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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fatty acids, the preferred substrate in normoxic myocardium, are derived from either exogenous or endogenous triacylglycerols. The supply of exogenous fatty acids is dependent of the rate of lipolysis in adipose tissue and of the lipoprotein lipase activity at the coronary vascular endothelium. A large part of the liberated fatty acids is reesterified with glycerol-3-phosphate and converted to triacylglycerols. Endogenous lipolysis and lipogenesis are intracellular compartmentalized multienzyme processes of which individual hormone-sensitive steps have been demonstrated in adipose tissue. The triacylglycerol lipase is the rate-limiting enzyme of lipolysis and glycerol-3-phosphate acyltransferase and possibly phosphatidate phosphohydrolase are the rate-limiting enzymes of lipogenesis. The hormonal regulation of both processes in heart is still a matter of dispute. Triacylglycerol lipase activity in myocardial tissue has two intracellular sources: 1. the endoplasmic reticular and soluble neutral lipase, and 2. the lysosomal acid lipase. Studies in our laboratory have indicated that whereas lipolysis is enhanced during global ischemia and anoxia, overall lipolytic enzyme activities in heart homogenates were not altered. In addition we were unable to demonstrate alterations in tissue triacylglycerol content and glycerol-3-phosphate acyltransferase activity under these conditions. Lipolysis, is subject to feedback inhibition by product fatty acids. Therefore all processes leading to an increased removal of fatty acids from the catalytic site of the lipase will stimulate lipolysis. These studies will be reviewed. In addition, studies from our department have demonstrated the capacity of myocardial lysosomes to take up and degrade added triacylglycerol-particles in vitro. Such a process, stimulated by Ca2+ and stimulated by acidosis, offers another physiological target for hormone actions.
Mol Cell Biochem
PMID:Hormones and triacylglycerol metabolism under normoxic and ischemic conditions. 267 63

Since we have previously reported that hyperthyroidism induces adipose tissue hyperplasia in the young rat, the effect of thyroid hormones on growth and differentiation of preadipocytes from retroperitoneal (RPAT) and epididymal (EAT) adipose tissue was studied in a primary culture system which allows a precocious cell differentiation. In this culture system, preadipocytes from RPAT exhibited a greater potentially to differentiate than cells from EAT. Chronic exposure to triiodothyronine (T3) induced an acceleration of the differentiating process as shown by a transient increase of the number of differentiated cells without alteration of cell multiplication. This effect was more important in cultures of cells from RPAT than from EAT. T3 was ineffective on lipoprotein-lipase activity but induced a stimulation of the esterification pathway which was durable and could likely be related to an increased lipid turn-over. T3 induced also a stimulation of fatty acid biosynthesis, only on the first stages of morphological differentiation which suggests that this effect could be specifically in relation with the stimulation of adipose conversion.
Cell Mol Biol 1989
PMID:Acceleration by triiodothyronine of adipose conversion of rat preadipocytes from two adipose localizations. 270 55

We examined the mechanisms by which the phospholipid-sensitive, calcium-dependent protein kinase (protein kinase C) regulates prostacyclin synthesis by ovarian cells. In monolayer cultures of swine granulosa cells, specific phorbol esters significantly augmented production of the stable immunoreactive metabolite of prostacyclin, 6-keto-prostaglandin F1 alpha by 3- to 8-fold. These stimulatory actions were dose (0.03-30 ng/ml) and time (24-96 h) dependent, could be reproduced by non-diterpene activators of protein kinase C, and were corroborated by high performance liquid chromatography and mass spectrometry. The rank order of potency of phorbol esters was 12-O-tetradecanoylphorbol 13-acetate (TPA) greater than phorbol 12,13-dibenzoate greater than phorbol 12,13-dibutyrate greater than pure phorbol base. TPA enhanced de novo synthesis of prostacyclin, and synergized with the divalent cation ionophore, A23187. Although prostacyclin synthetase activity was not induced, microsomal cyclooxygenase activity was significantly increased by phorbol treatment. Moreover, TPA doubled the intracellular accumulation of free arachidonic acid. An inhibitor of phospholipase A2 (quinacrine 100 microM) impeded, whereas melittin (0.01 microM), an activator of cellular phospholipase A2, and purified bacterial phospholipase A2 (5 and 50 mU/ml) both augmented prostacyclin production. RH 59022 (30 microM), an inhibitor of diacylglyceride lipase, also suppressed prostacyclin synthesis. We conclude that the protein kinase C effector pathway is functionally coupled to de novo prostacyclin production in the swine granulosa cell. Increased eicosanoid synthesis can be accounted for by enhanced phospholipase A2 and diacylglyceride lipase-mediated availability of arachidonic acid substrate and an activated cyclooxygenase enzyme without a change in prostacyclin synthetase activity.
Mol Cell Endocrinol 1989 May
PMID:Mechanism(s) by which activation of protein kinase C is coupled to prostacyclin synthesis in granulosa cells. 275 27

