Abstract
Lecithin cholesterol acyltransferase (LCAT) is an enzyme involved in the intravascular metabolism of high density lipoproteins (HDLs). Overexpression of human LCAT (hLCAT) in transgenic rabbits leads to gene dose-dependent increases of total and HDL cholesterol concentrations. To elucidate the mechanisms responsible for this effect, 131I-HDL apoA-I kinetics were assessed in age- and sex-matched groups of rabbits (n=3 each) with high, low, or no hLCAT expression. Mean total and HDL cholesterol concentrations (mg/dl), respectively, were 162+/-18 and 121+/-12 for high expressors (HE), 55+/-6 and 55+/-10 for low expressors (LE), and 29+/-2 and 28+/-4 for controls. Fast protein liquid chromatography analysis of plasma revealed that the HDL of both HE and LE were cholesteryl ester and phospholipid enriched, as compared with controls, with the greatest differences noted between HE and controls. These compositional changes resulted in an incremental shift in apparent HDL particle size which correlated directly with the level of hLCAT expression, such that HE had the largest HDL particles and controls the smallest. In vivo kinetic experiments demonstrated that the fractional catabolic rate(FCR, d(-1)) of apoA-I was slowest in HE (0.328+/-0.03) followed by LE (0.408+/-0.01) and, lastly, by controls (0.528+/-0.04). ApoA-I FCR was inversely associated with HDL cholesterol level (r=-0.851,P<0.01) and hLCAT activity (r=-0.816, P<0.01). These data indicate that fractional catabolic rate is the predominant mechanism by which hLCAT overexpression differentially modulates HDL concentrations in this animal model. We hypothesize that LCAT-induced changes in HDL composition and size ultimately reduce apoA-I catabolism by altering apoA-I conformation and/or HDL particle regeneration.
Full Text
The Full Text of this article is available as a PDF (206.2 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Albers J. J., Adolphson J. L., Chen C. H. Radioimmunoassay of human plasma lecithin-cholesterol acyltransferase. J Clin Invest. 1981 Jan;67(1):141–148. doi: 10.1172/JCI110006. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Albers J. J., Bergelin R. O., Adolphson J. L., Wahl P. W. Population-based reference values for lecithin-cholesterol acyltransferase (LCAT). Atherosclerosis. 1982 Jun;43(2-3):369–379. doi: 10.1016/0021-9150(82)90036-3. [DOI] [PubMed] [Google Scholar]
- Albers J. J., Chen C. H., Adolphson J. L. Lecithin:cholesterol acyltransferase (LCAT) mass; its relationship to LCAT activity and cholesterol esterification rate. J Lipid Res. 1981 Nov;22(8):1206–1213. [PubMed] [Google Scholar]
- Barter P. J., Hopkins G. J., Gorjatschko L. Lipoprotein substrates for plasma cholesterol esterification. Influence of particle size and composition of the high density lipoprotein subfraction 3. Atherosclerosis. 1985 Dec;58(1-3):97–107. doi: 10.1016/0021-9150(85)90058-9. [DOI] [PubMed] [Google Scholar]
- Brinton E. A., Eisenberg S., Breslow J. L. A low-fat diet decreases high density lipoprotein (HDL) cholesterol levels by decreasing HDL apolipoprotein transport rates. J Clin Invest. 1990 Jan;85(1):144–151. doi: 10.1172/JCI114405. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brinton E. A., Eisenberg S., Breslow J. L. Elevated high density lipoprotein cholesterol levels correlate with decreased apolipoprotein A-I and A-II fractional catabolic rate in women. J Clin Invest. 1989 Jul;84(1):262–269. doi: 10.1172/JCI114149. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brinton E. A., Eisenberg S., Breslow J. L. Human HDL cholesterol levels are determined by apoA-I fractional catabolic rate, which correlates inversely with estimates of HDL particle size. Effects of gender, hepatic and lipoprotein lipases, triglyceride and insulin levels, and body fat distribution. Arterioscler Thromb. 1994 May;14(5):707–720. doi: 10.1161/01.atv.14.5.707. [DOI] [PubMed] [Google Scholar]
