Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LIPOPROTEIN LIPASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,639 records · Page 91Linked to original sources
PubMed1976

Effects of monoolein on hydrolysis of triglyceride by lipoprotein lipase in the presence of an inhibitory apolipoprotein.

The previously demonstrated inhibition of cow's milk lipoprotein lipase by apoLp-Ala and the deinhibition by monoglyceride have been studied in more detail. The apoLp-Ala inhibition is reversible by the addition of monoglyceride before or after enzyme additions. Quantities of monoglyceride accumulate during hydrolysis of triglyceride which are adequate to prevent inhibition by added apoLp-Ala. Accelerating reaction rates observed when the substrate contains the apoprotein at levels producing partial inhibition are also explained by monoglyceride production. These effects were observed with both crude preparations of skim milk and highly pruified lipase. It is suggested that the generation of monoglyceride may be important in facilitating hydrolysis of triglyceride in lipoproteins containing this inhibitory apolipoprotein.

Animals↗
PubMed1979

Changes in lipoprotein-lipase activity and lipid stores in human skeletal muscle with prolonged heavy exercise.

Lipoprotein-lipase (LPL) activity and intracellularly stored triglycerides were determined in muscle biopsies taken before and after an 85 km skiing race from 7 volunteers. The triglyceride stores were larger in slow twitch than in fast twitch fibres (proportions 5:1 before the race). The LPL activity increased and the triglyceride stores in slow twitch fibres decreased during the race. The best trained subjects had the largest TG stores before the race and their TG stores also decreased most during the race. These subjects also had very small increase of LPL activity. The least trained subject on the other hand showed a 6-fold increase of LPL activity. The high post-race LPL activity in less trained subjects indicates a higher capacity for uptake of fatty acids from serum TG as compared to the more trained subjects.

Adult↗
PubMed1997

Hyperinsulinemia and abdominal obesity affect the expression of hypertriglyceridemia in heterozygous familial lipoprotein lipase deficiency.

We have reported three missense mutations (G188E, P207L, and D250N) in the lipoprotein lipase (LPL) gene among French-Canadians, resulting in the absence of measurable postheparin plasma LPL activity in homozygotes. Presence of triglyceride- and cholesterol-rich VLDL, as well as cholesterol-poor HDL particles, has been shown in heterozygotes affected by partial reduction in postheparin LPL activity. However, significant heterogeneity in their plasma triglyceride levels has been found, even among individuals carrying the same LPL gene mutation, indicating that factors other than LPL deficiency could affect the phenotypic expression of hypertriglyceridemia in the heterozygous state. The aim of the present study was to examine the combined effects of abdominal fat accumulation and hyperinsulinemia on plasma triglyceride levels among heterozygous patients for familial LPL deficiency. Based on sex and BMI, 43 heterozygotes (25 women and 18 men) were matched with noncarrier control subjects. Our data indicate that heterozygotes with higher abdominal fat deposition, as defined as waist girth values above the 50th percentile, had higher plasma triglyceride levels than nonobese heterozygotes. However, an important proportion of male heterozygote subjects were hypertriglyceridemic, even in absence of abdominal obesity, suggesting that another factor(s) was involved in the modulation of hypertriglyceridemia in these subjects. Indeed, multivariate analyses revealed that fasting hyperinsulinemia was a significant correlate of hypertriglyceridemia among these heterozygotes. Results of the present study indicate that abdominal obesity and hyperinsulinemia both have deleterious effects on plasma triglyceride levels in familial LPL deficiency. It is suggested that heterozygotes with moderate obesity and/or insulin resistance may be at higher risk of coronary artery disease because of the expression of an atherogenic lipoprotein phenotype among these patients.

Abdomen↗
PubMed2004

Effect of Acanthopanax senticosus on lipoprotein lipase in 3T3-L1 adipocytes.

