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1.  Vaccinia virus leads to ATG12–ATG3 conjugation and deficiency in autophagosome formation 
Autophagy  2011;7(12):1434-1447.
The interactions between viruses and cellular autophagy have been widely reported. On the one hand, autophagy is an important innate immune response against viral infection. On the other hand, some viruses exploit the autophagy pathway for their survival and proliferation in host cells. Vaccinia virus is a member of the family of Poxviridae which includes the smallpox virus. The biogenesis of vaccinia envelopes, including the core envelope of the immature virus (IV), is not fully understood. In this study we investigated the possible interaction between vaccinia virus and the autophagy membrane biogenesis machinery. Massive LC3 lipidation was observed in mouse fibroblast cells upon vaccinia virus infection. Surprisingly, the vaccinia virus induced LC3 lipidation was shown to be independent of ATG5 and ATG7, as the atg5 and atg7 null mouse embryonic fibroblasts (MEFs) exhibited the same high levels of LC3 lipidation as compared with the wild-type MEFs. Mass spectrometry and immunoblotting analyses revealed that the viral infection led to the direct conjugation of ATG3, which is the E2-like enzyme required for LC3-phosphoethanonamine conjugation, to ATG12, which is a component of the E3-like ATG12–ATG5-ATG16 complex for LC3 lipidation. Consistently, ATG3 was shown to be required for the vaccinia virus induced LC3 lipidation. Strikingly, despite the high levels of LC3 lipidation, subsequent electron microscopy showed that vaccinia virus-infected cells were devoid of autophagosomes, either in normal growth medium or upon serum and amino acid deprivation. In addition, no autophagy flux was observed in virus-infected cells. We further demonstrated that neither ATG3 nor LC3 lipidation is crucial for viral membrane biogenesis or viral proliferation and infection. Together, these results indicated that vaccinia virus does not exploit the cellular autophagic membrane biogenesis machinery for their viral membrane production. Moreover, this study demonstrated that vaccinia virus instead actively disrupts the cellular autophagy through a novel molecular mechanism that is associated with aberrant LC3 lipidation and a direct conjugation between ATG12 and ATG3.
doi:10.4161/auto.7.12.17793
PMCID: PMC3327614  PMID: 22024753
ATG12; ATG3; autophagy; LC3 lipidation; vaccinia virus
2.  Autophagy and adipogenesis Implications in obesity and type II diabetes 
Autophagy  2010;6(1):179-181.
Obesity is a direct result of the accumulation of white adipose tissue (WAT). In this study, the role of autophagy in the differentiation of white adipose tissue was studied by deleting the autophagy-related 7 (atg7) gene from adipose tissue in mice. This deletion results in a striking phenotype at the cellular, tissue and whole-organism levels. Adipose tissue deposits in the mutant mice are much smaller in mass than those observed in their wild-type counterparts, and mutant adipocytes exhibit unusual morphological characteristics including multilocular lipid droplets and greatly increased numbers of mitochondria. The knockout mice are noticeably slimmer than their wild-type littermates, despite parity in food and water consumption. The mutant mice also exhibit higher basal physical activity levels and an array of metabolic changes revealed through blood tests. Most importantly, these mice show resistance to high-fat diet-induced obesity and markedly increased sensitivity to insulin. These findings establish a new function for autophagy and provide a new model system for use in the search for treatments for obesity and type II diabetes.
PMCID: PMC2883858  PMID: 20110772
atg7; adipose; knockout; obesity; diabetes
3.  Tumor suppression by autophagy through the management of metabolic stress 
Autophagy  2008;4(5):563-566.
Autophagy plays a critical protective role maintaining energy homeostasis and protein and organelle quality control. These functions are particularly important in times of metabolic stress and in cells with high energy demand such as cancer cells. In emerging cancer cells, autophagy defect may cause failure of energy homeostasis and protein and organelle quality control, leading to the accumulation of cellular damage in metabolic stress. Some manifestations of this damage, such as activation of the DNA damage response and generation of genome instability may promote tumor initiation and drive cell-autonomous tumor progression. In addition, in solid tumors, autophagy localizes to regions that are metabolically stressed. Defects in autophagy impair the survival of tumor cells in these areas, which is associated with increased cell death and inflammation. The cytokine response from inflammation may promote tumor growth and accelerate cell non-autonomous tumor progression. The overreaching theme is that autophagy protects cells from damage accumulation under conditions of metabolic stress allowing efficient tolerance and recovery from stress, and that this is a critical and novel tumor suppression mechanism. The challenge now is to define the precise aspects of autophagy, including energy homeostasis and protein and organelle turnover, that are required for the proper management of metabolic stress that suppress tumorigenesis. Furthermore, we need to be able to identify human tumors with deficient autophagy, and to develop rational cancer therapies that take advantage of the altered metabolic state and stress responses inherent to this autophagy defect.
