Regulation of membrane transport and metabolism in the HT29 human colonic adenocarcinoma cell line
The effects of insulin on glucose transport and metabolism were examined in cultured HT29 human colonic adenocarcinoma cells. The presence of glucose transporters was verified by D-glucose displaceable ({sup 3}H) cytochalasin B binding. Moreover, two classes of insulin binding sites were detected in radioligand binding experiments. Despite the presence of both glucose transporters and insulin receptors, insulin failed to stimulate glucose transport. However, insulin was found to activate glycolysis. These findings suggest that insulin directly influences substrate utilization through the glycolytic pathway in HT29 cells without activating the glucose transport pathway. A Na{sup +}/K{sup +}/Cl{sup {minus}} cotransport pathway was also detected in HT29 cells using {sup 86}Rb{sup +} as a K{sup +} congener. The identity of this pathway as a Na{sup +}/K{sup +}/Cl{sup {minus}} cotransporter has been deduced from the following findings: (1) {sup 86}Rb{sup +} influx was inhibited by loop diuretics, (2) {sup 86}Rb{sup +} influx ceased in the absence of any one of the transported ions, and (3) cotransport exhibited a stoichiometry approaching 1Na{sup +}:1K{sup +}:2Cl{sup {minus}}. Na{sup +}/K{sup +}/Cl{sup {minus}} cotransport was found to be exquisitely sensitive to cellular ATP and cyclic AMP levels. These results suggest that HT29 cells contain a Na{sup +}/K{sup +}/Cl{sup {minus}} cotransport pathway that can be regulated by the second messenger cyclic AMP and is highly sensitive to the metabolic state of the cell. The involvement of protein kinase C in the regulation of Na{sup +}/K{sup +}/Cl{sup {minus}} cotransport was also investigated. Phorbol 12-myristate 13-acetate (PMA), which stimulated protein kinase C activity, produced a transient increase in cotransport followed by a near abolition of cotransport by 2 h.
- Research Organization:
- Missouri Univ., Columbia, MO (USA)
- OSTI ID:
- 5526530
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
GLUCOSE
MEMBRANE TRANSPORT
INSULIN
BIOCHEMICAL REACTION KINETICS
LARGE INTESTINE
CARCINOMAS
PHORBOL ESTERS
BIOLOGICAL EFFECTS
TUMOR CELLS
METABOLISM
AMP
ATP
BIOLOGICAL PATHWAYS
CHLORIDES
ENZYME ACTIVITY
MAN
PHOSPHOTRANSFERASES
POTASSIUM COMPOUNDS
RECEPTORS
RUBIDIUM 86
SODIUM COMPOUNDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALDEHYDES
ALKALI METAL COMPOUNDS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOHYDRATES
CARCINOGENS
CHLORINE COMPOUNDS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DISEASES
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
ESTERS
GASTROINTESTINAL TRACT
HALIDES
HALOGEN COMPOUNDS
HEXOSES
HORMONES
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTESTINES
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MINUTES LIVING RADIOISOTOPES
MONOSACCHARIDES
NEOPLASMS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PHOSPHORUS-GROUP TRANSFERASES
PRIMATES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RUBIDIUM ISOTOP
SACCHARIDES
TRANSFERASES
VERTEBRATES
550501* - Metabolism- Tracer Techniques
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