The effect of Acanthopanax senticosus (AS) leaves on lipoprotein lipase (LPL) was investigated in 3T3-L1 adipocytes. A water extract of AS leaves increased the LPL activity in culture medium of adipocytes in a dose- and time-dependent manner. The AS extract contained heparin-like LPL releasing components, however, the increase of medium LPL activity was continued up until 12 h, in contrast to the rapid decline after heparin treatment. The increase of LPL mRNA was also observed after AS extract treatment, suggesting that LPL induction occurs at the transcriptional level. The AS extract could partially reverse the LPL suppression by tumour necrosis factor-alpha in 3T3-L1 adipocytes. These results of an AS extract-induced increase of LPL activity in vitro suggest the possible action of AS as a facilitator of plasma triglyceride clearance.

3T3 Cells↗
PubMed1999

Insulin-induced up-regulation of lipoprotein lipase messenger ribonucleic acid and activity in mammary gland.

The effects of insulin on lipoprotein lipase (LPL) messenger RNA (mRNA) were studied in mammary glands from virgin and late-pregnant rats. Virgin and pregnant rats (at 17 days of gestation) were subjected to a continuous infusion (35 ml/day) with 50% glucose for 72 h to produce a prolonged hyperinsulinemic-euglycemic condition. Gestation causes a 4-fold increase in LPL mRNA accompanied by a 3- to 4-fold increase in total LPL activity. Experimental hyperinsulinemia, generated by the 50% glucose infusion, had a similar effect in both pregnant and virgin rats, by enhancing (2- to 3-fold) both their LPL activity and LPL mRNA. Thus, total LPL activity and LPL mRNA significantly correlated with plasma insulin (r = 0.789, P < 0.001; and r = 0.772, P < 0.001, respectively). Furthermore, total LPL activity was correlated with LPL mRNA (r = 0.765, P = 0.001). In conclusion, the present study shows that insulin participates in the control of LPL expression in mammary glands, revealing its role as a modulator of the enzyme at a mRNA level.

Animals↗
PubMed1981

Relationship between plasma triglyceride concentration and adipose tissue lipoprotein lipase activity in rats of different ages.

Plasma triglyceride (TG) concentration and adipose tissue lipoprotein lipase (LPL) activity was determined in male and female rats aged 40 days, 100 days and 1 year. Plasma TG levels increased with age in both sexes, but the rate of rise was greater in female as compared to male rats. As a consequence, plasma TG levels, which were lower in 40 and 100 day old female rats, were similar in both sexes at 1 year. Adipose tissue LPL activity, measured at the same time of day as were plasma TG levels, did not vary as a function of either age or sex. On the other hand, when adipose tissue LPL activity was measured in the early morning, just after rats had finished eating, there was a marked increase in the activity of 40 day old rats of either sex. This dietary-induced rise in adipose tissue LPL activity following eating was not seen in 100 day and 1-year-old rats. Thus, changes in adipose tissue LPL activity cannot account for previously described effects of age and sex on plasma TG concentration.

Adipose Tissue↗
PubMed1989

Genomic organization of the region encoding guinea pig lipoprotein lipase; evidence for exon fusion and unconventional splicing.

The coding sequence of guinea pig lipoprotein lipase (LPL) is organized into nine exons and spans a region of approximately 14 kb of the guinea pig genome. A non-conforming 5'-splice site is located on the first intron, which exhibits a 12-nucleotide perfect match with the 5'-end of the second exon. A previously described tryptic cleavage site is located on exon V, close to the 3' end of this exon. A similarity to vitellogenin resides on exons IV and V, and a putative active site is found on exon IV. A novel similarity to a fatty-acid-binding protein is noted on exon VI, adjacent to the postulated heparin-binding region. We suggest that free fatty acids (FFA) and heparin to some extent share the same site of interaction on the LPL molecule; and that a high local concentration of FFA can displace LPL from its site of action--the vascular endothelium--by competing for binding to heparan sulfate.

Amino Acid Sequence↗
PubMed1994

Macronutrient regulation of lipoprotein lipase is posttranslational.

