133 research outputs found
Morphological and biochemical alterations in the jejunum following iodoacetamide-induced colitis in rats
No full textThis study aims to describe the morphological alterations in the small and large intestines as well as the expression of some enterocyte enzymes and carriers in a rat model of iodoacetamide-induced colitis. Biopsies from the large and small intestines were taken at 1, 2, 4, 8, and 16 days postinduction and studied by light microscopy. The expressions of lactase, sucrase, aminopeptidase, and Glut-5 in the jejunum were studied by immunohistochemistry. Gene expressions of enterocyte lactase and sucrase were determined by RT-PCR using specific oligonucleotides. Microscopic examination of the large intestines revealed manifestations concordant with inflammation. Such alterations peaked at 2 days, were maintained to a lesser extent for 4 days, regressed by 8 days, and healed by 16 days. In the jejunum, the expression of lactase, sucrase, and aminopeptidase decreased 2 days after colitis induction, and recovered 2 days later. Similarly, Glut-5 expression decreased transiently with partial recovery by day 8. Compared with sham, gene expression of jejunal brush border enzymes sucrase and lactase showed a 4-fold increase in lactase and a 9-fold increase in sucrase after 4 days. We conclude that colitis can induce significant functional abnormalities in distant noninflamed small bowel regions. © 2006 NRC.Abreu Maria T, 2002, Curr Gastroenterol Rep, V4, P481, DOI 10.1007-s11894-002-0024-0; ANDERSSO.H, 1971, ACTA MED SCAND, V190, P407; ANDREWS CW, 1992, HUM PATHOL, V23, P774, DOI 10.1016-0046-8177(92)90347-6; ARVANITAKIS C, 1979, DIGESTION, V19, P259; Aube AC, 1999, NEUROGASTROENT MOTIL, V11, P55; BARADA KA, 2004, GUT S6, V53, pA46; Barada KA, 2001, LIFE SCI, V69, P3121, DOI 10.1016-S0024-3205(01)01418-7; BINDER HJ, 1970, J LAB CLIN MED, V76, P915; Brown KA, 2002, AM J GASTROENTEROL, V97, P2603; BROYART JP, 1990, BIOCHIM BIOPHYS ACTA, V1087, P61, DOI 10.1016-0167-4781(90)90121-H; Carty E, 2000, GUT, V46, P487, DOI 10.1136-gut.46.4.487; CHAKRAVA.KR, 1973, AM J DIG DIS, V18, P191, DOI 10.1007-BF01071972; CHALFIN D, 1967, AM J DIG DIS, V53, P890; DANIELSEN EM, 1989, J BIOL CHEM, V264, P13726; Darakhshan F, 1998, BIOCHEM J, V336, P361; Dieleman LA, 1996, AM J PHYSIOL-GASTR L, V271, pG130; Duluc I, 1997, J CELL SCI, V110, P1317; FABIA R, 1993, SCAND J GASTROENTERO, V28, P155, DOI 10.3109-00365529309096063; Fries W, 1999, LAB INVEST, V79, P49; HIRATA I, 1986, DIGEST DIS SCI, V31, P593, DOI 10.1007-BF01318690; Jacobson K, 1997, GASTROENTEROLOGY, V112, P156, DOI 10.1016-S0016-5085(97)70230-0; JACOBSON K, 1995, GASTROENTEROLOGY, V109, P718, DOI 10.1016-0016-5085(95)90378-X; JANKEY N, 1969, GUT, V10, P267, DOI 10.1136-gut.10.4.267; JURJUS AR, 2000, J PHARM TOXICOL METH, V50, P81; Karlinger K, 2000, EUR J