Glucose deprivation causes posttranscriptional enhancement of brain capillary endothelial glucose transporter gene expression via GLUT1 mRNA stabilization. 1993

R J Boado, and W M Pardridge
Department of Medicine, UCLA School of Medicine 90024.

The absence of neuroglucopenia symptoms in chronic hypoglycemia may be due to up-regulation of the blood-brain barrier glucose transporter type 1 (GLUT1). Therefore, we investigated the effect of glucose deprivation on the abundance of the GLUT1 transcript in bovine brain capillary endothelial cells in tissue culture (ECL). Northern blot analysis performed under high stringency conditions with 4-5 micrograms of ECL poly(A)+ mRNA showed that glucose deprivation (5 mg% glucose) caused a 2.4 +/- 0.2-fold increase in the GLUT1/actin mRNA ratio versus control incubations (100 mg% glucose). This rise was dose and time dependent, and the maximum effect was observed 20-24 h after the hexose deprivation. Nuclear transcription run-on assay showed no changes in either the GLUT1 or actin gene transcription rate 24 h after glucose deprivation. To determine whether the increase in the abundance of the GLUT1 mRNA induced by glucose deprivation was due to increased stability of this transcript, the GLUT1 mRNA half-life was measured in ECL cells incubated with actinomycin D. The levels of the GLUT1 transcript continued to be augmented in glucose-deprived cells compared with controls 2 and 4 h after the transcription inhibitor was added to the media. Glucose deprivation induced a 78% increase in the t1/2 of the GLUT1 mRNA (from 3.6 to 6.4 h). Incubation of ECL cells with the protein synthesis inhibitor, cycloheximide, for 4 h partially reversed the effect of glucose deprivation on the abundance of the GLUT1 transcript. On the other hand, incubation with cycloheximide for 24 h completely blocked the effect of glucose deprivation on the GLUT1 transcript. Desensitization of cellular protein kinase C was performed by incubation of ECL cells with 1 microM phorbol ester for 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D009004 Monosaccharide Transport Proteins A large group of membrane transport proteins that shuttle MONOSACCHARIDES across CELL MEMBRANES. Hexose Transport Proteins,Band 4.5 Preactin,Erythrocyte Band 4.5 Protein,Glucose Transport-Inducing Protein,Hexose Transporter,4.5 Preactin, Band,Glucose Transport Inducing Protein,Preactin, Band 4.5,Proteins, Monosaccharide Transport,Transport Proteins, Hexose,Transport Proteins, Monosaccharide,Transport-Inducing Protein, Glucose
D011061 Poly A A group of adenine ribonucleotides in which the phosphate residues of each adenine ribonucleotide act as bridges in forming diester linkages between the ribose moieties. Adenine Polynucleotides,Polyadenylic Acids,Poly(rA),Polynucleotides, Adenine
D011493 Protein Kinase C An serine-threonine protein kinase that requires the presence of physiological concentrations of CALCIUM and membrane PHOSPHOLIPIDS. The additional presence of DIACYLGLYCEROLS markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by PHORBOL ESTERS and it is believed that protein kinase C is the receptor protein of tumor-promoting phorbol esters. Calcium Phospholipid-Dependent Protein Kinase,Calcium-Activated Phospholipid-Dependent Kinase,PKC Serine-Threonine Kinase,Phospholipid-Sensitive Calcium-Dependent Protein Kinase,Protein Kinase M,Calcium Activated Phospholipid Dependent Kinase,Calcium Phospholipid Dependent Protein Kinase,PKC Serine Threonine Kinase,Phospholipid Sensitive Calcium Dependent Protein Kinase,Phospholipid-Dependent Kinase, Calcium-Activated,Serine-Threonine Kinase, PKC
D002196 Capillaries The minute vessels that connect arterioles and venules. Capillary Beds,Sinusoidal Beds,Sinusoids,Bed, Sinusoidal,Beds, Sinusoidal,Capillary,Capillary Bed,Sinusoid,Sinusoidal Bed
D002417 Cattle Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor. Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002467 Cell Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed) Cell Nuclei,Nuclei, Cell,Nucleus, Cell
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D002560 Cerebrovascular Circulation The circulation of blood through the BLOOD VESSELS of the BRAIN. Brain Blood Flow,Regional Cerebral Blood Flow,Cerebral Blood Flow,Cerebral Circulation,Cerebral Perfusion Pressure,Circulation, Cerebrovascular,Blood Flow, Brain,Blood Flow, Cerebral,Brain Blood Flows,Cerebral Blood Flows,Cerebral Circulations,Cerebral Perfusion Pressures,Circulation, Cerebral,Flow, Brain Blood,Flow, Cerebral Blood,Perfusion Pressure, Cerebral,Pressure, Cerebral Perfusion
D003513 Cycloheximide Antibiotic substance isolated from streptomycin-producing strains of Streptomyces griseus. It acts by inhibiting elongation during protein synthesis. Actidione,Cicloheximide

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