To examine the relative impact of diet and meal composition on lipoprotein lipase (LPL), high fat (60% of energy) (HF) and high carbohydrate (68%) (HC) diets were fed to Sprague-Dawley rats for 2-3 wk, followed by overnight food deprivation and a meal of the same composition. Heparin-releasable LPL activities, mass and mRNA were measured in heart, diaphragm and soleus muscle and epididymal fat after food deprivation and 1, 2, 4 and 8 h postprandially. No effect of dietary macronutrient composition on LPL activity, protein or mRNA in food-deprived rats was demonstrated. However, in cardiac and diaphragm muscle, heparin-releasable LPL activity was suppressed by HC but stimulated by HF meal-feeding at 4 h. Moreover, in adipose tissue, the HC meal increased LPL activity at 1, 2 and 4 h relative to the basal period. Although there were no consistent effects of meal composition on LPL mass or mRNA in any one tissue, overall LPL mass was generally increased by HC meal-feeding. Because there were meal composition-dependent differences in LPL activity but no detectable differences in mass or mRNA in a particular tissue, LPL regulation by meals seems to be predominantly posttranslational.

Adipose Tissue↗
PubMed1981

Lipoprotein lipase activities in adipose tissues and muscle in the obese Zucker rat.

Activity of lipoprotein lipase (LPL) was determined in whole adipose tissue and isolated adipocytes, and in heart and skeletal muscle that contained predominantly red or white fiber types in lean and obese Zucker rats. In rats of both sexes at 9-11 and 26-30 wk of age, no differences were observed between lean and obese rats when LPL activity of the perirenal (PR), subcutaneous (SC), and mesenteric (M) adipose tissues was expressed per millimole of tissue triglyceride. Within each sex, data relating the LPL content of isolated adipocytes to cell size was a linear function in which data for lean and obese rats fell on the same regression line. Measurement of the distribution of adipose tissue LPL activity between adipocytes and other tissue constituents showed no differences between lean and obese rats, a finding that is inconsistent with the hypothesis that obesity results in part by an alteration in adipose tissue enzyme distribution. Activity of LPL in the myocardium and red fiber types in the younger group of both sexes showed significant decreases in obese animals. This was also true for white fibers of males but not females. No differences in heart or muscle LPL between lean and obese rats were observed in the older group of either sex.

Adipose Tissue↗
PubMedDate not supplied

Cachexia induction by EL-4 lymphoma in mice and possible involvement of impaired lipoprotein lipase activity.

Several lines of evidence have postulated that reduction in the activity of lipoprotein lipase (LPL) is involved in cachexia induction in cancer patients. Recently we have demonstrated that murine melanoma B16 has the ability to reduce the LPL activity and thereby induce cachexia symptoms in mice following intraperitoneal inoculation. In order to further investigate the relationship between LPL activity and cachectic syndrome, cachexia models other than melanoma B16 are required. However, there are few animal cachexia models in which LPL activity is involved in the induction of cachectic symptoms. In this study, cachectic symptoms and plasma LPL activity were investigated in mice bearing EL-4 mouse lymphoma. In EL-4 bearing mice the body weight including tumor weight in the abdominal cavity was rather higher than that of normal mice without tumor, whereas weights of carcass wet and gastrocnemius muscle were significantly decreased in EL-4 bearing mice. Elevated blood levels of triglyceride and non-esterified fatty acid were observed in mice bearing EL-4, associated with the impaired plasma LPL activity. Overall, this study indicated that EL-4 lymphoma in mice results in a severe cachexia which is possibly related to impaired LPL activity and also provided a useful cachexia model for understanding the role of LPL in the development of cancer cachexia.

Animals↗
PubMed1995

Tumor necrosis factor-alpha eliminates binding of NF-Y and an octamer-binding protein to the lipoprotein lipase promoter in 3T3-L1 adipocytes.

