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 1,513 records · Page 84Linked to original sources
PubMed2003

Isoproterenol increases active lipoprotein lipase in adipocyte medium and in rat plasma.

White adipose tissue (WAT) lipoprotein lipase (LPL) activity channels diet fat towards storage in adipocytes. Adrenaline (ADR) is accepted to reduce WAT or adipocyte LPL activity (LPLa), but available data are not clear-cut regarding long exposure to ADR in vitro or in vivo. We studied the effects of long exposures to ADR or beta-adrenergic agonist on LPL: in isolated rat adipocytes (3 h) and in rats (>1 day). Isoproterenol (ISO) (1 microM) did not alter LPLmRNA nor LPLa in adipocytes, but increased LPLa in medium more than twofold (3.58 +/- 0.35 vs. 1.32 +/- 0.35 mU/10(6) adipocytes, P < 0.001). Effect was time (not present at 1 h, clear at 2 h) and concentration dependent (high sensitivity from 10 to 100 nM, max at 1 microM). Adenylate cyclase activator or cyclic AMP (cAMP) analogue produced a similar increase. Thus in adipocytes ISO produced an increase in LPLa release and/or a decrease in extracellular LPLa degradation. ADR or ISO treated rats had a two to fourfold decrease in WAT LPLa vs. unchanged LPLmRNA. This decrease was 10-fold in WAT heparin-releasable LPLa (5.7 +/- 0.6 vs. 57.3 +/- 10.2 mU/g, P < 0.001), which represents peri/extracellular LPLa. Plasma LPLa was increased 11-fold by ADR (3.30 +/- 0.58 vs. 0.32 +/- 0.08 mU/ml, P < 0.001) whereas only threefold by ISO (P > 0.01). We suggest that in vivo ADR increased release of active LPL to plasma from endothelial cells of LPL-rich tissue(s)-WAT was probably one of these tissues releasing LPL since it lost 90% of its peri/extracellular LPLa-and/or decreased degradation of plasma active LPL. Since liver LPLa was not increased, plasma active LPL might be kept away from hepatic degradation by binding to stabilising entities in plasma (fatty acids (FA), lipoproteins or soluble heparan sulphates (HS)). In conclusion, we believe this is the first report stating that: (a) ISO increases LPLa in isolated adipocyte medium, and (b) ADR administration to rats decreases WAT extracellular active LPL and increases preheparin plasma active LPL.

Actins↗
PubMed1993

Assembly of lipoprotein lipase in perfused guinea-pig hearts.

It has been suggested that lipoprotein lipase (LPL) can be assembled into its catalytically active dimeric form only after its oligosaccharide chains have been processed in the Golgi. To study this in a complete organ, LPL was metabolically labelled with [35S]methionine in perfused guinea-pigs hearts. After 10 min pulse-labelling, LPL protein was eluted as two peaks from heparin-agarose: peak 1 at about 0.65 M NaCl, peak 2 at about 0.95 M NaCl. Catalytic activity was associated only with peak 2. Model studies with bovine LPL showed that active dimeric LPL is eluted in peak 2, but after treatments that dissociate the enzyme into inactive monomers it is eluted in peak 1. Pulse-labelled LPL in both peak 1 and peak 2 was fully sensitive to treatment with endoglycosidase (Endo) H. With chase, peak 1 disappeared and peak 2 acquired resistance to Endo H. These findings suggest that core glycosylated LPL is assembled into dimers already in the endoplasmic reticulum and that processing of the oligosaccharide chains occurs after dimerization.

Animals↗
PubMed1985

[Activity of lipoprotein lipase in different adipose deposits and its relation to adipocyte size in the cow during fattening or early lactation].