Purified inhibitor of the cyclic AMP-dependent protein kinase (PKI) has been used as a probe to determine if hormone and cyclic AMP-induced activation of the cardiac alkaline triacylglycerol (TG) lipase is mediated through the cAMP-dependent protein kinase. Addition of CAM (cyclic AMP, Mg-ATP, and 3-isobutyl, 1-methylxanthine) to any of the four fractions (homogenate, 10,000 g supernatant, 105,000 g supernatant, or heparin-Sepharose eluate) from heparin perfused heart activated the TG lipase 60% to 110%. Preincubation of these fractions with 33 ng of PKI had no effect on control enzyme activity. Addition of PKI (33 ng) to extracts following CAM activation had little effect on homogenate TG lipase activity, but reduced activities in 10,000 g and 105,000 g supernatant fractions to their respective control levels, and inhibited TG hydrolase activity of activated heparin-Sepharose eluate to 50% below the control activity. If extracts were preincubated with PKI prior to CAM addition, TG lipase activity was reduced to approximately 50% below control levels in all fractions. PKI addition (33 ng) to 105,000 g supernatant obtained from hearts stimulated 60% by epinephrine perfusion reduced activity to 50% below the control level. PKI inhibition of TG lipase activity of 105,000 g supernatant could be reversed by adding 0.5 microgram of catalytic subunit of protein kinase (PKC) to the extract. The inhibition below control levels caused by CAM and PKI indicate that the PKI-PKC complex by itself or in combination with other extract molecules, has an inhibitory effect on the TG lipase.(ABSTRACT TRUNCATED AT 250 WORDS)
J Mol Cell Cardiol 1987 Jul
PMID:Protein kinase inhibitor blocks the activation of a myocardial triacylglycerol lipase. 282 94

Horse (Equus caballus) pancreatic lipase (EC 3.1.1.3) has been crystallized using the hanging drop method of vapour diffusion at 20 degrees C. The best crystals were grown from an 8 mg/ml solution in 10 to 20% (w/v) polyethylene glycol 8000, 10 mM-MgCl2, 0.1 M-NaCl, 0.1 M-Mes buffer (pH 5.6). They reach dimensions of 0.8 mm x 0.4 mm x 0.6 mm. X-ray examination of the lipase crystals shows that they are orthorombic with a space group P2(1)2(1)2(1). Their cell dimensions are a = 79.8 A, b = 97.2 A c = 145.3 A. Two molecules per asymmetric unit give a Vm value of 2.82 A3/dalton (56% water content). Lipase crystals strongly diffract to at least 1.8 A resolution. Some molecular properties of horse lipase compared to those of the better-known porcine enzyme are also presented.
J Mol Biol 1989 Jan 05
PMID:Crystallization and preliminary X-ray study of horse pancreatic lipase. 292 6

The lipase (lip) gene of Staphylococcus hyicus was used to study the expression of the Escherichia coli beta-lactamase (bla) gene in S. carnosus. The bla gene, devoid of its promotor and most of the signal sequence, was fused to the lip structural gene at various positions. A set of 11 secretion vectors (pLL beta 1 to pLL beta 11) was isolated and analysed. All secretion vectors caused beta-lactamase production and activity in S. carnosus. However, the amount of hybrid proteins secreted was influenced by the length of the NH2-terminal lipase portion. An increased concentration, comparable to that of the native lipase, of secreted lipase/beta-lactamase hybrid proteins was only found when the lipase portion of the construct comprised more than 101 amino acids of the NH2-terminal region of the lipase preprotein; the proposed lipase signal peptide is 36 amino acids long. If the hybrid proteins constructed contained 101 or less amino acids of the NH2-terminal lipase preprotein, only low amounts of secreted hybrid proteins were detectable and a significant portion of the hybrid proteins and beta-lactamase activity was found in the cellular fraction. The results indicate that the lipase possesses adjacent to the signal peptide a peptide domain that is essential for the secretion of the lipase/beta-lactamase hybrid proteins.
Mol Gen Genet 1986 Jul
PMID:Studies on lipase directed export of Escherichia coli beta-lactamase in Staphylococcus carnosus. 301 41