RADIOL, V35, P154, DOI 10.1016-S0720-048X(00)00238-2; Kishi K, 1999, J NUTR, V129, P953; LEEPER LL, 1990, AM J PHYSIOL, V258, pG52; LEVINE JB, 1995, GASTROENTEROL CLIN N, V24, P633; LIU T, 1992, AM J PHYSIOL, V263, pG538; Miampamba M, 1999, J AUTONOM NERV SYST, V77, P140, DOI 10.1016-S0165-1838(99)00048-X; MORRIS GP, 1989, GASTROENTEROLOGY, V96, P795; Mourad FH, 2006, AM J PHYSIOL-GASTR L, V290, pG262, DOI 10.1152-ajpgi.00271.2005; NEWCOMER AD, 1967, GASTROENTEROLOGY, V53, P890; Podolsky DK, 2002, NEW ENGL J MED, V347, P417, DOI 10.1056-NEJMra020831; RAO SSC, 1987, GASTROENTEROLOGY, V93, P934; RAUL F, 1978, ENZYME, V23, P89; Rayhorn Nancy, 2002, Nurse Pract, V27, P13, DOI 10.1097-00006205-200211000-00003; SALEM SN, 1965, BRIT MED J, V1, P827; Sanovic S, 1999, AM J PATHOL, V155, P1051, DOI 10.1016-S0002-9440(10)65207-8; Satoh H, 1997, JPN J PHARMACOL, V73, P299, DOI 10.1254-jjp.73.299; Schaeffer C, 2000, GUT, V47, P192, DOI 10.1136-gut.47.2.192; Schmitz H, 1999, GASTROENTEROLOGY, V116, P301, DOI 10.1016-S0016-5085(99)70126-5; Schwarz NT, 2004, GASTROENTEROLOGY, V126, P159, DOI 10.1053-j.gastro.2003.10.060; SOULE JC, 1984, GASTROEN CLIN BIOL, V8, P800; SYMONS LEA, 1978, J PARASITOL, V64, P958, DOI 10.2307-3279552; SZABO S, 1981, SCIENCE, V214, P200, DOI 10.1126-science.7280691; Tanaka M, 1999, SCAND J GASTROENTERO, V34, P55; Washington K, 2002, AM J SURG PATHOL, V26, P1441, DOI 10.1097-00000478-200211000-00006; Zetzel L, 1942, AM J DIG DIS, V9, P74; Ziambaras T, 1996, J BIOL CHEM, V271, P123768
Death receptor pathway activation and increase of ROS production by the triple epigenetic inhibitor, UVI5008
No full text"Deregulation of the epigenome is recognized as cause of cancer and epigenetic factors are receiving major attention as therapeutic targets; yet, the molecular mode of action of existing epi-drugs is largely elusive. Here, we report on the decryption of the mechanism of action of UVI5008, a novel epigenetic modifier, that inhibits histone deacetylases, sirtuins, and DNA methyltransferases. UVI5008 highly efficiently induces cancer cell-selective death in a variety of models and exerts its activities in several human tumor xenografts and genetic mouse models of human breast cancer in vivo. Its anticancer activity involves independent activation of death receptors and reactive oxygen species production. Importantly, UVI5008 action is not critically dependent on p53, Bcl-2 modifying factor, and\/or TNF-related apoptosis-inducing ligand as cell death is efficiently induced in cells mutated or deficient for these factors limiting the risk of drug resistance development and maximizing its application spectrum. The simultaneous modulation of multiple (epigenetic) targets promises to open new avenues with unanticipated potential against cancer.
The product of the adenovirus intermediate gene IX is a transcriptional activator.