Twelve dry and eight lactating cows were slaughtered and the whole body was chemically analysed. Adipose tissue lipid and adipose cell size varied greatly with body condition and also with anatomical site (perirenal, omental, intermuscular, rump subcutaneous, leg subcutaneous). Lipoprotein lipase activity per adipose cell was very low in lactating cows, but very high in dry cows during fattening. Activity tended to be higher in omental adipose tissue and lower in subcutaneous adipose tissue. Total adipose lipoprotein lipase activity per cow was positively related with energy balance and negatively related with plasma non-esterified fatty acids. There was no correlation with body fatness or adipose cellularity.

Adipose Tissue↗
PubMed2001

Food deprivation increases post-heparin lipoprotein lipase activity in humans.

OBJECTIVE: To study the effect of fasting on lipoprotein lipase (LPL) activity in human post-heparin plasma, representing the functional pool of LPL. DESIGN: Fourteen healthy volunteers were recruited for the study. The subjects were fasted for 30 h. Activities of LPL and hepatic lipase (HL), and LPL mass, were measured in pre- and post-heparin plasma in the fed and in the fasted states, respectively. For comparison, LPL and HL activities were measured in pre- and post-heparin plasma from fed and 24-h-fasted guinea pigs. RESULTS: Fasting caused a significant drop in the levels of serum insulin, triglycerides and glucose in the human subjects. Post-heparin LPL activity increased from 79 +/- 6.4 mU mL-1 in the fed state to 112 +/- 10 mU mL-1 in the fasted state (P < 0.01), while LPL mass was 361 +/- 29 in the fed state and 383 +/- 28 in the fasted state, respectively (P = 0.6). In contrast, fasting of guinea pigs caused an 80% drop in post-heparin LPL activity. The effect of fasting on human and guinea pig post-heparin HL activity were moderate and statistically not significant. CONCLUSIONS: In animal models such as rats and guinea pigs, post-heparin LPL activity decreases on fasting, presumably due to down-regulation of adipose tissue LPL. In humans, fasting caused increased post-heparin LPL activity.

Adipose Tissue↗
PubMed2006

Glucose administration downregulates lipoprotein lipase activity in vivo: a study using repeated intravenous fat tolerance test.

Lipoprotein lipase (LPL) is a key factor determining the clearance of triglycerides from the circulation. The enzyme activity is tissue-specifically regulated by insulin, but it is not clear yet how insulin regulates the total LPL activity in the circulation. To answer such question, we measured LPL activity using the intravenous fat tolerance test (IVFTT) that was carried out 1 h before as well as 2 h and 4 h after oral administration of glucose (75 g) in eleven healthy male volunteers. In control experiments, no glucose was given to the subjects. Glucose administration resulted in an expected increase in plasma glucose and insulin and in a suppression of non-esterified fatty acid concentration. The LPL activity assessed in IVFTT as a k(2) rate constant did not change in control experiments and decreased to 78 % and 73 % of baseline values 2 h and 4 h after glucose administration, respectively (p=0.01). Similarly, LPL activity measured in the plasma after intravenous injection of heparin at the end of the experiments was 16 % lower (p<0.05) after glucose administration. In conclusion, LPL activity is already downregulated in vivo 2 h after glucose administration. The results of our study indicate that repeated IVFTT is a promising approach for studying acute changes in LPL activity.

Adult↗
PubMed1985

Effects of cold acclimation on the activity of lipoprotein lipase in adipose tissues of genetically obese Zucker rats.

The activity of lipoprotein lipase (LPL) was studied in interscapilar brown adipose tissue (BAT), epididymal white adipose tissue (WAT) and in the heart of lean and obese adult Zucker rats maintained at 22 degrees C or adapted to cold (10 degrees C). In WAT the specific activity per gram of tissue was lower in obese than in lean rats but the total activity within the tissue was three-fold higher. Cold acclimation did not modify total activity in either lean or obese rats. In BAT, but not in the heart, both specific and total activities were lower in obese than in lean animals. They were enhanced in both tissues following cold acclimation. Six-hour fasting led to a decrease in specific activity in WAT of lean rats but had no effect in obese animals; an increase was observed in BAT and heart of both genotypes. Insulin administration has no effect on activities in WAT in either 22 or 10 degrees C adapted obese rats. Norepinephrine administration stimulates LPL activity in BAT and heart of all groups. It is concluded that the lack of development of obesity previously observed in obese rats following cold acclimation is not due to a decreased capacity of lipid uptake by WAT. It might in part be due to an increased lipid oxidation in BAT.

