Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0031511 (pheochromocytoma)
 14,622 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transglutaminases are a class of enzymes capable of covalently cross-linking both intracellular and extracellular proteins. The activity of tissue transglutaminase is known to decrease precipitously following neoplastic transformation, and it has been hypothesized that transglutaminase may be involved in growth regulation. We have found that the differentiation promoter sodium butyrate is able to cause a marked increase in transglutaminase activity in PC12 pheochromocytoma cells in a time- and dose-dependent manner. This increased transglutaminase activity is associated with growth arrest, as well as with striking morphological changes including increased cell adhesion. The transglutaminase induced by sodium butyrate appears to be tissue transglutaminase, based on its cytosolic localization, thermal lability at basic pH, and elution profile on anion-exchange chromatography. Untreated PC12 cells contain only small amounts of transglutaminase which resembles epidermal transglutaminase, an enzyme previously described only in skin. In contrast to sodium butyrate, nerve growth factor did not stimulate tissue transglutaminase in PC12 cells, although it, too, caused growth arrest. It is hypothesized that transglutaminase may be involved in certain morphological changes accompanying cellular differentiation and neoplastic transformation, rather than in growth regulation per se.
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PMID:Two types of transglutaminase in the PC12 pheochromocytoma cell line. Stimulation by sodium butyrate. 288 61

Activation of rat pheochromocytoma tyrosine hydroxylase by limited tryptic proteolysis was investigated. The modifications produced upon the enzyme's structure were analyzed with the use of sodium dodecyl sulfate/polyacrylamide gel electrophoresis and tyrosine hydroxylase activity was measured all through the digestion. During the proteolysis the activity of tyrosine hydroxylase was elevated threefold at the same time as a 56-kDa tryptic fragment was formed. When the enzyme was phosphorylated, at its N-terminal region, by a kinase copurified with tyrosine hydroxylase, the major 56-kDa species did not appear to be phosphorylated on the autoradiograph, suggesting that it was derived from the native subunit by cleavage of the N-terminal of the protein. The reactivity of the 2/40/15 anti-(tyrosine hydroxylase) monoclonal antibody with the N-terminal of tyrosine hydroxylase was also investigated, using the Western-blot technique. This antibody reacted with the 62-kDa hydroxylase subunit but not with the 60-kDa tryptic fragment; the amino acid sequences of these two species showed that the 60-kDa fragment lacked the first 16 N-terminal amino acids of the native molecule. These results suggest that the N-terminal region of tyrosine hydroxylase is apparently responsible for an inhibition of the hydroxylase activity and that the first N-terminal amino acids of the hydroxylase are necessary for the recognition of the enzyme by its antibody.
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PMID:Role of the N-terminus of rat pheochromocytoma tyrosine hydroxylase in the regulation of the enzyme's activity. 289 26

Tyrosine hydroxylase activity is reversibly modulated by the actions of a number of protein kinases and phosphoprotein phosphatases. A previous report from this laboratory showed that low-molecular-weight substances present in striatal extracts lead to an irreversible loss of tyrosine hydroxylase activity under cyclic AMP-dependent phosphorylation conditions. We report here that ascorbate is one agent that inactivates striatal tyrosine hydroxylase activity with an EC50 of 5.9 microM under phosphorylating conditions. Much higher concentrations (100 mM) fail to inactivate the enzyme under nonphosphorylating conditions. Isoascorbate (EC50, 11 microM) and dehydroascorbate (EC50, 970 microM) also inactivated tyrosine hydroxylase under phosphorylating but not under nonphosphorylating conditions. In contrast, ascorbate sulfate was inactive under phosphorylating conditions at concentrations up to 100 mM. Since the reduced compounds generate several reactive species in the presence of oxygen, the possible protecting effects of catalase, peroxidase, and superoxide dismutase were examined. None of these three enzymes, however, afforded any protection against inactivation. We also examined the effects of ascorbate and its congeners on the activity of tyrosine hydroxylase purified to near homogeneity from a rat pheochromocytoma. This purified enzyme was also inactivated by the same agents that inactivated the impure corpus striatal enzyme. Under conditions in which ascorbate almost completely abolished enzyme activity, we found no indication for significant proteolysis of the purified enzyme as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We also found that pretreatment of PC12 cells in culture for 4 h with 1 mM ascorbate, dehydroascorbate, or isoascorbate (but not ascorbate sulfate) also decreased tyrosine hydroxylase activity 25-50%.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Inactivation of tyrosine hydroxylase activity by ascorbate in vitro and in rat PC12 cells. 290 63