- Brinton E. A., Eisenberg S., Breslow J. L. Increased apo A-I and apo A-II fractional catabolic rate in patients with low high density lipoprotein-cholesterol levels with or without hypertriglyceridemia. J Clin Invest. 1991 Feb;87(2):536–544. doi: 10.1172/JCI115028. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Børresen A. L., Kindt T. J., Berg K. Partial purification and characterization of the inherited Hl 1 and R 67 antigens of rabbit serum high density lipoprotein. J Immunogenet. 1978 Apr;5(2):71–86. doi: 10.1111/j.1744-313x.1978.tb00633.x. [DOI] [PubMed] [Google Scholar]
- Castro G. R., Fielding C. J. Early incorporation of cell-derived cholesterol into pre-beta-migrating high-density lipoprotein. Biochemistry. 1988 Jan 12;27(1):25–29. doi: 10.1021/bi00401a005. [DOI] [PubMed] [Google Scholar]
- Chapman M. J. Animal lipoproteins: chemistry, structure, and comparative aspects. J Lipid Res. 1980 Sep;21(7):789–853. [PubMed] [Google Scholar]
- Clay M. A., Hopkins G. J., Ehnholm C. P., Barter P. J. The rabbit as an animal model of hepatic lipase deficiency. Biochim Biophys Acta. 1989 Apr 3;1002(2):173–181. doi: 10.1016/0005-2760(89)90284-1. [DOI] [PubMed] [Google Scholar]
- Fielding C. J., Shore V. G., Fielding P. E. A protein cofactor of lecithin:cholesterol acyltransferase. Biochem Biophys Res Commun. 1972 Feb 25;46(4):1493–1498. doi: 10.1016/0006-291x(72)90776-0. [DOI] [PubMed] [Google Scholar]
- Fielding C. J. The origin and properties of free cholesterol potential gradients in plasma, and their relation to atherogenesis. J Lipid Res. 1984 Dec 15;25(13):1624–1628. [PubMed] [Google Scholar]
- Fielding P. E., Kawano M., Catapano A. L., Zoppo A., Marcovina S., Fielding C. J. Unique epitope of apolipoprotein A-I expressed in pre-beta-1 high-density lipoprotein and its role in the catalyzed efflux of cellular cholesterol. Biochemistry. 1994 Jun 7;33(22):6981–6985. doi: 10.1021/bi00188a030. [DOI] [PubMed] [Google Scholar]
- Forte T. M., Carlson L. A. Electron microscopic structure of serum lipoproteins from patients with fish eye disease. Arteriosclerosis. 1984 Mar-Apr;4(2):130–137. doi: 10.1161/01.atv.4.2.130. [DOI] [PubMed] [Google Scholar]
- Forte T., Norum K. R., Glomset J. A., Nichols A. V. Plasma lipoproteins in familial lecithin: cholesterol acyltransferase deficiency: structure of low and high density lipoproteins as revealed by elctron microscopy. J Clin Invest. 1971 May;50(5):1141–1148. doi: 10.1172/JCI106586. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Garber D. W., Venkatachalapathi Y. V., Gupta K. B., Ibdah J., Phillips M. C., Hazelrig J. B., Segrest J. P., Anantharamaiah G. M. Turnover of synthetic class A amphipathic peptide analogues of exchangeable apolipoproteins in rats. Correlation with physical properties. Arterioscler Thromb. 1992 Aug;12(8):886–894. doi: 10.1161/01.atv.12.8.886. [DOI] [PubMed] [Google Scholar]
- Glomset J. A., Janssen E. T., Kennedy R., Dobbins J. Role of plasma lecithin:cholesterol acyltransferase in the metabolism of high density lipoproteins. J Lipid Res. 1966 Sep;7(5):638–648. [PubMed] [Google Scholar]
- Glomset J. A. The plasma lecithins:cholesterol acyltransferase reaction. J Lipid Res. 1968 Mar;9(2):155–167. [PubMed] [Google Scholar]
- Goldstein J. L., Brown M. S., Anderson R. G., Russell D. W., Schneider W. J. Receptor-mediated endocytosis: concepts emerging from the LDL receptor system. Annu Rev Cell Biol. 1985;1:1–39. doi: 10.1146/annurev.cb.01.110185.000245. [DOI] [PubMed] [Google Scholar]
- Gregg R. E., Zech L. A., Schaefer E. J., Brewer H. B., Jr Apolipoprotein E metabolism in normolipoproteinemic human subjects. J Lipid Res. 1984 Nov;25(11):1167–1176. [PubMed] [Google Scholar]
- Gylling H., Miettinen T. A. Non-cholesterol sterols, absorption and synthesis of cholesterol and apolipoprotein A-I kinetics in a Finnish lecithin-cholesterol acyltransferase deficient family. Atherosclerosis. 1992 Jul;95(1):25–33. doi: 10.1016/0021-9150(92)90172-d. [DOI] [PubMed] [Google Scholar]
- Ha Y. C., Barter P. J. Differences in plasma cholesteryl ester transfer activity in sixteen vertebrate species. Comp Biochem Physiol B. 1982;71(2):265–269. doi: 10.1016/0305-0491(82)90252-8. [DOI] [PubMed] [Google Scholar]
