Dataset Information

Rab18 is not necessary for lipid droplet biogenesis or turnover in human mammary carcinoma cells.

ABSTRACT: Rab GTPases recruit peripheral membrane proteins and can define organelle identity. Rab18 localizes to the endoplasmic reticulum (ER) but also to lipid droplets (LDs), where it has been implicated in effector protein recruitment and in defining LD identity. Here, we studied Rab18 localization and function in a human mammary carcinoma cell line. Rab18 localized to the ER and to LD membranes on LD induction, with the latter depending on the Rab18 activation state. In cells lacking Rab18, LDs were modestly reduced in size and numbers, but we found little evidence for Rab18 function in LD formation, LD turnover on cell starvation, or the targeting of several proteins to LDs. We conclude that Rab18 is not a general, necessary component of the protein machinery involved in LD biogenesis or turnover.

SUBMITTER: Jayson CBK

PROVIDER: S-EPMC6232964 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Rab18 is not necessary for lipid droplet biogenesis or turnover in human mammary carcinoma cells.

Jayson Christina B K CBK Arlt Henning H Fischer Alexander W AW Lai Zon Weng ZW Farese Robert V RV Walther Tobias C TC

Molecular biology of the cell 20180627 17

Rab GTPases recruit peripheral membrane proteins and can define organelle identity. Rab18 localizes to the endoplasmic reticulum (ER) but also to lipid droplets (LDs), where it has been implicated in effector protein recruitment and in defining LD identity. Here, we studied Rab18 localization and function in a human mammary carcinoma cell line. Rab18 localized to the ER and to LD membranes on LD induction, with the latter depending on the Rab18 activation state. In cells lacking Rab18, LDs were ...[more]

PMID: 29949452

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Project description:BackgroundClear cell renal cell carcinoma (ccRCC), the predominant subtype of kidney cancer, possesses characteristic alterations to multiple metabolic pathways, including the accumulation of cytosolic lipid droplets. However, the pathways that drive lipid droplet accumulation in ccRCC cells and their importance to cancer biology remain poorly understood.MethodsWe sought to identify the carbon sources necessary for lipid droplet accumulation using Oil red O staining and isotope-tracing lipidomics. The role of the acyl-CoA synthetase (ACSL) family members, an important group of lipid metabolic enzymes, was investigated using siRNA and drug mediated inhibition. CTB and XTT assays were performed to determine the effect of ACSL3 knockdown and lipid starvation on ccRCC cell viability and shRNA was used to study the effect of ACSL3 in an orthotopic mouse model. The relationship between ferroptosis susceptibility of ccRCC and ACSL3 controlled lipid metabolism was examined using CTB and FACS-based assays. The importance of 5-LOX in ferroptosis susceptibility in ccRCC was shown with XTT survival assays, and the expression level and predictive value of 5-LOX in TCGA ccRCC data was assessed.ResultsWe found that ccRCC cells obtain the necessary substrates for lipid droplet accumulation by metabolizing exogenous serum derived lipids and not through de novo lipogenesis. We show that this metabolism of exogenous fatty acids into lipid droplets requires the enzyme acyl-CoA synthetase 3 (ACSL3) and not other ACSL family proteins. Importantly, genetic or pharmacologic suppression of ACSL3 is cytotoxic to ccRCC cells in vitro and causes a reduction of tumor weight in an orthotopic mouse model. Conversely, ACSL3 inhibition decreases the susceptibility of ccRCC cells to ferroptosis, a non-apoptotic form of cell death involving lipid peroxidation. The sensitivity of ccRCC to ferroptosis is also highly dependent on the composition of exogenous fatty acids and on 5-lipoxygenase (5-LOX), a leukotriene producing enzyme which produces lipid peroxides that have been implicated in other cancers but not in ccRCC.ConclusionsACSL3 regulates the accumulation of lipid droplets in ccRCC and is essential for tumor growth. In addition, ACSL3 also modulates ferroptosis sensitivity in a manner dependent on the composition of exogenous fatty acids. Both functions of ACSL3 could be exploited for ccRCC therapy.

Dataset Information

Rab18 is not necessary for lipid droplet biogenesis or turnover in human mammary carcinoma cells.

Publications

Rab18 is not necessary for lipid droplet biogenesis or turnover in human mammary carcinoma cells.

Similar Datasets

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