Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During adipose tissue development changes in lipoprotein lipase activity per adipocyte precede significant changes in fat cell size. Lipoprotein lipase activity per adipocyte increases fourfold from the second to seventh postnatal week. Furthermore, when isolated adipocytes and stromal--vascular cells are prepared by collagenase digestion of adipose tissue, there is a progressive shift in enzyme activity during development from the stromal-vascular compartment to the adipocyte fraction. The data support the concept that during normal development a "bed" of preadipocytes is synthesized during the suckling period. The data further suggest a regulatory role for lipoprotein lipase in the control of "lipid-filling" during early postnatal development.
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PMID:A comparison of lipoprotein lipase activity and adipocyte differentiation in growing male rats. 1 47

To identify cells developing into adipocytes by accumulation of triglyceride, rat epididymal fat pad cells from small rats were exposed to (3)H-labeled chylomicron fatty acids in vivo and then liberated with collagenase. Tissue remnants were removed by filtration and mature fat cells by flotation. Aggregating cells were then removed by filtration through a 25- micro m nylon screen. Further purification of cells labeled in vivo was obtained by removing floating cells from those adhering to the bottom of a culture dish. The adhering cells multiplied to a confluent monolayer when cultured in Medium 199 containing serum, glucose, insulin, and a triglyceride emulsion. The cells then gradually enlarged due to granulation of the cytoplasm by a lipid-staining material. After about 2 weeks these granules had coalesced forming mature adipocytes of typical signet-ring appearance. Free adipocytes could then be recovered from the cultures by collagenase treatment. After about 2 weeks of culture these cells had the same size (about 30 micro m) as adipocytes recovered in the original collagenase preparation of the rat epididymal fat pad. They contained triglyceride lipase activity and incorporated glucose into triglycerides to the same extent as cells developed in vivo but had higher lipoprotein lipase activity. In vitro, heparin in a low concentration, prostaglandin E(1), isobutylmethylxanthine, and cholera toxin markedly promoted the development of these cells into adipocytes. This could be shown to occur almost completely indicating that this fraction of cells was homogeneous and consisted of cells with the capacity to form adipocytes. The duplication time was about 2 days and did not change with subculturing. Preadipocytes could be obtained by density gradient centrifugation, isolating triglyceride-containing cells either directly from the pad or after 3 days in culture. All of these cells developed into adipocytes as described above but did not multiply as readily. It was concluded that cells from the epididymal fat pad from small rats can be isolated in a homogenous fraction that develops in culture into cells of identical morphology and function as adipocytes formed in vivo. The differentiation of these cells into adipocytes may be manipulated in vitro.
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PMID:Isolation and characterization of cells from rat adipose tissue developing into adipocytes. 20 38

This study supports the possibility for multiple subcellular forms of lipoprotein lipase. 1. The total activity of lipoprotein lipase per g of intact epididymal adipose tissue from fed rats is much higher than that from starved rats. 2. The isolated fat-cells of fed and of starved rats have lipoprotein lipase of almost the same activity per g of fat-pads. The isolated fat-cells of starved rats have a much higher proportion of total activity per g of the intact tissue than do those of fed rats. 3. Under the conditions of homogenization used, only a small proportion of the total activity per g of intact tissue from fed rats was associated with the fat layer which floated to the top of the homogenate during low-speed centrifugation. The different proportions of the specific enzyme activity found in each subcellular fraction are described. 4. Lipoprotein lipase from plasma membranes and microsomal fractions from starved and fed rats was purified by affinity chromatography. 5. The total activity of microsomal lipoprotein lipase per g of intact adipose tissue is enhanced by a normal diet. 6. In intact epididymal adipose tissue from fed rats, the activity per g of tissue of lipoprotein lipase of plasma membranes is much higher than that in the same fraction from starved rats. By contrast, the activities per g of tissue in plasma membranes obtained from starved or from fed rats by collagenase treatment were similar.
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PMID:Effect of nutrition on subcellular localization of rat fat-cell lipoprotein lipase. 66 42

Cell strains were derived from the stromal-vascular fraction of human omental adipose tissue and grown in culture. Since the purpose of this study was to isolate adipocyte precursors from adults, the cells were obtained from nonobese patients 40-60 yr of age. After treatment of adipose tissue with collagenase, mature adipocytes were separated from stromal-vascular fraction cells, and cell strains of the latter replicated in culture with a doubling time of 40-60 h. They were initially fusiform; upon reaching monolayer confluency, they accumulated lipid and became rounder. Skin fibroblasts from the same patients and grown under the same culture conditions remained fusiform and did not accumulate lipid. The stromal-vascular fraction cells of adipose tissue may be fibroblasts with the potential to become adipocyte precursors. Subcellular preparations of the cells grown from the stromal-vascular fraction revealed lipoprotein lipase activity (characterized by such properties as inhibition by 1 M NaCl) that was not detectable in skin fibroblasts. The overall specific activity of the enzymes that catalyze triglyceride synthesis was 15 times higher and that of fatty acid synthetase was 2 times higher in the cells cultured from the stromal-vascular fraction. The difference was significant in each case. Conversely, when isolated mature adipocytes were cultured, they lost considerable lipid and acquired morphological characteristics similar to those of stromal-vascular fraction cells. Thus, adipose tissue stromal-vascular fraction cells acquire in culture many of the morphological and enzymological characteristics of mature fat cells.
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PMID:Cytological and enzymological characterization of adult human adipocyte precursors in culture. 95 96

