The isolation and characterization of phosphofructokinase from the epithelial cells of rat small intestine.
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ABSTRACT:
SUBMITTER: Khoja SM
PROVIDER: S-EPMC1154369 | biostudies-other | 1983 May
REPOSITORIES: biostudies-other
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Project description:Phosphofructokinase from the epithelial cells of rat small intestine was characterized with respect to isoenzyme type in a comparison of its properties with those of the skeletal-muscle, brain and major liver isoenzymes by using five different techniques, namely electrophoresis on cellulose acetate and in polyacrylamide gels, chromatography on DEAE-cellulose, (NH4)2SO4 precipitation and immunotitration. When precautions were taken to inhibit the formation of active proteolytic artifacts by the action of endogenous proteinases, each technique revealed that rat intestinal mucosa contains only a single form of phosphofructokinase. The mucosal isoenzyme was found to be very similar to, although not identical with, the major liver isoenzyme and to be quite distinct from the skeletal-muscle isoenzyme when studied by the techniques of cellulose acetate electrophoresis, chromatography on DEAE-cellulose and immunotitration, whereas the converse was true when studied by the techniques of (NH4)2SO4 precipitation and polyacrylamide-gel electrophoresis. The mucosal isoenzyme was distinct from the brain isoenzyme when studied by each of the five techniques. Tsai & Kemp [(1973) J. Biol. Chem. 248, 785-792] reported that animal tissues contain three principal isoenzymes of phosphofructokinase, type A found as the sole isoenzyme in skeletal muscle, type B found as the major isoenzyme in liver and type C found as a significant isoenzyme in brain. Phosphofructokinase from mucosa is distinct from each of these isoenzymes. Following the nomenclature of Tsai & Kemp (1973), the isoenzyme from the mucosa of rat intestinal epithelial cells is designated phosphofructokinase D. The mucosal and liver isoenzymes behave so similarly with respect to their charge and immunological characteristics, on which the typing of isoenzymes is conventionally based, that it is likely that some tissues reported to contain the liver isoenzyme contain instead the mucosal isoenzyme.
| S-EPMC1152401 | biostudies-other
Project description:1. Homogenization of the epithelial cells of rabbit small intestine in 0.3m-sucrose-5mm-EDTA, pH7.4, maintains intact the microvillus sheets that form the lumenal surface of the cells, the nuclei, the mitochondria and the vesicles (microsomes) formed from the endoplasmic reticulum. 2. These particulate components of the cell, and the cell-sap fraction, have been isolated by differential centrifuging of cell homogenates. 3. The nuclei and microvillus sheets sediment together and it has been impossible to separate these subcellular components by centrifugal methods. 4. The isolated subcellular fractions have been identified by a combination of light-microscopic examination, electron-microscopic examination, chemical analysis and assay for selected enzyme activities.
| S-EPMC1206917 | biostudies-other
Project description:1. The effect of depriving rats of food for 48 h on the specific activity of phosphofructokinase in the epithelial cells of the small intestine and on the regulatory properties of the enzyme displayed in crude (particle-free) mucosal extracts was studied. 2. The specific activity of phosphofructokinase, measured under optimal conditions at pH8, in the mucosa of fed rats showed a negative aboral gradient along the intestine, decreasing from 15.2 +/- 1.2 units (mumol/min)/g wet wt. in the proximal jejunum to 4.6 +/- 1.2 units/g wet wt. in the terminal ileum. 3. After starvation, the gradient was diminished, but not abolished; the diminution in gradient was due almost exclusively to a decrease in the specific activity of phosphofructokinase in the proximal jejunum by about 30%, there being no change in the terminal ileum. 4. In fed rats, the susceptibility of phosphofructokinase to inhibition by ATP, when assayed in crude mucosal extracts under suboptimal conditions, was independent of length along the small intestine; the ratio of the activity observed at pH 7.0 in the presence of 0.5 mM-fructose 6-phosphate and 2.5 mM-ATP to the optimal activity at pH 8, v0.5/V, was 0.36 +/- 0.05 in the proximal jejunum and 0.42 +/- 0.07 in the terminal ileum. 5. After starvation, the susceptibility of phosphofructokinase to inhibition by ATP was increased and was again found to be independent of length along the small intestine: after starvation, v0.5/V was 0.19 +/- 0.04 and 0.20 +/- 0.07 for the proximal jejunum and the terminal ileum respectively. 6. Re-feeding of previously starved rats on a high-carbohydrate diet overnight for 16 h restored both the specific activities of phosphofructokinase and its susceptibility to inhibition by ATP to normal values for fed rats. 7. The data support the idea that the specific activities and the regulatory properties of phosphofructokinase in the epithelial cells of rat small intestine are mediated by distinct humoral factors. 8. The changes in glucose utilization rate of the jejunum when rats are starved can in principle be accounted for by a combination of changes in the specific activity and in the regulatory properties of mucosal phosphofructokinase.
