Clusterin as a potential marker of brain ischemia-reperfusion injury in patients undergoing carotid endarterectomy

Decoding CLU (Clusterin): Conquering cancer treatment resistance and immunological barriers

One major obstacle in the treatment of cancer is the presence of proteins resistant to cancer therapy, which can impede the effectiveness of traditional approaches such as radiation and chemotherapy. This resistance can lead to disease progression and cause treatment failure. Extensive research is currently focused on studying these proteins to create tailored treatments that can circumvent resistance mechanisms. CLU (Clusterin), a chaperone protein, has gained notoriety for its role in promoting resistance to a wide range of cancer treatments, including chemotherapy, radiation therapy, and targeted therapy. The protein has also been discovered to have a role in regulating the immunosuppressive environment within tumors. Its ability to influence oncogenic signaling and inhibit cell death bolster cancer cells resistant against treatments, which poses a significant challenge in the field of oncology. Researchers are actively investigating to the mechanisms by which CLU exerts its resistance-promoting effects, with the ultimate goal of developing strategies to circumvent its impact and enhance the effectiveness of cancer therapies. By exploring CLU's impact on cancer, resistance mechanisms, tumor microenvironment (TME), and therapeutic strategies, this review aims to contribute to the ongoing efforts to improve cancer treatment outcomes.

Effects of leptin treatment immediately after neonatal seizures on serum clusterin and VEGF levels and brain oxidative stress-related proteins and neurobehavioral phenotypes

The developing infant brain has a different response mechanism and repair potential for injury than the adult brain. There is an urgent need for new anticonvulsants to effectively control neonatal seizures while minimizing the drug's toxic damage to the developing brain. Leptin protects neuronal plasma membrane integrity, while it has clinical advantages in terms of anticonvulsant properties as well. This study aimed to evaluate the effect of immediate leptin treatment on the serum concentration of clusterin and vascular endothelial growth factor (VEGF), neuronal plasma membrane integrity-related proteins, and the neurobehavioral phenotypes following neonatal seizures. Leptin was injected i.p at a dose of 4 mg/kg 1 hour after daily 30 minutes prolonged seizures for consecutive 10 days. The serum biomarkers (clusterin and VEGF), and brain protein expression of ATF-4/GRP78/autophagy axis were measured by enzyme-linked immunosorbent assay and western blot in the acute phase (24 hours after the last seizures), respectively. Behavioral and histopathological phenotypes and seizure threshold were conducted from P23 to P34, respectively. There were rapid elevation of serum VEGF and clusterin as well as upregulated protein expression of ATF-4, GRP78, Beclin-1, and LC3 in the cerebral cortex and hippocampus following a neonatal seizure, which was restored by immediate treatment with leptin after seizures. In addition, leptin improved seizure-induced impaired neuropsychological, and cognitive functioning. Furthermore, leptin succeeded in ameliorating markers of neuronal excitability, including seizure threshold and hippocampal mossy fiber sprouting. In conclusion, this study verified that immediate treatment with leptin after neonatal seizures restored both rapid elevation of serum clusterin as well as upregulated protein expression of ATF-4/GRP78/autophagy axis in the cerebral cortex and hippocampus, which contributes to the recovery of neurological function.

Study on the Mechanism of Platelet-Released Clusterins Inducing Restenosis after Carotid Endarterectomy by Activating TLR3/NF-κb p65 Signaling Pathway

This study aimed to explore the role of clusterin released by platelet aggregation in restenosis after carotid endarterectomy. 35 patients who underwent carotid endarterectomy due to carotid artery stenosis were enrolled in this study. They were admitted to the Third Affiliated Hospital of Qiqihar Medical University from January 2018 to January 2019. All the patients were divided into two groups: the restenosis group and the nonrestenosis group, according to the follow-up results within 12 months. Peripheral blood was collected on the first day, 6 months, and 12 months after operation. The expression of CLU in serum of plasma and platelet culture medium was detected by an ELISA experiment. The vascular endothelial cells were cultured in vitro with 100 ng/mL of human recombinant CLU added to the medium. Cell proliferation, migration, and invasion were detected by CCK8, scratch, and Transwell invasion tests. The expression level of TLR3 and NF-κb p65 proteins in cells was detected by western blot. TLR3 knockout plasmids in vascular endothelial cell lines were transfected. Cell proliferation and migration were detected by CCK8 and the scratch assay. The CLU content in peripheral blood plasma and supernatant of platelet culture medium was significantly higher in the restenosis group than that of the control group (p=0.003) 6 months after operation (p=0.047) and 12 months after operation (p=0.011). When CLU was added to vascular endothelial cell culture medium, the proliferation and migration were significantly enhanced. The TLR3/NF-κb p65 protein expression level in cells also significantly increased. After the transfection of TLR3 knockout plasmids into vascular endothelial cell lines, CLU cannot promote the proliferation and migration of vascular endothelial cells. Platelet-released clusterin can induce vascular endothelial cell proliferation and migration by activating the TLR3/NF-kb p65 signaling pathway, leading to carotid artery restenosis after carotid endarterectomy.

