Oxidized VLDL induces less triglyceride accumulation in J774 macrophages than native VLDL due to an impaired extracellular lipolysis

The present study examined the relative contributions of the different pathways by which oxidatively modified VLDL (oxVLDL) promotes the uptake and intracellular accumulation of lipids in J774 macrophages. VLDL was oxidized for a maximum of 4 hours, resulting in an increase in thiobarbituric acid- reactive substances and an increased...

Apolipoprotein E is resistant to intracellular degradation in vitro and in vivo. Evidence for retroendocytosis

Apolipoprotein E (apoE) is an important determinant for the uptake of triglyceride-rich lipoproteins and emulsions by the liver, but the intracellular pathway of apoE following particle internalization is poorly defined. In the present study, we investigated whether retroendocytosis is a unique feature of apoE as compared with apoB by studying...

Binding of β-VLDL to heparan sulfate proteoglycans requires lipoprotein lipase, whereas apoE only modulates binding affinity

The binding of β-VLDL to heparan sulfate proteoglycans (HSPG) has been reported to be stimulated by both apoE and lipoprotein lipase (LPL). In the present study we investigated the effect of the isoform and the amount of apoE per particle, as well as the role of LPL on the binding of β-VLDL to HSPG. Therefore, we isolated β-VLDL from transgenic...

Not the mature 56 kDa lipoprotein lipase protein but a 37 kDa protein co-purifying with the lipase mediates the binding of low density lipoproteins to J774 macrophages

Lipoprotein lipase (LPL) purified from bovine milk showed variable abilities to stimulate the binding of low density lipoprotein (LDL) to J774 macrophages. The presence of a 37 kDa protein in the LPL sample seemed to be of importance for its stimulatory capacity. In order to investigate this, we isolated LPL from bovine milk via heparin...

Lipoprotein lipade-mediated interactions of lipoproteins with macrophages

Uptake by J774 macrophages of very-low-density lipoproteins isolated from apoE-deficient mice is mediated by a distinct receptor and stimulated by lipoprotein lipase

Apolipoprotein (apo) E-deficient mice display marked accumulation in the plasma of VLDL deficient in both apoE and apoBl00 but containing apoB48, apoA-1, apoCs, and apoA-IV. Since apoE-deficient mice develop severe atherosclerotic lesions with lipid-laden macrophages, we reasoned that the uptake of lipoproteins by intimal macrophages can take...

Lipoprotein lipase stimulates the binding and uptake of moderately oxidized low-density lipoprotein by J774 macrophages

Lipoprotein lipase (LPL) stimulates the uptake of low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) in different cell types, including macrophages, through bridging of LPL between lipoproteins and extracellular heparan sulphate proteoglycans (HSPG). Because macrophages produce LPL and because modified lipoproteins are present...