PMCID: PMC2857579  PMID: 18326941
autophagy; beclin1; cancer
4.  Role of Autophagy in Cancer 
Autophagy  2007;3(1):28-31.
Human breast, ovarian, and prostate tumors display allelic loss of the essential autophagy gene beclin1 with high frequency, and an increase in the incidence of tumor formation is observed in beclin1+/− mutant mice. These findings suggest a role for beclin1 and autophagy in tumor suppression; however, the mechanism by which this occurs has been unclear. Autophagy is a bulk degradation process whereby organelles and cytoplasm are engulfed and targeted to lysosomes for proteolysis,1,2 There is evidence that autophagy sustains cell survival during nutrient deprivation through catabolism, but also that autophagy is a means of achieving cell death when executed to completion. If or how either of these diametrically opposing functions proposed for autophagy may be related to tumor suppression is unknown. We found that metabolic stress is a potent trigger of apoptotic cell death, defects in which enable long-term survival that is dependent on autophagy both in vitro and in tumors in vivo.3 These findings raise the conundrum whereby inactivation of a survival pathway (autophagy) promotes tumorigenesis. Interestingly, when cells with defects in apoptosis are denied autophagy, this creates the inability to tolerate metabolic stress, reduces cellular fitness, and activates a necrotic pathway to cell death. This necrosis in tumors is associated with inflammation and enhancement of tumor growth, due to the survival of a small population of surviving, but injured, cells in a microenvironment that favors oncogenesis. Thus, by sustaining metabolism through autophagy during periods of metabolic stress, cells can limit energy depletion, cellular damage, and cell death by necrosis, which may explain how autophagy can prevent cancer, and how loss of a survival function can be tumorigenic.
PMCID: PMC2770734  PMID: 16969128
autophagy; apoptosis; necrosis; Beclin1; cancer
5.  Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes 
Klionsky, Daniel J. | Abeliovich, Hagai | Agostinis, Patrizia | Agrawal, Devendra K. | Aliev, Gjumrakch | Askew, David S. | Baba, Misuzu | Baehrecke, Eric H. | Bahr, Ben A. | Ballabio, Andrea | Bamber, Bruce A. | Bassham, Diane C. | Bergamini, Ettore | Bi, Xiaoning | Biard-Piechaczyk, Martine | Blum, Janice S. | Bredesen, Dale E. | Brodsky, Jeffrey L. | Brumell, John H. | Brunk, Ulf T. | Bursch, Wilfried | Camougrand, Nadine | Cebollero, Eduardo | Cecconi, Francesco | Chen, Yingyu | Chin, Lih-Shen | Choi, Augustine | Chu, Charleen T. | Chung, Jongkyeong | Clarke, Peter G.H. | Clark, Robert S.B. | Clarke, Steven G. | Clavé, Corinne | Cleveland, John L. | Codogno, Patrice | Colombo, María I. | Coto-Montes, Ana | Cregg, James M. | Cuervo, Ana Maria | Debnath, Jayanta | Demarchi, Francesca | Dennis, Patrick B. | Dennis, Phillip A. | Deretic, Vojo | Devenish, Rodney J. | Di Sano, Federica | Dice, J. Fred | DiFiglia, Marian | Dinesh-Kumar, Savithramma | Distelhorst, Clark W. | Djavaheri-Mergny, Mojgan | Dorsey, Frank C. | Dröge, Wulf | Dron, Michel | Dunn, William A. | Duszenko, Michael | Eissa, N. Tony | Elazar, Zvulun | Esclatine, Audrey | Eskelinen, Eeva-Liisa | Fésüs, László | Finley, Kim D. | Fuentes, José M. | Fueyo, Juan | Fujisaki, Kozo | Galliot, Brigitte | Gao, Fen-Biao | Gewirtz, David A. | Gibson, Spencer