Differential tissue-specific expression of human apoA-I and apoA-II

• Published in: Journal of lipid research 1991-05, Vol.32 (5), p.821-828
• Main Authors: EGGERMAN, T. L, HOEG, J. M, MENG, M. S, TOMBRAGEL, A, BOJANOVSKI, D, BREWER, H. B
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Apolipoprotein A-I; Apolipoprotein A-II; Apolipoproteins A - biosynthesis; Apolipoproteins A - genetics; Biological and medical sciences; Blotting, Northern; Carcinoma, Hepatocellular; DNA Probes; Fundamental and applied biological sciences. Psychology; Humans; Intestinal Mucosa - metabolism; Intestinal Neoplasms; Intestine, Small - metabolism; Lipoproteins, myelin; Liver - metabolism; Liver Neoplasms; Organ Culture Techniques; Organ Specificity; Proteins; RNA, Messenger - biosynthesis; Tumor Cells, Cultured
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1016/S0022-2275(20)42034-6

To evaluate the sources of high density lipoprotein (HDL) particles containing only apolipoprotein A-I (apoA-I), the synthesis of apoA-I and apolipoprotein A-II (apoA-II) was examined in human liver and small intestine as well as the human intestinally derived cell line, Caco-2. Human liver contained apoA-I, apoA-II as well as apolipoprotein B (apoB) mRNA. In contrast, human adult small intestine total and polyA+ RNA had little or no apoA-II despite the presence of apoA-I and apoB. Intestinal biopsies from normal individuals failed to show de novo apoA-II protein synthesis in the media of organ cultures during [35S]methionine pulse-chase labeling, whereas apoA-I could be readily detected. Caco-2 cells contained apoA-II mRNA and secreted apoA-II protein into the tissue culture media. These data indicate that the primary site of human apoA-II synthesis is in the liver and that the small intestine secretes apoA-I-containing high density lipoproteins.