| S-EPMC1154198 | biostudies-other
Project description:1. The preparation of gram quantities of isolated epithelial-cell ;ghosts' from mucosal scrapings of rat small intestine is described. The method involves dispersing the tissue by gentle homogenization in 6% dextran in Krebs-Ringer phosphate, pH7.4, followed by filtration through nylon cloth and sedimentation by low-speed centrifuging. 2. The isolated epithelial-cell ;ghosts' contained all of the DNA, but only 52% of the protein and 53-57% of the RNA of the original homogenate. They contained most of the activity of the following enzymes found in the homogenate: aminopeptidase (71%); alkaline beta-glycerophosphatase (82%); invertase (92%); adenosine triphosphatase (93-116%); acid beta-glycerophosphatase (83%); nonspecific esterase (76%); succinate dehydrogenase (96%). Only small proportions of the total lactate-dehydrogenase (10%) and phosphoglucose-isomerase (2%) activities found in the homogenate were recovered in the isolated cell ;ghosts'. 3. The epithelial-cell ;ghost' preparation did not respire unless cofactors and substrates were added, and did not consume glucose or produce lactic acid from glucose. 4. The effect of varying the composition of the homogenization medium was studied. Concentrations of dextran (mol.wt. 15x10(4)) from 1 to 12%, solutions of dextrans (all at 6%) with mol.wt. varying between 3.6x10(4) and 2x10(6), and a solution of 8% polyethylene glycol (mol.wt. 4000) served equally well for the production of epithelial-cell ;ghosts'. Two of these solutions, however, 12% dextran (mol.wt.15x10(4)) and 6% dextran (mol.wt. 2x10(6)), were too viscous to allow the complete sedimentation of the cell ;ghosts' at low relative centrifugal forces. Omission of either Krebs-Ringer phosphate or dextran from the medium resulted in almost complete cell breakage during the homogenization. 5. The isolated cell ;ghosts' were used as a starting material for subcellular fractionation of rat intestinal mucosa by differential centrifugation. The distributions of protein and succinate-dehydrogenase activity among the fractions were compared with corresponding values in fractions isolated by differential centrifugation of mucosa homogenized in 0.3m-sucrose-5mm-EDTA, pH7.4. The method in which cell ;ghosts' were used as starting material gave a better separation and cleaner fractions than the method in which untreated mucosal scrapings were used.
| S-EPMC1207073 | biostudies-other
Project description:Phosphodiesterase II activity was determined by using a synthetic substrate, the 2,4-dinitrophenyl ester of thymidine 3'-phosphate. The enzyme activity was determined in fractions obtained by differential centrifugation of homogenates of epithelial cells from the small intestinal mucosa of guinea pigs and rats. In guinea-pig preparations phosphodiesterase II occurred with highest specific activity in those fractions rich in succinate dehydrogenase and acid phosphatase. A lysosomal location for the guinea-pig enzyme was indicated by its structure-linked latency and by its association with particles that under-went a characteristic decrease in equilibrium density when Triton WR-1339 was injected into the animals. With rat preparations a much greater proportion of the phosphodiesterase II activity was found in the soluble fraction after ultracentrifugation. The rat enzyme exhibited a lower degree of latency and administration of Triton WR-1339 had no effect. The rat enzyme further differed from that of the guinea pig in other respects; it was more labile at 60 degrees C, it exhibited a lower pH optimum and it had a higher molecular weight as determined by gel-filtration chromatography.
| S-EPMC1168318 | biostudies-other
Project description:Human noroviruses are a major cause of diarrheal illness, but pathogenesis is poorly understood. Here, we investigate the cellular tropism of norovirus in specimens from four immunocompromised patients. Abundant norovirus antigen and RNA are detected throughout the small intestinal tract in jejunal and ileal tissue from one pediatric intestinal transplant recipient with severe gastroenteritis. Negative-sense viral RNA, a marker of active viral replication, is found predominantly in intestinal epithelial cells, with chromogranin A-positive enteroendocrine cells (EECs) identified as a permissive cell type in this patient. These findings are consistent with the detection of norovirus-positive EECs in the other three immunocompromised patients. Investigation of the signaling pathways induced in EECs that mediate communication between the gut and brain may clarify mechanisms of pathogenesis and lead to the development of in vitro model systems in which to evaluate norovirus vaccines and treatment.
