title: Monoclonal antibodies that bind to the Ly6 domain of GPIHBP1 abolish the binding of LPL.
abstract: GPIHBP1, an endothelial cell protein, binds LPL in the interstitial spaces and shuttles it to its site of action inside blood vessels. For years, studies of human GPIHBP1 have been hampered by an absence of useful antibodies. We reasoned that monoclonal antibodies (mAbs) against human GPIHBP1 would be useful for 1) defining the functional relevance of GPIHBP1's Ly6 and acidic domains to the binding of LPL; 2) ascertaining whether human GPIHBP1 is expressed exclusively in capillary endothelial cells; and 3) testing whether GPIHBP1 is detectable in human plasma. Here, we report the development of a panel of human GPIHBP1-specific mAbs. Two mAbs against GPIHBP1's Ly6 domain, RE3 and RG3, abolished LPL binding, whereas an antibody against the acidic domain, RF4, did not. Also, mAbs RE3 and RG3 bound with reduced affinity to a mutant GPIHBP1 containing an Ly6 domain mutation (W109S) that abolishes LPL binding. Immunohistochemistry studies with the GPIHBP1 mAbs revealed that human GPIHBP1 is expressed only in capillary endothelial cells. Finally, we created an ELISA that detects GPIHBP1 in human plasma. That ELISA should make it possible for clinical lipidologists to determine whether plasma GPIHBP1 levels are a useful biomarker of metabolic or vascular disease.
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors.forename: Xuchen
authors.initials: X
authors.lastname: Hu
authors.affiliation: Monash Biomedicine Discovery Institute and Antibody Technologies Facility, Monash University, Victoria, Australia.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Sleeman
authors.affiliation: Department of Clinical Laboratory Medicine, Graduate School of Medicine, Gunma University, Maebashi, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Miyashita
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University Medical Center, Nashville, TN.
authors.forename: MacRae F
authors.initials: MF
authors.lastname: Linton
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Allan
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors.forename: Cuiwen
authors.initials: C
authors.lastname: He
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors.forename: Mikael
authors.initials: M
authors.lastname: Larsson
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Tu
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors.forename: Norma P
authors.initials: NP
authors.lastname: Sandoval
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Jung
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors.forename: Alaleh
authors.initials: A
authors.lastname: Mapar
authors.affiliation: Department of Clinical Laboratory Medicine, Graduate School of Medicine, Gunma University, Maebashi, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Machida
authors.affiliation: Department of Clinical Laboratory Medicine, Graduate School of Medicine, Gunma University, Maebashi, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Murakami
authors.affiliation: Department of Clinical Laboratory Medicine, Graduate School of Medicine, Gunma University, Maebashi, Japan.
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: Finsen Laboratory, Rigshospitalet, Copenhagen, Denmark.|Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Ploug
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA lfong@mednet.ucla.edu sgyoung@mednet.ucla.edu abeigneux@mednet.ucla.edu.
authors.forename: Loren G
authors.initials: LG
authors.lastname: Fong
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA lfong@mednet.ucla.edu sgyoung@mednet.ucla.edu abeigneux@mednet.ucla.edu.|Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Young
authors.affiliation: Departments of Medicine University of California Los Angeles, Los Angeles, CA lfong@mednet.ucla.edu sgyoung@mednet.ucla.edu abeigneux@mednet.ucla.edu.
authors.forename: Anne P
authors.initials: AP
authors.lastname: Beigneux
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001665:Binding Sites / Q000276:immunology; D002460:Cell Line; D004330:Drosophila; D042783:Endothelial Cells / Q000201:enzymology / Q000276:immunology; D006801:Humans; D008071:Lipoprotein Lipase / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000302:isolation & purification; D051379:Mice; D018110:Receptors, Lipoprotein / Q000235:genetics / Q000276:immunology*; D014280:Triglycerides / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; C523701:GPIHBP1 protein, human; D018110:Receptors, Lipoprotein; D014280:Triglycerides; D008071:Lipoprotein Lipase
keywords: chylomicrons; dyslipidemias; endothelial cells; lipoprotein lipase; triglycerides