TNF alpha has been shown to reduce lipoprotein lipase (LPL) activity in adipose tissue. Regulation of LPL by TNF alpha occurs at the level of LPL gene transcription and posttranscriptionally. To elucidate further the transcriptional mechanism of TNF alpha inhibition of LPL gene transcription, transfection analysis was used to locate the site(s) of the LPL promoter that imparts the TNF alpha response. Transient transfections using LPL promoter deletions fused to luciferase in differentiated 3T3-L1 cells with and without TNF alpha treatment indicated that a DNA region downstream of -180 bp confers the TNF alpha effect. Electrophoretic mobility shift assays using two 32P-labeled LPL probes spanning the region between -180 and +44 bp revealed the loss of several LPL DNA-protein interactions after TNF alpha treatment, including the binding of NF-Y to the CCAAT box and a protein to the octamer consensus sequence. Protein binding to the OCT-1 consensus sequence is unaffected until after 4 h of TNF alpha treatment. In addition, the amount of mRNA for OCT-1 is not altered with TNF alpha treatment. These results indicate that TNF alpha regulates at least two DNA-binding proteins on the proximal promoter, thereby inhibiting LPL gene transcription.

3T3 Cells↗
PubMed1990

The response of lipoprotein lipase to feeding and fasting. Evidence for posttranslational regulation.

The regulation of adipose tissue lipoprotein lipase (LPL) was examined in rats fed or fasted overnight, and was found to be controlled posttranslationally. LPL catalytic activity decreased by 50% after fasting while LPL mRNA levels and rates of synthesis increased nearly 2-fold; enzyme mass remained unchanged. The distribution of LPL within the endoplasmic reticulum (ER) and Golgi/post-Golgi secretory pathway was assessed by differentiating between LPL high mannose and complex forms. After fasting, the majority of LPL is in the high mannose ER form (65%, 0.97 micrograms/g wet weight tissue), whereas the LPL complex form comprises only 35% (or 0.52 micrograms/g). After refeeding, however, the Golgi-derived LPL complex form predominates (65%, 1.03 micrograms/g) over the high mannose ER form (35%, 0.55 micrograms/g). Kinetic analysis suggests that high mannose LPL disappears with a half-life of t0.5 = 40 min in both fed and fasted rats, indicating that the redistribution of LPL mass during feeding/fasting does not arise by differential retention within ER. Instead, the fractional catabolic rate of complex LPL within the Golgi/post-Golgi secretory compartment can be calculated to be 3.5-fold greater in fasting. In heart, changes in LPL activity in response to feeding/fasting are also not due to differences in mRNA levels or rates of synthesis. Based on these findings, a model of LPL posttranslational regulation is proposed and discussed.

Adipose Tissue↗
PubMed1983

The influence of starvation and refeeding on the lipoprotein lipase activity of skeletal muscle and adipose tissue of lean and obese Zucker rats.

Lipoprotein lipase (LPL) activities of skeletal muscles, heart and adipose tissue were investigated during feeding, prolonged food restriction, and refeeding. The influence of the duration of starvation on adipose tissue LPL activity was to cause it to decrease throughout starvation, whereas heart LPL activity increased during the first 24 hours of fasting and then declined for the remainder of the fast. Starvation of 10-week-old female, lean and obese rats to 80% of initial body weight required 5 and 9 days, respectively. In fed controls, no differences between phenotypes were found for any tissue in the LPL activities expressed per gram tissue. However, obese rats exhibited significantly smaller muscle mass and a resulting 29% lower total skeletal muscle LPL activity. No phenotype differences were detected for tissue LPL activities during starvation or refeeding. During caloric restriction, the LPL activities were reduced in heart (-18%) and adipose (-52%) tissues, but skeletal muscle was unchanged except for the slow-twitch, oxidative soleus muscle, which was increased approximately two-fold. After refeeding to initial body weight, the LPL activity of heart returned to normal, but adipose tissue was dramatically increased (+300%) for both lean and obese Zucker rats. These data suggest that reduced skeletal muscle mass with normal LPL activity per gram tissue may contribute to an increased availability of plasma triglyceride fatty acids to adipose tissue of the genetically obese rat.

