Inactivation of lipoprotein lipase occurs on the surface of THP-1 macrophages where oligomers of angiopoietin-like protein 4 are formed

Journal Article · Fri Aug 24 04:00:00 EDT 2012 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2012.07.048· OSTI ID:22210196

Makoveichuk, Elena; Sukonina, Valentina; Kroupa, Olessia ^[1]; Thulin, Petra; Ehrenborg, Ewa ^[2]; Olivecrona, Thomas ^[1]; Olivecrona, Gunilla ^[1]

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1. Department of Medical Biosciences, Physiological Chemistry Umea University, SE-901 87 Umea (Sweden)
2. Atherosclerosis Research Unit, Department of Medicine, Karolinska Institutet, SE-171 76 Stockholm (Sweden)

Highlights: Black-Right-Pointing-Pointer Lipoprotein lipase (LPL) activity is controlled by ANGPTL4 in THP-1 macrophages. Black-Right-Pointing-Pointer Both LPL and ANGPTL4 bind to THP-1 macrophages in a heparin-releasable fashion. Black-Right-Pointing-Pointer Only monomers of ANGPTL4 are present within THP-1 macrophages. Black-Right-Pointing-Pointer Covalent oligomers of ANGPTL4 appear on cell surface and in medium. Black-Right-Pointing-Pointer Inactivation of LPL coincide with ANGPTL4 oligomer formation on cell surfaces. -- Abstract: Lipoprotein lipase (LPL) hydrolyzes triglycerides in plasma lipoproteins causing release of fatty acids for metabolic purposes in muscles and adipose tissue. LPL in macrophages in the artery wall may, however, promote foam cell formation and atherosclerosis. Angiopoietin-like protein (ANGPTL) 4 inactivates LPL and ANGPTL4 expression is controlled by peroxisome proliferator-activated receptors (PPAR). The mechanisms for inactivation of LPL by ANGPTL4 was studied in THP-1 macrophages where active LPL is associated with cell surfaces in a heparin-releasable form, while LPL in the culture medium is mostly inactive. The PPAR{delta} agonist GW501516 had no effect on LPL mRNA, but increased ANGPTL4 mRNA and caused a marked reduction of the heparin-releasable LPL activity concomitantly with accumulation of inactive, monomeric LPL in the medium. Intracellular ANGPTL4 was monomeric, while dimers and tetramers of ANGPTL4 were present in the heparin-releasable fraction and medium. GW501516 caused an increase in the amount of ANGPTL4 oligomers on the cell surface that paralleled the decrease in LPL activity. Actinomycin D blocked the effects of GW501516 on ANGPTL4 oligomer formation and prevented the inactivation of LPL. Antibodies against ANGPTL4 interfered with the inactivation of LPL. We conclude that inactivation of LPL in THP-1 macrophages primarily occurs on the cell surface where oligomers of ANGPTL4 are formed.

• OSTI ID: 22210196
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 2 Vol. 425; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
ACETATES
ACTINOMYCIN
ADIPOSE TISSUE
ALBUMINS
ANTIBODIES
ARTERIES
ARTERIOSCLEROSIS
CARBOXYLIC ACIDS
CATTLE
CULTURE MEDIA
DIMERS
DMSO
FOAMS
HEPARIN
INACTIVATION
LEAD SULFIDES
LIPASES
LIPOPROTEINS
MACROPHAGES
MESSENGER-RNA
MONOMERS
MUSCLES
PH VALUE
PHOSPHATES
RECEPTORS
SODIUM CHLORIDES
TRIGLYCERIDES