- Herz J., Hamann U., Rogne S., Myklebost O., Gausepohl H., Stanley K. K. Surface location and high affinity for calcium of a 500-kd liver membrane protein closely related to the LDL-receptor suggest a physiological role as lipoprotein receptor. EMBO J. 1988 Dec 20;7(13):4119–4127. doi: 10.1002/j.1460-2075.1988.tb03306.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hoeg J. M., Vaisman B. L., Demosky S. J., Jr, Meyn S. M., Talley G. D., Hoyt R. F., Jr, Feldman S., Bérard A. M., Sakai N., Wood D. Lecithin:cholesterol acyltransferase overexpression generates hyperalpha-lipoproteinemia and a nonatherogenic lipoprotein pattern in transgenic rabbits. J Biol Chem. 1996 Feb 23;271(8):4396–4402. doi: 10.1074/jbc.271.8.4396. [DOI] [PubMed] [Google Scholar]
- Hopkins G. J., Barter P. J. Role of triglyceride-rich lipoproteins and hepatic lipase in determining the particle size and composition of high density lipoproteins. J Lipid Res. 1986 Dec;27(12):1265–1277. [PubMed] [Google Scholar]
- Horowitz B. S., Goldberg I. J., Merab J., Vanni T. M., Ramakrishnan R., Ginsberg H. N. Increased plasma and renal clearance of an exchangeable pool of apolipoprotein A-I in subjects with low levels of high density lipoprotein cholesterol. J Clin Invest. 1993 Apr;91(4):1743–1752. doi: 10.1172/JCI116384. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ikewaki K., Rader D. J., Sakamoto T., Nishiwaki M., Wakimoto N., Schaefer J. R., Ishikawa T., Fairwell T., Zech L. A., Nakamura H. Delayed catabolism of high density lipoprotein apolipoproteins A-I and A-II in human cholesteryl ester transfer protein deficiency. J Clin Invest. 1993 Oct;92(4):1650–1658. doi: 10.1172/JCI116750. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ikewaki K., Rader D. J., Schaefer J. R., Fairwell T., Zech L. A., Brewer H. B., Jr Evaluation of apoA-I kinetics in humans using simultaneous endogenous stable isotope and exogenous radiotracer methods. J Lipid Res. 1993 Dec;34(12):2207–2215. [PubMed] [Google Scholar]
- Ikewaki K., Zech L. A., Kindt M., Brewer H. B., Jr, Rader D. J. Apolipoprotein A-II production rate is a major factor regulating the distribution of apolipoprotein A-I among HDL subclasses LpA-I and LpA-I:A-II in normolipidemic humans. Arterioscler Thromb Vasc Biol. 1995 Mar;15(3):306–312. doi: 10.1161/01.atv.15.3.306. [DOI] [PubMed] [Google Scholar]
- Jiao S., Cole T. G., Kitchens R. T., Pfleger B., Schonfeld G. Genetic heterogeneity of lipoproteins in inbred strains of mice: analysis by gel-permeation chromatography. Metabolism. 1990 Feb;39(2):155–160. doi: 10.1016/0026-0495(90)90069-o. [DOI] [PubMed] [Google Scholar]
- Jonas A. Lecithin-cholesterol acyltransferase in the metabolism of high-density lipoproteins. Biochim Biophys Acta. 1991 Jul 30;1084(3):205–220. doi: 10.1016/0005-2760(91)90062-m. [DOI] [PubMed] [Google Scholar]
- Klein H. G., Lohse P., Duverger N., Albers J. J., Rader D. J., Zech L. A., Santamarina-Fojo S., Brewer H. B., Jr Two different allelic mutations in the lecithin:cholesterol acyltransferase (LCAT) gene resulting in classic LCAT deficiency: LCAT (tyr83-->stop) and LCAT (tyr156-->asn). J Lipid Res. 1993 Jan;34(1):49–58. [PubMed] [Google Scholar]
- Liang H. Q., Rye K. A., Barter P. J. Dissociation of lipid-free apolipoprotein A-I from high density lipoproteins. J Lipid Res. 1994 Jul;35(7):1187–1199. [PubMed] [Google Scholar]
- Melchior G. W., Castle C. K., Murray R. W., Blake W. L., Dinh D. M., Marotti K. R. Apolipoprotein A-I metabolism in cholesteryl ester transfer protein transgenic mice. Insights into the mechanisms responsible for low plasma high density lipoprotein levels. J Biol Chem. 1994 Mar 18;269(11):8044–8051. [PubMed] [Google Scholar]
- Melchior G. W., Castle C. K., Vidmar T. J., Polites H. G., Marotti K. R. Apo A-I metabolism in cynomolgus monkeys: male-female differences. Biochim Biophys Acta. 1990 Mar 12;1043(1):97–105. doi: 10.1016/0005-2760(90)90115-e. [DOI] [PubMed] [Google Scholar]
