Disease relevance of LPL

• Conversely, human GH (hGH) treatment had no influence on body weight, increased serum hGH levels, decreased fat cell size (P<.05) and LPL activity (P<.05) but had no influence on lipid accretion [1].
• First, VLDL acquisition is attenuated by the increased matrix LPL content in the developing atheroma [2].
• Administration of a large dose of glucose to fasted guinea pigs, which have shown a similar weight loss, but less LPL loss than TCDD-treated animals, had the effect of elevating their adipose LPL levels back to a near normal level, whereas the same treatment caused no significant increase in the LPL levels of TCDD-treated animals [3].

High impact information on LPL

• In addition, a potential binding site for the triacylglycerol substrate and a carbohydrate-binding domain for lipoprotein lipase are postulated [4].
• The catalytic activity, molecular size, and heparin-binding characteristics of the released LPL was similar to native LPL [5].
• Analysis of the time course of LPL dissociation from endothelial cells at 4 degrees C yielded a dissociation rate constant of 3.9 x 10(-6)s-1 [5].
• Addition of heparin to the medium or pretreatment of the cells with heparinase markedly reduced the amount of LPL internalized, establishing a requirement for cell surface heparan sulfate proteoglycans in the process [5].
• The release of radiolabeled LPL by VLDL correlated with the generation of free fatty acids from the hydrolysis of VLDL triglyceride by LPL bound to the cells [6].

Biological context of LPL

• The deduced amino acid sequence shows a high degree of identity to LPL from other species, and contains the Ser/His/Asp triade characteristic of serine proteases and esterases [7].
• Isolation and sequencing of porcine lipoprotein lipase cDNA and its use in multiallelic restriction fragment length polymorphism detection [7].
• Mapping of the porcine lipoprotein lipase (LPL) gene to chromosome 14q12----q14 by in situ hybridization [8].
• Studies examining the effect of pH on dissociation of LPL from its binding site showed less dissociation of cell surface bound LPL at pH 5.5 compared with pH 7.4 and 8 [5].
• The present study is the first to demonstrate in neonatal pigs that, as in growing pigs, ST regulates adipose tissue metabolism through decreasing lipid synthesis and LPL activity and increasing lipolysis [9].

Anatomical context of LPL

• We postulate that similar mechanisms may be important in the regulation of LPL activity at the vascular endothelium [6].
• In previous studies we reported that in the major LPL-producing tissues (muscles, adipose tissue, and mammary gland) the enzyme is made by the major cell types [10].
• All adipocytes from obese fetuses (domestic and feral) were lipoprotein lipase (LPL)-positive whereas all cells from lean fetuses were negative for LPL activity [11].
• Based on morphological criteria we can suggest that, contrary to the main LPL-producing tissues, in these tissues the enzyme is made by scattered cells, such as macrophages in the lung and spleen and Kupffer cells in the liver; endothelial cells present but do not synthesize the enzyme, indicating that the endothelial LPL originates in other cells [10].
• Quantitative analysis of sections of perirenal and subcutaneous adipose tissue indicated that T4 increased LPL activity (P<.05), slightly increased fat cell size, and more than doubled (P<.05) lipid accretion [1].

Associations of LPL with chemical compounds

• Lipoprotein lipase (LPL) hydrolyzes triglyceride in plasma lipoprotein primarily while bound to vascular endothelial cells [5].
• Radiolabeled LPL protein was released from endothelial cells by chylomicrons, VLDL, and by free fatty acids (i.e. oleic acid bound to bovine serum albumin) [6].
• Furthermore, polyarginine or polylysine markedly decreased 125I-LDL binding to LPL-containing matrix, whereas polyleucine was ineffective [12].
• Oral administration of glucose restored LPL activity in TCDD-treated animals after 1 day but only partially after 2 and 5 days, and had no effect after 10 days of exposure [13].
• Within 1 hr of intraperitoneal administration of 1 microgram 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)/kg, lipoprotein lipase (LPL) activity was reduced 38% from initial levels in the adipose tissue of the guinea pig [13].

Physical interactions of LPL

• We have previously shown that addition of lipoprotein lipase (LPL) markedly increased binding of apolipoprotein B (apoB)-containing lipoproteins to an endothelial cell-derived matrix, and this enhanced lipoprotein binding was inhibited by apoE [12].

Regulatory relationships of LPL

• Apolipoprotein B and E basic amino acid clusters influence low-density lipoprotein association with lipoprotein lipase anchored to the subendothelial matrix [12].

Other interactions of LPL

• In muscle, ME and G6PDH activities and GLUT4 mRNA were higher (P < 0.05) in F than in SM and SR pigs; LPL was not detected [14].
• The LPL and leptin increased continuously [15].
• The degree of esterase and G6PDH, but not LPL response to HC, was greater during the 90- to 105-day period than during the earlier period [16].
• In the liver, TNF caused a marked increase in LPL mRNA levels, which are normally very low [17].
• Although HDL-C levels rose only slightly (P less than 0.09) with exercise, a significant shift was noted in the distribution of cholesterol from the HDL3 to the HDL2 fractions, perhaps mediated by the substantial increase in LPL activity [18].

Analytical, diagnostic and therapeutic context of LPL

• Northern blot analysis demonstrated the same three species of LPL mRNA in ovaries (1.8, 3.1, and 3.5 kb) as in adipose tissue [19].
• A similar difference between male and female guinea pigs was detected in the effect of TCDD on lipoprotein lipase (LPL) activity, except that a significant decrease in LPL activity was observed 28 d after treatment [20].
• Cycloheximide added at the start of the perfusion had no effect on the peak or on the early part of the shoulder, but the LPL activity released from 30 min continuously decreased so that at 60 min it was less than half of that in controls [21].
• Suitable conditions for pulse and chase and for immunoprecipitation of LPL were worked out [22].
• This dissociation of apo C-II from LPL by oleic acid was also demonstrated using gel-filtration chromatography [23].

References