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Biomedical subjects

S H Zeisel

Publications and source records attributed to S H Zeisel.

At least 19 recordsLinked to original sources
PubMed1999

Maternal dietary choline availability alters mitosis, apoptosis and the localization of TOAD-64 protein in the developing fetal rat septum.

Maternal changes in dietary choline availability alter brain biochemistry and hippocampal development in the offspring resulting in lifelong behavioral changes in the offspring. In order to better understand the relationship between maternal diet, brain cytoarchitecture and behavior, we investigated the effects of choline availability on cell proliferation, apoptosis and differentiation in the fetal rat brain septum. Timed-pregnant rats on day E12 were fed AIN-76 diet with varying levels of dietary choline for 6 days. We found that choline deficiency (CD) significantly decreased the rate of mitosis in the progenitor neuroepithelium adjacent to the septum. In addition, we found an increased number of apoptotic cells in the septum of CD animals compared to controls (3.5+/-0.5 vs. 1.7+/-0.5 apoptotic cells per section; p<0.05). However, CD had no effect on apoptosis in the indusium griseum (IG), a region of cortex dorsal to the septum. Using an unbiased image analysis method and a monoclonal antibody we found a decreased expression of the TOAD-64 kDa protein, a marker of commitment to neuronal differentiation during fetal development, in the dorsal lateral septum of CD animals. CD also decreased the expression of TOAD-64 kDa protein in the IG and cortical plate adjacent to the septum. These results show that dietary choline availability during pregnancy alters the timing of mitosis, apoptosis and the early commitment to neuronal differentiation by progenitor cells in regions of the fetal brain septum, as well as hippocampus, two brain regions known to be associated with learning and memory.

Animals↗
PubMed1999

Choline availability alters embryonic development of the hippocampus and septum in the rat.

Choline availability in the diet during pregnancy alters fetal brain biochemistry with resulting behavioral changes that persist throughout the lifetime of the offspring. In the present study, the effects of dietary choline on cell proliferation, migration, and apoptosis in neuronal progenitor cells in the hippocampus and septum were analyzed in fetal brains at different stages of embryonic development. Timed-pregnant rats on day E12 were fed AIN-76 diet with varying levels of dietary choline for 6 days, and, on days E18 or E20, fetal brain sections were collected. We found that choline deficiency (CD) significantly decreased the rate of mitosis in the neuroepithelium adjacent to the hippocampus. An increased number of apoptotic cells were found in the region of the dentate gyrus of CD hippocampus compared to controls (5.5+/-0.7 vs. 1.9+/-0.3 apoptotic cells per section; p<0.01). Using a combination of bromodeoxyuridine (BrdU) labeling and an unbiased computer-assisted image analysis method, we found that modulation of dietary choline availability changed the distribution and migration of precursor cells born on E16 in the fimbria, primordial dentate gyrus, and Ammon's horn of the fetal hippocampus. CD also decreased the migration of newly born cells from the neuroepithelium into the lateral septum, thus indicating that the sensitivity of fetal brain to choline availability is not restricted to the hippocampus. We found an increase in the expression of TOAD-64 protein, an early neuronal differentiation marker, in the hippocampus of CD day E18 fetal brains compared to controls. These results show that dietary choline availability alters the timing of the genesis, migration, and commitment to differentiation of progenitor neuronal-type cells in fetal brain hippocampal regions known to be associated with learning and memory processes in adult brain.

Animals↗
PubMed1999

Choline deficiency-induced apoptosis in PC12 cells is associated with diminished membrane phosphatidylcholine and sphingomyelin, accumulation of ceramide and diacylglycerol, and activation of a caspase.