| S-EPMC7265440 | biostudies-literature
Project description:In common with other phosphofructokinase isoenzymes, phosphofructokinase in the epithelial cells of rat small-intestinal mucosa is activated by fructose 2,6-bisphosphate. However, fructose 2,6-bisphosphate was found not to be present in mucosa as judged by three criteria: (1) chromatography on Sephadex G-25 of crude mucosal extracts from fed rats did not result in a decrease, or indeed any change, in the activity of phosphofructokinase under suboptimal conditions at pH7; (2) ultrafiltrates of mucosal extracts did not possess any acid-labile activating activity when tested against chromatographed liver phosphofructokinase; (3) phosphofructokinase-2 activity was not detectable in mucosal extracts. Furthermore, the perfusion in vitro of isolated loops of jejunum or the incubation of mucosal scrapings from either fed rats or rats starved for 48 h showed that the activity of mucosal phosphofructokinase is not subject to short-term regulation by glucose. These observations are consistent with the view that phosphofructokinase is the rate-limiting enzyme of glycolysis in intestinal mucosa and account for the fact that the rate of glucose utilization by rat small intestine is not very responsive to changes in the concentration of glucose in the lumen.
| S-EPMC1153360 | biostudies-other
Project description:The functional roles of transient receptor potential (TRP) channels in the gastrointestinal tract have garnered considerable attention in recent years. We previously reported that daikenchuto (TU-100), a traditional Japanese herbal medicine, increased intestinal blood flow (IBF) via adrenomedullin (ADM) release from intestinal epithelial (IE) cells (Kono T et al. J Crohns Colitis 4: 161-170, 2010). TU-100 contains multiple TRP activators. In the present study, therefore, we examined the involvement of TRP channels in the ADM-mediated vasodilatatory effect of TU-100. Rats were treated intraduodenally with the TRP vanilloid type 1 (TRPV1) agonist capsaicin (CAP), the TRP ankyrin 1 (TRPA1) agonist allyl-isothiocyanate (AITC), or TU-100, and jejunum IBF was evaluated using laser-Doppler blood flowmetry. All three compounds resulted in vasodilatation, and the vasodilatory effect of TU-100 was abolished by a TRPA1 antagonist but not by a TRPV1 antagonist. Vasodilatation induced by AITC and TU-100 was abrogated by anti-ADM antibody treatment. RT-PCR and flow cytometry revealed that an IEC-6 cell line originated from the small intestine and purified IE cells expressed ADM and TRPA1 but not TRPV1. AITC increased ADM release in IEC cells remarkably, while CAP had no effect. TU-100 and its ingredient 6-shogaol (6SG) increased ADM release dose-dependently, and the effects were abrogated by a TRPA1 antagonist. 6SG showed similar TRPA1-dependent vasodilatation in vivo. These results indicate that TRPA1 in IE cells may play an important role in controlling bowel microcirculation via ADM release. Epithelial TRPA1 appears to be a promising target for the development of novel strategies for the treatment of various gastrointestinal disorders.
| S-EPMC3566615 | biostudies-literature
Project description:In epithelial cells isolated from rat small intestine, we have studied the influence of vasoactive intestinal peptide (VIP), a neurotransmitter which markedly increases enterocyte cyclic AMP, and of two cyclic AMP analogues (8-bromo cyclic AMP and N6,2'-O-dibutyryl cyclic AMP) on the rate of glycolysis, fructose 2,6-bisphosphate concentration and 6-phosphofructo-2-kinase activity, as well as on the rate of 3-O-methyl-D-[14C]glucose uptake. Our results show that, without affecting the rate of 3-O-methyl-D-[14C]glucose accumulation, VIP and cyclic AMP analogues were able to inhibit glucose consumption and L-lactate formation by isolated rat enterocytes. These effects occurred parallel to a significant decrease in the cellular concentration of fructose 2,6-bisphosphate and to a partial inactivation of 6-phosphofructo-2-kinase. These findings support the hypothesis that VIP inhibits glycolysis in rat enterocytes through a cyclic AMP-dependent mechanism.
| S-EPMC1133281 | biostudies-other
Project description:BackgroundEnterocytes exert an absorptive and protective function in the intestine, and they encounter many different challenging factors such as feed, bacteria, and parasites. An intestinal epithelial in vitro model can help to understand how enterocytes are affected by these factors and contribute to the development of strategies against pathogens.ResultsThe present study describes a novel method to culture and maintain primary chicken enterocytes and their characterization by immunofluorescence and biomolecular approaches. Starting from 19-day-old chicken embryos it was possible to isolate viable intestinal cell aggregates that can expand and produce a self-maintaining intestinal epithelial cell population that survives until 12?days in culture. These cells resulted positive in immunofluorescence to Cytokeratin 18, Zonula occludens 1, Villin, and Occludin that are common intestinal epithelial markers, and negative to Vimentin that is expressed by endothelial cells. Cells were cultured also on Transwell® permeable supports and trans-epithelial electrical resistance, was measured. This value gradually increased reaching 64??*cm2 7?days after seeding and it remained stable until day 12.ConclusionsBased on these results it was confirmed that it is possible to isolate and maintain chicken intestinal epithelial cells in culture and that they can be suitable as in vitro intestinal model for further studies.
| S-EPMC7881477 | biostudies-literature