| 1. |
- East, Brett S., et al.
(author)
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Human Apolipoprotein E Genotype Differentially Affects Olfactory Behavior and Sensory Physiology in Mice
- 2018
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In: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 380, s. 103-110
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Journal article (peer-reviewed)abstract
- Apolipoprotein E (ApoE) is an important lipid carrier in both the periphery and the brain. The ApoE epsilon 4 allele (ApoE4) is the single most important genetic risk-factor for Alzheimer's disease (AD) while the epsilon 2 allele (ApoE2) is associated with a lower risk of AD-related neurodegeneration compared to the most common variant, epsilon 3 (ApoE3). ApoE genotype affects a variety of neural circuits; however, the olfactory system appears to provide early biomarkers of ApoE genotype effects. Here, we directly compared olfactory behavior and olfactory system physiology across all three ApoE genotypes in 6-month- and 12-month-old mice with targeted replacement for the human ApoE2, ApoE3, or ApoE4 genes. Odor investigation and habituation were assessed, along with, olfactory bulb and piriform cortical local field potential activity. The results demonstrate that while initial odor investigation was unaffected by ApoE genotype, odor habituation was impaired in E4 relative to E2 mice, with E3 mice intermediate in function. There was also significant deterioration of odor habituation from 6 to 12 months of age regardless of the ApoE genotype. Olfactory system excitability and odor responsiveness were similarly determined by ApoE genotype, with an ApoE4 > ApoE3 > ApoE2 excitability ranking. Although motivated behavior is influenced by many processes, hyper-excitability of ApoE4 mice may contribute to impaired odor habituation, while hypo-excitability of ApoE2 mice may contribute to its protective effects. Given that these ApoE mice do not have AD pathology, our results demonstrate how ApoE affects the olfactory system at early stages, prior to the development of AD.
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| 2. |
- Kaeser, Stephan A., et al.
(author)
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Cystatin C modulates cerebral beta-amyloidosis
- 2007
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 39:12, s. 1437-1439
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Journal article (peer-reviewed)abstract
- The CST3 Thr25 allele of CST3, which encodes cystatin C, leads to reduced cystatin C secretion and conveys susceptibility to Alzheimer's disease. Here we show that overexpression of human cystatin C in brains of APP-transgenic mice reduces cerebral amyloid-beta deposition and that cystatin C binds amyloid-beta and inhibits its fibril formation. Our results suggest that cystatin C concentrations modulate cerebral amyloidosis risk and provide an opportunity for genetic risk assessment and therapeutic interventions.
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| 3. |
- Kaur, Gurjinder, et al.
(author)
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Cystatin C Rescues Degenerating Neurons in a Cystatin B-Knockout Mouse Model of Progressive Myoclonus Epilepsy.
- 2010
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In: American Journal of Pathology. - : Elsevier BV. - 1525-2191 .- 0002-9440. ; 177, s. 2256-2267
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Journal article (peer-reviewed)abstract
- In vitro studies have shown that cystatin C (CysC) is neuroprotective. Here we demonstrate that CysC is neuroprotective in vivo, in a mouse model of the inherited neurodegenerative disorder, progressive myoclonic epilepsy type 1 (EPM1). Loss-of-function mutations in the cystatin B (CysB) gene, an intracellular cysteine protease inhibitor, lead to this human disease. A CysB-knockout (CysBKO) mouse model develops symptoms that mimic EPM1. CysB deficiency in these mice results in enhanced cathepsin B and D activities, indicating lysosomal dysfunction. We show that expression of CysC is enhanced in the brains of CysBKO mice. Crossbreeding of CysBKO mice with either CysC-overexpressing transgenic mice or CysC-knockout mice demonstrates that clinical symptoms and neuropathologies, including motor coordination disorder, cerebellar atrophy, neuronal loss in the cerebellum and cerebral cortex, and gliosis caused by CysB deficiency, are rescued by CysC overexpression and exacerbated by CysC deficiency. Thus, CysC effectively rescues the CysB loss-of-function mutations, facilitating the reversal of pathophysiological changes and suggesting a novel therapeutic intervention for patients with EPM1 and other neurodegenerative disorders.
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| 4. |
- Klionsky, Daniel J., et al.
(author)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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In: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Research review (peer-reviewed)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 5. |
- Levy, Efrat, et al.