It is not well appreciated that nutritional status can modulate apoptosis, a process that eliminates unwanted or damaged cells. Choline is an essential nutrient, and its absence induces apoptosis. When PC12 cells were cultivated in a choline-free medium, apoptosis was induced (27.4% of cells apoptotic at 72 h as compared to 4.4% in control medium). In choline-free medium at 72 h, there was a 49% decrease in phosphatidylcholine concentration (P<0.01) and a 34% decrease in sphingomyelin concentration (P<0.01); however, there was no change in phosphatidylethanolamine concentration. Before detecting increased apoptosis in choline-deficient cells, we measured a significant increase in ceramide (218% control) and diacyglycerol (155% control) concentrations. The addition of a cell-permeable ceramide to cells in control medium induced apoptosis; however, adding a cell-permeable diacyglycerol did not induce apoptosis. Caspase is a common mediator of apoptosis, and choline deficiency-induced apoptosis was prevented completely by replacing choline or adding a caspase inhibitor into the medium within 48 h of initial choline deprivation. In those cells rescued by replacing choline at 36 h, the concentrations of phosphatidylcholine, sphingomyelin, ceramide, and diacyglycerol returned to levels of control cells. In those cells rescued by adding a caspase inhibitor at 36 h, the concentrations of sphingomyelin and ceramide returned to control levels, but the concentrations of phosphatidylcholine and diacyglycerol did not return to normal. We propose that availability of dietary factors (choline in this model) can modulate apoptosis. Mechanisms that we identify using this model may help us to explain why dietary choline influences brain development.

Amino Acid Chloromethyl Ketones↗
PubMed1998

One-methyl group metabolism in non-ketotic hyperglycinaemia: mildly elevated cerebrospinal fluid homocysteine levels.

Non-ketotic hyperglycinaemia (NKH) is a rare, severe brain disease caused by deficient glycine cleavage enzyme complex activity resulting in elevated glycine concentrations. Recent experience suggests that factors in addition to glycine kinetics are involved in its pathogenesis. The glycine cleavage reaction through the formation of methylenetetrahydrofolate is an important one-methyl group donor. A deficiency in one-methyl group metabolites, in particular of choline, has been hypothesized in NKH. We investigated metabolites involved in one-methyl group metabolism in plasma and CSF of 8 patients with NKH, and monitored the effect of treatment with choline in one patient. Plasma and CSF choline and phosphatidylcholine concentrations were normal, except for a low plasma choline in the single neonate studied. Choline treatment did not change brain choline content, and was not associated with clinical or radiological improvement. Methionine concentrations and, in one-patient, S-adenosylmethionine and 5-methyltetrahydrofolate concentrations were normal in CSF. Homocysteine concentrations in CSF, however, were slightly but consistently elevated in all four patients examined, but cysteine, cysteinylglycine and glutathione were normal. Serine is important in the transfer of one-methyl groups from mitochondria to cytosol. Serine concentrations were normal in plasma and CSF, but dropped to below normal in CSF in three patients on benzoate treatment. These observations add to our understanding of the complex metabolic disturbances in NKH.

Amino Acid Metabolism, Inborn Errors↗
PubMed1998

Choline availability modulates the expression of TGFbeta1 and cytoskeletal proteins in the hippocampus of developing rat brain.

Choline availability influences long-term memory in concert with changes in the spatial organization and morphology of septal neurons, however little is known concerning the effects of choline on the hippocampus, a region of the brain also important for memory performance. Pregnant rats on gestational day 12 were fed a choline control (CT), choline supplemented (CS), or choline deficient (CD) diet for 6 days and fetal brain slices were prepared on embryonic day 18 (E18). The hippocampus in these brain slices was studied for the immunohistochemical localization of the growth-related proteins transforming growth factor beta type 1 (TGFbeta1) and GAP43, the cytoskeletal proteins vimentin and microtubule associated protein type 1 (MAP1), and the neuronal cell marker neuron specific enolase (NSE). In control hippocampus, there was weak expression of TGFbeta1 and vimentin proteins, but moderately intense expression of MAP1 protein. These proteins were not homogeneously distributed, but were preferentially localized to cells with large cell bodies located in the central (approximately CA1-CA3) region of the hippocampus, and to the filamentous processes of small cells in the fimbria region. Feeding a choline-supplemented diet decreased, whereas a choline-deficient diet increased the intensity of immunohistochemical labeling for these proteins in E18 hippocampus. GAP43 and NSE were localized to peripheral nervous tissue but not hippocampus, indicating that the maturation of axons and neurite outgrowth in embryonic hippocampus were unaffected by the availability of choline in the diet. These data suggest that the availability of choline affects the differentiation of specific regions of developing hippocampus.

Aging↗
PubMed1998

Choline deficiency induces apoptosis and decreases the number of eosinophilic preneoplastic foci in the liver of OXYS rats.

