A Molecular Probe for the Detection of Polar Lipids in Live Cells

PLoS One. 2016 Aug 23;11(8):e0161557. doi: 10.1371/journal.pone.0161557. eCollection 2016.

Abstract

Lipids have an important role in many aspects of cell biology, including membrane architecture/compartment formation, intracellular traffic, signalling, hormone regulation, inflammation, energy storage and metabolism. Lipid biology is therefore integrally involved in major human diseases, including metabolic disorders, neurodegenerative diseases, obesity, heart disease, immune disorders and cancers, which commonly display altered lipid transport and metabolism. However, the investigation of these important cellular processes has been limited by the availability of specific tools to visualise lipids in live cells. Here we describe the potential for ReZolve-L1™ to localise to intracellular compartments containing polar lipids, such as for example sphingomyelin and phosphatidylethanolamine. In live Drosophila fat body tissue from third instar larvae, ReZolve-L1™ interacted mainly with lipid droplets, including the core region of these organelles. The presence of polar lipids in the core of these lipid droplets was confirmed by Raman mapping and while this was consistent with the distribution of ReZolve-L1™ it did not exclude that the molecular probe might be detecting other lipid species. In response to complete starvation conditions, ReZolve-L1™ was detected mainly in Atg8-GFP autophagic compartments, and showed reduced staining in the lipid droplets of fat body cells. The induction of autophagy by Tor inhibition also increased ReZolve-L1™ detection in autophagic compartments, whereas Atg9 knock down impaired autophagosome formation and altered the distribution of ReZolve-L1™. Finally, during Drosophila metamorphosis fat body tissues showed increased ReZolve-L1™ staining in autophagic compartments at two hours post puparium formation, when compared to earlier developmental time points. We concluded that ReZolve-L1™ is a new live cell imaging tool, which can be used as an imaging reagent for the detection of polar lipids in different intracellular compartments.

MeSH terms

  • Adipocytes
  • Adipose Tissue / metabolism
  • Amino Acids / metabolism
  • Animals
  • Autophagy
  • Biological Transport
  • Carbohydrate Metabolism
  • Cell Physiological Phenomena*
  • Drosophila
  • Lipid Droplets / metabolism
  • Lipid Metabolism*
  • Lipids* / chemistry
  • Metamorphosis, Biological
  • Mice
  • Molecular Probes*
  • Spectrum Analysis, Raman
  • Staining and Labeling

Substances

  • Amino Acids
  • Lipids
  • Molecular Probes

Grants and funding

This work was supported by funding from the University of South Australia, an ITEK catalyst grant and a BioSA Innovation grant awarded to DAB, SP and MM. This work was co-funded by an NHMRC development grant (APP1092904) and the ARC (FT1301000033 to MM) and (DP130103566 and DP140100176 to PAL). We are also grateful for an ARC LIEF grant (LE0560680) and University of Sydney NHMRC equipment grants for the Raman Spectrometer. Ramaciotti Foundation is thanked for financing the use of AMNIS imaging flow cytometer at University of South Australia. We confirm that the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.