==PHEOCHROMACYTOMA== MEDLINE J Neurosci 1998 Mar 15;18(6):2040-2055 Manganese superoxide dismutase protects nNOS neurons from NMDA and nitric oxide-mediated neurotoxicity. Gonzalez-Zulueta M, Ensz LM, Mukhina G, Lebovitz RM, Zwacka RM, Engelhardt JF, Oberley LW, Dawson VL, Dawson TM Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA. Neuronal nitric oxide synthase (nNOS) neurons kill adjacent neurons through the action of NMDA-glutamate receptor activation, although they remain relatively resistant to the toxic effects of NMDA and NO. The molecular basis of the resistance of nNOS neurons to toxic insults is unknown. To begin to understand the molecular mechanisms of the resistance of nNOS neurons, we developed a pheochromacytoma-derived cell line (PC12) that is resistant to the toxic effects of NO. We found through serial analysis of gene expression (SAGE) that manganese superoxide dismutase (MnSOD) is enriched in the NO-resistant PC12 cell-derived line (PC12-R). Antisense MnSOD renders PC12-R cells sensitive to NO toxicity and increases the sensitivity to NO in the parental, NO-sensitive PC12 line (PC12-S). Adenoviral transfer of MnSOD protects PC12-S cells against NO toxicity. We extended these studies to cortical cultures and showed that MnSOD is enriched in nNOS neurons and that antisense MnSOD renders nNOS neurons susceptible to NMDA neurotoxicity, although it has little effect on the overall susceptibility of cortical neurons to NMDA toxicity. Overexpression of MnSOD provides dramatic protection against NMDA and NO toxicity in cortical cultures, but not against kainate or AMPA neurotoxicity. Furthermore, nNOS neurons from MnSOD -/- mice are markedly sensitive to NMDA toxicity. Adenoviral transfer of MnSOD to MnSOD-/- cultures restores resistance of nNOS neurons to NMDA toxicity. Thus, MnSOD is a major protective protein that appears to be essential for the resistance of nNOS neurons in cortical cultures to NMDA mediated neurotoxicity. ---------- Proc Natl Acad Sci U S A 1997 Sep 2;94(18):9705-9710 Compromised mitochondrial function leads to increased cytosolic calcium and to activation of MAP kinases. Luo Y, Bond JD, Ingram VM Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. We have investigated in rat pheochromacytoma PC12 cells the activation of the mitogen-activated protein kinases ERK1 and ERK2 by the mitochondrial uncoupler carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP). This treatment slowly decreases ATP levels to 30% of control, whereas the internal calcium level rises very rapidly to 250% of control, derived from internal stores. Tyrosine phosphorylation of ERK1 and ERK2 increases gradually, starting after 5 min of treatment, to reach a maximum at 30 min; the kinase activity reaches 250% when measured after 1 hr of treatment. The drop in ATP levels is slower still. Comparison of the time courses of the rapid rise in cytosolic calcium with the slower increase in ERK1 and ERK2 activation suggests one or more intermediate stages in this pathway. Chelation of cytosolic calcium with dimethyl bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid abolished the FCCP-stimulated rise in internal calcium, as well as the tyrosine phosphorylation and the activation of the ERKs. Surprisingly, caffeine, which releases calcium from different internal stores, did not increase the tyrosine phosphorylation and did not activate the ERKs. The FCCP effect on calcium storage may be related to mitochondrial dysfunction in Alzheimer disease, which might result in ineffective buffering of cytosolic calcium that leads to mitogen-activated protein kinase activation and subsequent protein phosphorylations. ---------- Pharmacol Biochem Behav 1995 Sep;52(1):85-91 Cytosolic calcium responses to extracellular adenosine 5',5" '-P1,P4-tetraphosphate in PC12 cells. Nordone AJ, Pivorun EB Department of Environmental Toxicology, Clemson University, Pendleton, SC 29670, USA. Binding of adenosine 5',5" '-P1,P4-tetraphosphate (Ap4A) to a purinoceptor on nerve growth factor-differentiated (NGF) pheochromacytoma (PC12) cells modulated cytosolic Ca2+ levels. Both Ap4A and ATP elicited an influx of extracellular Ca2+, but both the sensitivity of the response and the flux profile were different. Preincubation of the PC12 cells with the compounds adenosine 5'-0-(2-thio)diphosphate (ADP-beta-S) and periodate-oxidized ATP had differential effects upon the Ap4A and ATP-induced response. These results indicate that Ap4A and ATP were either interacting with distinct purinoceptor subclasses or with the same purinoceptor with differing affinities. Simultaneous depolarization and application of either Ap4A or ATP to the PC12 cells induced an additive effect on the calcium flux. Preincubation with verapamil negated the effects of depolarization without significantly modifying the ligand-elicited Ca2+ fluxes, suggesting the presence of Ap4A ligand-gated channels that may function as modulators of PC12 cell function. ---------- Proc Natl Acad Sci U S A 1995 Mar 14;92(6):1861-1865 Activation of a neurofilament kinase, a tau kinase, and a tau phosphatase by decreased ATP levels in nerve growth factor-differentiated PC-12 cells. Bush ML, Miyashiro JS, Ingram VM Department of Biology, Massachusetts Institute of Technology, Cambridge 02139. Brain pathology in Alzheimer disease and in aged controls shows hyperphosphorylation of tau and of neurofilament proteins. Roder and Ingram [Roder, H.M. & Ingram, V.M. (1991) J. Neurosci. 