Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A clonal cell line that responds to insulin and to lipolytic hormones has been established from the epididymal fat pad of the C57BL/6J ob/ob mouse. This line, designated ob 17, has a doubling time of 12.5 or 19 hr in 10% or 1% fetal calf serum, respectively. It presents a heterogeneous chromosome number with 40% of the cells containing 35-44 chromosomes and expresses the characteristic H2-LA antigen. After cessation of growth, ob 17 cells accumulate droplets of triglycerides; this accumulation occurs to a significant extent even in the absence of insulin normally added after confluence. Lipoprotein lipase activity is negligible in exponentially growing cells but appears at its maximal level just after confluence with or without insulin. Acid:CoA ligase and acylCoA:diglyceride acyltransferase develop later than lipoprotein lipase. The appearance of lipolytic and lipogenic enzymes, but not of triglycerides, seems to be independent of the presence of lipoproteins or of unesterified fatty acids in the culture medium. Therefore, the differentiation program becomes operative when growth is arrested, and differentiation occurs, providing a source of exogenous lipids. Differentiated ob 17 cells in which endogenous triglycerides have been prelabeled on the fatty acid moiety do respond to epinephrine and corticotropin by release of radioactive fatty acid. This lipolytic response is counteracted by prior addition of insulin. The ob 17 cell line appears to be a useful model for study of growth and differentiation of adipose cells as compared to preadipocyte cell lines from the nongenetically obese mouse.
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PMID:Establishment of preadipocyte clonal line from epididymal fat pad of ob/ob mouse that responds to insulin and to lipolytic hormones. 21 11

Wistar male rats, both fed and fasting for 16 h prior to irradiation, were exposed to a single lethal X-ray dose of 387 mC X kg-1 (1 500R). The activity of lipoprotein lipase in white adipose (epididymal) tissue and heart muscle and the concentration of serum triglycerides were determined at 1, 6, 24, 48, and 72 h after radiation exposure. In the early time periods, at 1 and 6 h after exposure, the activity of lipoprotein lipase was decreased in adipose tissue and increased in heart muscle of the irradiated fed rats; in fasting rats it was decreased in heart muscle at 1 h after exposure. The concentration of serum triglycerides was increased at 1 h and decreased at 6 h after exposure in fed rats. In these rats, alterations in serum triglycerides correlated with changes in lipoprotein lipase activity in adipose tissue. Alterations observed at the later time periods were more dependent on the time interval between radiation exposure and the analysis. Lipoprotein lipase activity increased with time after radiation exposure up to the maximal values at 72 h. Fasting prior to and after irradiation substantially modified the response of animals to radiation.
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PMID:The effect of a single lethal x-irradiation exposure on the activity of lipoprotein lipase in the tissues of the rat. 49 96

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

Lipoprotein lipase (LPL) enzyme activity in epididymal adipose tissue from obese and lean Zucker rats was measured. At 5, 10, 13, and 20 wk of age obese rats have heavier fat pads, larger fat cells, and more LPL per epididymal fat pad and per fat cell than do their lean littermate controls. Although LPL per fat cell increased as fat cell size increased in lean rats, the increased LPL activity in the obese could not be attributed solely to increased fat cell size. When obese and lean rats had similar cell sizes, LPL per fat cell was still significantly increased in the obese compared to lean. Furthermore LPL activity was increased in "preobese" (fa/fa) rats compared to either lean genotype (Fa/fa or Fa/Fa) during the second postnatal week. The data suggest that early increments in LPL activity in adipose tissue of the "pre-obese" rat may significantly contribute to the early fat cell hypertrophy seen during the development of this genetic obesity. Furthermore, early increased LPL activity may prove useful as a predictor of the onset of obesity.
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PMID:Increased adipose tissue lipoprotein lipase activity during the development of the genetically obese rat (fa/fa). 72 44

Subcutaneous injections of the lipotropic agent, ethyl trichloracetate, to rats with established choline deficiency raised their plasma triglycerides by 60% and completely removed the hyperglyceridaemic response of Triton WR 1339. The plasma triglyceride levels of choline-supplemented rats were depressed slightly by ethyl trichloracetate administration, which was effective in abolishing response to Triton WR 1339. Lipoprotein lipase activity of epididymal fat pad was stimulated 60% while plasma lipoprotein was not stimulated by ethyl trichloracetate. The increased peripheral removal of low-density lipoprotein-triglyceride complex, allowing greater use to be made of existing apo-proteins, may explain the lipotropic character of the ester.
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PMID:Factors influencing lipoprotein lipase activity in choline deficiency. 75 35