Choline deficiency (CD) was previously shown to trigger apoptosis in rat hepatocytes in culture and in vivo. In the present study we investigated the effects of short-term withdrawal of choline from the diet on the expression of putative preneoplastic foci in OXYS rats, an inbred strain with an inherited overproduction of free radicals. Animals were fed a defined, choline-sufficient (CS, control) or choline-deficient (CD) diet for 6 weeks. Eosinophilic, glutathione S-transferase (pi class) (+) preneoplastic foci were found in histologic sections of control OXYS rat liver. CD caused a 60% decrease in the number of eosinophilic foci per liver section (27.0+/-6.1 vs. 10.6+/-4.6 foci/section) compared to CS controls. Apoptotic bodies were detected in 0.18+/-0.03% of hepatocytes in CD livers compared to 0.05+/-0.009% of hepatocytes in controls. Cells which exhibited an apoptotic morphology in hematoxylin and eosin-stained sections were TUNEL-positive, confirming the induction of apoptosis. Also in CD animals compared to controls, there was an increased expression of p27Kip1 protein, and a reduction in PCNA nuclear labeling and the number of mitotic figures, consistent with an inhibition of cell proliferation in the livers of CD animals. This study shows that the liver of OXYS rats with an inherited overgeneration of free radicals retains sensitivity to CD, and that this p53-independent trigger of apoptosis can decrease the number of eosinophilic foci in the livers of these animals.

Animals↗
PubMed1997

Hepatic protein kinase C is not activated despite high intracellular 1,2-sn-diacylglycerol in obese Zucker rats.

High intracellular 1,2,-sn-diacylglycerol (DAG) usually activates protein kinase C (PKC). In choline-deficient Fischer 344 rats, we previously showed that fatty liver was associated with elevated hepatic DAG and sustained activation of PKC. Steatosis is a sequelae of many liver toxins, and we wanted to determine whether fatty liver is always associated with accumulation of DAG with activation of PKC. Obese Zucker rats had 11-fold more triacylglycerol in their livers and 2-fold more DAG in their hepatic plasma membrane than did lean control Zucker rats. However, this increased diacylglycerol was not associated with translocation or activation of PKC in hepatic plasma membrane (activity in obese rats was 897 pmol/mg protein X min(-1) vs. 780 pmol/mg protein X min(-1) in lean rats). No differences in PKC isoform expression were detected between obese and lean rats. In additional studies, we found that choline deficiency in the Zucker rat did not result in activation of PKC in liver, unlike our earlier observations in the choline deficient Fischer rat. This dissociation between fatty liver, DAG accumulation and PKC activation in Zucker rats supports previous reports of abnormalities in PKC signaling in this strain of rats.

Animals↗
PubMed1997

Apoptosis is induced by choline deficiency in fetal brain and in PC12 cells.

Treatment of rats with choline during critical periods in brain development results in long-lasting enhancement of spatial memory in their offspring. Apoptosis is a normal process during brain development, and, in some tissues, is modulated by the availability of the nutrient choline. In these studies, we examined whether availability of choline influences apoptosis in fetal brain and in the PC12 cell line derived from a rat pheochromocytoma. Timed-bred Sprague Dawley rats were fed a choline-deficient (CD), choline-control, or choline-supplemented (CS) diet for 6 days and, on embryonic day 18, fetal brain slices were prepared and apoptosis was assessed using terminal dUTP nucleotide end labeling (TUNEL) to detect DNA strand breaks and by counting of apoptotic bodies. TUNEL-positive cells were detected in 15.9% (P < 0.01), 8.7% and 7.2% of hippocampal cells from fetuses of dams fed the CD, control or CS diets, respectively. A similar inverse relationship between dietary intake of choline and TUNEL positive cells was detected in an area of cerebral cortex from these fetal brain slices. Counts of apoptotic bodies in fetal brain slices correlated inversely with choline intake of the mothers (6.2% (P < 0.01), 2.5% and 1.9% of hippocampal cells had apoptotic bodies in fetuses of dams fed the CD, control and CS diets, respectively). PC12 cells were grown in DMEM/F12 media supplemented with 70 microM choline or with 0 microM choline. The number of apoptotic bodies in PC12 cells increased when cells were grown in 0 microM choline medium (1.5%; P < 0.05) compared to 70 microM choline medium (0.55%). In PC12 cells, TUNEL labeling (DNA strand breaks) increased in choline deficient (13.5%, P < 0.05) compared to sufficient medium (5.0%). In addition, cleavage of genomic DNA-into 200 bp internucleosomal fragments was detected in choline-deficient cells. These results show that choline deficiency induces-apoptotic cell death in neuronal-type cells and in whole brain. We suggest that variations in choline availability to brain modulate apoptosis rates during development.

