Molecular cloning of nonsecreted endothelial cell-derived lipase isoforms.
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.
Ishida
Tatsuro
T
Donald W. Reynolds Cardiovascular Clinical Research Center, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.
Zheng
Zhi
Z
Dichek
Helén L
HL
Wang
Huijian
H
Moreno
Ismael
I
Yang
Eugene
E
Kundu
Ramendra K
RK
Talbi
Said
S
Hirata
Ken-ichi
K
Leung
Lawrence L
LL
Quertermous
Thomas
T
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
D007527:Isoenzymes; D012333:RNA, Messenger; D011994:Recombinant Proteins; C410382:LIPG protein, human; D008049:Lipase