No full textInternational audienceWe have investigated the functional properties of the product of the adenovirus type 5 gene IX. This gene, which is expressed at intermediate times postinfection, encodes a small polypeptide (pIX) of 140 residues that has previously been shown to be incorporated into the viral capsid. Here, we show that pIX, in addition to its structural contribution, exhibits transcriptional properties. In transient transfection experiments, expression of pIX stimulated adenovirus major late promoter activity. The effect was independent of other viral proteins, but the level of promoter activation appeared strongly pIX dose dependent; similar levels of induction were observed with other cellular or viral TATA-containing (but not with TATA-less) promoters. This promoter specificity could be reproduced in a cell-free transcription system by the addition of purified recombinant pIX, further stressing the transcriptional nature of the phenomenon. A preliminary structural analysis of pIX indicated that the integrity of a putative leucine zipper at the carboxy-terminal end of the molecule, as well as elements within the amino-terminal half, was critical for pIX transcriptional activity. The relevance of these findings in adenovirus infection is discussed
Perinatal expression of brush-border hydrolases in rat colon: hormonal and tissue regulations
No full text The evolution pattern of brush-border digestive hydrolases and their hormonal regulation were studied in the proximal colon of newborn rats. The potentiality of the colon to express a small intestinal enzymatic pattern was also examined in associations made up of colonic endoderm and small intestinal mesenchyme, developed as either intracelomic grafts in 3-day-old chick embryos or as intrarenal grafts in adult rats. A transient increase of lactase- and aminopeptidase-specific activities occurred in the colon from the 19th day of gestation to 14 days after birth, but sucrase activity could never be detected. Immunocytochemical studies with antibodies specific for rat lactase, aminopeptidase, and sucrase confirmed these results. However, the levels of hydrolase activities were lower in the colon than in the jejunum at the same age. Thyroxine or hydrocortisone treatment during the first 4 days postpartum decreased lactase activity by 70 and 30%, respectively, but did not affect aminopeptidase activity. A slight but significant induction of sucrase activity was obtained with both hormones. In contrast, in the jejunum, only thyroxine decreased lactase activity with a lesser effect (30%), but both hormones increased aminopeptidase activity and induced the marked well-known appearance of sucrase activity. The fetal small intestinal mesenchyme was not able to induce the colonic endoderm to achieve a small intestinal-like differentiation. But the exposure of the developed hybrid intestines to glucocorticoids in organ culture allowed expression of sucrase in one-third of the cases. These results demonstrate the presence of brush-border hydrolases in the proximal colon of newborn rats, normally expressed in the small intestine, but never in the adult colon.(ABSTRACT TRUNCATED AT 250 WORDS) </jats:p
The product of the adenovirus intermediate gene IX is a transcriptional activator.
No full textInternational audienceWe have investigated the functional properties of the product of the adenovirus type 5 gene IX. This gene, which is expressed at intermediate times postinfection, encodes a small polypeptide (pIX) of 140 residues that has previously been shown to be incorporated into the viral capsid. Here, we show that pIX, in addition to its structural contribution, exhibits transcriptional properties. In transient transfection experiments, expression of pIX stimulated adenovirus major late promoter activity. The effect was independent of other viral proteins, but the level of promoter activation appeared strongly pIX dose dependent; similar levels of induction were observed with other cellular or viral TATA-containing (but not with TATA-less) promoters. This promoter specificity could be reproduced in a cell-free transcription system by the addition of purified recombinant pIX, further stressing the transcriptional nature of the phenomenon. A preliminary structural analysis of pIX indicated that the integrity of a putative leucine zipper at the carboxy-terminal end of the molecule, as well as elements within the amino-terminal half, was critical for pIX transcriptional activity. The relevance of these findings in adenovirus infection is discussed
The differentiating intestinal epithelial cell : establishment and maintenance of functions through interactions between cellular structures
No full text
(Na+ + K+)-ATPase and plasma membrane polarity of intestinal epithelial cells : presence of a brush border antigen in the distal large intestine that is immunologically related to beta subunit
