In vitro and in vivo assay of the ER lipid scramblase TMEM41B

Wu, Lingzhi; Liu, Lu; Xu, Bing; Huang, Dong; Chen, Xiao Wei

doi:10.1016/j.xpro.2022.101333

Cited by 1 publication

(1 citation statement)

References 21 publications

(39 reference statements)

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“…To test the afore-described spatial regulation by CLCC1 may impact phospholipid equilibration at the ER membrane, we employed a cell-based chemical biology assay 31 , wherein defective in vivo phospholipid scrambling across the ER bilayer would result in an accumulation of alkyne-labeled phosphatidylcholine (PC) in cells (Extended Data Figure 5b). Loss of the TMEM41B scramblase in cells caused PC accumulation (Figure 3h), as expected.…”

Section: Leaflet Imbalance Directs Lipids Into Giant Er-enclosed Lipi...mentioning

confidence: 99%

CLCC1 Governs Bilayer Equilibration at the Endoplasmic Reticulum to Maintain Cellular and Systemic Lipid Homeostasis

Wu,

Wang,

Wang

et al. 2024

Preprint

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The intricate orchestration of lipid production, storage, and mobilization is vital for cellular and systemic homeostasis1,2. Dysfunctional plasma lipid control represents the major risk factor for cardio-metabolic diseases, the leading cause of human mortality3,4. Within the cellular landscape, the endoplasmic reticulum (ER) is the central hub of lipid synthesis and secretion, particularly in metabolically active hepatocytes in the liver or enterocytes in the gut5,6. Initially assembled in the ER lumen, lipid-ferrying lipoproteins necessitate the cross-membrane transfer of both neutral and phospho-lipids onto the lumenal apolipoprotein B (APOB), in a poorly-defined process7–10. Here we show that trans-bilayer equilibration of phospholipids, regulated by the ER protein CLCC1, determines lipid partition across the ER membrane and consequently systemic lipid homeostasis. CLCC1 partners with the phospholipid scramblase TMEM41B11,12to recognize imbalanced bilayers and promote lipid scrambling, thereby licensing lipoprotein biogenesis and the subsequent bulk lipid transport. Strikingly, loss of CLCC1 or TMEM41B leads to the emergence of giant lumenal lipid droplets enclosed by extensively imbalanced ER bilayers, and consequently drastically accelerated pathogenesis of metabolic-dysfunction-associated liver steatohepatitis (MASH). The above results establish phospholipid scrambling at the ER as the lynchpin to maintain a dynamic equilibrium. Considering the requirement of trans-bilayer phospholipid equilibration in numerous biological processes, ranging from catabolic autophagy to viral infection13–16, our study may enable further elucidation of a previously under-appreciated homeostatic control mechanism intrinsic to the ER function in lipid biogenesis and distribution.

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Section: Leaflet Imbalance Directs Lipids Into Giant Er-enclosed Lipi...mentioning

confidence: 99%