Adipose Tissue↗
PubMed1996

Fatty acids regulate the expression of lipoprotein lipase gene and activity in preadipose and adipose cells.

During fasting, a reduction in lipoprotein lipase (LPL) activity has been observed in rat fat pad with no change in enzyme mass, whereas LPL mRNA and synthesis are increased, suggesting that insulin and/or fatty acids (FA) regulate LPL activity post-translationaly [Doolittle, Ben-Zeev, Elovson, Martin and Kirchgessner (1990) J. Biol. Chem. 265, 4570-4577]. To examine the role of FA, either preadipose Ob1771 cells or Ob1771 and 3T3-F442A adipose cells were exposed to long-chain FA and to 2-bromopalmitate, a non-metabolized FA. A rapid (2-8 h) and dose-dependent increase (up to 6-fold) in LPL mRNA occurred, primarily due to increased transcription, which is accompanied by a decrease (down to 4-fold) in LPL cellular activity. Under these conditions, secretion of active LPL was nearly abolished. Removal of FA led to full recovery of LPL activity. LPL gene expression in 3T3-C2 fibroblasts was not affected by FA treatment. However fatty acid-activated receptor transfected-3T3-C2 cells, which show FA responsiveness, had increased LPL gene expression upon FA addition. LPL synthesis and cellular content appeared unaffected by FA treatment, whereas secretion of LPL was inhibited. These results indicate that FA regulate the post-translational processing of LPL. It is proposed that the regulation of LPL activity by FA is important with regard to the fine-tuning of FA entry into adipocytes during fasting/feeding periods.

3T3 Cells↗
PubMed1990

Lipoprotein lipase stored in adipocytes and muscle cells is a cryptic enzyme.

The status of lipoprotein lipase (LPL) has been examined in different cell types (adipose, skeletal muscle, and heart muscle cells) and different tissues (adipose, muscle, and cardiac tissues) from mouse, rat, and human. Cell and secreted activities were compared in cycloheximide-, heparin-treated cells present in culture. A gross underestimation of cell LPL activity was found; excess of LPL over substrate and/or apolipoprotein C-II was excluded as well as inhibition by cell component(s) or detergent molecules used to disrupt membrane structures in the cell lysates. Unmasking of LPL activity occurred upon dilution: the higher the concentration of LPL, the higher were the dilution factor and the concentration of heparin required to reach a plateau of activity. This maximal value was found to be identical to that determined in the secretion medium, indicating that the cell LPL activity can be determined in toto. The unmasking effect of dilution upon LPL activity was extended to adipose, muscle, and cardiac tissues from rat and to adipose tissues from mouse and human. In agreement with previous results (Vannier et al., 1989, J. Biol. 264: 13199-13205), our results are in favor of LPL as being cryptic within the cell. A model is proposed, in which potentially active LPL molecules are present as aggregates in various membrane compartments. It is concluded that the determination of the pool size of catalytically active cell LPL has to be estimated in vitro under the appropriate conditions described herein.

Adipose Tissue↗
PubMed1996

Family study of lipoprotein lipase gene polymorphisms and plasma triglyceride levels.

To better characterize the role of the lipoprotein lipase (LPL) gene in the determination of triglyceride levels in healthy subjects, a study was performed in 193 nuclear families (384 parents, means age = 42.0 +/- 5.2 years; 399 offspring, mean age = 14.6 +/- 4.3 years) volunteering to have a free health checkup examination. The pattern of familial resemblance was compatible with a zero correlation between spouses, a weak father-offspring correlation (0.099 +/- 0.054; P < 0.07), and significant mother-offspring (0.235 +/- 0.053; P < 10(-4)) and sib-sib (0.294 +/- 0.064; P < 10(-4)) correlations. Associations of triglyceride levels with the LPL HindIII and PvuII polymorphisms were investigated by a familial measured genotype analysis, specifying sex- and age-dependent polymorphism effects. The effects associated with both polymorphisms were significant only in fathers, the H+ and P+ alleles being associated with raised triglyceride levels. The HindIII and PvuII polymorphisms explained 3.5% and 3%, respectively, of the variability of triglycerides in fathers. The relationship was weakened after prior adjustment on body mass index, but remained significant for PvuII. Because of the lack of effect in mothers and offspring, the polymorphisms did not contribute to the covariance of triglyceride levels in relatives. In conclusion, this family study showed a weak relationship of the HindIII and PvuII polymorphisms to plasma triglyceride levels in young healthy male subjects. The effects detectable only in fathers suggest a possible modulation of the LPL expression by hormonal or lifestyle factors.

