scholarly journals Stimulation of CTP:Phosphocholine Cytidylyltransferase by Free Cholesterol Loading of Macrophages Involves Signaling through Protein Dephosphorylation

1995 ◽  
Vol 270 (50) ◽  
pp. 29894-29903 ◽  
Author(s):  
Yoshimune Shiratori ◽  
Martin Houweling ◽  
Xiaohui Zha ◽  
Ira Tabas
Keyword(s):  
Free Cholesterol ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Protein Dephosphorylation ◽  
Stimulation Of

scholarly journals Protein phosphatase-type 2B is involved in the regulation of the acrosome reaction but not in the temperature-dependent flagellar movement of fowl spermatozoa

Reproduction ◽  
2004 ◽  
Vol 128 (6) ◽  
pp. 783-787 ◽  
Author(s):  
K Ashizawa ◽  
G J Wishart ◽  
A R A H Ranasinghe ◽  
S Katayama ◽  
Y Tsuzuki
Keyword(s):  
Protein Phosphatase ◽  
Acrosome Reaction ◽  
Molecular Mechanisms ◽  
Dependent Manner ◽  
Temperature Dependent ◽  
Acrosomal Exocytosis ◽  
Protein Dephosphorylation ◽  
Dose Dependent ◽  
Protein Phosphatase Type ◽  
Stimulation Of

The motility and acrosomal integrity of fowl spermatozoa in TES/NaCl buffer, with or without homogenized inner perivitelline layers (IPVL) prepared from laid fowl eggs, was almost negligible at 40 °C. However, motility became vigorous even at 40 °C when 2 mmol CaCl2/l was added, and the acrosome reaction was also stimulated in the presence, but not in the absence, of IPVL. The presence of deltamethrin or fenvalerate, specific inhibitors of protein phosphatase-type 2B (PP2B), did not permit the restoration of motility at 40 °C but, in the presence of IPVL, these compounds stimulated the acrosome reaction in a dose-dependent manner in the range of 1–1000 nmol/l. These results suggest that IPVL is necessary for the activation of the acrosome reaction in fowl spermatozoa and that Ca2+ plays an important role in the stimulation of motility and acrosomal exocytosis. Furthermore, it appears that the intracellular molecular mechanisms for the regulation of the acrosome reaction of fowl spermatozoa are different from those for the restoration of motility, i.e. protein dephosphorylation by PP2B in the former but not in the latter case.

Stimulation of taurocholic acid synthesis and biliary excretion of lipids

1961 ◽  
Vol 200 (4) ◽  
pp. 855-859 ◽  
Author(s):  
Robert E. Kay ◽  
Cecil Entenman
Keyword(s):  
Bile Duct ◽  
Bile Acids ◽  
Biliary Excretion ◽  
Free Cholesterol ◽  
Acid Synthesis ◽  
Taurocholic Acid ◽  
Perfused Liver ◽  
Cholesterol Esters ◽  
Bile Fistula ◽  
Stimulation Of

The rates of excretion of taurocholic acid and lipids in the bile of the isolated perfused liver and the bile fistula rat were determined. In the bile fistula rats, there was, during the first 12 hours after cannulation, a fall in the excretion of taurocholic acid, which was then followed by an increase in the rate of excretion. The excretion of free cholesterol and phospholipids followed the same excretion pattern as for taurocholic acid, whereas the biliary excretion of glycerides and cholesterol esters was nearly constant. Livers perfused immediately after cannulation of the bile duct excreted only very small amounts of bile acids and lipids in the bile. On the other hand, when livers were perfused 48 hours after cannulation, the bile acids were excreted at a greatly accelerated rate and increased amounts of free cholesterol and phospholipids appeared in the bile. The infusion of cholic acid into a liver, perfused immediately after cannulation of the bile duct, gave rise to an increased biliary excretion of bile acids, free cholesterol and phospholipids.

scholarly journals Phosphatidylcholine metabolism in rat liver after partial hepatectomy. Evidence for increased activity and amount of CTP:phosphocholine cytidylyltransferase

1991 ◽  
Vol 278 (2) ◽  
pp. 347-351 ◽  
Author(s):  
M Houweling ◽  
L B M Tijburg ◽  
H Jamil ◽  
D E Vance ◽  
C B Nyathi ◽  
...  
Keyword(s):  
Partial Hepatectomy ◽  
Rat Liver ◽  
Sham Operation ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Enzyme Molecules ◽  
Increased Activity ◽  
Phosphatidylcholine Metabolism ◽  
Control Sham ◽  
Stimulation Of

