Abstract
Low‐density lipoprotein (LDL)‐cholesterol delivery from late endosomes to the plasma membrane regulates focal adhesion dynamics and cell migration, but the mechanisms controlling it are poorly characterized. Here, we employed auxin‐inducible rapid degradation of oxysterol‐binding protein‐related protein 2 (ORP2/OSBPL2) to show that endogenous ORP2 mediates the transfer of LDL‐derived cholesterol from late endosomes to focal adhesion kinase (FAK)‐/integrin‐positive recycling endosomes in human cells. In vitro, cholesterol enhances membrane association of FAK to PI(4,5)P2‐containing lipid bilayers. In cells, ORP2 stimulates FAK activation and PI(4,5)P2 generation in endomembranes, enhancing cell adhesion. Moreover, ORP2 increases PI(4,5)P2 in NPC1‐containing late endosomes in a FAK‐dependent manner, controlling their tubulovesicular trafficking. Together, these results provide evidence that ORP2 controls FAK activation and LDL‐cholesterol plasma membrane delivery by promoting bidirectional cholesterol/PI(4,5)P2 exchange between late and recycling endosomes.
Highlights
Mammalian cells acquire cholesterol, a vital component of cell membranes, via receptor-mediated uptake of low-density lipoprotein (LDL) (Brown & Goldstein, 1986; Ikonen, 2008)
Niemann–Pick C1 (NPC1)-GFP-expressing cells were loaded with 2 lg/mL integrin b1 antibody for 30 min before fixation and stained with pFAK antibody followed by secondary antibodies
We found that rapidly after becoming accessible in NPC1 organelles, LDL-cholesterol becomes accessible in integrin recycling organelles
Summary
A vital component of cell membranes, via receptor-mediated uptake of low-density lipoprotein (LDL) (Brown & Goldstein, 1986; Ikonen, 2008). The LDL-derived cholesterol is transported to the plasma membrane (PM), to serve a structural role as a major PM constituent. Cholesterol hydrolyzed from LDL in endo-lysosomes adds to the accessible PM cholesterol pool (Das et al, 2014). We have reported that NPC1 organelles and LDL-cholesterol are transported toward the cell periphery via Rab8a-MyosinVb-actindependent membrane trafficking (Kanerva et al, 2013). This route delivers LDL-cholesterol to the PM in the proximity of focal adhesions (FAs), stimulating FA dynamics and cell migration (Kanerva et al, 2013). The available evidence indicates that cholesterol modulates membrane order in integrinmediated adhesion sites (Gaus et al, 2006; Lietha & Izard, 2020) and affects integrin recycling pathways (Reverter et al, 2014)
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