Adolescent↗
PubMed1997

Induction of human skeletal muscle lipoprotein lipase gene expression by short-term exercise is transient.

Exercise increases skeletal muscle lipoprotein lipase (LPL) expression, but the time course of this response is not known. In the present study, we examined the time course of the LPL response to both short-term and acute exercise and measured circulating levels of putative regulators of muscle LPL. Nine adults underwent short-term exercise training (60-90 min of stationary cycling at 55-70% of leg ergometer peak oxygen uptake on 5 consecutive days). Five vastus lateralis biopsies were performed: before training, 20 h after the fourth bout (immediately before the 5th bout), and 0.2, 4, and 8 h after the fifth bout. After four bouts of exercise in 4 days, there was no increase in LPL mass or LPL mRNA exactly 20 h after the fourth bout. However, when tissues were sampled closer to the exercise bout on the 5th day, transient increases were seen. On day 5, LPL mRNA increased by 127% (P < 0.05) at 4 h postexercise and was followed by an increase in LPL mass of 93% (P < 0.05) at 8 h postexercise. Serum triglycerides decreased by 23% (P < 0.05) during the protocol. Two nonexercising subjects showed no consistent change in LPL mRNA or mass. Acute exercise transiently increased levels of norepinephrine (9-fold) and epinephrine (5-fold) and reduced insulin levels. Acute exercise preceded by four daily bouts of exercise induces a transient rise in LPL mRNA followed by rise in LPL mass, suggesting that these responses are temporally related. This induction of LPL gene expression may result from dynamic changes in serum catecholamines, plasma insulin, or events intrinsic to muscle contraction itself.

Adult↗
PubMed1997

Insulin stimulates lipoprotein lipase activity and synthesis in adipocytes from septic rats.

Gram-negative sepsis suppresses lipoprotein lipase (LPL) activity in adipose tissue which contributes, in part, to the altered clearance of triglycerides. The suppression in LPL activity occurs when plasma insulin concentrations are elevated and insulin-stimulated glucose utilization is impaired. This study was planned to evaluate whether the presence of insulin resistance was responsible for the decrease in adipose LPL activity. Adipocytes were isolated from epididymal fat pads 24 h after inducing sepsis in male Lewis rats by intravenous injection of 4 x 10(8) colonies of live Escherichia coli/100 g body wt. The decrease in heparin-releasable (HR) LPL activity in adipocytes from the septic rats was evident at the time of isolation and maintained in a 20-h culture. After overnight incubation with insulin (10(-8) M), HR LPL activity was stimulated to a greater extent in adipocytes from septic rats (298%) than in adipocytes from control rats (88%). The insulin stimulation of LPL activity during sepsis could not be attributed to insulin-like growth factor-I (IGF-I) as adipocytes from septic rats appeared to be IGF-I resistant. Insulin-treatment (10(-8) M) increased LPL synthesis 99% in adipocytes from control rats and 136% in adipocytes from septic rats. Insulin treatment also led to a 65 and 62% increase in LPL mass in adipocytes from control and septic rats, respectively. These findings indicate that the sepsis-induced decrease in adipose LPL is not due to insulin resistance with respect to LPL. The insulin stimulation of LPL activity in adipocytes from septic rats appears to be mediated by an increase in LPL synthesis.

Adipocytes↗