Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A glycerol-requiring mutant of Salmonella typhimurium was used in a study of the biosynthesis and assembly of a structural lipoprotein in the cell envelope of gram-negative bacteria. Upon removal of glycerol from the growth medium, the biosynthesis of lipoprotein, as measured by radioactive arginine incorporation, was reduced by the same extent as that of other envelope proteins, the cumulative incorporation of arginine being 20% of that of the unstarved control cells. However, the incorporation of radioactive palmitate into lipoprotein was more severely curtailed after glycerol starvation, the cumulative rate of which was 8% of that observed in the unstarved cells. It was further observed that the lipoprotein synthesized in the glycerol-starved cells was more enriched in unmodified cysteine, which is known to be the N-terminal amino acid of lipoprotein, than that synthesized in the unstarved cells. We conclude that the synthesis of the apoprotein portion of Braun's lipoprotein proceeds independently of the attachment of diglyceride to the sulfhydryl group of the N-terminal cysteine and may, in fact, precede the incorporation of the diglyceride moiety.
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PMID:Biosynthesis and assembly of envelope lipoprotein in a glycerol-requiring mutant of Salmonella typhimurium. 76 31

Cellular content and rates of synthesis of the apoprotein subunits of phycocyanin in Anacystis nidulans cultures undergoing, and recovering from, nitrate starvation were measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total and immunoprecipitable soluble proteins. Results indicated that (i) nitrate starvation provokes coordinate degradation of apoprotein subunits: (ii) de novo synthesis of these subunits is selectively depressed during starvation; (iii) nitrate restoration provokes coordinate increases in the rates of synthesis of these subunits, although maximal rates are not achieved for 6 to 10 h after readdition of nitrate; and (iv) illumination affects both relative and absolute rates of apoprotein formation.
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PMID:Phycocyanin synthesis and degradation in the blue-green bacterium Anacystis nidulans. 92 72

Pulmonary surfactant isolated from bronchoalveolar lavage fluid of rat lung contained a high content of surfactant protein A (SP-A) in starved for 2 days compared to fed controls, but this phenomena returned to baseline following more than 4 days starvation. As determined by immunoperoxidase staining of lung sections using SP-A antibody, SP-A could be consistently observed in nonciliated bronchiolar (Clara) cells, alveolar type II cells and some alveolar macrophages (AM). Fc receptor-mediated phagocytosis of AM was enhanced by SP-A, which was dependent on the dosis and reached a maximum at 10 micrograms of SP-A/ml. Antibody to SP-A completely inhibited the enhanced response of phagocytosis. When exposed AM subpopulations, separated into four fractions (I, II, III and IV) by discontinuous Percoll gradient, to SP-A or pulmonary surfactant prepared from rats fed and starved for 2 days enhanced their phagocytic activity in high dense cells (III and IV), particularly to SP-A and pulmonary surfactant from rats starved for 2 days. Whereas little change in lower dense fractions (I and II) were seen in all exposures except for SP-A that enhanced the cells of fraction II. These results supported the concept that pulmonary surfactant and its apoprotein, SP-A, are a factor to regulate lung defense system including activation of AM that undergo different processes following starvation.
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PMID:Effects of pulmonary surfactant and surfactant protein A on phagocytosis of fractionated alveolar macrophages: relationship to starvation. 157 41