The effect of partial (70%) hepatectomy on phosphatidylcholine (PC) synthesis in rat liver was investigated during the first 4 post-operative days. Between 4 and 96 h after partial hepatectomy, the mass of PC increased from 30% to 80% of sham-operation values, being comparable with the restoration of total liver mass after partial hepatectomy. Relative to control (sham-operation), the incorporation in vivo of [3H]choline into PC was stimulated 2.6-fold at 22 h after partial hepatectomy. Moreover, CTP:phosphocholine cytidylyltransferase (EC 2.7.7.15) activity was significantly enhanced, and the pool size of phosphocholine decreased at 22 and 48 h after partial hepatectomy, whereas the activity of choline kinase (EC 2.7.1.32) was augmented at a later stage of liver regeneration (48 and 96 h). Stimulation of CTP:phosphocholine cytidylyltransferase activity by partial hepatectomy occurred in both the microsomal and cytosolic fractions. The stimulatory effect in the cytosolic fraction was mainly due to an increase in the number of enzyme molecules, as demonstrated by immunotitration of the amount of cytosolic cytidylyltransferase protein.

scholarly journals The choline-depleted type II pneumonocyte. A model for investigating the synthesis of surfactant lipids

1984 ◽  
Vol 224 (1) ◽  
pp. 253-262 ◽  
Author(s):  
M M Anceschi ◽  
G C Di Renzo ◽  
M D Venincasa ◽  
J E Bleasdale
Keyword(s):  
Specific Activity ◽  
Water Soluble ◽  
Choline Oxidase ◽  
Type Ii ◽  
Free Medium ◽  
Extracellular Medium ◽  
Adult Rats ◽  
New Model ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Stimulation Of

When type II pneumonocytes from adult rats were maintained in a medium that lacked choline, the incorporation of [14C]glycerol into phosphatidylcholine was not greatly diminished during the period that the cells displayed characteristics of type II pneumonocytes. Cells that were maintained in choline-free medium that contained choline oxidase and catalase, however, became depleted of choline and subsequent synthesis of phosphatidylcholine by these cells was responsive to choline in the extracellular medium. Incorporation of [14C]glycerol into phosphatidylcholine by choline-depleted cells was stimulated maximally (approx. 6-fold) by extracellular choline at a concentration (0.05 mM) that also supported the greatest incorporation into phosphatidylglycerol. The incorporation of [14C]glycerol into other glycerophospholipids by choline-depleted cells was not increased by extracellular choline. When cells were incubated in the presence of [3H]cytidine, the choline-dependent stimulation of the synthesis of phosphatidylcholine and phosphatidylglycerol was accompanied by an increased recovery of [3H]CMP. This increased recovery of [3H]CMP reflected an increase in the intracellular amount of CMP from 48 +/- 9 to 76 +/- 16 pmol/10(6) cells. Choline-depleted cells that were exposed to [3H]choline contained [3H]CDP-choline as the principal water-soluble choline derivative. As the extracellular concentration of choline was increase, however, the amount of 3H in phosphocholine greatly exceeded that in all other water-soluble derivatives. Choline-depletion of cells resulted in an increase in the specific activity of CTP:phosphocholine cytidylyltransferase in cell homogenates (from 0.40 +/- 0.15 to 1.31 +/- 0.20 nmol X min-1 X mg of protein-1). These data are indicative that the biosynthesis of phosphatidylcholine is integrated with that of phosphatidylglycerol and are consistent with the proposed involvement of CMP in this integration. The choline-depleted type II pneumonocyte provides a new model for investigating the regulation of CTP:phosphocholine cytidylyltransferase activity.

Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver

1971 ◽  
Vol 29 ◽  
pp. 570-571
Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman
Keyword(s):  
Chemical Composition ◽  
Rat Liver ◽  
Future Study ◽  
Mode Of Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Effective Inhibitor ◽  
Biochemical Effects ◽  
Glycerophosphate Dehydrogenase ◽  
Stimulation Of

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.

Gap junctions in the prothoracic glands of the tobacco hornworm, Manduca sexta

1992 ◽  
Vol 50 (1) ◽  
pp. 706-707
Author(s):  
Ji-da Dai ◽  
M. Joseph Costello ◽  
Lawrence I. Gilbert
Keyword(s):  
Gap Junctions ◽  
Small Molecules ◽  
Manduca Sexta ◽  
Freeze Fracture ◽  
Cell Communication ◽  
Cellular Level ◽  
Thin Sections ◽  
Prothoracic Glands ◽  
Polyhydroxylated Steroids ◽  
Stimulation Of

Insect molting and metamorphosis are elicited by a class of polyhydroxylated steroids, ecdysteroids, that originate in the prothoracic glands (PGs). Prothoracicotropic hormone stimulation of steroidogenesis by the PGs at the cellular level involves both calcium and cAMP. Cell-to-cell communication mediated by gap junctions may play a key role in regulating signal transduction by controlling the transmission of small molecules and ions between adjacent cells. This is the first report of gap junctions in the PGs, the evidence obtained by means of SEM, thin sections and freeze-fracture replicas.

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