Animals↗
PubMed1997

Methyl-group donors cannot prevent apoptotic death of rat hepatocytes induced by choline-deficiency.

Choline-deficiency causes liver cells to die by apoptosis, and it has not been clear whether the effects of choline-deficiency are mediated by methyl-deficiency or by lack of choline moieties. SV40 immortalized CWSV-1 hepatocytes were cultivated in media that were choline-sufficient, choline-deficient, choline-deficient with methyl-donors (betaine or methionine), or choline-deficient with extra folate/vitamin B12. Choline-deficient CWSV-1 hepatocytes were not methyl-deficient as they had increased intracellular S-adenosylmethionine concentrations (132% of control; P < 0.01). Despite increased phosphatidylcholine synthesis via sequential methylation of phosphatidylethanol-amine, choline-deficient hepatocytes had significantly decreased (P < 0.01) intracellular concentrations of choline (20% of control), phosphocholine (6% of control), glycerophosphocholine (15% of control), and phosphatidylcholine (55% of control). Methyl-supplementation in choline-deficiency enhanced intracellular methyl-group availability, but did not correct choline-deficiency induced abnormalities in either choline metabolite or phospholipid content in hepatocytes. Methyl-supplemented, choline-deficient cells died by apoptosis. In a rat study, 2 weeks of a choline deficient diet supplemented with betaine did not prevent the occurrence of fatty liver and the increased DNA strand breakage induced by choline-deficiency. Though dietary supplementation with betaine restored hepatic betaine concentration and increased hepatic S-adenosylmethionine/S-adenosylhomocysteine ratio, it did not correct depleted choline (15% of control), phosphocholine (6% control), or phosphatidylcholine (48% of control) concentrations in deficient livers. These data show that decreased intracellular choline and/or choline metabolite concentrations, and not methyl deficiency, are associated with apoptotic death of hepatocytes.

Animals↗
PubMed1997

Diet, apoptosis, and carcinogenesis.

It is known that long-term withdrawal of choline from the diet induces hepatocellular carcinomas in animal models in the absence of known carcinogens. We hypothesize that a choline deficient diet (CD) alters the balance of cell growth and cell death in hepatocytes and thus promotes the survival of clones of cells capable of malignant transformation. When grown in CD medium (5 microM or 0 microM choline) CWSV-1 rat hepatocytes immortalized with SV40 large T-antigen underwent p53-independent apoptosis (terminal dUTP end-labeling of fragmented DNA; laddering of DNA in agarose gel). CWSV-1 cells which were adapted to survive in 5 microM choline acquired resistance to CD-induced apoptosis and were able to form hepatocellular carcinomas in nude mice. These adapted CWSV-1 cells express higher amounts of both the 32 kDa membrane-bound and 6 kDa mature form of TGF alpha compared to cells made acutely CD. Control (70 microM choline) and adapted cells, but not acutely deficient hepatocytes, could be induced to undergo apoptosis by neutralization of secreted TGF alpha. Protein tyrosine phosphorylation is known to protect against apoptosis. We found decreased EGF receptor tyrosine phosphorylation in acutely choline deficient CWSV-1 cells. TGF beta 1 is an important growth-regulator in the liver. CWSV-1 cells express TGF beta 1 receptors and this peptide induced cell detachment and death in control and acutely deficient cells. Hepatocytes adapted to survive in low choline were also resistant to TGF beta 1, although TGF beta 1 receptors and protein could be detected in the cytoplasm of these cells. The non-essential nutrient choline is important in maintaining plasma membrane structure and function, and in intracellular signaling. Our results indicate that acute withdrawal of choline induces p53-independent programmed cell death in hepatocytes, whereas cells adapted to survive in low choline are resistant to this form of apoptosis, as well as to cell death induced by TGF beta 1. Our results also suggest that CD may induce alterations (mutations?) in growth factor signaling pathways which may enhance cell survival and malignant transformation.

Animals↗
PubMed1997

Prolonged fasting in humans results in diminished plasma choline concentrations but does not cause liver dysfunction.

