Membrane organization and intracellular transport of a fluorescent analogue of 27-hydroxycholesterol

Maria Szomek, Laust Moesgaard, Peter Reinholdt, Sophia Bell Haarhøj Hald, Daniel Petersen, Kathiresan Krishnan, Douglas F. Covey, Jacob Kongsted, Daniel Wüstner

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Oxysterols are cholesterol metabolites with multiple functions in controlling cellular homeostasis. In particular, 27-hydroxycholesterol (27-OH-Chol) has been shown to regulate a variety of physiological functions, but little is known about its uptake, intracellular trafficking, and efflux from cells. This is largely due to a lack of suitable analogs of 27-OH-Chol, which mimic this oxysterol closely. Here, we present the intrinsically fluorescent 27-hydroxy-cholestatrienol (27-OH-CTL), which differs from 27-OH-Chol only by having two additional double bonds in the steroid ring system. Based on molecular dynamics (MD) simulations, we show that 27-OH-CTL possesses almost identical membrane properties compared to 27-OH-Chol. By comparative imaging of 27-OH-CTL and of the cholesterol analogue cholestatrienol (CTL) in living cells, we assess the impact of a single hydroxy group on sterol trafficking. We find that human fibroblasts take up more CTL than 27-OH-CTL, but efflux the oxysterol analogue more efficiently. For both sterols, efflux includes shedding of vesicles from the plasma membrane. Intracellular, 27-OH-CTL accumulates primarily in lipid droplets (LDs), while CTL is mostly found in endosomes and lysosomes. Using fluorescence recovery after photobleaching (FRAP), we find for both sterols a rapidly exchanging pool, which moves orders of magnitude faster than sterol containing vesicles and LDs. In summary, by applying a new fluorescent derivative of 27-OH-Chol we demonstrate that human cells can distinguish sterols based on a single hydroxy group in the side chain, resulting in different transport itineraries, dynamics, and efflux kinetics. Both intrinsically fluorescent cholesterol and oxysterol analogues show rapid non-vesicular transport in human fibroblasts.

Original languageEnglish
Article number105004
JournalChemistry and Physics of Lipids
Volume233
DOIs
StatePublished - Nov 2020

Keywords

  • Cholesterol
  • Fluorescence
  • Livecell imaging
  • Molecular dynamics
  • Non-vesicular transport
  • Oxysterol
  • Probes
  • Quantum calculations
  • Single-cell
  • Spectroscopy
  • Synthesis

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