The Dual Roles of Clusterin in Extracellular and Intracellular Proteostasis

Clusterin (CLU) was the first reported secreted mammalian chaperone and impacts on serious diseases associated with inappropriate extracellular protein aggregation. Many studies have described intracellular CLU in locations outside the secretory system and recent work has shown that CLU can be released into the cytosol during cell stress. In this article, we critically evaluate evidence relevant to the proposed origins of cellular CLU found outside the secretory system, and advance the hypothesis that the cytosolic release of CLU induced by stress serves to facilitate the trafficking of misfolded proteins to the proteasome and autophagy for degradation. We also propose future research directions that could help establish CLU as a unique chaperone performing critical and synergic roles in both intracellular and extracellular proteostasis.

Association of CLU gene polymorphism with Parkinson's disease in the Chinese Han population

BACKGROUND

Clusterin (CLU) plays important role in the pathology of neurodegenerative disorders. Recently, a genetic variant of CLU rs9331896 has been reported as a risk estimate for Alzheimer's disease (AD). However, the association between this variant and the risk of Parkinson's disease (PD) in the Chinese Han population remains elusive.

METHODS

We sequenced CLU rs9331896 in 353 PD patients and 326 healthy-matched individuals of the Chinese Han population. The genotypes of rs9331896 were analyzed using MassArray (Agena Bioscience, San Diego, CA, USA) in accordance with the manufacturer's instructions. The distribution of genotypes and allelic frequencies was analyzed by a chi-squared test. Additionally, the expression of CLU protein in plasma was evaluated by an enzyme-linked immunosorbent assay and analysed with a t-test.

RESULTS

The TT genotype in rs9331896 in a recessive model was found to be associated with the increased risk of PD (odds ratio = 1.408, 95% confidence interval = 1.034-1.916, p = 0.029). Subgroup analysis indicated that TT genotype carriers showed a significantly higher risk in male PD patients compared to male healthy controls (odds ratio = 1.611, 95% confidence interval = 1.046-2.483, p = 0.030). In addition, CLU levels in the plasma of PD patients were significantly higher than controls (p = 0.024).

CONCLUSIONS

The CLU-rs9331896-TT genotype was a risk factor for PD, particularly in males. PD patients also expressed a high level of CLU in plasma.

Baicalin ameliorates neuropathology in repeated cerebral ischemia-reperfusion injury model mice by remodeling the gut microbiota

We investigated the neuroprotective effects of baicalin and the role of gut microbiota in a mouse model of cerebral ischemia-reperfusion injury. Repeated cerebral ischemia-reperfusion significantly increased plasma levels of trimethylamine (TMA), trimethylamine-N-oxide (TMAO), and clusterin (a neuroinflammation biomarker). These changes correlated with cognitive decline; short-term memory deficits; abnormal long term potentiation (LTP); decreased functional connectivity (FC) between various brain regions; reduced plasticity and dendritic spine density in the hippocampus; increased levels of the pro-inflammatory cytokines IL-1β, IL-6, and TNFα; and altered the gut microbial composition. Treatment with 50-100 mg/Kg baicalin for 7 days after cerebral ischemia-reperfusion significantly restored normal plasma levels of TMA, TMAO, and clusterin. Baicalin treatment also suppressed neuroinflammation, remodeled the gut microbial composition back to normal, and improved cognition, memory, LTP, cerebral FC, and hippocampal neuronal plasticity. The neuroprotective effects of baicalin were diminished when mice undergoing repeated cerebral ischemia-reperfusion were pretreated with broad-spectrum antibiotics to deplete gut microbial populations. This suggests the neuroprotective effects of baicalin in cerebral ischemia-reperfusion injury are mediated by the gut microbiota. It thus appears that baicalin ameliorates neuropathology in a repeated cerebral ischemia-reperfusion model mice by remodeling the gut microbiota.