Online Poster Portal

  • Author
    Xuchen Hu
  • Co-author

  • Title

    GPIHBP1 expression in gliomas promotes utilization of lipoprotein-derived nutrients

  • Abstract

    GPIHBP1, a glycolipid-anchored protein of capillary endothelial cells, binds lipoprotein lipase (LPL) in the interstitial spaces (where it is secreted by parenchymal cells) and transports it to its site of action in the capillary lumen. The presence of GPIHBP1-bound LPL on the luminal surface of capillaries is essential for the margination of triglyceride-rich lipoproteins (TRLs). In the absence of GPIHBP1, LPL never reaches the capillary lumen, and TRLs never stop along capillaries. The lipolytic processing of TRLs by the LPL–GPIHBP1 complex releases fatty acids for uptake and utilization by vital tissues such as the heart. GPIHBP1 is expressed in capillary endothelial cells of nearly all peripheral tissues, with the highest levels in striated muscle and adipose tissue. Interestingly, GPIHBP1 is not expressed in capillaries of the brain, which largely relies on glucose for fuel. While GPIHBP1 is not expressed in the normal brain, we suspected that it might be expressed in gliomas, a devastating brain tumor in which capillaries are morphologically abnormal and where the blood–brain barrier is often defective. We took advantage of monoclonal antibodies against GPIHBP1 to determine whether GPIHBP1 is expressed in gliomas. We found that GPIHBP1 is absent in capillaries of mouse and human brain, but that it is easily detectable in capillary endothelial cells of mouse and human gliomas. Importantly, the GPIHBP1 in glioma capillaries captures locally produced LPL. We document, by NanoSIMS imaging, that TRLs marginate along glioma capillaries and that there is uptake of TRL-derived lipid nutrients by surrounding glioma cells. Thus, GPIHBP1 expression in gliomas facilitates TRL processing and provides a source of lipid nutrients for glioma cells.

  • College


  • Zoom

  • PDF