Two major forms of hepatic microsomal cytochrome P-450 were purified from starved and acetone-treated rats. On the basis of amino acid sequence analysis, they were identified as P-450j and P-450b. Ethanol or acetone treatment of rats caused a 9-fold increase in the amount of P-450j in liver microsomes accompanied by similar increases in the rate of NADPH-dependent metabolism of carbon tetrachloride, acetone, and benzene. Immunological experiments indicated that P-450j constitutes the major catalyst of the microsomal metabolism of the latter agents and contributes by about 50% to microsomal P-450-dependent ethanol oxidation under the conditions used. The P-450j-dependent catalytic activities had a high rate of turnover. In contrast, this was not the case for the immunodetectable P-450j, indicating the occurrence of inactive forms of this protein in microsomes. Starvation or ethanol or acetone treatment caused 10-30-fold increases in the amount of both mRNA and apoprotein of P-450b,e compared to control. Run-on experiments and the concomitant increases of the P-450b,e gene products at the mRNA and protein levels indicated the appearance of mainly a transcriptional activation by acetone, ethanol, or starvation. Fasting exerted, in addition, a pronounced synergistic effect on acetone-dependent induction of P-450b,e mRNA (3-fold), apo-P-450b,e (4.3-fold), P-450j mRNA (2-fold), and apo-P-450j (2-fold). No increase of mRNA coding for P-450j, compared to control, was seen after acetone or ethanol treatment alone. The results indicate that effects of ethanol, acetone, and/or starvation on drug and xenobiotic metabolism are caused by the induction of P-450 forms belonging to at least two gene subfamilies.
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PMID:Ethanol-, fasting-, and acetone-inducible cytochromes P-450 in rat liver: regulation and characteristics of enzymes belonging to the IIB and IIE gene subfamilies. 337 38

Chronic ethanol exposure causes marked induction of the ethanol-inducible cytochrome P450 (CYP) 2E1 isozyme in the centrilobular liver region, where alcoholic damage commonly is initiated. In contrast to most other CYP forms, which are ligand-activated at the transcriptional level, ethanol induction of CYP2E1 has been found to be post-translational. However, transcriptional activation of the CYP2E1 gene was recently described in fed animals maintained at very high ethanol levels. To further evaluate mechanisms of ethanol-mediated CYP2E1 induction we compared the effect of short-term heavy-ethanol treatment and fasting on CYP2E1 mRNA, protein and catalytic activity. High blood-ethanol levels (20-70 mM) were maintained for 3 days by regular alcohol intubations to fed or fasted rats. During this period, the amount of liver CYP2E1 apoprotein increased a maximum of 20-fold and catalytic activity 16-fold, both in fed and fasted animals, whereas starvation alone caused only a 4- to 5-fold increase. By comparison, the amount of CYP2E1 mRNA, as assayed both by Northern blot and slot blot, was significantly increased (5- to 6-fold) by ethanol only in fasted rats; this increase was smaller than that observed after fasting alone (8- to 9-fold). Analysis of cell lysates isolated from the periportal and perivenous region revealed that the increase in CYP2E1 mRNA by fasting occurred in the perivenous region. Thus no evidence was obtained for an increased pretranslational CYP2E1 gene expression as a consequence of the continuous presence of ethanol at intoxicating levels for 3 days. CYP2E1 mRNA elevation seems to be strongly associated with starvation while alcohol treatment increases the amount of enzyme, primarily by ligand-dependent stabilization of the synthesized protein. Our results indicate that transcriptional activation of CYP2E1 requires the long-term presence of highly intoxicating ethanol levels. It is conceivable that such activation occurs via indirect physiological responses related to those triggered by starvation.
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PMID:Induction mechanisms of cytochrome P450 2E1 in liver: interplay between ethanol treatment and starvation. 763 58

