title: Molecular cloning of nonsecreted endothelial cell-derived lipase isoforms.
abstract: To expand our knowledge of factors involved in lipid metabolism in the blood vessel wall, we have cloned unique molecular isoforms of endothelial cell-derived lipase (EDL) (HGMW-approved symbol/LIPG). One isoform encoded a truncated protein (EDL2a) lacking the first 80 amino acid residues of the previously characterized EDL1a isoform, including the signal peptide. A similar second clone (EDL2b) was identified that lacked not only the first 80 amino acids, but also a 74-amino-acid region that encodes a portion of the lid domain. RT-PCR analysis confirmed expression of EDL2a/2b isoforms in several human tissues and cultured cells, including endothelial cells. Western blot and immunofluorescence studies using stable transfectants revealed that EDL2a and EDL2b were localized in the cytosol, while, EDL1a was secreted into the culture medium. Cell extracts of EDL2a/2b transfectants did not have triglyceride or phospholipase activity. Thus endothelial cells express three EDL isoforms, two of which remain intracellular and do not function as lipases.
authors.affiliation: Donald W. Reynolds Cardiovascular Clinical Research Center, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Ishida
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zheng
authors.forename: Helén L
authors.initials: HL
authors.lastname: Dichek
authors.forename: Huijian
authors.initials: H
authors.lastname: Wang
authors.forename: Ismael
authors.initials: I
authors.lastname: Moreno
authors.forename: Eugene
authors.initials: E
authors.lastname: Yang
authors.forename: Ramendra K
authors.initials: RK
authors.lastname: Kundu
authors.forename: Said
authors.initials: S
authors.lastname: Talbi
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Hirata
authors.forename: Lawrence L
authors.initials: LL
authors.lastname: Leung
authors.forename: Thomas
authors.initials: T
authors.lastname: Quertermous
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D003600:Cytosol / Q000201:enzymology; D042783:Endothelial Cells / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D008049:Lipase / Q000235:genetics* / Q000378:metabolism; D050356:Lipid Metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014162:Transfection
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D011994:Recombinant Proteins; C410382:LIPG protein, human; D008049:Lipase