Autolysosome

About: Autolysosome is a research topic. Over the lifetime, 383 publications have been published within this topic receiving 37686 citations.

Does bafilomycin A1 block the fusion of autophagosomes with lysosomes

Abstract: Bafilomycin A1 is a specific inhibitor of the vacuolar type H+-ATPase (V-ATPase) in cells, and inhibits the acidification of organelles containing this enzyme, such as lysosomes and endosomes. Recently, while editing and reviewing chapters on autophagy for Methods in Enzymology, we noticed repeated references to the effect of bafilomycin A1 in blocking the fusion of autophagosomes with lysosomes. Of course we have seen this in various research papers as well, but reading this routinely in chapters written by various people over a short period of time really caused this to stand out. Every one of these chapters referred to the paper by Yamamoto et al. In that paper, treatment with 100 nM bafilomycin A1 for 1 h blocks the fusion of autophagosomes with lysosomes in the rat hepatoma H-4-II-E cell line, based on data from electron microscopy. However, data from one of our labs noted an apparently different result in a relatively recent manuscript. Therefore, we decided to look into this more carefully.

Bafilomycin A1 disrupts autophagic flux by inhibiting both V-ATPase-dependent acidification and Ca-P60A/SERCA-dependent autophagosome-lysosome fusion

Abstract: Autophagosome-lysosome fusion and autolysosome acidification constitute late steps in the autophagic process necessary to maintain functional autophagic flux and cellular homeostasis. Both of these...

Neuronal injury in rat model of permanent focal cerebral ischemia is associated with activation of autophagic and lysosomal pathways

Abstract: It has been reported that ischemic insult increases the formation of autophagosomes and activates autophagy. However, the role of autophagy in ischemic neuronal damage remains elusive. This study was taken to assess the role of autophagy in ischemic brain damage. Focal cerebral ischemia was introduced by permanent middle cerebral artery occlusion (pMCAO). Activation of autophagy was assessed by morphological and biochemical examinations. To determine the contribution of autophagy/lysosome to ischemic neuronal death, rats were pretreated with a single intracerebral ventricle injection of the autophagy inhibitors 3-methyl-adenine (3-MA) and bafliomycin A1 (BFA) or the cathepsin B inhibitor Z-FA-fmk after pMCAO. The effects of 3-MA and Z-FA-fmk on brain damage, expression of proteins involved in regulation of autophagy and apoptosis were assessed with 2,3,5-triphenyltetrazolium chloride (TTC) staining and immunoblotting. The results showed that pMACO increased the formation of autophagosomes and autolysosome...

Autophagy is activated in colorectal cancer cells and contributes to the tolerance to nutrient deprivation.

Abstract: Several types of cancer cells, including colorectal cancer-derived cell lines, show austerity, the resistance to nutrient starvation, but exactly how cancer cells obtain energy sources under conditions in which their external nutrient supply is extremely limited remains to be clarified. Because autophagy is a catabolic process by which cells supply amino acids from self-digested organelles, cancer cells are likely to use autophagy to obtain amino acids as alternative energy sources. Amino acid deprivation-induced autophagy was assessed in DLD-1 and other colorectal cancer-derived cell lines. The autophagosome-incorporated LC3-II protein level increased after treatment with a combination of autolysosome inhibitors, which interferes with the consumption of autophagosomes. Autophagosome formation was also morphologically confirmed using ectopically expressed green fluorescent protein-LC3 fusion proteins in DLD-1 and SW480 cells. These data suggest that autophagosomes were actively produced and promptly consumed in colorectal cancer cells under nutrient starvation. Autolysosome inhibitors and 3-methyl adenine, which suppresses autophagosome formation, remarkably enhanced apoptosis under amino acid-deprived and glucose-deprived condition. Similar results were obtained in the cells with decreased ATG7 level by the RNA interference. These data suggest that autophagy is pivotal for the survival of colorectal cancer cells that have acquired austerity. Furthermore, autophagosome formation was seen only in the tumor cells but not in the adjacent noncancerous epithelial cells of colorectal cancer specimens. Taken together, autophagy is activated in colorectal cancers in vitro and in vivo, and autophagy may contribute to the survival of the cancer cells in their microenvironment.