Acclimatization↗
PubMed2000

Seasonal variation in lipoprotein lipase and plasma lipids in physically active, normal weight humans.

Adipose tissue lipoprotein lipase (ATLPL) provides free fatty acids (FFA) for storage in adipocytes, whereas in skeletal muscle LPL (SMLPL) provides FFA for oxidation. In hibernating animals, the level of SMLPL is relatively higher in summer than winter (promoting fat oxidation), whereas the opposite is seen with ATLPL. A patient-controlled study was designed to determine whether such seasonal variation occurs in normal weight humans. Eighteen subjects were studied in the summer and winter. After 2 days of a standardized diet, they underwent muscle and adipose biopsies for LPL activity, assessment of fitness by VO2 max, and determination of body composition by hydrostatic weighing. The percentages of body fat, body mass index, VO2 max, insulin, glucose, FFA, glycerol, and leptin were not affected by the season. Total cholesterol was higher in the winter than in the summer (157 +/- 5.5 vs. 148 +/- 4.2 mg/dL respectively; P = 0.03). The ATLPL activity was also higher in the winter than in the summer (4.4 +/- 0.8 vs. 2.3 +/- 0.6 nmol FFA/10(6) cells-min; P = 0.04). SMLPL activity trended to be higher in the winter than in the summer (1.9 +/- 0.5 vs. 1.0 +/- 0.1 nmol FFA/g x min; P = 0.06). In summary, ATLPL is seasonally regulated. It appears that SMLPL is similarly regulated by season. For physically active lean subjects, this increase in SMLPL may be a compensatory mechanism to help protect from seasonal weight gain.

Adipose Tissue↗
PubMed1996

Forms of lipoprotein lipase in rat tissues: in adipose tissue the proportion of inactive lipase increases on fasting.

Previous studies have shown that the ratio of lipoprotein lipase (LPL) catalytic activity to LPL mass in tissues differs in different conditions, but it is not clear whether this occurs by a change in the catalytic efficiency of the LPL molecules, or because of a shift in the relation between active and inactive forms of the enzyme. To explore this, we have measured LPL activity and mass in detergent extracts of rat tissues. LPL specific activity was high and similar in heart, skeletal muscle, lung and brain. The liver had significantly lower specific activity, which is in accord with previous findings that the liver takes up and catabolizes LPL. The specific activity was also low in adipose tissue from fasted rats. When tissue extracts were applied to columns of heparin-agarose and eluted by a gradient of NaCl, a peak of active LPL was eluted at 1.0 M NaCl, but there was also a peak of inactive LPL protein, which was eluted at 0.6 M NaCl. In adipose tissue, LPL activity decreased by 70-80% during an overnight fast, whereas LPL mass decreased by only 20-40%. The mass ratio between inactive and active LPL, as separated by heparin-agarose chromatography, increased from 0.5 to over 2 during the fast. In hearts there was no significant difference between fed and fasted rats in total LPL activity, LPL mass or in the distribution between inactive and active forms. The results indicate that the relation between inactive (probably monomeric) and active (dimeric) forms of LPL is a target for post-translational regulation in adipose tissue.

Adipose Tissue↗
PubMed2006

Impact of lipoprotein lipase gene polymorphisms on ulcerative colitis.

