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

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

1. The metabolism of VLD lipoproteins (very-low-density lipoproteins) was studied in intact isolated beating-heart cells and isolated perfused rat heart from starved animals by using [14C]triacylglycerol fatty acid-labelled VLD lipoprotein prepared from rats previously injected with [1-14C]palmitate. 2. 14C-labelled VLD lipoprotein was metabolized by the isolated perfused heart, but was only minimally metabolized by the heart cells unless an exogenous source of lipoprotein lipase was added. 3. Measurements of lipoprotein lipase at pH 7.4 with the natural substrate 14C-labelled VLD lipoprotein indicated that during collagenase perfusion of the heart the enzyme was released into the perfusate, the activity released being proportional to the concentration of collagenase used. Lipoprotein lipase activity in homogenates of hearts that had been perfused with collagenase showed a corresponding loss of activity. 4. At high perfusate concentrations of collagenase, inactivation of the released lipoprotein lipase occurred. 5. Lipoprotein lipase activity was largely undetectable in the homogenate of the isolated heart cells. 6. It is concluded that the lipoprotein lipase responsible for the hydrolysis of VLD lipoprotein triacylglycerol is predominantly located externally to the heart muscle cells and that its release can be facilitated by perfusion of the heart with bacterial collagenase.
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PMID:Differences in the metabolism of very-low-density lipoproteins by isolated beating-heart cells and the isolated perfused rat heart. Evidence for collagenase-released extracellular lipoprotein lipase. 624 85

Lipogenesis from glucose and lipoprotein lipase activity were investigated in humans. The reliability of measurements was quantified and correlations with fat cell weight were assessed. Twenty-four subjects (7 women, 17 men) were studied twice within a 2-week period, along with 17 additional male subjects who were studied once and used only in the correlation analyses. All subjects were not regularly involved in an exercise-training program and were between 18 and 30 years of age. Following an overnight fast, adipose tissue specimens were obtained by suprailiac biopsy and fat cells were collagenase isolated. Mean fat cell weight was obtained from 400 to 500 cell diameter determinations per subject. Basal and insulin-stimulated fat cell lipogenesis from glucose were determined using D-[U-14C]glucose and were reported in nanomoles of glucose per hour per 10(6) cells. Adipose tissue heparin-releasable lipoprotein lipase activity was also determined and expressed in micromoles of free fatty acids per hour per gram of tissue and per 10(6) cells. Fat cell weight, basal and insulin-stimulated lipogenesis and lipoprotein lipase activity per gram showed high reliability of measurement, interclass and intraclass coefficients being 0.83 and over. Lipoprotein lipase activity per 10(6) cells showed a somewhat lower degree of reliability, interclass and intraclass coefficients being, respectively, 0.69 and 0.81. On the other hand, fat cell weight was positively correlated with lipoprotein lipase activity (r = 0.80), while no significant correlation was observed between basal lipogenesis and fat cell weight. Moreover, basal lipogenesis presented no significant correlation with lipoprotein lipase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lipogenesis and lipoprotein lipase in human adipose tissue: reproducibility of measurements and relationships with fat cell size. 639 48

The present study examined whether recombinant porcine leptin alters lipid synthesis in porcine adipocytes. The stromal-vascular cell fraction of neonatal pig subcutaneous adipose tissue was isolated by collagenase digestion, filtration, and subsequent centrifugation. These cells were seeded on 25-cm2 tissue culture flasks and proliferated to confluency in 10% (vol/vol) fetal bovine serum in Dulbecco's modified Eagle medium/F12 (DMEM/F12, 50:50). Cultures were differentiated using 2.5% pig serum (vol/vol), 10 nM insulin, 100 nM hydrocortisone. After 7 d of lipid filling, cultures were washed free of this medium, incubated overnight in DMEM/F12 containing 2% pig serum (vol/vol), and then used for experiments. Acute experiments assessed U-(14)C-glucose or 1-(14)C-palmitate metabolism in cultures exposed to porcine leptin (0 to 1,000 ng/mL medium) for 4 h. Chronic experiments used cultures incubated with 0 to 1,000 ng porcine leptin/mL medium for 44 h before measurements of U-(14)C-glucose and 1-(14)C-palmitate oxidation and incorporation into lipid. Another experiment examined whether chronic leptin treatment alters insulin responsiveness by including insulin (10 nM) with incubations containing leptin. Leptin had no acute effects on glucose oxidation or conversion to lipid (P > 0.05). Acute leptin treatment decreased palmitate incorporation into lipids up to 45% (P < 0.05). Chronic leptin exposure decreased glucose oxidation (21%), total lipid synthesis (18%), and fatty acid synthesis (23%) at 100 ng/mL medium (P < 0.05). Insulin increased rates of glucose oxidation, total lipid, and fatty acid synthesis (P < 0.05); however, chronic exposure to 10 ng leptin/mL medium decreased the effectiveness of 10 nM insulin to affect these measures of glucose metabolism by approximately 18 to 46% (P < 0.05). Higher concentrations of leptin inhibited all effects of insulin on glucose metabolism (P < 0.05). Chronic exposure to leptin increased palmitate oxidation by 36% (P < 0.05). Chronic leptin exposure decreased palmitate incorporation into total lipids by 40% at 100 ng/mL medium (P < 0.05). Lipoprotein lipase activity was not affected (P > 0.05) by leptin. These data indicate that leptin functions to promote partitioning of energy away from lipid accretion within porcine adipose tissue by inhibiting glucose oxidation and lipogenesis indirectly, by decreasing insulin-mediated stimulation of lipogenesis, and by stimulating fatty acid oxidation while inhibiting fatty acid esterification.
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PMID:Porcine leptin inhibits lipogenesis in porcine adipocytes. 1467 56

We examined omental and subcutaneous adipose tissue adipocyte size, and lipolysis and lipoprotein lipase (LPL) activity in a sample of 33 men aged 22.6 to 61.2 years and with a body mass index ranging from 24.6 to 79.1 kg/m2. We tested the hypothesis that lipolysis rates would be higher in the omental fat depot than in subcutaneous adipose tissue and that this difference would persist across the spectrum of abdominal adiposity values. Omental and subcutaneous adipose tissue samples were obtained during surgery. Adipocytes were isolated by collagenase digestion. Adipocyte size and LPL activity as well as basal, isoproterenol-, forskolin-, and dibutyryl cyclic adenosine monophosphate-stimulated lipolysis were measured. Although adipocytes from both fat compartments were larger in obese subjects, no difference was observed in the size of omental vs subcutaneous fat cells. Lipoprotein lipase activity, expressed as a function of cell number, was significantly higher in omental than in subcutaneous fat tissue (P<.005). Basal lipolysis and lipolytic responses to isoproterenol, forskolin, or dibutyryl cyclic adenosine monophosphate, expressed either as a function of cell number or as a fold response over basal levels, were not significantly different in omental vs subcutaneous fat cells. When stratifying the sample in tertiles of waist circumference, adipocyte diameter was similar in the omental and subcutaneous depots for all adiposity values. Omental adipocyte size reached a plateau in the 2 upper tertiles of waist circumference, that is, from a waist circumference of 125 cm and above. Lipoprotein lipase activity was significantly higher in omental cells in the middle tertile of waist circumference (P=.05), and no regional difference was noted in lipolysis values across waist circumference tertiles. In conclusion, in normal-weight to morbidly obese men, although adipocyte size and lipolysis tended to increase with higher waist circumference, no difference was observed between the omental and subcutaneous fat depot.
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PMID:Regional differences in adipose tissue metabolism in obese men. 1737 13