RT Journal Article
SR Electronic
T1 Lysosome enlargement during inhibition of the lipid kinase PIKfyve proceeds through lysosome coalescence
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 295246
DO 10.1101/295246
A1 Christopher H. Choy
A1 Golam Saffi
A1 Matthew A. Gray
A1 Callen Wallace
A1 Roya M. Dayam
A1 Zhen-Yi A. Ou
A1 Guy Lenk
A1 Rosa Puertollano
A1 Simon C. Watkins
A1 Roberto J. Botelho
YR 2018
UL http://biorxiv.org/content/early/2018/04/05/295246.abstract
AB Lysosomes receive and degrade cargo from endocytosis, phagocytosis and autophagy. They also play an important role in sensing and instructing cells on their metabolic state. The lipid kinase PIKfyve generates phosphatidylinositol-3,5-bisphosphate to modulate lysosome function. PIKfyve inhibition leads to impaired degradative capacity, ion dysregulation, abated autophagic flux, and a massive enlargement of lysosomes. Collectively, this leads to various physiological defects including embryonic lethality, neurodegeneration and overt inflammation. While being the most dramatic phenotype, the reasons for lysosome enlargement remain unclear. Here, we examined whether biosynthesis and/or fusion-fission dynamics contribute to swelling. First, we show that PIKfyve inhibition activates TFEB, TFE3 and MITF enhancing lysosome gene expression. However, this did not augment lysosomal protein levels during acute PIKfyve inhibition and deletion of TFEB and/or related proteins did not impair lysosome swelling. Instead, PIKfyve inhibition led to fewer but enlarged lysosomes, suggesting that an imbalance favouring lysosome fusion over fission causes lysosome enlargement. Indeed, conditions that abated fusion curtailed lysosome swelling in PIKfyve-inhibited cells.Summary statement PIKfyve inhibition causes lysosomes to coalesce, resulting in fewer, enlarged lysosomes. We also show that TFEB-mediated lysosome biosynthesis does not contribute to swelling.DICDifferential interference contrastDMSODimethyl sulfoxideLYLucifer yellowMEFsmouse embryonic fibroblastsPtdInsPphosphoinositidesPtdIns(3)Pphosphatidylinositol-3-phosphatePtdIns(3,5)P2phosphatidylinositol-3,5-bisphosphateSTDstandard deviationSEMstandard error of the mean