Four types of virus-specific particles with different sedimentation coefficients and buoyant densities in CsCl were shown to be accumulated in hepatitis A virus (strain HAS-15) infected fetal rhesus monkey kidney cells (FRhK-4 line). Unlike the mature virions (155S, 1.34 g/cm3), cell-associated isosedimenting 92 S-particles (buoyant densities of 1.30 and 1.20 g/cm3) proved to be sensitive to lipase action. Particles of all four types were shown to contain similar sets of polypeptides, and, with the exception of "empty" 1.30 g/cm3-particles, appeared to be "full" under the immune electron microscopic examination. The viral RNA was unequivocally identified by the molecular hydridization test only in the mature virions.
Mol Gen Mikrobiol Virusol 1987 Mar
PMID:[Properties of hepatitis A virus particles produced during infection in vitro]. 303 82

The impact of lowering the ovarian L(iver)-type lipase activity on cholesterol homeostasis in the ovaries was studied in superovulated rats. L-type lipase activity increased rapidly after injection with chorionic gonadotrophin (HCG) (day 0), its activity remained high between days 3 and 8. During this period plasma progesterone and 20 alpha-hydroxyprogesterone were raised. The ovarian content of unesterified cholesterol remained constant during this period while cholesterol esters increased. Lowering of the L-type lipase activity by in vivo treatment with anti-liver lipase (ALLA) during 4-5 h did not affect plasma hormones or ovarian cholesterol contents. However, de novo cholesterol synthesis in the ovaries was significantly increased by about 40%. After pretreatment of the rats with aminogluthetimide, ALLA administration led to a 250% increase in de novo cholesterol synthesis in the unesterified cholesterol fraction, but was without effect on plasma hormones and on the ovarian cholesterol content. Administration of the cholesterol synthesis inhibitor Simvastatin led to a 25% lowering in ovarian cholesterol synthesis without effect on plasma hormones or ovarian cholesterol content. Additional administration of ALLA affected only the plasma progesterone (-30%). These results indicate that L-type lipase is involved in ovarian cholesterol homeostasis.
Mol Cell Endocrinol 1988 May
PMID:L-type lipase activity in ovaries of superovulated rats. Relation to cholesterol homeostasis. 339 58

The lipase activity of the adult rat heart consists of at least two components; a lipoprotein lipase and a "hormone-sensitive" or triglyceride lipase. The control of the triglyceride lipase by intermediates of lipid metabolism was studied in rat heart homogenates. Perfusion of hearts with fatty acids, glucose or no exogenous substrate did not alter lipase activity. Bovine serum albumin (BSA) stimulated the in vitro lipase activity whereas palmityl-coenzyme A (CoA) was a potent inhibitor. Other fatty acid intermediates such as acetyl-CoA, acetyl-carnitine, palmityl-carnitine and palmitate had little or no effect. Long-chain acyl CoA may be an important intermediate for matching triglyceride hydrolysis with the supply of extracellular fatty acids and the rates of fatty acid oxidation.
J Mol Cell Cardiol 1988 Mar
PMID:Inhibition of myocardial lipase by palmityl CoA. 341 15

The conditions for an in vitro assay of liver-type lipase, i.e. an enzyme resembling the lipase releasable from the liver by heparin (liver lipase), in rat ovaries were established. The liver-type lipase activity in the ovaries was almost completely (greater than 95%) located in the corpora lutea and its activity ranged from 0.44 to 0.77 mU per corpus luteum of (pseudo)pregnant rats. Preovulatory ovarian follicles contained very low lipase activity. During the estrous cycle the pattern of lipase activity was similar to that of serum progesterone levels (maximal at diestrus 1 and minimal at diestrus 2). In the individual rats liver-type lipase activity in the ovaries was strongly correlated with serum progesterone and 20 alpha-hydroxyprogesterone. The activity of liver-type lipase also varied during lactation. It was relatively low at an early stage (2-3 days) but increased during later stages of lactation. The serum progesterone level was relatively low in rats lactating for 2-3 or 22-24 days. During the intervening time, its concentrations was elevated. Since serum 20 alpha-hydroxyprogesterone levels varied inversely to progesterone, the total amount of progestagens in blood during lactation remained constant. The cholesterol content of the corpora lutea of the lactating rats was initially high and decreased during the lactation.
Mol Cell Endocrinol 1985 Oct
PMID:Localization of liver-type lipase in rat ovaries and its activity during the estrous cycle and lactation. 404 19


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