scholarly journals Nature of the stimulation of biogenesis of cholesterol in the liver by noradrenaline

1977 ◽  
Vol 162 (3) ◽  
pp. 493-499 ◽  
Author(s):  
R George ◽  
T Ramasarma
Keyword(s):  
Protein Synthesis ◽  
Adrenergic Receptors ◽  
De Novo ◽  
Direct Action ◽  
Time Intervals ◽  
Coa Reductase ◽  
Short Time ◽  
Stimulation Of

1. Administration of noradrenaline increased the incorporation of [1-14C]acetate into hepatic sterols and the activity of liver microsomal 3-hydroxy-3-methylglutaryl-CoA reductase. 2. The stimulation was observed at short time-intervals with a maximum at 4h and was progressive with increasing concentrations of noradrenaline. 3. Protein synthesis de novo was a necessary factor for the effect. 4. The stimulatory effect was not mediated through the adrenergic receptors, but appears to involve a direct action of the hormone within the hepatocyte.

T3 potentiates the adrenergic stimulation of type II 5'-deiodinase activity in cultured rat brown adipocytes

1996 ◽  
Vol 271 (1) ◽  
pp. E15-E23 ◽  
Author(s):  
A. Hernandez ◽  
M. J. Obregon
Keyword(s):  
Protein Synthesis ◽  
Adrenergic Receptors ◽  
Inhibitory Action ◽  
De Novo ◽  
Type Ii ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic Receptors ◽  
Brown Adipocytes ◽  
De Novo Protein Synthesis ◽  
Stimulation Of

Iodothyronine type II 5'-deiodinase (5'D-II) activities were studied in cultures of rat brown adipocytes. In the presence of serum, the adrenergically stimulated 5'D-II activities were very low. In the absence of serum, adenosine 3',5'-cyclic monophosphate (cAMP) analogues stimulated 5'D-II activity. Thyroxine (T4) inhibited these increases. Norepinephrine slightly increased 5'D-II activity in hypothyroid conditions, but 3,5,3'-triiodothyronine (T3) strongly potentiated the adrenergic stimulation of 5'D-II (20-fold). T3 amplification of the adrenergic stimulation was via beta-adrenergic receptors, specifically mimicked by beta3-agonists, but it was not observed using cAMP analogues. The stimulatory effect of T3 predominated over the inhibitory action of T4, increased with exposure to T3, and required de novo protein synthesis. The half-life of 5'D-II was 30 min, suggesting that stabilization of 5'D-II did not occur. The effect was only observed in differentiated adipocytes. Retinoic acid has similar although smaller effects than T3. In conclusion, the presence of T3 is required and strongly potentiates the noradrenergic stimulation of 5'D-II activity in rat brown adipocytes.

Stimulation of Myoblast Membrane Protein Synthesis by 25-Hydroxy-Vitamin D 3

1989 ◽  
Vol 44 (9-10) ◽  
pp. 807-812
Author(s):  
Teresita Bellido ◽  
Ricardo Boland
Keyword(s):  
Vitamin D ◽  
Protein Synthesis ◽  
Plasma Membranes ◽  
De Novo ◽  
Phosphate Uptake ◽  
Leucine Incorporation ◽  
Similar Treatment ◽  
25 Hydroxy Vitamin D ◽  
Alpha Bungarotoxin ◽  
Stimulation Of

Abstract The effects of 25-hydroxy-vitamin D3 (25 OHD3) on myoblast protein synthesis were studied in connection with its role on muscle cell phosphate metabolism . The sterol markedly increased leucine incorporation into total cell proteins in cultured chick embryo myoblasts. This enhance­ment was greater than that produced by 1,25-dihydroxy-vitamin D3 (1,25(OH)2D3) and occurred prior to a significant stimulation of cell phosphate accumulation. Maximum effects of 25 OHD3 (8 h) on myoblast phosphate uptake were suppressed by cycloheximide indicating that they are mediated by de novo protein synthesis. At a similar treatment period, labelling of myoblasts with [3H]leucine (control) and [14C]leucine (+ 25 OHD3) followed by co-electrophoresis of total protein extracts on SDS-PAGE and isoelectrofocusing gels revealed that the sterol selectively affects the synthesis of proteins of 20 kDa and 50 kDa. These macromolecules were recovered in the microsomal fraction after differential centrifugation of homogenates. Further fractionation of myoblast microsomes on sucrose density gradients show ed co-localization of the 50 kDa and 20 kDa proteins with microsomal subfractions which preferentially bind [3H -alpha]bungarotoxin, suggesting that the proteins induced by 25 OHD3 are associated to plasma membranes and may play a role in the effects of the sterol on cell phosphate uptake.

