Clusterin in neurological disorders: Molecular perspectives and clinical relevance
ABSTRACT Firstly discovered in rete testis fluid, clusterin is a glycoprotein present in most of the other biological fluids. Several isoforms of clusterin are encoded from a single gene located on chromosome 8 in human species. Among the different isoforms, the secreted form of clusterin is expressed by a variety of tissues, including the nervous system under normal conditions. This form is presumed to play an anti-apoptotic role and seems to be a major determinant in cell survival and neuroplasticity after stroke. In animal models of this pathology, both neuronal and astroglial subpopulations express high levels of clusterin early after the ischemic damage. Recent lines of evidence point also to its possible involvement in neurodegenerative disorders. It is thought that in Alzheimer's disease the association between amyloidogenic peptides and clusterin contributes to limit Aβ species misfolding and facilitates their clearance from the extracellular space. Thus, intercellular and intracellular factors that modulate local clusterin expression in the nervous system may represent potent targets for neurodegenerative disease therapies. In this review we provide a critical overview of the most recent data on the involvement of clusterin in neurodegenerative diseases with special reference to their putative clinical relevance.
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ABSTRACT: Background: Organisms are constantly exposed to physiological and environmental stresses and therefore require an efficient surveillance of genome and proteome quality in order to prevent disruption of homeostasis. Central to the intra- and extracellular proteome surveillance system are the molecular chaperones that contribute to both proteome maintenance and clearance. The conventional protein product of the apolipoprotein J/clusterin (CLU) gene is a heterodimeric secreted glycoprotein (also termed as sCLU) with a ubiquitous expression in human tissues. CLU exerts a small heat shock protein-like stress-induced chaperone activity and has been functionally implicated in numerous physiological processes as well as in ageing and most age-related diseases including tumorigenesis, neurodegeneration, and cardiovascular and metabolic syndromes. Objective: The CLU gene is differentially regulated by a wide variety of stimuli due to the combined presence of many distinct regulatory elements in its promoter that make it an extremely sensitive cellular biosensor of environmental and/or oxidative stress. Downstream to CLU gene induction, the CLU protein seems to actively intervene in pathological states of increased oxidative injury due to its chaperone-related property to inhibit protein aggregation and precipitation (a main feature of oxidant injury), as well as due to its reported distribution in both extra- and, most likely, intracellular compartments. Conclusion: On the basis of these findings, CLU has emerged as a unique regulator of cellular proteostasis. Nevertheless, it seemingly exerts a dual function in pathology. For instance, in normal cells and during early phases of carcinogenesis, CLU may inhibit tumor progression as it contributes to suppression of proteotoxic stress. In advanced neoplasia, however, it may offer a significant survival advantage in the tumor by suppressing many therapeutic stressors and enhancing metastasis. This review will critically present a synopsis of recent novel findings that relate to the function of this amazing molecule and support the notion that CLU is a biosensor of oxidative injury; a common link between ageing and all pathologies where CLU has been implicated. Potential future perspectives, implications and opportunities for translational research and the development of new therapies will be discussed.Gerontology 05/2013; 59(6). DOI:10.1159/000351207 · 3.06 Impact Factor
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ABSTRACT: Baicalin, which is isolated from Scutellariae Radix, has been evidenced to possess several pharmacological effects. The present study focuses on the in vitro protective effect of baicalin on oxygen-glucose deprivation (OGD) injured brain microvascular endothelial cells (BMECs) via anti-inflammation and mechanisms against BMECs damaged by OGD. Cultured primary rat BMECs were exposed to baicalin at the concentrations of 100μM (high dose) and 10μM (low dose) for 6h after a two hours' OGD. The effects of baicalin were evaluated in terms of (i) cell viability; (ii) lactate dehydrogenase (LDH) leakage rate; (iii) levels of TNF-α, IL-1β, IL-6 in culture media; (iv) protein expressions of p-MEK6, p-MEK1/2, p-ERK, p-IκBα, NF-κB p65, p-IKKα, p-IKKβ and p-p38; and (v) nuclear translocation of NF-κB p65 and p-IκBα. The results showed that OGD treatment could reduce cell viability, increase LDH leakage rate, increase the levels of TNF-α, IL-1β and IL-6 in the culture media. These effects were suppressed by baicalin with high or low dose. In addition, baicalin could notably down-regulate the phosphorylation of proteins in MAPK signaling pathway such as p-MRK1/2, p-ERK and p-p38. While low dose of baicalin could significantly suppress the phosphorylation of proteins in NF-кB signaling pathway such as p-IKKα, p-IKKβ and p-IκBα. Furthermore, baicalin at 10μM could remarkably inhibit nuclear transcriptional activity triggered via NF-κB p65 and p-IκBα in BMECs. In conclusion, baicalin displays a protective effect on OGD-injured BMECs in vitro by attenuating inflammatory factors via downregulated the MAPK and NF-κB signaling pathway.Brain research bulletin 05/2013; 97. DOI:10.1016/j.brainresbull.2013.05.005 · 2.72 Impact Factor
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ABSTRACT: Lipoprotein-A (LpA) is an emerging independent risk factor for cerebro- and cardio-vascular diseases (CCVD). Recognizing its function and its normal distribution is of fundamental importance for a better understanding of CCVD patho-physiology. The present study evaluated plasma LpA levels of healthy university students using turbidi-metric methods. Medians and inter-quartile differences obtained for male and female participants were 11.3mg/dL (3.1-30.7) and 20.9mg/dL (6.5-42.3), respectively, demonstrating a significant difference (P=0.017) between men and women. A third of students showed plasma concentrations above reference values. Our results indicate that 33% of students possess a hidden independent risk factor for CCVD. Multi-disciplinary evaluation and characterization of young individuals should be recommended in an attempt to take early preventive measures and to eliminate possible modifiable risk factors such as sedentary lifestyle, smoking, hypertension, obesity and atherogenic diet.Brain research bulletin 05/2013; 97. DOI:10.1016/j.brainresbull.2013.05.012 · 2.72 Impact Factor