Lipoprotein lipase activity in intact epididymal adipose tissue of fasted rats increased rapidly after treatment with insulin in vivo. In contrast, lipoprotein lipase activity in adipocytes isolated from the contralateral fat pads remained essentially unchanged. When adipocytes were incubated for 30 min at ambient temperature in vitro, about 2 times more lipoprotein lipase activity was found in the medium of cells from insulin-treated rats than in medium from cells of control animals. Following insulin treatment, extracts of tissue acetone powders separated by gel chromatography showed increases in both enzyme activity fractions obtained (designated lipoprotein lipase a and b). However, no consistent differences were observed between fractions derived from adipocyte acetone powders of insulin-treated and control animals. All the observed effects of insulin on lipoprotein lipase activity were abolished by cycloheximide treatment in vivo. These data indicate that following insulin treatment, increased lipoprotein lipase activity in adipose tissue results from enhanced enzyme secretion by the fat cell and subsequent accumulation in the tissue, thus implicating the adipocyte secretory mechanism as a major site of regulation of lipoprotein lipase activity in adipose tissue.
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PMID:Regulation of lipoprotein lipase. Induction by insulin. 125 91

Adipose tissue has been reported to contain relatively high levels of the specific mRNA for retinol-binding protein (RBP) (Makover A., Soprano, D.R., Wyatt, M. L., and Goodman, D.S. (1989) J. Lipid Res. 30, 171-180). Studies were conducted to explore retinoid and retinoid-binding protein storage and metabolism in adipose tissue. In these studies, we measured RBP and cellular retinol-binding protein (CRBP) mRNA levels and retinoid levels in 6 adipose depots in male rats. Total RNA was isolated from inguinal, dorsal, mesenteric, epididymal, perinephric, and brown adipose tissue, and average RBP and CRBP mRNA levels were determined by Northern blot analysis. The relative levels of RBP mRNA in these 6 anatomically different adipose depots averaged, respectively, 6.3, 6.7, 16, 34, 37, and 21% of the level in a rat liver RNA standard. Retinoid levels in the 6 depots were similar and averaged approximately 6-7 micrograms of retinol eq/g of adipose tissue. Since adipose tissue contains several cell types, the cellular localizations of RBP and CRBP expression and retinoid storage were examined. RNA was prepared from isolated rat adipocytes and stromal-vascular cells. Cellular levels of the mRNAs for RBP, CRBP, apolipoprotein E (apoE), lipoprotein lipase, adipocyte P2, and adipsin were measured by Northern blot analysis. RBP was expressed almost exclusively in the adipocytes and only weakly in the stromal-vascular cells. Both CRBP and apoE mRNA levels were relatively high in the stromal-vascular cell preparations and only very low mRNA levels were found in the adipocytes. Lipoprotein lipase, adipsin, and adipocyte P2 mRNAs were found in substantial levels in both the adipocytes and stromal-vascular cells, but with higher levels present in the adipocytes. Cultured adipocytes synthesized RBP protein and secreted it into the medium. Only adipocytes (not stromal-vascular cells) contained retinol, at levels between 0.65-0.8 micrograms of retinol eq/10(6) cells. These studies demonstrate that adipocytes store retinoid and synthesize and secrete RBP, and suggest that rat adipocytes may be dynamically involved in retinoid storage and metabolism.
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PMID:Retinoids and retinoid-binding protein expression in rat adipocytes. 137 Apr 81