Lectin Stimulation of Tissue Thromboplastin Activity in Human Monocytes in vitro

1979 ◽  
Vol 42 (05) ◽  
pp. 1574-1579 ◽  
Author(s):  
T Lyberg ◽  
H Prydz
Keyword(s):  
Protein Synthesis ◽  
Concanavalin A ◽  
Wheat Germ ◽  
Actinomycin D ◽  
De Novo ◽  
Human Monocytes ◽  
Tissue Thromboplastin ◽  
De Novo Protein Synthesis ◽  
Stimulation Of

SummaryLectins (phytohaemagglutinin, concanavalin A and wheat germ agglutinin) trigger an increase in tissue thromboplastin activity of human monocytes in vitro. The presence of serum was not necessary and did not enhance the activity. The increase was inhibited by cycloheximide and actinomycin D, suggesting that de novo protein synthesis is involved.

Regulation glykolytischen Umsatzes durch Synthese und Abbau von Enzymen Regulation of Glycolysis by the Synthesis and Degradation of Enzymes

1969 ◽  
Vol 24 (12) ◽  
pp. 1544-1549 ◽  
Author(s):  
G. Kahl ◽  
H. Lange ◽  
G. Rosenstock
Keyword(s):  
Protein Synthesis ◽  
Cell Walls ◽  
De Novo ◽  
Glutamate Pyruvate Transaminase ◽  
Cell Compartments ◽  
Lower Extent ◽  
Long Time ◽  
Glutamate Pyruvate ◽  
Short Time ◽  
Synthesis And Degradation

Differential derepression of the genome of potato tuber cells causes the onset of a vigorous metabolic activity, which is initiated by rapid synthesis of different RNA species, various proteins and phospholipids. Consequently enhanced respiration and the build up of cell compartments such as ribosomes and mitochondria as well as the performance of cell divisions and suberization of new-formed cell walls occur. Although there is an activation of metabolism in general with a concomitant rise in concentration of most glycolytic metabolites — as was proved for fructose-1.6-diphosphate, dihydroxyacetone, glyceraldehade-3-phosphate, phosphoenolepyruvate and pyruvate — the activities of the corresponding enzymes do not reflect these uniform metabolic changes. Aldolase and in a pronounced manner enolase and glutamate — pyruvate — transaminase lower their activities suddenly after derepression. The activity of triosephosphateisomerase remains constant. In contrast phosphoglyceromutase, pyruvate kinase and to a lower extent malic enzyme enhance their action during the same time.Without doubt, differential lowering and enhancing the activity of glycolytic chain constituents at the same time is an important regulatory mechanism of the cell. The activation represents de novo synthesis of the protein concerned whereas the inactivation depends largely on protein synthesis. This is clearly shown by experiments with inhibitors of protein synthesis.It is proposed that this differential synthesis and degradation represent a “long-time-regulation” of enzymatic activity of the cell in contrast to the known “short-time-regulation” by feedback or competition.

scholarly journals Myc regulates aggresome formation, the induction of Noxa, and apoptosis in response to the combination of bortezomib and SAHA

Blood ◽  
2008 ◽  
Vol 112 (7) ◽  
pp. 2917-2926 ◽  
Author(s):  
Steffan T. Nawrocki ◽  
Jennifer S. Carew ◽  
Kirsteen H. Maclean ◽  
James F. Courage ◽  
Peng Huang ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
Histone Deacetylase Inhibitor ◽  
Proteasome Inhibitor ◽  
De Novo ◽  
Deacetylase Inhibitor ◽  
Aggresome Formation ◽  
Induced Apoptosis ◽  
De Novo Protein Synthesis ◽  
Stimulation Of