Hypertensive emergencies are life-threatening situations caused by acute blood pressure elevation. They require immediate treatment with antihypertensive drugs. Such emergencies include hypertensive crisis, acute left ventricular heart failure or intracranial bleeding in patients with hypertension, malignant hypertension resistant to treatment, and serious blood pressure elevations after vascular surgery. A hypertensive crisis may be defined as a sudden increase in systolic and diastolic blood pressure that causes functional disturbances of the central nervous system, the heart or the kidneys. In patients with hypertensive crisis, treatment should be started with an alpha receptor-blocking agent if pheochromocytoma has not been excluded by previous workup. Antihypertensive agents with a rapid onset of action--nifedipine, clonidine, dihydralazine, diazoxide and sodium nitroprusside--are being used.
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PMID:How should we treat a hypertensive emergency? 291 57

Nerve growth factor is a polypeptide hormone that is required for the normal growth and development of the embryonic sensory and sympathetic nervous systems. On these cells, there are two different receptors for the nerve growth factor. Recently, these receptors have been isolated from three cell types and shown to have essentially the same binding characteristics. Molecular weights for receptors from two of these cell types, embryonic sensory and rat pheochromocytoma cells, have been determined. In addition, the formation of a covalent nerve growth factor, nerve growth factor receptor complex, has been investigated on embryonic sensory and sympathetic neurons. The formation of this covalent complex containing 125I-beta nerve growth factor is prevented by the addition of excess unlabeled nerve growth factor or by the addition of sodium fluoride and dinitrophenol. This complex forms at 4 degrees, 22 degrees, and 37 degrees, indicating that it is occurring on the cell surface. A disulfide bond is involved in the formation of this covalent complex.
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PMID:Characteristics of the nerve growth factor receptors and a nerve growth factor receptor--nerve growth factor covalent complex. 298 46

Incubation of Synechocystis PCC 6714 in liquid medium devoid of Na+ results in a light-dependent loss in photosynthetic O2 evolving capacity within 1 h. Photosynthetic activity is fully restored and normal growth resumes after Na+ is supplied to culture medium of depleted cells. If external Na+ is provided as soon as inhibition becomes complete, normal photosynthesis is restored within 3 min. However, if cells are further illuminated for several h under Na+ stress, then full recovery takes much longer, and requires new protein synthesis. Electron transport assays using isolated membranes demonstrate that the immediate inhibition resulting from Na+ depletion involves the O2 evolving site, while the secondary effect requiring new protein synthesis occurs near the reaction center of Photosystem II. Experiments conducted at different pH values and in the absence of inorganic carbon demonstrate that within the short time duration of these experiments Na+ does not inhibit photosynthesis by restricting bicarbonate movement into the cells. These experiments extend previous results with other cyanobacteria which demonstrated that Ca2+ and Na+ stress cause reversible damage at a site near the reaction center of Photosystem II. The damage can be characterized as a primary ion effect at the oxygen evolving site and a secondary photoinhibition near the reaction center of Photosystem II.
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PMID:Sequential effects of sodium depletion on photosystem II in Synechocystis. 313 83

Chlorpromazine (CPZ) is an effective cyanide antidote, with its greatest efficacy displayed when combined with the antidotes, sodium nitrite and sodium thiosulfate. Since the central nervous system is a primary target organ in cyanide toxicity, the objective of the present study was to determine the mechanisms by which CPZ prevents cyanide-induced damage in neural systems. KCN (10 mM) increased cytosolic free calcium in rat pheochromocytoma (PC12) cells as indicated by the fluorescent dye quin 2. This was blocked by addition of CPZ (0.1 mM) to the cells 15 min prior to addition of KCN. Incubation of cells with KCN (0.1 mM) increased the levels of lipid conjugated dienes and this was blocked by addition of CPZ (1 microM). Peroxidation of brain lipids in mice administered KCN (7-15 mg/kg, sc) was also attenuated by pretreatment with CPZ. Furthermore, production of lipid peroxidation in fresh mouse brain slices, following incubation with 0.1 mM KCN, was blocked by simultaneous addition of CPZ. These observations indicate CPZ prevents cyanide-induced calcium influx and decreases peroxidation of membrane lipids. Thus the antidotal activity of CPZ in cyanide toxicity appears to be related to maintenance of cellular calcium homeostasis and membrane integrity.
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PMID:Cyanide-induced neurotoxicity: mechanisms of attenuation by chlorpromazine. 318 27

