An SPNS1-dependent lysosomal lipid transport pathway that enables cell survival under choline limitation

SG Scharenberg, W Dong, A Ghoochani, K Nyame… - Science …, 2023 - science.org
Science Advances, 2023science.org
Lysosomes degrade macromolecules and recycle their nutrient content to support cell
function and survival. However, the machineries involved in lysosomal recycling of many
nutrients remain to be discovered, with a notable example being choline, an essential
metabolite liberated via lipid degradation. Here, we engineered metabolic dependency on
lysosome-derived choline in pancreatic cancer cells to perform an endolysosome-focused
CRISPR-Cas9 screen for genes mediating lysosomal choline recycling. We identified the …
Lysosomes degrade macromolecules and recycle their nutrient content to support cell function and survival. However, the machineries involved in lysosomal recycling of many nutrients remain to be discovered, with a notable example being choline, an essential metabolite liberated via lipid degradation. Here, we engineered metabolic dependency on lysosome-derived choline in pancreatic cancer cells to perform an endolysosome-focused CRISPR-Cas9 screen for genes mediating lysosomal choline recycling. We identified the orphan lysosomal transmembrane protein SPNS1 as critical for cell survival under choline limitation. SPNS1 loss leads to intralysosomal accumulation of lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE). Mechanistically, we reveal that SPNS1 is a proton gradient–dependent transporter of LPC species from the lysosome for their re-esterification into phosphatidylcholine in the cytosol. Last, we establish that LPC efflux by SPNS1 is required for cell survival under choline limitation. Collectively, our work defines a lysosomal phospholipid salvage pathway that is essential under nutrient limitation and, more broadly, provides a robust platform to deorphan lysosomal gene function.
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