(author)
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The role of cystatin C in cerebral amyloid angiopathy and stroke: Cell biology and animal models : cell biology and animal models
- 2006
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In: Brain Pathology. - : Wiley. - 1750-3639 .- 1015-6305. ; 16:1, s. 60-70
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Journal article (peer-reviewed)abstract
- A variant of the cysteine protease inhibitor, cystatin C, forms amyloid deposited in the cerebral vasculature of patients with hereditary cerebral hemorrhage with amyloidosis, Icelandic type (HCHWA-I), leading to cerebral hemorrhages early in life. However, cystatin C is also implicated in neuronal degenerative diseases in which it does not form the amyloid protein, such as Alzheimer disease (AD). Accumulating data suggest involvement of cystatin C in the pathogenic processes leading to amyloid deposition in cerebral vasculature and most significantly to cerebral hemorrhage in patients with cerebral amyloid angiopathy (CAA). This review focuses on cell culture and animal models used to study the role of cystatin C in these processes.
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| 6. |
- Li, Wei, et al.
(author)
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Autophagy dysfunction and regulatory cystatin C in macrophage death of atherosclerosis
- 2016
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In: Journal of Cellular and Molecular Medicine. - : Wiley. - 1582-1838 .- 1582-4934. ; 20:9, s. 1664-1672
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Journal article (peer-reviewed)abstract
- Autophagy dysfunction in mouse atherosclerosis models has been associated with increased lipid accumulation, apoptosis and inflammation. Expression of cystatin C (CysC) is decreased in human atheroma, and CysC deficiency enhances atherosclerosis in mice. Here, we first investigated the association of autophagy and CysC expression levels with atheroma plaque severity in human atherosclerotic lesions. We found that autophagy proteins Atg5 and LC3β in advanced human carotid atherosclerotic lesions are decreased, while markers of dysfunctional autophagy p62/SQSTM1 and ubiquitin are increased together with elevated levels of lipid accumulation and apoptosis. The expressions of LC3β and Atg5 were positively associated with CysC expression. Second, we investigated whether CysC expression is involved in autophagy in atherosclerotic apoE-deficient mice, demonstrating that CysC deficiency (CysC-/-) in these mice results in reduction of Atg5 and LC3β levels and induction of apoptosis. Third, macrophages isolated from CysC-/- mice displayed increased levels of p62/SQSTM1 and higher sensitivity to 7-oxysterol-mediated lysosomal membrane destabilization and apoptosis. Finally, CysC treatment minimized oxysterol-mediated cellular lipid accumulation. We conclude that autophagy dysfunction is a characteristic of advanced human atherosclerotic lesions and is associated with reduced levels of CysC. The deficiency of CysC causes autophagy dysfunction and apoptosis in macrophages and apoE-deficient mice. The results indicate that CysC plays an important regulatory role in combating cell death via the autophagic pathway in atherosclerosis. Copyright
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| 7. |
- Tizon, Belen, et al.
(author)
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Induction of Autophagy by Cystatin C: A Mechanism That Protects Murine Primary Cortical Neurons and Neuronal Cell Lines
- 2010
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:3
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Journal article (peer-reviewed)abstract
- Cystatin C (CysC) expression in the brain is elevated in human patients with epilepsy, in animal models of neurodegenerative conditions, and in response to injury, but whether up-regulated CysC expression is a manifestation of neurodegeneration or a cellular repair response is not understood. This study demonstrates that human CysC is neuroprotective in cultures exposed to cytotoxic challenges, including nutritional-deprivation, colchicine, staurosporine, and oxidative stress. While CysC is a cysteine protease inhibitor, cathepsin B inhibition was not required for the neuroprotective action of CysC. Cells responded to CysC by inducing fully functional autophagy via the mTOR pathway, leading to enhanced proteolytic clearance of autophagy substrates by lysosomes. Neuroprotective effects of CysC were prevented by inhibiting autophagy with beclin 1 siRNA or 3-methyladenine. Our findings show that CysC plays a protective role under conditions of neuronal challenge by inducing autophagy via mTOR inhibition and are consistent with CysC being neuroprotective in neurodegenerative diseases. Thus, modulation of CysC expression has therapeutic implications for stroke, Alzheimer's disease, and other neurodegenerative disorders.
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