Abstract The histone deacetylase inhibitor SAHA enhances cell death stimulated by the proteasome inhibitor bortezomib (BZ) by disrupting BZ-induced aggresome formation. Here we report that Myc regulates the sensitivity of multiple myeloma (MM) cells to BZ + SAHA–induced cell death. In MM cells, Myc expression directly correlated with intracellular ER content, protein synthesis rates, the percentage of aggresome-positive cells, and the sensitivity to BZ + SAHA–induced cell death. Accordingly, Myc knockdown markedly reduced the sensitivity of MM cells to BZ + SAHA–mediated apoptosis. Furthermore, activation of Myc was sufficient to provoke aggresome formation and thus sensitivity to BZ + SAHA, and these responses required de novo protein synthesis. BZ + SAHA–mediated stimulation of apoptosis includes the induction of the proapoptotic BH3-only protein Noxa as well as endoplasmic reticular stress, a disruption of calcium homeostasis, and activation of capase-4. Finally, knockdown studies demonstrated that both caspase-4 and Noxa play significant roles in Myc-driven sensitivity to BZ + SAHA–induced apoptosis. Collectively, our results establish a mechanistic link between Myc activity, regulation of protein synthesis, increases in HDAC6 expression and aggresome formation, induction of Noxa, and sensitivity to BZ + SAHA–induced apoptosis. These data suggest that MM patients with elevated Myc activity may be particularly sensitive to the BZ + SAHA combination.

scholarly journals Insulin-stimulated α-(methyl)aminoisobutyric acid uptake in skeletal muscle. Evidence for a short-term activation of uptake independent of Na+ electrochemical gradient and protein synthesis

1988 ◽  
Vol 253 (3) ◽  
pp. 625-629 ◽  
Author(s):  
A Gumà ◽  
X Testar ◽  
M Palacín ◽  
A Zorzano
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Insulin Action ◽  
De Novo ◽  
Acid Transport ◽  
Electrochemical Gradient ◽  
Aminoisobutyric Acid ◽  
System A ◽  
Stimulation Of

1. The present study was designed to explore the mechanisms by which insulin stimulates system A of amino acid transport in extensor digitorum longus (EDL) muscles, by using a system A analogue, alpha-(methyl)aminoisobutyric acid (MeAIB). 2. Insulin stimulation of MeAIB uptake was noted after only 30 min of incubation and was maximal at 60 min. Kinetics of the insulin effect on MeAIB uptake were characterized by an increased Vmax. without modification of Km for MeAIB. 3. Incubation of EDL muscles with cycloheximide for 90 min did not modify MeAIB uptake in either the presence or the absence of insulin, indicating the independence of insulin action from protein synthesis de novo. Incubations for 180 min with cycloheximide caused a decrease in basal MeAIB uptake; however, the percentage stimulation of amino acid transport by insulin was unaltered. Basal MeAIB uptake was increased by incubation for 180 min, but under these conditions no change in the percentage effect of insulin was found. 4. Ouabain, gramicidin D, or both, markedly decreased basal MeAIB uptake by EDL muscle, but the percentage effect of insulin was unaltered. 5. We conclude that insulin action on amino acid transport through system A in muscle is rapid, is characterized by an increased Vmax., and is independent of protein synthesis de novo and the Na+ electrochemical gradient. Our data are compatible with insulin acting directly on the system A transporter.

Evidence for cAMP as a mediator of gonadotropin secretion from female pituitaries

1987 ◽  
Vol 253 (3) ◽  
pp. E290-E295
Author(s):  
G. A. Bourne ◽  
D. M. Baldwin
Keyword(s):  
Protein Synthesis ◽  
Phase Ii ◽  
Potential Role ◽  
De Novo ◽  
Female Rats ◽  
Dibutyryl Camp ◽  
Gonadotropin Secretion ◽  
De Novo Protein Synthesis ◽  
Stimulation Of

Sodium flufenamate, which inhibited gonadotropin-releasing hormone (GnRH)-stimulated increases in adenosine 3',5'-cyclic monophosphate (cAMP), was used to evaluate the potential role of cAMP as a mediator of GnRH-stimulated gonadotropin secretion. Quartered pituitaries from diestrous II female rats were perifused at 37 degrees C, and sequential effluent fractions were collected every 10 min. Administration of GnRH resulted in a characteristic biphasic response for both luteinizing hormone (LH) and follicle-stimulating hormone (FSH), whereas 5 microM cycloheximide inhibited the secondary augmented responses (phase II) of both hormones. Infusions of 0.1 mM flufenamate inhibited GnRH-stimulated gonadotropin secretion in a manner similar to that of cycloheximide, whereas the administration of 5 mM dibutyryl cAMP in combination with GnRH and flufenamate resulted in the restoration of LH and FSH secretion. The dibutyryl cAMP-restored response appeared to be protein synthesis dependent and specific for cAMP. These results suggest that although the cyclic nucleotide is not involved in the acute release of LH and FSH, it does appear to play a pivotal but indirect role in phase II release of the hormones, by effects involving the stimulation of de novo protein synthesis.