AIM: To examine the influence of lipoprotein lipase (LPL) gene polymorphism in ulcerative colitis (UC) patients. METHODS: Peripheral blood was obtained from 131 patients with UC and 106 healthy controls for DNA extraction. We determined LPL gene polymorphisms affecting the enzyme at Ser447stop, as well as Hind III and Pvu II polymorphisms using PCR techniques. PCR products were characterized by PCR-RFLP and direct sequencing. Polymorphisms were examined for association with clinical features in UC patients. Genotype frequencies for LPL polymorphisms were also compared between UC patients and controls. RESULTS: In patients with onset at age 20 years or younger, C/G and G/G genotypes for Ser447stop polymorphism were more prevalent than C/C genotype (OR = 3.13, 95% CI = 0.95-10.33). Patients with H(+/-) or H(-/-) genotype for Hind III polymorphism also were more numerous than those with H(+/+) genotype (OR = 2.51, 95% CI = 0.85-7.45). In the group with H(+/+) genotype for Hind III polymorphism, more patients had serum triglyceride concentrations over 150 mg/dL than patients with H(+/-) or H(-/-) genotype (P < 0.01, OR = 6.46, 95% CI = 1.39-30.12). Hypertriglycemia was also more prevalent in patients with P(+/+) genotypes for Pvu II polymorphism (P < 0.05, OR = 3.0, 95% CI = 1.06-8.50). Genotype frequency for LPL polymorphism did not differ significantly between UC patients and controls. CONCLUSION: Ser447stop and Hind III LPL polymorphisms may influence age of onset of UC, while Hind III and Pvu II polymorphisms influence serum triglyceride in UC patients.

Adult↗
PubMed1998

Circadian rhythms of lipoprotein lipase and hepatic lipase activities in intermediate metabolism of adult rat.

Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variations in lipoprotein lipase (LPL) and hepatic lipase (HL) activities during the 24-h period, and there is also a lack of adequate statistical analysis. Here, adult male rats were fed ad libitum and kept at 21 degrees C under 12:12-h light-dark cycles. They were killed in batches every 3 h over a 24-h period. Lipase activities were determined in plasma and fresh homogenates of epididymal white adipose tissue (EWAT), interscapular brown adipose tissue (IBAT), heart, skeletal muscle, and liver. Plasma insulin, corticosterone, glucose, triacylglycerol (TAG), cholesterol, glycerol, beta-hydroxybutyrate, and liver and muscle glycogen were determined. Cosinor analysis was used to evaluate the presence (significance of fit of cosine curve to data and variance explained by rhythm) and characteristics of possible circadian rhythms [acrophase (phi), mesor, and amplitude]. Statistically significant circadian rhythms were detected for 1) all metabolites studied, except TAG, cholesterol, and liver HL activity; 2) LPL and HL activity in plasma (both phi in light phase); and 3) LPL activity in all tissues studied (phi: heart in light phase; skeletal muscle, IBAT, and EWAT in dark phase). Liver also showed a circadian rhythm of LPL activity, with phi near that in plasma. These findings demonstrate for the first time that, in physiological conditions, LPL activities in plasma and various tissues, including liver, and HL activity in plasma follow circadian rhythms. Their metabolic significance is discussed.

3-Hydroxybutyric Acid↗
PubMed1992

Geographic distribution and genealogy of mutation 207 of the lipoprotein lipase gene in the French Canadian population of Québec.

