Lipoprotein lipase reaches the capillary lumen in chickens despite an apparent absence of GPIHBP1
Cuiwen He, Xuchen Hu, Rachel S. Jung, Mikael Larsson, Yiping Tu, Sandra Duarte-Vogel, Paul Kim, Norma P. Sandoval, Tara R. Price, Christopher M. Allan, Brian Raney, Haibo Jiang, André Bensadoun, Rosemary L. Walzem, Richard I. Kuo, Anne P. Beigneux, Loren G. Fong, Stephen G. Young
Cuiwen He, Xuchen Hu, Rachel S. Jung, Mikael Larsson, Yiping Tu, Sandra Duarte-Vogel, Paul Kim, Norma P. Sandoval, Tara R. Price, Christopher M. Allan, Brian Raney, Haibo Jiang, André Bensadoun, Rosemary L. Walzem, Richard I. Kuo, Anne P. Beigneux, Loren G. Fong, Stephen G. Young
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Research Article Metabolism

Lipoprotein lipase reaches the capillary lumen in chickens despite an apparent absence of GPIHBP1

Abstract

In mammals, GPIHBP1 is absolutely essential for transporting lipoprotein lipase (LPL) to the lumen of capillaries, where it hydrolyzes the triglycerides in triglyceride-rich lipoproteins. In all lower vertebrate species (e.g., birds, amphibians, reptiles, fish), a gene for LPL can be found easily, but a gene for GPIHBP1 has never been found. The obvious question is whether the LPL in lower vertebrates is able to reach the capillary lumen. Using purified antibodies against chicken LPL, we showed that LPL is present on capillary endothelial cells of chicken heart and adipose tissue, colocalizing with von Willebrand factor. When the antibodies against chicken LPL were injected intravenously into chickens, they bound to LPL on the luminal surface of capillaries in heart and adipose tissue. LPL was released rapidly from chicken hearts with an infusion of heparin, consistent with LPL being located inside blood vessels. Remarkably, chicken LPL bound in a specific fashion to mammalian GPIHBP1. However, we could not identify a gene for GPIHBP1 in the chicken genome, nor could we identify a transcript for GPIHBP1 in a large chicken RNA-seq data set. We conclude that LPL reaches the capillary lumen in chickens — as it does in mammals — despite an apparent absence of GPIHBP1.

Authors

Cuiwen He, Xuchen Hu, Rachel S. Jung, Mikael Larsson, Yiping Tu, Sandra Duarte-Vogel, Paul Kim, Norma P. Sandoval, Tara R. Price, Christopher M. Allan, Brian Raney, Haibo Jiang, André Bensadoun, Rosemary L. Walzem, Richard I. Kuo, Anne P. Beigneux, Loren G. Fong, Stephen G. Young

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Figure 8

Wild-type chicken lipoprotein lipase (cLPL-wt), but not a mutant cLPL with a p.C420Y mutation, binds to GPIHBP1.

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Wild-type chicken lipoprotein lipase (cLPL-wt), but not a mutant cLPL wi...
CHO pgsA-745 cells were transiently transfected with S-protein–tagged wild-type human (h) or mouse (m) GPIHBP1 (or hGPIHBP1-W109S or mGPIHBP1-W108S) and coplated with cells that had been transfected with V5-tagged versions of cLPL (wt or C420Y). Immunocytochemistry studies were performed on permeabilized and nonpermeabilized cells with a goat antibody against the S-protein tag (red) and a mouse monoclonal antibody against the V5 tag (green). DNA was stained with DAPI (blue). (A) Immunocytochemistry studies showing that cLPL-wt bound avidly to neighboring CHO cells expressing wild-type hGPIHBP1 (hence cLPL-wt colocalized with hGPIHBP1), whereas cLPL-C420Y had no capacity to bind to cells expressing wild-type hGPIHBP1 (no colocalization). Cells expressing hGPIHBP1-W109S did not bind cLPL-wt. (B) Immunocytochemistry studies showing that cLPL-wt bound avidly to CHO cells expressing wild-type mGPIHBP1 (colocalization), while LPL-C420Y had no capacity to bind to cells expressing wild-type mGPIHBP1 (no colocalization). Cells expressing mGPIHBP1-W108S did not bind cLPL-wt. Scale bars: 20 μm.