Lipoprotein lipase (LPL) is an enzyme found in adipose tissue that is important in the hydrolysis of triglyceride rich lipoproteins, and in the uptake of FFA lipid into the adipocyte. To examine the effects of glucocorticoids on adipose tissue LPL, male Sprague-Dawley rats were injected with dexamethasone (1 mg/kg) every other day for 10 days, followed by measurement of LPL in epididymal adipose tissue. Compared to sham-injected controls, heparin-releasable LPL activity and LPL mass in the dexamethasone-treated rats were 44% and 62% of those in control rats, respectively. Adipocytes were prepared from the fat pads and pulse labeled with [35S]methionine, demonstrating a decrease in the LPL synthetic rate in the treated rats to 57% of the rate in control rats. In addition, LPL mRNA was quantitated by Northern blotting, demonstrating a decrease in LPL mRNA in the dexamethasone-treated rats. A simultaneous decrease in the message for gamma-actin was also noted. To examine the effects of dexamethasone on LPL in vitro, adipocytes were prepared from normal rats and treated with dexamethasone for 24 h in vitro. Dexamethasone decreased heparin-releasable LPL activity in cultured adipocytes to 40 +/- 6% of the control value (P less than 0.01). This decrease in LPL activity was accompanied by a decrease in the LPL synthetic rate using [35S]methionine labeling, to 33% of the control value, and no specific change in LPL turnover or secretion. In addition, dexamethasone added to adipocytes decreased LPL mRNA levels. Because the combination of insulin plus dexamethasone has been shown to yield synergistic increases in LPL in adipose tissue pieces, insulin was added to isolated adipocytes in combination with dexamethasone. Whereas insulin and dexamethasone individually had opposite effects on LPL, the combination of insulin plus dexamethasone resulted in no change in any aspect of LPL gene expression. Thus, dexamethasone resulted in a decrease in adipocyte LPL mRNA levels both when added to cultured adipocytes in vitro as well as when injected into rats. This decreased LPL mRNA level yielded corresponding changes in the LPL synthetic rate and LPL activity.
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PMID:The regulation of lipoprotein lipase gene expression by dexamethasone in isolated rat adipocytes. 154 42

Lipoprotein lipase (LPL) is an important enzyme in lipid metabolism, and adipose LPL activity is increased in rats that are deficient in thyroid hormone. To examine the mechanism of thyroid hormone's effect on LPL, LPL gene expression was assessed in the epididymal fat pads of hypothyroid rats. When compared to control rats, LPL activity, mass, and synthetic rate in hypothyroid rats were increased; heparin-releasable LPL activity and mass were increased to 448% and 300% of control, respectively, and [35S]methionine incorporation into LPL was increased to 250% of control. The increases in LPL activity and mass were reversed by treatment of hypothyroid rats with triiodothyronine (T3). However, there was no change in the level of LPL mRNA when compared to the level of gamma-actin mRNA and no effect on LPL transcription using run-off assays. Isolated adipocytes were prepared from normal rats and exposed to 2 nM T3 in vitro for 24 h. The addition of T3 to cultures of adipocytes resulted in a decrease in LPL activity, mass, and [35S]methionine incorporation, but still no change in LPL mRNA level. To determine whether thyroid hormone regulated catecholamine responsiveness, adipocytes were prepared from hypothyroid and control rats, and the responses to epinephrine were compared. Although epinephrine inhibited [35S]methionine incorporation into LPL in control rat adipocytes, there was essentially no effect in hypothyroid rat cells. In addition, T3 treatment of the hypothyroid rats restored the responsiveness to epinephrine. Thus, thyroid hormone regulates LPL in rat adipose tissue posttranscriptionally, resulting in parallel changes in LPL synthetic rate, immunoreactive mass, and activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of adipose tissue lipoprotein lipase gene expression by thyroid hormone in rats. 156 76

Lipoprotein lipase (LPL) activity and mRNA levels were measured in cardiac muscle and adipose tissue from lean, obese, and weight-stable reduced-obese Zucker rats, both fasted and 2 h after feeding. Fasting epididymal fat LPL activity was substantially higher in obese rats relative to lean rats [6.9 vs. 0.2 nmol free fatty acid (FFA).10(6) cells-1.min-1; P = 0.0001], and was higher still in reduced-obese rats (15.7 nmol FFA.10(6) cells-1.min-1; P = 0.002). Adipose tissue LPL increased with feeding in all three groups. In marked contrast, fasting cardiac muscle LPL was lower in obese rats relative to lean (28.8 vs. 38.5 nmol FFA.g-1.min-1; P = 0.0064) and was lower still in reduced-obese rats (14.5 nmol FFA.g-1.min-1; P = 0.0001). LPL mRNA levels increased in adipose tissue along with enzyme activity; however, the magnitude of the changes were relatively small, suggesting that the primary regulatory steps are posttranslational. Weight reduction studies were also carried out in Sprague-Dawley rats with similar results. These studies show that sustained weight reduction results in coordinate changes in tissue-specific LPL, favoring delivery of lipoprotein triglyceride fatty acids to adipose tissue relative to cardiac muscle and the restoration of energy stores.
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PMID:Weight reduction increases adipose but decreases cardiac LPL in reduced-obese Zucker rats. 187 86


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