Mutations in the lipoprotein lipase (LPL) gene, leading to partial or total inactivation of the enzyme, result in a hereditary clinical syndrome called familial LPL deficiency. The French Canadian population, which is primarily and historically located in the province of Québec, has the highest worldwide frequency of LPL-deficient patients. We have analyzed the prevalence, spatial distribution, and genealogy in the Québec population of a LPL gene mutation, M-207 (P207L in conventional notation), which changes the amino acid proline to leucine in position 207 of the LPL protein and inactivates the enzyme. Our results show that M-207 is the most prevalent LPL gene mutation among French Canadians and accounts for the largest proportion of LPL-deficient patients in this population. Genealogical reconstruction of French Canadian LPL-deficient patients point to 16 founders of M-207, all of whom migrated to Québec in the early seventeenth century from the north-western part of France, especially from the region of Perche. Most of the carriers of M-207 are, at present, found in Charlevoix, Saguenay-Lac-St-Jean regions of eastern Québec. On the basis of the number of homozygote M-207 LPL-deficient patients so far identified, we estimate that there are at least 31,000 carriers of this mutation in the province of Québec. This constitutes a large pool of individuals at risk for atherosclerosis and other lipid-related diseases, since LPL deficiency is considered to be a significant contributing factor in the etiology and development of these diseases.

Alleles↗
PubMed1976

Reversal of decreased human adipose tissue lipoprotein lipase and hypertriglyceridemia after treatment of hypothyroidism.

To determine whether adipose tissue lipoprotein lipase (LPL) plays a role in the regulation of triglyceride (TG) metabolism in hypothyroidism, the activity of the enzyme was measured in the subcutaneous adipose tissue of six hypothyroid patients before and during therapy with L-thyroxine. The activity of the activated form of the enzyme, measured as heparin elutable LPL, was lower in hypothyroid patients (1.54 +/- 0.93; mU/10(6) cells; mean +/- SD) than in controls (3.26 +/- 1.49; P less than .02) and increased (163 +/- 89%; P less than .01) with treatment to levels comparable to the controls. The total activity of LPL, measured in ammonium hydroxide extracts of acetone ether tissue powders, was in the low normal range in the hypothyroid patients (0.68 +/- 0.42), but not significantly different from normal (1.10 +/- 0.58) and did not increase significantly (92 +/- 105%), with treatment. Plasma post heparin lipolytic activity (PHLA) was low in hypothyroidism and increased (111 +/- 78%; P less than .05) with treatment. These increases in PHLA correlated with the increases in the activity of heparin elutable LPL (r = .88, P less than .05). In all patients fasting plasma TG levels decreased (-43 +/- 25%; P less than .02) after treatment. Serial determination of heparin elutable LPL activity, PHLA, and plasma TG during L-thyroxine treatment revealed a correlation between the per cent changes in PHLA and heparin elutable LPL activity (r = .68, P less than .05), an inverse correlation between plasma TG levels and heparin elutable LPL (r = -0.53,P less than .05) and no correlation between plasma TG and PHLA (r = -0.05). These results suggest that the low PHLA and hypertriglyceridemia of hypothyroidism are related to low adipose tissue LPL activity. All these parameters return to normal after treatment with L-thyroxine and attainment of euthyroidism.

Adipose Tissue↗
PubMed1997

Ethnic variation and in vivo effects of the -93t-->g promoter variant in the lipoprotein lipase gene.

Recently, a (t-->g) transition at nucleotide -93 in the lipoprotein lipase (LPL) gene promoter has been observed in Caucasians. Here, we have compared the frequency of the -93g carriers in three distinct populations (Caucasians, South African Blacks, and Chinese). The carrier frequency in the Caucasian population was 1.7% (4/232), which was in contrast to the South African Black population, which had a frequency for this allele of 76.4% (123/161) of the individuals tested. This transition was not observed in the Chinese population under study. Near complete linkage disequilibrium between the -93g and the previously described D9N mutation was observed in the Caucasian population but not in South African Blacks. To further assess the ancestral origins of these DNA changes, DNA haplotyping using a CA repeat 5' to these substitutions was performed. The -93t allele was associated with only a few specific dinucleotide repeat sizes. In contrast, the -93g allele occurred on chromosomes with many different repeat lengths. The broad distribution of repeats on -93g carrying chromosomes, their high frequency in the South African Black population, and the conservation of the -93g allele among different species may suggest that the -93g allele is the ancestral allele on which a transition to t and the D9N mutations arose. The very high frequency of the -93g allele distinct from the N9 allele in a cohort of Black South Africans allowed us to specifically assess the phenotypic effects of the -93g allele on lipids. Individuals homozygous for the g allele at -93 showed mildly decreased triglycerides compared with individuals homozygous for the t allele (1.14 +/- 0.66 mmol/L versus 0.82 +/- 0.3; P = .04). Thus, the -93g allele in this cohort is associated with low plasma triglyceride levels.