Several studies have shown lipoprotein lipase (LPL) activity in human placenta, but the quantitative significance and cellular specificity of LPL in this organ are unknown. The objective of this report is to investigate the metabolism of very-low-density lipoprotein triglycerides (VLDL-TG) by the placenta, the role of LPL in this process, and the types of cells involved. Placental cells were obtained by enzymatic digestion (collagenase, hyaluronidase, and DNA-ase) and separated on a 40% Percoll gradient. The trophoblasts were the predominant cell type (80% to 85% pure) isolated at d = 1.033 to 1.048 and macrophages were predominant at d = 1.077 to 1.100 (greater than 95% pure), as characterized by eight immunocytochemical assays using cell protein-specific monoclonal antibodies. Macrophages represented 50% to 60% of cells isolated, and trophoblasts, 40% to 50%. LPL activity was assessed by VLDL-TG hydrolysis in primary 3- to 4-day tissue culture. In a representative experiment, LPL activity (nmol fatty acids (FA)/mg protein/24 h) was 101.3 +/- 5.3 in macrophages and 29.9 +/- 6.5 in the predominant trophoblast cell types, with approximately 20% of these amounts incorporated and reesterified. VLDL-TG hydrolysis and cell lipid uptake in both placental cell types was essentially abolished by a monoclonal anti-LPL antibody. When compared with a model of hepatocytes (Hep G2 cells), the hydrolysis of VLDL-TG was almost undetectable in these cells. In contrast, free fatty acids (FFA) uptake by Hep G2 cells was fourfold to sixfold greater than that by macrophages and trophoblasts, respectively. In conclusion, macrophages and trophoblasts are the two predominant placental cells isolated by enzymatic digestion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolism of very-low-density lipoprotein triglyceride by human placental cells: the role of lipoprotein lipase. 164 Aug 46

1. Gluteal adipose tissue was examined in 13 patients with generalized adiposis dolorosa, a clinical condition characterized by painful adiposity with a chronic intractable course. The total metabolic activity of fat cells, isolated by collagenase and suspended in Krebs-Ringer bicarbonate buffer with glucose and insulin, was assessed by the measurement of heat production at 37 degrees C using microcalorimetry. 2. Fat cells were markedly enlarged; their metabolic activity expressed in terms of microW/g, but not in pW/cell, was significantly decreased when compared with both lean and weight-matched non-painful subjects. Both mean values were, however, significantly higher than in grossly obese subjects with similar mean cell size. Heat production as expressed per g of tissue, but not per cell, was inversely correlated with body mass index. One additional patient had unilateral disease, and fat cells from the painful side had a lower heat production than cells from the unaffected side. 3. The fatty acid composition of adipose tissue, as determined by g.c., revealed a significantly increased proportion of monounsaturated (18:1 and 16:1) at the expense of saturated (14:0 and 18:0) fatty acids compared with healthy control subjects. The activity of adipose tissue lipoprotein lipase was slightly, but not significantly, decreased. 4. It is concluded that a metabolic pathogenetic factor cannot be ruled out in adiposis dolorosa. As the results do not explain the nature of the diffuse pain, further studies need to be performed.
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PMID:Fat-cell heat production, adipose tissue fatty acids, lipoprotein lipase activity and plasma lipoproteins in adiposis dolorosa. 166 86

