Amphisomes are intermediate/hybrid organelles produced through the fusion of endosomes with autophagosomes within cells. Amphisome formation is an essential step during a sequential maturation process of autophagosomes before their ultimate fusion with lysosomes for cargo degradation. This process is highly regulated with multiple protein machineries, such as SNAREs, Rab GTPases, tethering complexes, and ESCRTs, are involved to facilitate autophagic flux to proceed. In neurons, autophagosomes are robustly generated in axonal terminals and then rapidly fuse with late endosomes to form amphisomes. This fusion event allows newly generated autophagosomes to gain retrograde transport motility and move toward the soma, where proteolytically active lysosomes are predominantly located. Amphisomes are not only the products of autophagosome maturation but also the intersection of the autophagy and endo-lysosomal pathways. Importantly, amphisomes can also participate in non-canonical functions, such as retrograde neurotrophic signaling or autophagy-based unconventional secretion by fusion with the plasma membrane. In this review, we provide an updated overview of the recent discoveries and advancements on the molecular and cellular mechanisms underlying amphisome biogenesis and the emerging roles of amphisomes. We discuss recent developments towards the understanding of amphisome regulation as well as the implications in the context of major neurodegenerative diseases, with a comparative focus on Alzheimer's disease and Parkinson's disease.
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May 2021
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Amphisomes are intermediate/hybrid organelles produced through the fusion of endosomes with autophagosomes within cells. In this issue Ganesan and Cai (pp. 1959–1976) provide an updated overview of the recent discoveries and advancements on the molecular and cellular mechanisms underlying amphisome biogenesis and the emerging roles of amphisomes. The image shows amphisome retrograde transport in the axons of neurons. Image courtesy of Qian Cai.
Review Article|
May 28 2021
Understanding amphisomes
Dhasarathan Ganesan;
Dhasarathan Ganesan
Department of Cell Biology and Neuroscience, Division of Life Science, School of Arts and Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, U.S.A.
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Qian Cai
Department of Cell Biology and Neuroscience, Division of Life Science, School of Arts and Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, U.S.A.
Correspondence: Qian Cai (cai@biology.rutgers.edu)
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Publisher: Portland Press Ltd
Received:
March 15 2021
Revision Received:
April 27 2021
Accepted:
May 06 2021
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2021 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2021
Biochem J (2021) 478 (10): 1959–1976.
Article history
Received:
March 15 2021
Revision Received:
April 27 2021
Accepted:
May 06 2021
Citation
Dhasarathan Ganesan, Qian Cai; Understanding amphisomes. Biochem J 28 May 2021; 478 (10): 1959–1976. doi: https://doi.org/10.1042/BCJ20200917
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