Adult↗
PubMed1984

Insulin responsiveness of adipose tissue lipoprotein lipase is delayed but preserved in obesity.

Because increases in adipose tissue lipoprotein lipase (ATLPL) may be important in the pathogenesis of obesity, the response of ATLPL to insulin during maintenance of euglycemia was examined in 22 obese and 8 normal weight subjects. Basal levels of ATLPL per g fat tissue for the obese and control groups were 18.7 +/- 2.0 (+/- SEM) and 9.6 +/- 2.7 neq/g X min, respectively. Insulin and glucose infusion rapidly produced antilipolysis in both groups, as evidenced by large falls in FFA by 20 min. When the responses of ATLPL in absolute change from basal were compared between the obese and control groups, no significant differences were found. However, because of the higher baseline ATLPL values in the obese subjects, the percent change in ATLPL from basal was significantly blunted at the 80 (P = 0.02), 180 (P less than 0.05), and 360 (P = 0.005) min timepoints compared to those in the normal subjects. By 3 h into the infusion, the control group had a significant rise in ATLPL above the basal level (4.2 +/- 1.3 ngq/g X min; P = 0.01), whereas the obese group did not (2.3 +/- 1.9 neq/g X min; P = NS). However, by 6 h, the ATLPL per g response above baseline was significantly increased in both normal (19.2 +/- 6.5 neq/g X min; P = 0.01) and obese subjects (9.8 +/- 2.3; P less than 0.001). Because adipose cell size was greater in obese subjects, data were also expressed per 10(6) cells. Basal ATLPL per 10(6) cells [11.8 +/- 1.7 neq/10(6) cells X min (obese); 3.4 +/- 0.9 neq/10(6) cells X min (normal)] was a function of cell size (rs = 0.713; P less than 0.001), body mass index (rs = 0.565; P less than 0.005), and basal insulin levels (rs = 0.434; P less than 0.05). As with the ATLPL per g response, the increases in ATLPL per 10(6) cells above basal were significant at both the 3 and 6 h marks for the normal subjects, but only at the 6 h timepoint for the obese group. Both steady state insulin levels [342 +/- 24 microU/ml (obese); 251 +/- 27 microU/ml (normal)] and the glucose infusion rates needed to maintain euglycemia [319 +/- 23 mg/m2 X min (obese); 312 +/- 33 mg/m2 X min (normal)] did not correlate with changes in ATLPL. Thus, insulin responsiveness of ATLPL in obese subjects was delayed but preserved. This phenomenon may be important in maintenance of the obese state.

Adipose Tissue↗
PubMed1995

The lipoprotein lipase HindIII polymorphism modulates plasma triglyceride levels in visceral obesity.