The lipoprotein lipase activity in the liver of neonatal (1 day old) rats was about 3 times that in the liver of adult rats. Perfusion of the neonatal liver with collagenase decreased the tissue-associated activity by 77%. When neonatal-rat liver cells were dispersed, hepatocyte-enriched (fraction I) and haemopoietic-cell-enriched (fraction II) populations were obtained. The lipoprotein lipase activity in fraction I was 7 times that in fraction II. On the basis of those activities and the proportion of both cell types in either fraction, it was estimated that hepatocytes contained most, if not all, the lipoprotein lipase activity detected in collagenase-perfused neonatal-rat livers. From those calculations it was also concluded that haemopoietic cells did not contain lipoprotein lipase activity. When the hepatocyte-enriched cell population was incubated at 25 degrees C for up to 3 h, a slow but progressive release of enzyme activity to the incubation medium was found. However, the total activity (cells + medium) did not significantly change through the incubation period. Cycloheximide produced a time-dependent decrease in the cell-associated activity. Heparin increased the amount of lipoprotein lipase activity released to the medium. Because the cell-associated activity was unchanged, heparin also produced a time-dependent increase in the total activity. In those cells incubated with heparin, cycloheximide did not affect the initial release of lipoprotein lipase activity to the medium, but blocked further release. The cell-associated activity was also decreased by the presence of cycloheximide in those cells. It is concluded that neonatal-rat hepatocytes synthesize active lipoprotein lipase.
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PMID:Lipoprotein lipase activity in neonatal-rat liver cell types. 271 40

A method for the isolation of brown adipocytes free of fat interferences and sensitive to noradrenalin is presented. The cells were isolated from pieces of brown adipose tissue with a collagenase treatment. The cells were obtained in the presence of heparin, in order to free the lipoprotein lipase attached to the cell surface. The cells were isolated in the presence of Amberlite XAD-2 [polymeric hydrophobic absorbent beads], which retained most of the fat droplets, formed from broken cells, during the process of disaggregation. The combined use of heparin and Amberlite XAD-2 during the isolation procedure resulted in a lowered cell basal oxygen consumption rate when compared with that of cells isolated with standard methods. The treatment presented lowered the availability of extracellular fatty acids for the isolated brown fat cells, resulting in lower operation of the thermogenin shunt, and thence in decreased basal oxygen consumption and higher sensitivity to glucose and noradrenalin stimulation.
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PMID:An improved procedure for the isolation of rat brown adipose tissue cells. 339 95

The present study investigated the interaction of genotype and short-term overfeeding on adipose tissue metabolism of six pairs of male monozygotic twins. The sedentary nonobese twins were submitted to a 22-day overfeeding period in which their normal daily intake was supplemented by an additional 1,000 kcal/day. A fat tissue biopsy was performed in the suprailiac region before and after overfeeding to determine fat cell diameter and basal and maximal stimulated epinephrine, norepinephrine, and isoproterenol lipolysis from collagenase-isolated fat cells. Fat cell basal and maximal insulin-stimulated glucose conversion into triglycerides (basal and stimulated lipogenesis) were measured using [14C]glucose. Adipose tissue heparin-releasable lipoprotein lipase activity (LPL) was also determined. A repeated measures analysis of variance revealed overfeeding induced significant elevations in basal lipogenesis (P less than 0.05) and fat cell diameter (P less than 0.05). No significant group changes were noted in basal, epinephrine-, norepinephrine-, and isoproterenol-stimulated lipolysis, insulin-stimulated lipogenesis, and LPL activity due to large individual variation in the response to overfeeding. However, significant intrapair resemblance was noted in the changes of the aforementioned variables, suggesting a coherent within-twin pair response, despite large between-pair variation in response. Less within-pair similarity was noted in changes in basal lipogenesis and fat cell diameter. The results of the present study suggest that overfeeding induced a large range of adipose tissue metabolic responses and that the genotype plays a role in determining the sensitivity of adipose tissue adaptation to caloric affluence.
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PMID:Genotype dependency of adaptation in adipose tissue metabolism after short-term overfeeding. 351 66

In order to study the acute effects of exercise on adipose tissue metabolism, 27 sedentary male subjects, 18 to 27 years of age, performed a prolonged aerobic exercise test. Biopsies of adipose tissue were obtained from the suprailiac fat depot before and immediately after a 90-minute period of exercise on ergocycle at an average intensity of 88% of maximal heart rate. Fat cells, isolated by collagenase digestion, were measured for their glucose conversion into triglycerides and for lipolytic activity. Adipose tissue lipoprotein lipase activity released by heparin was also determined. Mean basal and insulin-stimulated glucose conversion into triglycerides decreased significantly with exercise (P less than .05) while adipose tissue lipoprotein lipase activity increased (P less than .01). Fat cell lipolysis increased during exercise only for its epinephrine-stimulated values (P less than .05). The total amount of work performed during the test was correlated only with changes in lipoprotein lipase activity (r = .42, P less than .05). Finally, the changes induced by exercise in lipoprotein lipase activity (r = .37, P less than .05) and insulin-stimulated glucose conversion into triglycerides (r = .61, P less than .01) were positively correlated with fat cell weight. These results indicate that adipose tissue metabolic activities are selectively influenced by endurance exercise. They also suggest that these metabolic changes are not closely coupled with the amount of work performed in a prolonged exercise bout.
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PMID:Acute effects of endurance exercise on human adipose tissue metabolism. 355 50


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