What happens to autolysosomes when they've completed degradation of their content?
This is a great question and I also like to know. I aasume the membrane can be recycled back after the content is released as building block for other metabolic process. If we block the process then disease will develop at least in Hungtinton disease by one report. So, I guess once the process turns on it is irreversible.
Certainly I agree with Dr. Teng. I feel most of (in fact all) the cellular processes are interlinked to each other under active conditions and autophagy is not an exception. When the job is done by the autolysosomes, they might get recycled back to either endosomal compartments or plasma membrane. But if some body provides any reference for the same, it would be great I think !!
Presumably, when the autophagosome fuses with a lysosome, the content gets degraded and the lysosome is reconstituted from an hybrid autophagosome-lysosome (or autolysosome). As cargos inside the autolysosome and the inner membrane of the former autophagosome are degraded, the possibility to revert to an autophagosome is lost. The details surrounding the lysosome reconstitution process is not completely clear, but appears to involve retrieval and condensation mechanisms (at least in the case of late endosome-lysosome fusion) and it is likely to be similar in the case of autophagosome-lysosome fusion. A nice review about lysosome fusion is available in Nat. Rev. Mol. Cell. Bio. Luzio JP et al. (2007) entitled: Lysosomes: fusion and function. PMID: 17637737
I think so. Besides, we also know that autophagosomes are also degraded by autophagy itself, so we can assume that the process is reversible.
You need to take care what you meat by 'irreversible' and 'reversible'. I am pretty sure that if autophagosome fuses with a lysosome, it cannot go backword in the sense that it could turn into an autophagosome again. In that sense, the fusion is irreversible. However, lysosomes obviously can reform from autolysosomes, as recent papers have shown (the so-called autophagic lysosome reformation).
A recent review on this topic:
Autophagic lysosome reformation.
Chen Y, Yu L.
Exp Cell Res. 2012 Sep 19. pii: S0014-4827(12)00396-5. doi: 10.1016/j.yexcr.2012.09.004. [Epub ahead of print]
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