Insulin-like growth factor I stimulates Na-dependent Pi transport in cultured kidney cells

1989 ◽  
Vol 257 (5) ◽  
pp. F712-F717 ◽  
Author(s):  
J. Caverzasio ◽  
J. P. Bonjour
Keyword(s):  
Protein Synthesis ◽  
Growth Factor ◽  
De Novo ◽  
Maximal Response ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Pi Transport ◽  
Igf I ◽  
Growth Factor I ◽  
Stimulation Of

The effect of recombinant insulin-like growth factor I (IGF-I/somatomedin C) on the transport of inorganic phosphate (Pi) was studied in cultured kidney epithelia. In opossum kidney (OK) epithelia, IGF-I (5 x 10(-10) to 10(-7) M) induced a dose-related stimulation of the Na-dependent Pi transport (NaPiT). A maximal response was observed at 10(-7) M (IGF-I 1.64 +/- 0.12; vehicle 0.90 +/- 0.02 nmol.mg protein-1. 4 min-1, P less than 0.001). Kinetic analysis of the stimulatory effect of IGF-I on NaPiT indicated an increase in Vmax and no change in Km. Insulin also stimulated NaPiT in OK epithelia but only at concentrations 20-40 times higher than IGF-I. The effect of IGF-I on Pi transport was detectable in less than 30 min with a maximal response occurring after 4-5 h. It was selective for NaPiT, since the Na-dependent alanine transport was not affected by IGF-I. Inhibition of protein synthesis by either cycloheximide or cordycepin markedly attenuated the stimulatory effect of IGF-I on NaPiT. The cellular adenosine 3',5'-cyclic monophosphate content was not modified by the growth factor. In conclusion, these data indicate that IGF-I increases NaPiT selectively through a mechanism that involves de novo protein synthesis. These observations suggest that growth and growth hormone-related stimulation of renal Pi transport could be mediated by IGF-I.

RESPONSE OF PLASMA NON-CONJUGATED OESTRADIOL TO MANIPULATED ADRENAL FUNCTION BY ACTH AND DEXAMETHASONE

1979 ◽  
Vol 90 (3) ◽  
pp. 525-533
Author(s):  
G. Reck ◽  
U. Noss ◽  
M. Breckwoldt
Keyword(s):  
Plasma Cortisol ◽  
Maximum Level ◽  
Adrenal Function ◽  
Strongly Correlated ◽  
Acth Secretion ◽  
Time Intervals ◽  
Short Time ◽  
Plasma Oestradiol ◽  
Free Plasma ◽  
Stimulation Of

ABSTRACT The present study is concerned with the regulation of free plasma oestradiol in relation to maternal adrenal function during late human pregnancy. Blood was collected in 9 patients at short time intervals of 30 min from 17 h to 3 h. In order to exclude endogenous ACTH-secretion 5 patients received 12 mg dexamethasone over 48 h. Between 20 h and 2 h 0.25 mg ACTH1-24 (Synacthen°) was infused into the subjects. Nonconjugated oestradiol was determined by radioimmunoassay and total plasma cortisol by protein binding method. During the application of ACTH free oestradiol increased from 21.3 ± 5.7 to 25.5 ± 7.1 ng/ml (P < 0.025) in the patients without dexamethasone. The increase was moderately correlated to rising cortisol (r = 0.58, P < 0.001). Plasma oestradiol reached its maximum level after 90 min, followed by a tendency to decline despite persisting stimulation of maternal adrenals. The patients receiving dexamethasone exhibited during ACTH-infusion a rise of oestradiol from 3.8 ± 1.9 to 7.8 ± 3.1 ng/ml (P < 0.001). Increasing oestradiol was strongly correlated to plasma cortisol (r = 0.67, P < 0.001). The phenomenon of earlier declining oestradiol levels did not occur. These results suggest that maternal adrenals predominantly regulate the formation of free oestradiol. Plasma cortisol indicating maternal precursor production balances the increase of oestradiol by suppressing foetal precursor supply.

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