Ethanol, acetone, diet and starvation, known modulators of the hepatic cytochrome P450 (CYP)-dependent microsomal monooxygenase system, were assessed for their effects on cytochrome P450 isozyme content and monooxygenase activities in the male rat kidney. In acute experiments, rats were either treated with acetone, fasted or given a combination of the two treatments. Acetone treatment alone induced CYP2E1-dependent p-nitrophenol hydroxylase activity in kidney microsomes by 8-fold. This was accompanied by a 6-fold increase in CYP2E1 apoprotein as determined by Western blot analysis. There was, however, no significant increase in steady-state levels of CYP2E1 mRNA as measured by Northern blot analysis. Starvation also induced CYP2E1 apoprotein in the kidney and, as has been reported previously in the liver, had a synergistic inductive effect with acetone. CYP2B and CYP3A apoproteins were also induced by acetone, starvation and starvation/acetone combinations in the kidney. Immunohistochemical analysis revealed localization of CYP2E1 and CYP2B principally in the cortex associated with tubular cells. This distribution was maintained upon starvation/acetone treatment. Two induction experiments were performed in which the ethanol was administered as part of a system of total enteral nutrition (TEN). A short-term study was conducted in which ethanol was administered for 8 days in two liquid diets of different composition, and a chronic experiment was performed in which ethanol was administered for 35 days. A diet-independent 6-fold increase in CYP2E1 apoprotein was observed in the short-term experiment. Expression of CYP3A and CYP2A cross-reactive apoproteins in kidney microsomes appeared to be affected by alterations in diet but, were unaffected by ethanol treatment. In the chronic 35-day ethanol exposure experiment, CYP2E1 apoprotein was also elevated 6-fold and this was found to be accompanied by a significant 3-fold increase in CYP2E1 mRNA. In the same study, no ethanol effects were apparent on expression of CYP2B and CYP3A apoproteins. Thus, acetone induced a variety of renal cytochrome P450 forms in addition to CYP2E1, while ethanol appeared to be a much more specific renal CYP2E1 inducer. Furthermore, as reported in the liver, acetone and ethanol appeared to induce CYP2E1 in the kidney by different mechanisms.
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PMID:Expression and distribution of cytochrome P450 enzymes in male rat kidney: effects of ethanol, acetone and dietary conditions. 944 34

Previous results indicate that apoE (apolipoprotein E) may be associated with the nucleus in specific cell types, particularly under stress conditions such as serum starvation. In addition, nuclear apoE localization in ovarian cancer was recently shown to be correlated with patient survival. In order to better understand the factors associated with apoE nuclear localization, we examined intracellular apoE trafficking using live-cell imaging of CHO (Chinese-hamster ovary) cells that constitutively expressed apoE-GFP (green fluorescent protein). In addition, we used biotinylated apoE (in a lipid-free state and as a lipidated discoidal complex) to track the uptake and potential nuclear targeting of exogenous apoE. Our results indicate that a small proportion of apoE-GFP is detected in the nucleus of living apoE-GFP-expressing CHO cells and that the level of apoE-GFP in the nucleus is increased with serum starvation. Exposure of control CHO cells to exogenous apoE-GFP did not result in nuclear apoE-GFP localization in the recipient cells. Similarly, biotinylated apoE did not reach the nucleus of control CHO cells or SK-N-SH neurons. In contrast, when biotinylated apoE was delivered to recipient cells as a lipidated apoE disc, apoE was detected in the nucleus, suggesting that the lipoprotein complex alters the intracellular degradation or trafficking of apoE. Biotinylated apoE discs containing each of the three common human apoE isoforms (E2, E3 and E4) were also tested for nuclear trafficking. All three apoE isoforms were equally detected in the nucleus. These studies provide new evidence that apoE may be targeted to the nucleus and shed light on factors that regulate this process.
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PMID:Analysis of apolipoprotein E nuclear localization using green fluorescent protein and biotinylation approaches. 1796 Nov 26

We have long thought that remnant lipoproteins (RLP) in plasma are significantly increased as the result of disturbed lipoprotein metabolism followed by obesity and insulin resistance. Therefore, it was believed that insulin resistance causes and enhances RLP formation. In contrast, this hypothesis states that RLP induces insulin resistance as the result of obesity associated with the excessive fat intake. The majority of plasma TG increased after fat intake is TG in RLP (RLP-TG) and the majority of postprandial RLP is VLDL remnants, not CM remnants. RLP is newly formed lipoproteins primarily for energy supply against starvation, like blood sugar after carbohydrate intake. Since RLP bearing apoE, LPL and Lp(a) function as ligands for the VLDL receptor, RLP interacts with the VLDL receptor in visceral fat adipocytes and stored as TG similar to excessive blood sugar. However, the excessive VLDL remnants induces obesity and its associated insulin resistance, which plays a major role as the initiator of metabolic domino effects, similar to blood sugar primarily serving as an energy supply to protect against starvation.
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PMID:Hypothesis: Postprandial remnant lipoproteins are the causal factors that induce the insulin resistance associated with obesity. 2995 88