Relation of C-6 glial cells in culture to myelin

Volpe, Joseph J.; Fujimoto, K; Marasa, Jayne; Agrawal, Harish C.

doi:10.1042/bj1520701

Cited by 84 publications

(36 citation statements)

References 18 publications

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“…Evidence also exists indicating that long-term changes in the activities of several lipogenic enzymes reflect changes in the rates of synthesis of the enzymes [l 1,22,25,26,38]. Our present results using inhibitors of protein synthesis suggest that the induction of the lipogenic enzymes due to the addition of fructose to the culture medium is a reflection of the synthesis of these proteins.…”

Section: Discussionsupporting

confidence: 55%

Induction of Lipogenic Enzymes in Primary Cultures of Rat Hepatocytes

Spence

Pitot

2005

European Journal of Biochemistry

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Using primary cultures of adult rat hepatocytes, the regulation of the following lipogenic enzymes was studied: glucose-6-phosphate dehydrogenase, malic enzyme, ATP-citrate lyase, acetyl-CoA carboxylase, fatty acid synthetase, and stearoyl-CoA desaturase. The addition to the culture medium of either insulin or triiodothyronine produced a 2-3-fold increase in each of the individual enzyme activities whereas glucagon slightly decreased enzyme activities. The addition to the medium of 8-bromoguanosine 3,'5'-monophosphate had no effect on any of the enzyme activities unless glucose was also added to the culture medium. Glucose addition alone to the culture medium was without any effect; however, glucose enhanced the stimulation of enzyme activity due to insulin. The addition of fructose or glycerol, even in the absence of insulin, increased the activities of each of the enzymes studied 2-3-fold. The increases in enzyme activity brought about by insulin or fructose were apparently the result of de n o w enzyme synthesis, as indicated by the observation that the increases were not noted in the presence of cordycepin or cycloheximide. Immunoprecipitation of ATP-citrate lyase from hepatocytes pulselabeled with [3H]leucine indicated that the induction of this enzyme in response to the addition of fructose or glycerol to the culture medium was the result of an increase in the rate of synthesis of the enzyme. These results indicate that the activity and synthesis of individual enzymes involved in lipogenesis are increased in response to the metabolism of carbohydrate independently in part from hormonal effects.Hepatic fatty acid synthesis is known to be regulated in response to the hormonal and nutritional state of the animal (see reviews, [1,2]). Dietary fructose has been shown to be as effective as glucose in increasing the hepatic production of fatty acids despite its weak action on insulin secretion [3]. Furthermore, Baker et al. [4] reported that dietary fructose, but not glucose, stimulated lipogenesis in diabetic rats. A number of enzymes involved in lipogenesis including ATPcitrate lyase [5,6], acetyl-CoA carboxylase [5,7], fatty acid synthetase [7,8] and stearoyl-CoA desaturase [9] have been induced in livers of diabetic rats by feeding fructose or glycerol.Based upon these and related observations, it has been suggested that the increase in fatty acid synthesis observed following carbohydrate feeding is the result of a buildup of carbohydrate metabolites [3,.Recently, we have presented evidence indicating that the synthesis of glucokinase is regulated in response to the breakdown of carbohydrates and that this regulation may be mediated via cGMP [lo]. It is intriguing to speculate that a common system of regulation may be responsible for the control of metabolic pathways which respond similarly to physiological stimuli. In this report, the regulation of the following lipogenic enzymes was studied using primary cultures of adult rat hepatocytes: glucose-6-phosphate de-

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Section: Discussionsupporting

confidence: 55%

Induction of Lipogenic Enzymes in Primary Cultures of Rat Hepatocytes

Spence

Pitot

2005

European Journal of Biochemistry

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“…This system has been considered a good model for the developing brain because although the cells resemble astrocytes morphologically they express some of the biochemical properties of oligodendrocytes (Volpe et al, 1975) and under appropriate stimuli can be induced to exhibit properties of either astrocytes or oligodendrocytes (Liao et al, 1978). As indicated earlier, one JHM strain of MHV can replicate in primary rat oligodendrocytes and not in primary astrocytes, whereas the MHV 3 strain can replicate in astrocytes and not in the oligodendrocytes (Beushausen & Dales, 1985).…”

Section: Discussionmentioning

confidence: 99%

Rat Glial C6 Cells are Defective in Murine Coronavirus Internalization

Dinter

Flintoff

1987

Journal of General Virology

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SUMMARYRat C6 glial cells were resistant to infection by several strains of murine coronaviruses. The restriction was not at the adsorption stage, since virus adsorbed to the C6 cells in a similar manner to mouse L cells which supported a lytic infection. The virus could not be internalized by the C6 cells. However, if the virus was introduced into the C6 cells by polyethylene glycol fusion, viral replication occurred and progeny virions were released from the infected cells. These studies indicated that the C6 cells were restrictive to coronavirus replication by preventing the early penetration stage of the viral replicative cycle.