Rat pheochromocytoma PC 12 cell membranes were shown to possess A2-like adenosine binding sites as assessed by using 5'-N-ethylcarboxamide[3H]adenosine [( 3H]NECA). Specific [3H]NECA binding to PC 12 cell membrane at 0 degrees C was saturable and showed a monophasic saturation profile. In contrast, [3H]NECA binding to PC 12 cell membrane at 30 degrees C exhibited a biphasic profile suggesting the presence of two specific binding site. The rank order of potency for inhibition of [3H]NECA binding at 0 degrees C was NECA greater than 2-chloroadenosine greater than 2',5'-dideoxyadenosine greater than isobutylmethylxanthine much greater than phenylisopropyladenosine. These adenosine binding sites were solubilized with sodium cholate and the solubilized portion retained the same ligand binding characteristics as those of the membrane-bound form. Gel filtration experiments indicated an apparent Stokes radius of 6.7 nm for these adenosine binding sites/detergent complexes.
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PMID:Adenosine binding sites of rat pheochromocytoma PC 12 cell membranes: partial characterization and solubilization. 324 Sep 87

B-cell stimulatory factor 2 (BSF-2) is a lymphokine which induces the final maturation of B cells. BSF-2 acts on a variety of cells other than B cells, and moreover, expression of BSF-2 mRNA is detected in interleukin-1 beta-stimulated glioblastoma and astrocytoma cell lines. Here, we studied the function of BSF-2 on pheochromocytoma PC12 cells, a model system for induction of neuronal differentiation. PC12 cells possess specific receptors for BSF-2. The BSF-2-stimulated PC12 cells expressed the c-fos proto-oncogene transiently, and they began to change morphologically to neurite-extending cells after several days. The number of voltage-dependent Na+ channels was also increased.
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PMID:Induction of neuronal differentiation in PC12 cells by B-cell stimulatory factor 2/interleukin 6. 326 80

The effect of feeding frequency and associated meal size on the renin-angiotensin-aldosterone system (RAAS) in seven horses was examined. A daily maintenance ration of hay-grain pellets was provided either as a multiple feeding regimen (MF), in which the ration was divided into six equal portions fed at 4-h intervals, or as a single large feeding (SF) given from 9 A.M. until 11 A.M. Plasma renin activity (PRA), aldosterone (PAC), cortisol (PCC), protein concentration (TP), packed cell volume (PCV), and serum sodium and potassium were measured serially. To prevent significant RAAS stimulation due to strenuous exercise or by assuming orthostatism after a period of recumbency, the horses were trained to stand in 1 X 4-m tie stalls during the experiments. Changes in Na intake were prevented by disallowing nonration salt sources. A 12:12 light-dark interval was maintained. During the MF experiment, only serum Na changed diurnally, with concentrations lowest in early morning and highest before midday. In contrast, during the SF experiment, PRA was increased at 0.5, 1.0, and 3.0 h and PAC was increased at 3.0, 5.0, and 7.0 h after onset of feeding (P less than 0.005). Increased TP and PCV suggested transient hypovolemia was responsible for renin release. Significant increases in Na and decreases in K occurred while eating; however, K increased postprandially to be coincident with aldosterone. Except for a transient increase during feeding in SF, PCC demonstrated a similar circadian rhythm in both experiments. It was concluded that 1) episodic feeding (SF) causes significant diurnal variation of the RAAS in the horse, and 2) spontaneous circadian activity of the RAAS cannot be demonstrated in this species during a steady-state feeding regimen (MF).
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PMID:Effect of feeding on renin-angiotensin-aldosterone system of the horse. 327 28


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