A new mechanism for the regulation of autophagy degradation by phase change during the development of online worm embryos is revealed.

On August 30, Cell magazine published online a research paper by Zhang Hong's research group of the Institute of Biophysics of the Chinese Academy of Sciences mTOR regulates separation of PGL granules to modulate their autophagic degradation, revealing a new mechanism by mTOR to control its autophage degradation during the development of online worm embryos.
-cell autophagy is a highly conservative degradation pathway in eukurical organisms, which refer to cells that wrap autophagy substrates and transport them to lysosomes by forming autophagy cells that form a double-layer membrane structure.
cell autophagy selectively degrades protein aggregates to maintain a steady-state cell balance.
Zhang Hong's team previously found that in the development of online worm embryos, the components PGL-1 and PGL-3 from the P particles of the egg cells were selectively degraded by the autophagy of the cells in the somatic cells, and SEPA-1 was mediated by the receptor protein (Zhang et al., Cell 2009). further studies
found that EPG-2 plays an important function in this process as a stent protein (Tian et al., Cell 2010), and that selective degradation of PGL-1 and PGL-3 is also regulated by the methyl enzyme EPG-11 (Li et al., Cell 2013) and its own component concentration (Zhang et al., Autophagy 2017).
however, the degradation mechanism of PGL particles and how the receptor protein and stent protein function during the degradation process are not clear.
Zhang Hong's team has long found that PGL particles are assembled by liquid-phase separation (liquid-phase separation, LLPS), and the size and biophysical properties of PGL particles determine their autophagy degradation efficiency.
receptor protein SEPA-1 promotes phase change in PGL-1/-3, and stent protein EPG-2 controls the size of PGL-1/-3 and promotes their transformation from liquid to hydrogel state.
in high temperature environments, mTOR-mediated PGL-1/-3 phosphorylation levels are enhanced, accelerating the phase change of PGL-1/-3 and preventing them from being self-degraded by autophagy.
accumulated PGL particles are necessary for the normal development of nematode embryos under heat stress.
this work reveals a new mechanism for mTOR as a receptor to feel heat stress by regulating the phase change of PGL particles to control their autophagy degradation and protect the nematodes from heat stress.
the work was completed by Zhang Hong's team.
Zhang Hong is the communication author of the article, Zhang Hong's team doctoral student Zhang Gangming is the first author of the article, Zhang Hong's group of associate researcher Wang Qi and the Chinese Academy of Sciences Institute of Genetics and Developmental Biology researcher Du Xuan also participated in the study.
the project was funded by the Leading Class B project of the Chinese Academy of Sciences, the National Natural Science Foundation of China, the National Key Research and Development Program Project and the Frontier Science Focus Research Program.
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