The aim of this study was to investigate the potential interaction between the lipoprotein lipase (LPL) HindIII polymorphism and visceral adipose tissue (AT) accumulation in the modulation of triglyceride levels in visceral obesity. The LPL-HindIII genotype was determined by polymerase chain reaction in 52 min. Twenty-three subjects were heterozygous (+/-) and 28 were homozygous (+/+) for the presence of the restriction site. One subject who was homozygous for the--allele was excluded from analysis. Body mass index (BMI), fasting insulin level, and visceral AT area as measured by computed tomography were positively correlated with triglyceride levels only in subjects homozygous for the + allele. Furthermore, whereas these variables were negatively correlated with plasma HDL2 cholesterol concentrations in the +/+ group, these associations were not found in +/- heterozygotes, with the exception of BMI. To further investigate the interaction of the LPL-HindIII polymorphism with visceral obesity and hyperinsulinemia, the two genotype groups were further subdivided on the basis of BMI (low versus high), fasting insulin level (low versus high), and visceral AT area (low versus high), and their lipoprotein profiles were compared. Elevated levels of abdominal visceral AT were significantly associated with increased triglyceride concentrations in +/+ homozygous men, suggesting that visceral obesity may lead to hypertriglyceridemia in the presence of the +/+ genotype. In the +/- group, variation in the amount of visceral AT was not associated with differences in triglyceride concentration. However, hypertriglyceridemia and an increased cholesterol-to-HDL cholesterol ratio were observed in the hyperinsulinemic state irrespective of LPL-HindIII genotype status.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1981

Modified lipoprotein lipase activities, rates of lipogenesis, and lipolysis as factors leading to lipid depletion in C57BL mice bearing the preputial gland tumor, ESR-586.

The biochemical basis for the observed depletion of adipose tissue in C57BL mice bearing a transplantable nonmetastasizing preputial gland tumor, ESR-586, has been investigated. The results have shown that there are a number of significant changes in both deposition and mobilization of lipid as the tumor grows. The first change, before the tumor reached 2 g, was a decline in the activity of adipose tissue lipoprotein lipase to levels normally found in starved animals. This was accompanied by a slight increase in lipoprotein lipase activity in heart and appearance of substantial activity in large tumors. Together, these would result in impaired uptake of exogenous fatty acids by adipose tissue, and dietary lipid would be directed away from storage. This was followed by a marked decline in endogenous lipid synthesis in adipose tissue which commenced when the tumor weighed between 2 and 3 g, as measured in vivo by the incorporation of radioactivity into lipid from tritiated water. The basal rate of lipolysis was enhanced 2-fold in epididymal fat pads from mice bearing tumors that weighed between 2 and 4 g, although there was no difference in the epinephrine-stimulated activity.

Adipose Tissue↗
PubMed1997

Efficient adenovirus-mediated ectopic gene expression of human lipoprotein lipase in human hepatic (HepG2) cells.

Gene therapy to deliver and express a corrective lipoprotein lipase (LPL) gene may improve the lipid profile and reduce the morbidity and potential atherogenic risk from hypertriglyceridemia and dyslipoproteinemia in patients with complete or partial LPL deficiency. We have used an E1-/E3- adenoviral vector, with an RSV-driven human LPL cDNA expression cassette (Ad-RSV-LPL), to achieve high ectopic LPL gene expression in the human hepatoma cell line HepG2, an accepted hepatocellular model of lipoprotein metabolism. Ad-RSV-LPL transduction of HepG2 cells with a multiplicity of infection (moi) between 12.5 and 100 yielded dose-dependent increments in LPL mass and activity. Peak levels of LPL protein of 2,032.1 +/- 274.5 ng/10(5) cells per ml (mol 100) correlated with increased activity of 92.7 +/- 22.6 mU/10(5) cells per ml relative to negligible LPL levels in Ad-RSV-LacZ (beta-galactosidase) controls. Exogenous LPL expression over a 5-day period peaked at day 3. Susceptibility to inhibition by 1 M NaCl and an anti-LPL monoclonal antibody confirmed that lipase activity was indeed derived from human LPL. Hydrolysis, by LPL-overexpressing HepG2 cells, of TG carried in very-low-density lipoprotein (VLDL) showed that greater than 50% of the triglycerides (TG) disappeared after 4 hr of incubation. These results were compatible with FPLC evidence of a marked reduction in VLDL-TG. These results provide strong in vitro evidence that adenoviral-mediated ectopic expression of the human LPL gene could render hepatic cells capable of VLDL catabolism and thus support the possibility for in vivo adenoviral vector-mediated liver-targeted LPL gene therapy.

Adenoviridae↗