- Pape M. E., Rehberg E. F., Marotti K. R., Melchior G. W. Molecular cloning, sequence, and expression of cynomolgus monkey cholesteryl ester transfer protein. Inverse correlation between hepatic cholesteryl ester transfer protein mRNA levels and plasma high density lipoprotein levels. Arterioscler Thromb. 1991 Nov-Dec;11(6):1759–1771. doi: 10.1161/01.atv.11.6.1759. [DOI] [PubMed] [Google Scholar]
- Patsch J. R., Gotto A. M., Jr, Olivercrona T., Eisenberg S. Formation of high density lipoprotein2-like particles during lipolysis of very low density lipoproteins in vitro. Proc Natl Acad Sci U S A. 1978 Sep;75(9):4519–4523. doi: 10.1073/pnas.75.9.4519. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rader D. J., Castro G., Zech L. A., Fruchart J. C., Brewer H. B., Jr In vivo metabolism of apolipoprotein A-I on high density lipoprotein particles LpA-I and LpA-I,A-II. J Lipid Res. 1991 Nov;32(11):1849–1859. [PubMed] [Google Scholar]
- Rader D. J., Ikewaki K., Duverger N., Schmidt H., Pritchard H., Frohlich J., Clerc M., Dumon M. F., Fairwell T., Zech L. Markedly accelerated catabolism of apolipoprotein A-II (ApoA-II) and high density lipoproteins containing ApoA-II in classic lecithin: cholesterol acyltransferase deficiency and fish-eye disease. J Clin Invest. 1994 Jan;93(1):321–330. doi: 10.1172/JCI116962. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ross A. C., Zilversmit D. B. Chylomicron remnant cholesteryl esters as the major constituent of very low density lipoproteins in plasma of cholesterol-fed rabbits. J Lipid Res. 1977 Mar;18(2):169–181. [PubMed] [Google Scholar]
- Schaefer E. J., Zech L. A., Jenkins L. L., Bronzert T. J., Rubalcaba E. A., Lindgren F. T., Aamodt R. L., Brewer H. B., Jr Human apolipoprotein A-I and A-II metabolism. J Lipid Res. 1982 Aug;23(6):850–862. [PubMed] [Google Scholar]
- Shepherd J., Packard C. J., Gotto A. M., Jr, Taunton O. D. A comparison of two methods to investigate the metabolism of human apolipoproteins A-I and and A-II. J Lipid Res. 1978 Jul;19(5):656–661. [PubMed] [Google Scholar]
- Sparks D. L., Anantharamaiah G. M., Segrest J. P., Phillips M. C. Effect of the cholesterol content of reconstituted LpA-I on lecithin:cholesterol acyltransferase activity. J Biol Chem. 1995 Mar 10;270(10):5151–5157. doi: 10.1074/jbc.270.10.5151. [DOI] [PubMed] [Google Scholar]
- Stokke K. T., Norum K. R. Determination of lecithin: cholesterol acyltransfer in human blood plasma. Scand J Clin Lab Invest. 1971 Feb;27(1):21–27. doi: 10.3109/00365517109080184. [DOI] [PubMed] [Google Scholar]
- Strickland D. K., Ashcom J. D., Williams S., Burgess W. H., Migliorini M., Argraves W. S. Sequence identity between the alpha 2-macroglobulin receptor and low density lipoprotein receptor-related protein suggests that this molecule is a multifunctional receptor. J Biol Chem. 1990 Oct 15;265(29):17401–17404. [PubMed] [Google Scholar]
- Tall A. R. Plasma cholesteryl ester transfer protein. J Lipid Res. 1993 Aug;34(8):1255–1274. [PubMed] [Google Scholar]
- Vaisman B. L., Klein H. G., Rouis M., Bérard A. M., Kindt M. R., Talley G. D., Meyn S. M., Hoyt R. F., Jr, Marcovina S. M., Albers J. J. Overexpression of human lecithin cholesterol acyltransferase leads to hyperalphalipoproteinemia in transgenic mice. J Biol Chem. 1995 May 19;270(20):12269–12275. doi: 10.1074/jbc.270.20.12269. [DOI] [PubMed] [Google Scholar]
- Vega G. L., Gylling H., Nichols A. V., Grundy S. M. Evaluation of a method for study of kinetics of autologous apolipoprotein A-I. J Lipid Res. 1991 May;32(5):867–875. [PubMed] [Google Scholar]
- Warnick G. R., Benderson J., Albers J. J. Dextran sulfate-Mg2+ precipitation procedure for quantitation of high-density-lipoprotein cholesterol. Clin Chem. 1982 Jun;28(6):1379–1388. [PubMed] [Google Scholar]
- Westerlund J. A., Weisgraber K. H. Discrete carboxyl-terminal segments of apolipoprotein E mediate lipoprotein association and protein oligomerization. J Biol Chem. 1993 Jul 25;268(21):15745–15750. [PubMed] [Google Scholar]