B. | Gohla, Antje | Goldberg, Alfred L. | Gonzalez, Ramon | González-Estévez, Cristina | Gorski, Sharon | Gottlieb, Roberta A. | Häussinger, Dieter | He, You-Wen | Heidenreich, Kim | Hill, Joseph A. | Høyer-Hansen, Maria | Hu, Xun | Huang, Wei-Pang | Iwasaki, Akiko | Jäättelä, Marja | Jackson, William T. | Jiang, Xuejun | Jin, Shengkan | Johansen, Terje | Jung, Jae U. | Kadowaki, Motoni | Kang, Chanhee | Kelekar, Ameeta | Kessel, David H. | Kiel, Jan A.K.W. | Kim, Hong Pyo | Kimchi, Adi | Kinsella, Timothy J. | Kiselyov, Kirill | Kitamoto, Katsuhiko | Knecht, Erwin | Komatsu, Masaaki | Kominami, Eiki | Kondo, Seiji | Kovács, Attila L. | Kroemer, Guido | Kuan, Chia-Yi | Kumar, Rakesh | Kundu, Mondira | Landry, Jacques | Laporte, Marianne | Le, Weidong | Lei, Huan-Yao | Lenardo, Michael J. | Levine, Beth | Lieberman, Andrew | Lim, Kah-Leong | Lin, Fu-Cheng | Liou, Willisa | Liu, Leroy F. | Lopez-Berestein, Gabriel | López-Otín, Carlos | Lu, Bo | Macleod, Kay F. | Malorni, Walter | Martinet, Wim | Matsuoka, Ken | Mautner, Josef | Meijer, Alfred J. | Meléndez, Alicia | Michels, Paul | Miotto, Giovanni | Mistiaen, Wilhelm P. | Mizushima, Noboru | Mograbi, Baharia | Monastyrska, Iryna | Moore, Michael N. | Moreira, Paula I. | Moriyasu, Yuji | Motyl, Tomasz | Münz, Christian | Murphy, Leon O. | Naqvi, Naweed I. | Neufeld, Thomas P. | Nishino, Ichizo | Nixon, Ralph A. | Noda, Takeshi | Nürnberg, Bernd | Ogawa, Michinaga | Oleinick, Nancy L. | Olsen, Laura J. | Ozpolat, Bulent | Paglin, Shoshana | Palmer, Glen E. | Papassideri, Issidora | Parkes, Miles | Perlmutter, David H. | Perry, George | Piacentini, Mauro | Pinkas-Kramarski, Ronit | Prescott, Mark | Proikas-Cezanne, Tassula | Raben, Nina | Rami, Abdelhaq | Reggiori, Fulvio | Rohrer, Bärbel | Rubinsztein, David C. | Ryan, Kevin M. | Sadoshima, Junichi | Sakagami, Hiroshi | Sakai, Yasuyoshi | Sandri, Marco | Sasakawa, Chihiro | Sass, Miklós | Schneider, Claudio | Seglen, Per O. | Seleverstov, Oleksandr | Settleman, Jeffrey | Shacka, John J. | Shapiro, Irving M. | Sibirny, Andrei | Silva-Zacarin, Elaine C.M. | Simon, Hans-Uwe | Simone, Cristiano | Simonsen, Anne | Smith, Mark A. | Spanel-Borowski, Katharina | Srinivas, Vickram | Steeves, Meredith | Stenmark, Harald | Stromhaug, Per E. | Subauste, Carlos S. | Sugimoto, Seiichiro | Sulzer, David | Suzuki, Toshihiko | Swanson, Michele S. | Tabas, Ira | Takeshita, Fumihiko | Talbot, Nicholas J. | Tallóczy, Zsolt | Tanaka, Keiji | Tanaka, Kozo | Tanida, Isei | Taylor, Graham S. | Taylor, J. Paul | Terman, Alexei | Tettamanti, Gianluca | Thompson, Craig B. | Thumm, Michael | Tolkovsky, Aviva M. | Tooze, Sharon A. | Truant, Ray | Tumanovska, Lesya V. | Uchiyama, Yasuo | Ueno, Takashi | Uzcátegui, Néstor L. | van der Klei, Ida | Vaquero, Eva C. | Vellai, Tibor | Vogel, Michael W. | Wang, Hong-Gang | Webster, Paul | Wiley, John W. | Xi, Zhijun | Xiao, Gutian | Yahalom, Joachim | Yang, Jin-Ming | Yap, George | Yin, Xiao-Ming | Yoshimori, Tamotsu | Yu, Li | Yue, Zhenyu | Yuzaki, Michisuke | Zabirnyk, Olga | Zheng, Xiaoxiang | Zhu, Xiongwei | Deter, Russell L.
Autophagy  2007;4(2):151-175.
Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is 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 verify an autophagic response.
PMCID: PMC2654259  PMID: 18188003
autolysosome; autophagosome; flux; lysosome; phagophore; stress; vacuole

Results 1-5 (5)