Choline is a major donor of methyl groups, a precursor for membrane synthesis, and a component of the neurotransmitter acetylcholine. Choline-deficient diets deplete humans of choline and cause hepatic dysfunction and steatosis. In this study we determined whether acute starvation also depletes choline, as indicated by changes in plasma choline or phosphatidylcholine. Healthy humans (n = 10) fasted for 7 d, ingesting only water and mineral-vitamin supplements. Their mean (+/- SEM) plasma choline concentration was 9.5 +/- 0.5 micromol/L at the start of the study and dropped to 7.8 +/- 0.3 micromol/L after 1 wk of fasting (P < 0.01). The plasma phosphatidylcholine concentration did not change significantly (2.2 +/- 0.1 mmol/L at the start of the study and 2.4 +/- 0.2 mmol/L after 1 wk of fasting). Capacity of the liver to secrete lipoproteins was not affected by prolonged fasting. The mean plasma concentration of low-density-lipoprotein cholesterol was 3.3 +/- 0.2 mmol/L (126 +/- 8 mg/dL) at the start of the study and 4.9 +/- 0.5 mmol/L (188 +/- 19 mg/dL) after 1 wk of fasting. Liver damage assessed by serum alanine aminotransferase activity occurred in only 1 of 10 subjects. We conclude that prolonged fasting in humans modestly diminished plasma choline but was not associated with signs of choline deficiency, such as perturbed lipoprotein secretion and liver damage.

Adult↗
PubMed1997

Choline deficiency selects for resistance to p53-independent apoptosis and causes tumorigenic transformation of rat hepatocytes.

The mechanisms which drive initiated cells to progress to form carcinomas are poorly understood. CWSV-1 rat hepatocytes, in which p53 protein is inactivated by SV40 large T antigen, respond by inducing p53-independent apoptosis when acutely switched to medium containing low choline (16% apoptotic at 48 h in 5 microM choline) as compared with controls (1% apoptotic at 48 h in 70 microM choline). The rate of apoptosis was inversely correlated with cellular phosphatidylcholine content. Choline deficiency (CD)-induced apoptosis is probably mediated by TGFbeta1 and reactive oxygen species, since immunoneutralization of TGFbeta1 in the medium or treatment with N-acetylcysteine (an antioxidant) or addition of neocuproine (a transition metal chelator) prevented CD-induced apoptosis. CWSV-1 hepatocytes could be gradually adapted to survive in 5 microM choline. CD-adapted cells had increased membrane phosphatidylcholine concentrations (compared with acute CD cells). Adapted cells acquired relative resistance to CD-induced apoptosis (7% of adapted cells compared with 19% of non-adapted cells were apoptotic at 48 h in 5 microM choline). They also became relatively resistant to another p53-independent form of apoptosis (TGFbeta1-induced). CD-adapted hepatocytes developed increased capability for anchorage-independent growth and formed tumors when transplanted into nude mice; passage-matched control hepatocytes did not possess these properties. Cell transformation was dependent on exposure to the selective pressure of CD apoptosis, as we observed that when CD apoptosis was inhibited with an antioxidant during adaptation, cells did not become anchorage independent. Acquisition by p53-deficient cells of resistance to p53-independent inducers of apoptosis (CD, TGFbeta1 and reactive oxygen species) may leave cells without another important apoptotic defensive barrier and may be responsible for the progression of initiated cells to frank carcinomas.

Animals↗
PubMed1997

Choline deficiency causes increased localization of transforming growth factor-beta1 signaling proteins and apoptosis in the rat liver.

Dietary restriction is known to decrease cell proliferation and increase apoptosis in the liver; however, the role of withdrawal of single dietary factors on cells of the liver is less well understood. In this study, we investigated the effects of short-term choline deficiency (CD; also for choline deficient) on cell survival, proliferation and the expression of proteins related to the transforming growth factor-beta1 (TGF-beta1) growth-inhibitory signaling pathway in the liver. In animals fed a CD diet for 6 weeks, classical apoptotic bodies were detected in 0.28 +/- 0.04% of hepatocytes in CD livers compared to 0.096 +/- 0.006% of hepatocytes in control rats fed a choline-sufficient (CS) diet. These classical apoptotic cells exhibited DNA fragmentation when probed with an in situ end-labeling immunohistochemical method; TUNEL-positive nuclei were also seen in hepatocytes in CD livers which had accumulated large amounts of lipid, consistent with the known DNA-damaging effects of CD. In CS control livers, TGF-beta1 protein was found only in bile duct epithelium and nonparenchymal-type cells, and not in hepatocytes. However, the majority of hepatocytes in the CD liver expressed high levels of TGF-beta1 protein, as well as TGF-beta1 receptor types I and II. Nuclear localization of p27Kip1 protein, which may link TGF-beta1 expression to apoptosis, showed a 10-fold increase in CD hepatocytes (4.1 +/- 1.1 vs. 0.35 +/- 0.04% of cells) compared to controls. In addition, there was a 5-fold increase (0.54 +/- 0.031 vs. 0.011 +/- 0.007% of cells) in the mitotic index in CD-compared control livers. We conclude that feeding a CD diet for 6 weeks induces apoptosis in hepatocytes in the whole rat liver and that this form of cell death appears to be mediated, in part, by TGF-beta1 and related proteins.