11, 3325-3343 and Roder, H.M., Eden, P.A. & Ingram, V.M. (1993) Biochem. Biophys. Res. Commun. 193, 639-647] previously reported that the brain protein kinase PK40erk can hyperphosphorylate both tau and neurofilaments and interestingly, is strongly inhibited by ATP uncomplexed with Mg2+. We now report that the mitochondrial uncoupler carbonyl cyanide p-trifluoro-methoxyphenylhydrazone decreases ATP levels in rat pheochromacytoma (PC-12) cells differentiated with nerve growth factor and activates a neurofilament kinase, a tau kinase, and, unexpectedly, a tau phosphatase--either PP1 or PP2A. Such aberrant modulation of protein phosphorylation patterns could be the common biochemical basis for senile dementia and for Alzheimer disease and could explain the late-onset etiology of both conditions. ---------- Srp Arh Celok Lek 1991 May;119(5-6):169-171 [Diagnosis and monitoring of patients with type IIa multiple endocrine neoplasms]. [Article in Serbo-Croatian (Cyrillic)] Nesovic M, Ciric J, Trbojevic B, Zarkovic M Syndrome of multiple endocrine neoplasia, type IIa, is a rare disturbance made by medullar carcinoma of the thyroid gland, pheochromacytoma and hyperparathyroidism. The article deals with three patients with multiple endocrine neoplasia, type IIa, with special emphasis to detection of the disease in time and treatment of the patients in the early phase of the illness. This is a hereditary autosomal dominant disturbance. Tests performed among members of family with high risk factors of the disease are of great importance. In this way early diagnosis is possible, and consequently, prevention of fatal issue due to pheochromocytoma and medullar carcinoma. ---------- Harefuah 1989 Nov 15;117(10):302-304 [Retroperitoneal ganglioneuroma]. [Article in Hebrew] Kaplan O, Cohen Z, Lelcuk S, Rozin R Ganglioneuroma is an infrequent tumor composed of sympathetic ganglion cells and sheathed neurites. It arises mainly from the large sympathetic chains, most frequently in the posterior mediastinum and retroperitoneum, but rarely may develop from the peripheral sympathetic chains. It is usually benign, and may grow asymptomatically to relatively large size. However, it can cause symptoms due to local expansion and pressure on adjacent structures. It does not seem to have hormonal activity. Some ganglioneuromas contain immature cells or elements of neuroblastoma or pheochromacytoma and can metastasize. The preoperative diagnosis of retroperitoneal tumors has now become more frequent due to the extensive use of imaging modalities, mainly computed axial tomography. Whenever the imaging correlates with the clinical presentation, or there is a reasonable suspicion of a malignancy, operation is indicated. Many retroperitoneal space-occupying lesions are found in asymptomatic patients during attempts to diagnose other diseases. In these cases opinions differ as to therapeutic approach. Many adrenal tumors may be benign adenomas, and several therapeutic protocols have been proposed. The clinician can decide on the basis of clinical presentation and radiographic features whether a conservative approach rather than operation is indicated. Since the majority of retroperitoneal tumors are malignant, histologic diagnosis is essential and in such cases surgical intervention is warranted. A young patient with a retroperitoneal ganglioneuroma is presented. ---------- J Cell Biol 1988 May;106(5):1583-1591 Regulation of microtubule protein levels during cellular morphogenesis in nerve growth factor-treated PC12 cells. Drubin D, Kobayashi S, Kellogg D, Kirschner M Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448. Nerve growth factor induces neurite process formation in pheochromacytoma (PC12) cells and causes the parallel increase in levels of the microtubule-associated proteins, tau and MAP1, as well as increases in tubulin levels. Mechanisms to insure balanced accumulation of microtubule proteins and make their levels highly responsive to nerve growth factor were investigated. The effects on tau, MAP1, and tubulin are due to changes in protein synthesis rates, which for tau and tubulin we could show are due in part to changes in the mRNA levels. Whereas tubulin shows feedback regulation to modulate synthesis up or down, tau protein synthesis is not affected in a straightforward way by microtubule polymerization and depolymerization. The degradation of tau, MAP1, and both tubulin polypeptides, however, are stimulated by microtubule depolymerization caused by colchicine, or nerve growth factor removal. Combined feedback on synthesis and stability make tubulin levels highly responsive to assembly states. In addition, the linkage of tau and MAP1 turnover with the state of microtubule polymerization amplifies any change in their rate of synthesis, since tau and MAP1 promote microtubule polymerization. This linkage lends itself to rapid changes in the state of the system in response to nerve growth factor. ---------- Semin Oncol 1987 Sep;14(3):263-281 Somatostatinomas, PPomas, neurotensinomas. Vinik AI, Strodel WE, Eckhauser FE, Moattari AR, Lloyd R We have reviewed data pertinent to three tumor syndromes that derive from overproduction of three GEP