the phosphorylation of HSP27, thereby inhibiting cell apoptosis and protecting against cerebral I/R injury.

Mechanistic insights into heat shock protein 27, a potential therapeutic target for cardiovascular diseases

Heat shock protein 27 (HSP27) is a small chaperone protein that is overexpressed in a variety of cellular stress states. It is involved in regulating proteostasis and protecting cells from multiple sources of stress injury by stabilizing protein conformation and promoting the refolding of misfolded proteins. Previous studies have confirmed that HSP27 is involved in the development of cardiovascular diseases and plays an important regulatory role in this process. Herein, we comprehensively and systematically summarize the involvement of HSP27 and its phosphorylated form in pathophysiological processes, including oxidative stress, inflammatory responses, and apoptosis, and further explore the potential mechanisms and possible roles of HSP27 in the diagnosis and treatment of cardiovascular diseases. Targeting HSP27 is a promising future strategy for the treatment of cardiovascular diseases.

A Charcot-Marie-Tooth-Causing Mutation in HSPB1 Decreases Cell Adaptation to Repeated Stress by Disrupting Autophagic Clearance of Misfolded Proteins

Charcot-Marie-Tooth (CMT) disease is the most common inherited neurodegenerative disorder with selective degeneration of peripheral nerves. Despite advances in identifying CMT-causing genes, the underlying molecular mechanism, particularly of selective degeneration of peripheral neurons remains to be elucidated. Since peripheral neurons are sensitive to multiple stresses, we hypothesized that daily repeated stress might be an essential contributor to the selective degeneration of peripheral neurons induced by CMT-causing mutations. Here, we mainly focused on the biological effects of the dominant missense mutation (S135F) in the 27-kDa small heat-shock protein HSPB1 under repeated heat shock. HSPB1S135F presented hyperactive binding to both α-tubulin and acetylated α-tubulin during repeated heat shock when compared with the wild type. The aberrant interactions with tubulin prevented microtubule-based transport of heat shock-induced misfolded proteins for the formation of perinuclear aggresomes. Furthermore, the transport of autophagosomes along microtubules was also blocked. These results indicate that the autophagy pathway was disrupted, leading to an accumulation of ubiquitinated protein aggregates and a significant decrease in cell adaptation to repeated stress. Our findings provide novel insights into the molecular mechanisms of HSPB1S135F-induced selective degeneration of peripheral neurons and perspectives for targeting autophagy as a promising therapeutic strategy for CMT neuropathy.