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Resistance of chylomicron and VLDL remnants to post-heparin lipolysis in ApoE-deficient mice: the role of apoE in lipoprotein lipase-mediated lipolysis in vivo and in vitro.
J Lipid Res. 1998 Sep; 39(9):1852-61.JL

Abstract

The interaction of lipoprotein lipase (LPL) with triglyceride-rich lipoproteins is governed by a number of factors, such as apolipoprotein (apo) C-II. The role of apoE in lipolysis is controversial. We made the unexpected observation that apoE-deficient mice were resistant to heparin-induced lipolysis; this study aims at examining the underlying mechanism for this observation. Compared to wild-type mice, apoE-deficient mice had significantly higher very low density lipoprotein (VLDL) and chylomicron remnant (VLDL/CMR) concentrations and moderately lower lipase activity (15.5 +/- 1.3 mU/ml vs. 22.9 +/- 2.5 mU/ml). Unlike in wild-type mice where the injection of heparin reduced total plasma triglycerides by 50% and VLDL/CMR triglycerides by over 95%, the injection of heparin into apoE-deficient mice did not significantly affect plasma lipids. Similarly, in vitro, purified human LPL (hLPL) almost completely hydrolyzed VLDL/CMR isolated from wild-type mice, but had no effect on VLDL/CMR from apoE-deficient mice. However, when the amount of apoE-deficient VLDL/CMR was reduced to an equivalent level as in wild-type mice, LPL hydrolyzed 94% of VLDL/CMR triglycerides. In order to increase the ratio of LPL to VLDL/CMR in vivo, we injected an adenovirus containing the human LPL cDNA into apoE-deficient mice, which produced marked liver-specific overexpression of LPL and significant reduction of VLDL/CMR (93%) and total plasma triglyceride concentrations (87%). Thus, apoE is not required for LPL activity in vivo or in vitro. Under certain pathological conditions, such as severe hyperlipidemia, the LPL pathway may be saturated and efficient lipolysis can proceed only if the ratio of substrate particles to LPL is adjusted to a more normal range.

Authors+Show Affiliations

Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9741698

Citation

Zsigmond, E, et al. "Resistance of Chylomicron and VLDL Remnants to Post-heparin Lipolysis in ApoE-deficient Mice: the Role of apoE in Lipoprotein Lipase-mediated Lipolysis in Vivo and in Vitro." Journal of Lipid Research, vol. 39, no. 9, 1998, pp. 1852-61.
Zsigmond E, Fuke Y, Li L, et al. Resistance of chylomicron and VLDL remnants to post-heparin lipolysis in ApoE-deficient mice: the role of apoE in lipoprotein lipase-mediated lipolysis in vivo and in vitro. J Lipid Res. 1998;39(9):1852-61.
Zsigmond, E., Fuke, Y., Li, L., Kobayashi, K., & Chan, L. (1998). Resistance of chylomicron and VLDL remnants to post-heparin lipolysis in ApoE-deficient mice: the role of apoE in lipoprotein lipase-mediated lipolysis in vivo and in vitro. Journal of Lipid Research, 39(9), 1852-61.
Zsigmond E, et al. Resistance of Chylomicron and VLDL Remnants to Post-heparin Lipolysis in ApoE-deficient Mice: the Role of apoE in Lipoprotein Lipase-mediated Lipolysis in Vivo and in Vitro. J Lipid Res. 1998;39(9):1852-61. PubMed PMID: 9741698.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Resistance of chylomicron and VLDL remnants to post-heparin lipolysis in ApoE-deficient mice: the role of apoE in lipoprotein lipase-mediated lipolysis in vivo and in vitro. AU - Zsigmond,E, AU - Fuke,Y, AU - Li,L, AU - Kobayashi,K, AU - Chan,L, PY - 1998/9/19/pubmed PY - 1998/9/19/medline PY - 1998/9/19/entrez SP - 1852 EP - 61 JF - Journal of lipid research JO - J. Lipid Res. VL - 39 IS - 9 N2 - The interaction of lipoprotein lipase (LPL) with triglyceride-rich lipoproteins is governed by a number of factors, such as apolipoprotein (apo) C-II. The role of apoE in lipolysis is controversial. We made the unexpected observation that apoE-deficient mice were resistant to heparin-induced lipolysis; this study aims at examining the underlying mechanism for this observation. Compared to wild-type mice, apoE-deficient mice had significantly higher very low density lipoprotein (VLDL) and chylomicron remnant (VLDL/CMR) concentrations and moderately lower lipase activity (15.5 +/- 1.3 mU/ml vs. 22.9 +/- 2.5 mU/ml). Unlike in wild-type mice where the injection of heparin reduced total plasma triglycerides by 50% and VLDL/CMR triglycerides by over 95%, the injection of heparin into apoE-deficient mice did not significantly affect plasma lipids. Similarly, in vitro, purified human LPL (hLPL) almost completely hydrolyzed VLDL/CMR isolated from wild-type mice, but had no effect on VLDL/CMR from apoE-deficient mice. However, when the amount of apoE-deficient VLDL/CMR was reduced to an equivalent level as in wild-type mice, LPL hydrolyzed 94% of VLDL/CMR triglycerides. In order to increase the ratio of LPL to VLDL/CMR in vivo, we injected an adenovirus containing the human LPL cDNA into apoE-deficient mice, which produced marked liver-specific overexpression of LPL and significant reduction of VLDL/CMR (93%) and total plasma triglyceride concentrations (87%). Thus, apoE is not required for LPL activity in vivo or in vitro. Under certain pathological conditions, such as severe hyperlipidemia, the LPL pathway may be saturated and efficient lipolysis can proceed only if the ratio of substrate particles to LPL is adjusted to a more normal range. SN - 0022-2275 UR - https://www.unboundmedicine.com/medline/citation/9741698/Resistance_of_chylomicron_and_VLDL_remnants_to_post_heparin_lipolysis_in_ApoE_deficient_mice:_the_role_of_apoE_in_lipoprotein_lipase_mediated_lipolysis_in_vivo_and_in_vitro_ L2 - http://www.jlr.org/cgi/pmidlookup?view=long&pmid=9741698 DB - PRIME DP - Unbound Medicine ER -