Septin 9 and phosphoinositides regulate lysosome localization and their association with lipid droplets.
iScience 2022;
25:104288. [PMID:
35573204 PMCID:
PMC9097704 DOI:
10.1016/j.isci.2022.104288]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 12/21/2021] [Accepted: 04/20/2022] [Indexed: 11/23/2022] Open
Abstract
The accumulation of lipid droplets (LDs) in the liver is a hallmark of steatosis, which is often associated with lysosomal dysfunction. Nevertheless, the underlying mechanisms remain unclear. Here, using Huh7 cells loaded with oleate as a model to study LD metabolism, we show that cellular content and distribution of LDs are correlated with those of the lysosome and regulated by oleate and septin 9. High expression of septin 9 promotes perinuclear clustering of lysosomes which co-localized with Golgi and not with their surrounding LDs. On the other hand, knockdown of septin 9 disperses the two organelles which colocalize at the cell periphery. The Rab7 is present around these peripheral LDs. PtdIns5P which binds septin 9 and MTMR3 which converts PtdIns(3,5)P2 into PtdIns(5) recapitulates the effects of septin 9. By contrast, PtdIns(3,5)P2 promotes LD/lysosome co-localization. Overall, our data reveal a phosphoinositide/septin 9-dependent mechanism that regulates LD behavior through the control of their association with lysosomes.
Septin 9 is regulates oleate-induced lysosome perinuclear clustering
Septin 9 and MTs regulate oleate-induced lysosome co-localization with Golgi
LDs with high septin 9 have less interaction with Rab7 and LAMP1
PIs have specific effects on LD and lysosome
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