The size of cytoplasmic lipid droplets varies between tumour cell lines of the nervous system: a 1H NMR spectroscopy study
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Cytoplasmic lipid droplets (LDs) are dynamic cellular organelles; their accumulation is associated with several cellular processes, such as cell proliferation, apoptosis and necrosis. 1H Nuclear Magnetic Resonance (NMR) spectroscopy detects resonances from lipids present in cytoplasmic (LDs); an understanding of the relationship between LD characteristics and NMR lipid signals is important.
Materials and methods
In this study, five nervous system cancer cell lines were investigated. Nile red staining was used to measure the diameter of LDs. High-resolution magic angle spinning NMR (HR-MAS) was performed on harvested cell pellets to quantify the patterns of lipid signals.
LDs were present in all five cell lines with different morphology. An average LD diameter of approximately 0.2 μm was found in all cell types. Diameter of the largest LDs varied across the cell lines. The intensity of NMR lipid signals varied greatly between cell types, and a good correlation was found between total volume of LDs and the proton NMR lipid signal intensity at 0.9 and 1.3 ppm.
The correlation implied that little NMR signal is detected from LDs of diameters less than approximately 0.34 μm, most likely due to restriction of rotational motion of the lipids.
KeywordsLipid droplets Size NMR lipid signal
1H NMR experiments were carried out in the Henry Wellcome Building for Biomolecular NMR Spectroscopy at the University of Birmingham and we are grateful for the support of the staff at this facility. The work was partly funded by the Medical Research Council, UK (Grant G0601327), the Andrew McCartney Trust Fund for Brain Tumor Research, Birmingham Children’s Hospital Research Foundation and the Brain and Nervous System Tumor Research Fund.
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