Disease relevance of LPL

• Lymphocytes were isolated from the blood (PBL), mesenteric lymph nodes (MLN) and ileal lamina propria (LPL) of control sheep and of sheep with clinical Johne's disease due to infection with Mycobacterium avium ssp. paratuberculosis (M.a. paratuberculosis) [1].
• Body weight, adipocyte mean cell volume, the rates of fatty acid and acylglycerol glycerol synthesis, and lipoprotein lipase activity increased from October to May and then decreased over the following five months [2].

High impact information on LPL

• Receptor-mediated endocytosis of acetyl LDL by macrophages from LPL-expressing and LPL-KO mice was similar whether the cells were maintained in 5 or 1 mM glucose, and was not augmented by VLDL [3].
• Addition of oleic acid significantly enhanced phagocytosis by both LPL-expressing and LPL-KO macrophages maintained in 1 mM glucose [3].
• 2. The fall in the rate of growth of perirenal adipose tissue during the last month of gestation is associated with a diminished capacity for fatty acid synthesis and lipoprotein lipase activity, but no change in the rate of acylglycerol glycerol synthesis was observed [4].
• 1. Changes in the mean volume, the rate of fatty acid and acylglycerol glycerol synthesis, the activity of lipoprotein lipase and the numbers and affinities of insulin receptors of subcutaneous adipocytes are reported for sheep at different stages of pregnancy and lactation [5].
• To explore this, we measured the LPL activity and mRNA levels in perirenal AT and cardiac muscle (CM) of control, 7-d-underfed or 14-d-refed ewes [6].

Biological context of LPL

• Like humans, baboons have two transcript sizes of approx. 3.6 and 3.4 kb in most tissues that express LPL, and sequencing of the 3' untranslated region (UTR) shows this is due to two polyadenylation sites [7].
• The different regulation of CM-LPL between ewes and rats probably arises from peculiarities of ruminant species for nutrient digestion and absorption and liver lipogenesis [6].
• We used reverse transcription followed by PCR (RT-PCR), and anchor-ligated rapid amplification of cDNA ends (RACE) to amplify the remaining 5' region of the LPL transcript [7].
• The aa in the catalytic triad residues, the heparin-binding site in exon 6, as well as aa in positions where missense mutations cause LPL deficiency, are identical in baboons and humans [7].
• The main finding of this study is that, for a given level of food intake, long days (compared with short days) increased the LPL activity in the longissimus thoracis muscle and, in refed ewes, the activities of LPL and ME in subcutaneous AT [8].

Anatomical context of LPL

• Previous studies in rodents have shown that the lipoprotein lipase (LPL) regulation is complex and often opposite in adipose tissue (AT) and muscle in response to the same nutritional treatment [6].
• Characterization of the tissue-specific expression of LPL using Northern blots of total RNA showed that spinal cord expressed the most LPL transcripts of all baboon tissues examined [7].
• Flow cytometric analysis of cells isolated from PP, mucosal epithelium (IEL) and the lamina propria (LPL) revealed no significant alterations in the cell populations present in 'loop' tissues [9].
• The increased activity promoted by the factor(s) present in serum would ensure that those tissues (e.g. cardiac and skeletal muscle) which continue to synthesize lipoprotein lipase during fasting or nutritional restriction, are able to assimilate the relatively low amounts of circulating triacylglycerol [10].

Associations of LPL with chemical compounds

• Dexamethasone addition to the insulin-supplemented medium significantly increased LPL activity in ovine adipose tissue, whereas it was decreased in bovine adipose tissue on days 4 and 7 [11].
• Secretion was measured in these animals using Triton WR1339 to block lipoprotein lipase [12].
• The effects of species and plane of nutrition on serum activation of sheep adipose tissue lipoprotein lipase were studied over a range of substrate (triolein) concentrations [10].

Other interactions of LPL

• The amount of LPL mRNA was assayed relative to either that of gamma-actin (ACT) or cyclophilin (CYC) mRNA, used as endogenous standard [13].
• Thus, the SCD gene seems to be regulated in a depot-specific fashion and in a manner distinct from that of the ACC and LPL genes [14].
• Insulin significantly increased LPL activity in bovine but not in ovine adipose tissue, and it had no effect on G6PDH activity in the two species [11].

Analytical, diagnostic and therapeutic context of LPL

• We used RT-PCR to show that the polyadenylation signal that produces the 3.4-kb message is present in CNS LPL transcripts, but is not utilized [7].
• After optimizing the PCR cycle number and verifying that the amounts of ACT and CYC mRNA varied only weakly according to the nutritional conditions studied, we have tested the ability of the four procedures to quantify specific variations in LPL mRNA [13].

References