peptide hormones. The clinical syndrome of somatostatin excess remains well defined with diabetes, diarrhea, steatorrhea being predominant features. With the availability of assays and increasing awareness, more cases are being diagnosed in the intestine and these differ somewhat in their presentation with cholecystitis, GI bleeding, or a mass as the cardinal features. An unusual association with MEN II pheochromacytoma and neurofibromatosis is emerging. PPomas remain enigmatic. Although diarrhea is a feature, these tumors are usually silent and present with hypatomegally, abdominal pain, and jaundice because of the large size and malignant nature. Neurotensinomas remain rare and truly difficult to separate from the symptom complex produced by VIP excess. Edema, hypotension, cyanosis and flushing should alert one to the possibility of a neurotensin-secreting tumor. ---------- J Biol Chem 1985 Mar 25;260(6):3784-3790 Specificity of fatty acid acylation of cellular proteins. Olson EN, Towler DA, Glaser L Labeling of the BC3H1 muscle cell line with [3H] palmitate and [3H]myristate results in the incorporation of these fatty acids into a broad spectrum of different proteins. The patterns of proteins which are labeled with palmitate and myristate are distinct, indicating a high degree of specificity of fatty acylation with respect to acyl chain length. The protein-linked [3H]palmitate is released by treatment with neutral hydroxylamine or by alkaline methanolysis consistent with a thioester linkage or a very reactive ester linkage. In contrast, only a small fraction of the [3H]myristate which is attached to proteins is released by treatment with hydroxylamine or alkaline methanolysis, suggesting that myristate is linked to proteins primarily through amide bonds. The specificity of fatty acid acylation has also been examined in 3T3 mouse fibroblasts and in PC12 cells, a rat pheochromacytoma cell line. In both cells, palmitate is primarily linked to proteins by a hydroxylamine-labile linkage while the major fraction of the myristic acid (60-70%) is linked to protein via amide linkage and the remainder via an ester linkage. Major differences were noted in the rate of fatty acid metabolism in these cells; in particular in 3T3 cells only 33% of the radioactivity incorporated from myristic acid into proteins is in the form of fatty acids. The remainder is presumably the result of conversion of label to amino acids. In BC3H1 cells, palmitate- and myristate-containing proteins also exhibit differences in subcellular localization. [3H]Palmitate-labeled proteins are found almost exclusively in membranes, whereas [3H]myristate-labeled proteins are distributed in both the soluble and membrane fractions. These results demonstrate that fatty acid acylation is a covalent modification common to a wide range of cellular proteins and is not restricted solely to membrane-associated proteins. The major acylated proteins in the various cell lines examined appear to be different, suggesting that the acylated proteins are concerned with specialized cell functions. The linkages through which fatty acids are attached to proteins also appear to be highly specific with respect to the fatty acid chain length. ---------- Diabete Metab 1975 Sep;1(3):201-208 [The role of glucagon in hyperglycemia. A review]. [Article in French] Luyckx A Glucagon is secreted not only by A2-cells of the pancreatic islets but also by A cells in the gastric fundus and duodenum. Several reports have demonstrated that the glucagon plasma concentration is increased in genetic diabetes as well as in many conditions associated with a decreased glucose tolerance such as hepatic cirrhosis, myocardial infarction, infectious diseases, burns, taumatic shock, glucagonomas, acute pancreatitis, acromegaly, pheochromacytoma and Cushing's syndrome. Hyperglucagonemia is particularly important in diabetic ketoacidosis and in non-ketotic hyperosmolar coma. The mechanisms responsible for the diabetic's hyperglucagonemia remain controversial. According to several authors, the increased glucagon secretion is, for its main part, secondary to a prolonged defect in insulin secretion and thus relatively insensitive to an acute insulin administration. According to others, the A cell abnormality is of primary origin, independant from insulin deficiency and its effects are cumulative with those of the insulin lack. Several reports dealing with induced or spontaneous experimental diabetes are in favor of the first or the second hypothesis. It appears likely that glucagon plays a role in the metabolic derangments of diabetes. Indeed, hepatic glucose production is closely related to the ratio of molar concentrations of insulin and glucagon. Finally, in insulin-dependant diabetics, somatostatin infusion reduces plasma glucagon concentration and blood glucose and prevents the development of ketosis after withdrawal of insulin therapy. These results illustrate the contribution of glucagon in the pathogenesis of hyperglycemia and ketosis. Several arguments have been accumulated in favor of the following concept: diabetes hyperglycemia results both from glucose under-utilization secondary to insulin lack and from hepatic glucose over-production due to glucagon excess. Although controversial, the role of glucagon in ketogenesis appears likely. ----------