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“…Within the central nervous system, CNP is generally regarded as specific to myelin and oligodendrocytes (14,17,19). The exact type of glial cell from which the C6 glioma arose is uncertain (33,34) but, although the cells resemble astrocytes morphologically, they express some of the biochemical properties characteristic of oligodendrocytes (15,35). The finding that the neurotransmitter NE stimulates CNP activity in glioma cells may be helpful in elucidating the role of CNP in the nervous system.…”

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confidence: 99%

Norepinephrine induces glial-specific enzyme activity in cultured plasma glioma cells.

McMorris¹

1977

Proc. Natl. Acad. Sci. U.S.A.

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Addition of 1 #M 1-norepinephrine to cultures of C6TK-rat glioma cells caused a 2-fold increase in specific activity of the glial-specific enzyme 2':3'-cyclic nucleotide 3'-phosphohydrolase (nucleoside-2':3'-cyclic-phosphate 3'-nucleotidohydrolase, EC 3.1.4.16). Specific activity could also be stimulated by analogues of 3':5'-cyclic AMP, and the effect of norepinepbrine could be blocked by P-adrenergic receptor antagonists but not by a-adrenergic antagonists. Norepinephrine or cyclic AMP analogues also increased the specific activity of this enzyme in other clones of glioma and Schwannoma cells and in glioma X neuroblastoma cell hybrids. These results show that the stimulatory effect of norepinephrine on cyclic AMP concentrations in glioma cells leads ultimately to a stimulation of glial-specific cell function. The neurotransmitter l-norepinephrine (NE) induces a dramatic increase in the intracellular concentration of adenosine 3':5'-cyclic monophosphate (cAMP) in brain slices (1) and in glioma cells in tissue culture (2-4). Although glioma cells were the first clonal cell type in which such a response was observed (2-4), the function of this NE-induced cAMP response remains obscure. It has been suggested that this increase in "second messenger" is involved in metabolic coupling between neurons and glia, which are in intimate contact in the central nervous system (2).Exposure of glioma cells to NE or to cAMP analogues affects several functions common to many cell types-including glycogenolysis (5, 6), lactate dehydrogenase (7), ornithine decarboxylase (8), cAMP phosphodiesterase (9, 10), and protein kinase activity (11)-and induces morphological changes in the cells (12), but no glial-specific enzyme or function has been shown to be altered by NE or cAMP.In this paper I report that physiological concentrations of NE cause an increase in the glial-specific enzyme 2':3'-cyclic nucleotide 3'-phosphohydrolase (CNP; nucleoside-2':3'-cyclicphosphate 3'-nucleotidohydrolase, EC 3.1.4.16) in C6TK-rat glioma cells in vitro and that this response is mediated by a #-adrenergic receptor and cAMP.CNP is a membrane-associated enzyme that is present at high specific activity in glial and Schwann cells and in myelin (13-16). Among glial cells, CNP activity is much higher in oligodendroglia, which produce myelin, than in astroglia (17). Activity is low or absent in non-neural tissues or in cloned cells other than glioma and Schwannoma (13-16), although CNP can be detected at low specific activity in purified erythrocyte membranes (18). CNP is therefore considered to be one of the most specific biochemical markers for myelin and oligodendroglia (19). CNP is inactive toward 3':5'-cyclic nucleotides (

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Relation of C-6 glial cells in culture to myelin

Cited by 84 publications

References 18 publications

Induction of Lipogenic Enzymes in Primary Cultures of Rat Hepatocytes

Induction of Lipogenic Enzymes in Primary Cultures of Rat Hepatocytes

Rat Glial C6 Cells are Defective in Murine Coronavirus Internalization

Norepinephrine induces glial-specific enzyme activity in cultured plasma glioma cells.

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