NanoSIMS Analysis of Intravascular Lipolysis and Lipid Movement across Capillaries and into Cardiomyocytes

Publication date: 1 May 2018
Source:Cell Metabolism, Volume 27, Issue 5
Author(s): Cuiwen He, Thomas A. Weston, Rachel S. Jung, Patrick Heizer, Mikael Larsson, Xuchen Hu, Christopher M. Allan, Peter Tontonoz, Karen Reue, Anne P. Beigneux, Michael Ploug, Andrea Holme, Matthew Kilburn, Paul Guagliardo, David A. Ford, Loren G. Fong, Stephen G. Young, Haibo Jiang
The processing of triglyceride-rich lipoproteins (TRLs) in capillaries provides lipids for vital tissues, but our understanding of TRL metabolism is limited, in part because TRL processing and lipid movement have never been visualized. To investigate the movement of TRL-derived lipids in the heart, mice were given an injection of [²H]triglyceride-enriched TRLs, and the movement of ²H-labeled lipids across capillaries and into cardiomyocytes was examined by NanoSIMS. TRL processing and lipid movement in tissues were extremely rapid. Within 30 s, TRL-derived lipids appeared in the subendothelial spaces and in the lipid droplets and mitochondria of cardiomyocytes. Enrichment of ²H in capillary endothelial cells was not greater than in cardiomyocytes, implying that endothelial cells may not be a control point for lipid movement into cardiomyocytes. Remarkably, a deficiency of the putative fatty acid transport protein CD36, which is expressed highly in capillary endothelial cells, did not impede entry of TRL-derived lipids into cardiomyocytes.

Graphical abstract

Teaser

He et al. used NanoSIMS to visualize the movement of triglyceride-rich lipoprotein (TRL)-derived lipids in the heart. TRL-derived lipids moved across endothelial cells and into cardiomyocyte mitochondria and lipid droplets within seconds. Also, loss of CD36 did not impede entry of TRL-derived lipids into cardiomyocytes.


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