Activin Receptors, Type I↗
PubMed1997

Choline: essential for brain development and function.

Pregnancy and lactation are periods when maternal reserves of choline are depleted. At the same time, the availability of choline for normal development of brain is critical. Variations in choline intake by mothers influence memory performance in their offspring. The mechanisms for this potent effect of choline are not yet elucidated but may involve changes in acetylcholine synthesis, transmembrane signal transduction, or regulation of apoptosis. These observations are important for the obstetrician and pediatrician as they consider the ideal dietary intake for mothers and their children.

Acetylcholine↗
PubMed1996

Choline and choline esters in human and rat milk and in infant formulas.

Large amounts of choline are required in neonates for rapid organ growth and membrane biosynthesis. Human infants derive much of their choline from milk. In our study, mature human milk contained more phosphocholine and glycerophosphocholine than choline, phosphatidylcholine, or sphingomyelin (P < 0.01). Previous studies have not recognized that phosphocholine and glycerophosphocholine exist in human milk. Concentrations of choline compounds in mature milk of mothers giving birth to preterm or full-term infants were not significantly different. Infant formulas also contained choline and choline-containing compounds. In infant formulas derived from soy or bovine milk, unesterified choline, phosphocholine, glycerophosphocholine, phosphatidylcholine, and sphingomyelin concentrations varied greatly. All infant formulas contained significantly less phosphocholine than did human milk. Soy-derived formulas contained significantly less glycerophosphocholine (P < 0.01) and phosphocholine (P < 0.01) and more phosphatidylcholine (P < 0.01) than did human or bovine milk or bovine milk-derived infant formulas. Rat milk contained greater amounts of glycerophosphocholine (almost 75% of the total choline moiety in milk) and phosphocholine than did human milk. When dams were provided with either a control, choline-deficient, or choline-supplemented diet, milk composition reflected the choline content of the diet. Because there are competing demands for choline in neonates, it is important to ensure adequate availability through proper infant nutrition. Although the free choline moiety is adequately provided by infant formulas and bovine milk, reevaluation of the concentrations of other choline esters, in particular glycerophosphocholine and phosphocholine, may be warranted.

Adolescent↗
PubMed1996

Choline deficiency induces apoptosis in SV40-immortalized CWSV-1 rat hepatocytes in culture.

Immortalized CWSV-1 rat hepatocytes, in which p53 protein is inactivated by SV40 large T antigen, had increased numbers of cells with strand breaks in genomic DNA (terminal dUTP end labeling) when grown in 0 Micron choline (67-73% of cells) than when grown in 70 Micron choline (2-3% of cells). Internucleosomal fragmentation of DNA (DNA ladders) was detected in cells grown with 5 Micron and 0 Micron choline for 72h. Cells treated with 0 or 5 Micron choline for 72h detached from the substrate in high numbers (58% of choline deficient cells vs. 1.4% of choline sufficient cells detached) exhibited a high incidence of apoptosis (apoptotic bodies were seen in 55-75% of cells; 67-73% had DNA strand breaks), and an absence of mitosis and proliferating cell nuclear antigen (PCNA) expression. Cells undergoing DNA fragmentation had functioning mitochondria. At 24h, cells grown in 0 or 5 Micron choline synthesize DNA more rapidly than those grown in 70 Micron choline. By 72h, the cells grown in 0 or 5 Micron choline were forming DNA much more slowly than control cells (assessed by thymidine incorporation, PCNA expression, and mitotic index). Western blot analysis showed that p53 in the nucleus of cells was detected in direct association with SV40 T-antigen, and was therefore likely to be inactive. We conclude that choline deficiency kills CWSV-1 hepatocytes in culture by inducing apoptosis via what may be a p53-independent process, and that this process begins in viable cells before they detach from the culture dish.

Animals↗