No full textThe previously produced monoclonal antibody IEC 1/48 against cultured rat intestinal crypt cells (Quaroni, A., and K. J. Isselbacher. 1981. J. Natl. Cancer Inst. 67:1353-1362) was extensively characterized and found to be directed against the beta subunit of (Na+ + K+)-ATPase as assessed by immunological and enzymatic criteria. Under nondenaturing conditions the antibody precipitated the alpha-beta enzyme complex (98,000 and 48,000 Mr). This probe, together with the monoclonal antibody C 62.4 against the alpha subunit (Kashgarian, M., D. Biemesderfer, M. Caplan, and B. Forbush. 1985. Kidney Int. 28:899-913), was used to localize (Na+ + K+)-ATPase in epithelial cells along the rat intestinal tract by immunofluorescence and immunoelectron microscopy. Both antibodies exclusively labeled the basolateral membrane of small intestine and proximal colon epithelial cells. However, in the distal colon, IEC 1/48, but not C 62.4, also labeled the brush border membrane. The cross-reacting beta-subunit-like antigen on the apical cell pole was tightly associated with isolated brush borders but was apparently devoid of (Na+ + K+)-ATPase activity. Subcellular fractionation of colonocytes in conjunction with limited proteolysis and surface radioiodination of intestinal segments suggested that the cross-reacting antigen in the brush border may be very similar to the beta subunit. The results support the notion that in the small intestine and proximal colon the enzyme subunits are exclusively targeted to the basolateral membrane while in the distal colon nonassembled beta subunit or a beta-subunit-like protein is also transported to the apical cell pole
Aerobic nitrogen fixation in Azotobacter vinelandii
No full textI ELECTRON DONATION TO NITROGENASEPaper I shows that the hypothesis, that a high ratio of (NADH + NADPH) / (NAD + + NADP + ) is the source of reducing power for nitrogenase in intact A.vinelandii, is invalid. On the contrary, with a decreasing ratio of reduced to oxidized pyridine nucleotides, the nitrogenase activity of whole cells increases. The experiments described in paper I, indicate that the reducing power necessary for nitrogen fixation in A.vinelandii is generated within the cytoplasmic membrane. It is demonstrated that transport of reducing equivalents to the nitrogenase requires a high energy level of the cytoplasmic membrane. The energy level of the cytoplasmic membrane was measured by the intracellular Alp concentration and by using 9-amino acridine as a fluorescent probe. Other regulating factors of the nitrogenase activity in A.vinelandii are shown to be the intracellular ATP/ ADP ratio and the presence of oxygen.Paper III shows that toluene makes A.vinelandii cells permeable for small molecules but not for enzymes. In toluene-treated cells, enzyme activities can be measured by adding the appropriate cofactors and substrates. It is possible to restore the oxidation of organic substrates but no concomitant nitrogenase activity can be observed. We suggest that an observed lack of energization of the cytoplasmic membranes is the missing link between oxidation and generation of the reducing equivalents for nitrogen fixation. In paper III and IV we show that the endogenous low potential electron carriers in toluene-treated cells are not reduced. In paper IV a membrane-bound NAD(P)H-flavodoxin oxidoreductase is demonstrated and a proposal is given in which NADH is the electron donor for nitrogenase. The electron carrier flavodoxin is reduced by the membrane-bound NADH-flavodoxin oxidoreductase at a low pH, that is developed in an energy-linked process.II OXYGEN PROTECTION OF NITROGENASEIn paper II the source of respiration protection is investigated. Experiments with radioactive pyruvate and sucrose show that the rate of sucrose oxidation by A.vinelandii is associated with the sucrose translocator activity. We show that the respiration protection of the nitrogen-fixing system in A.vinelandii is dependent of the oxygen input during growth. The oxidation capacity intrinsically depends on the type of substrate and can be partly adapted.Membranes rich in cytochromes c 4 + c 5 and o and with phosphorylation between NADH and c 4 + c 5 and oxygen and cytochrome c 4 + c 5 and oxygen, can be isolated from A.vinelandii grown O 2 -limited. Cytochromes b and d can be detected in addition when A.vinelandii cells are grown N 2 limited. The activity of the NADH oxidase system is increased in such cells and phosphorylation is only observed between CoQ and oxygen. Under saturating oxygen concentrations the type of respiratory membranes was not observed to influence the intracellular energy charge.In paper III and IV the mechanism of the conformational protection of nitrogenase was investigated. It is shown that nitrogenase can be isolated as an oxygen-stable complex form A.vinelandii independent of the cell rupture method. Also no influence of the cell rupture method on the rate of sedimentation of the nitrogenase can be observed. The rate of sedimentation of the nitrogenase is found to be concentration and pH dependent. At pH=7.4 the rate of sedimentation of the nitrogenase complex is comparable with that of the pyruvate dehydrogenase complex.No evidence was found for a particulate nitrogenase, it is demonstrated that the oxygen stability of nitrogenase in crude extracts is caused by complexation. of the nitrogenase components with an Fe-S protein. An alternative proposal for the switch-on switch-off phenomenon in whole Azotobacter cells is given. Nitrogenase is present in vivo as an active and oxygen tolerent complex but nitrogen fixation in whole cells is inhibited by the oxidation of flavodoxin hydroquinone.<p/
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