| 2. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)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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| 3. |
- Fucho, Raquel, et al.
(författare)
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ASMase regulates autophagy and lysosomal membrane permeabilization and its inhibition prevents early stage non-alcoholic steatohepatitis
- 2014
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Ingår i: Journal of Hepatology. - : Elsevier. - 0168-8278 .- 1600-0641. ; 61:5, s. 1126-1134
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: Acid sphingomyelinase (ASMase) is activated in non-alcoholic steatohepatitis (NASH). However, the contribution of ASMase to NASH is poorly understood and limited to hepatic steatosis and glucose metabolism. Here we examined the role of ASMase in high fat diet (HFD)-induced NASH. Methods: Autophagy, endoplasmic reticulum (ER) stress and lysosomal membrane permeabilization (LMP) were determined in ASMase(-/-) mice fed a HFD. The impact of pharmacological ASMase inhibition on NASH was analyzed in wild type mice fed a HFD. Results: ASMase deficiency determined resistance to hepatic steatosis mediated by a HFD or methionine-choline deficient diet. ASMase(-/-) mice were resistant to HFD-induced hepatic ER stress, but sensitive to tunicamycin-mediated ER stress, indicating selectivity in the resistance of ASMase(-/-) mice to ER stress and steatosis. Autophagic flux, determined in the presence of rapamycin and/or chloroquine, was lower in primary mouse hepatocytes (PMH) from ASMase(-/-) mice and accompanied by increased p62 levels, suggesting autophagic impairment. Moreover, autophagy suppression by chloroquine and brefeldin A caused ER stress in PMH from ASMase(+/+) mice but not in ASMase(-/-) mice. ASMase(-/-) PMH exhibited increased lysosomal cholesterol loading, decreased LMP and apoptosis resistance induced by 0-methylserine dodecylamide hydrochloride or palmitic acid, effects that were reversed by decreasing cholesterol levels by oxysterol 25-hydroxycholesterol. In vivo pharmacological ASMase inhibition by amitriptyline, a widely used tricyclic antidepressant, protected wild type mice against HFD-induced hepatic steatosis, fibrosis, and liver damage, effects indicative of early-stage NASH, Conclusions: These findings underscore a critical role for ASMase in diet-induced NASH and suggest the potential of amitriptyline as a treatment for patients with NASH.
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