Biomedical subjects

J C Aledo

Publications and source records attributed to J C Aledo.

21 records · Page 2Linked to original sources

PubMed1994

Phosphate-activated glutaminase expression during tumor development.

Changes in phosphate-activated glutaminase activities determined in intact cells and isolated mitochondria have been followed during mouse Ehrlich ascites carcinoma development. Glutaminase activities parallel the levels of poly(A)+ RNAs encoding for the mitochondrial phosphate activated glutaminase. During the exponential growth phase, maximum activity was observed and the relative abundance of glutaminase mRNA significantly increased with regard to the stationary growth phase. The presented results show that tumor phosphate-activated glutaminase is subject to long-term regulation by differential gene expression.

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PubMedDate not supplied

Native polyacrylamide gel electrophoresis of membrane proteins: glutaminase detection after in situ specific activity staining.

A new procedure for the analysis and detection of phosphate-activated glutaminase (EC 3.5.1.2) by native electrophoresis has been developed. The method is based on the in situ detection of glutaminase activity in two different systems of native polyacrylamide gradient gels, containing 3-(3-cholamidopropyl)-dimethyl-ammonio-1-propane sulfonate (CHAPS) or Triton X-100 as nondenaturant detergents. Crude Triton X-100 extracts of mitochondria were resolved by electrophoresis. The enzyme was specifically revealed by incubation of the gel with glutamine and coupling the oxidation of the glutamate formed to the reduction of a tetrazolium dye, in the presence of glutamate dehydrogenase trapped in a 1% agar solid overlay. Both Ehrlich ascitic cell and mouse kidney glutaminases were resolved by native electrophoresis and specifically detected with the activity staining. Moreover, the redox-cycling staining was tested in solution, showing linearity with the amount of glutamate or glutaminase activity present. The method described could be a useful tool for native polyacrylamide gel electrophoresis of membrane proteins.

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PubMedDate not supplied

Changes in mRNAs for enzymes of glutamine metabolism in the tumor-bearing mouse.

Changes in the relative mRNA levels of phosphate-activated glutaminase (PAG) and glutamine synthetase (GS) in the liver and kidney of mice bearing a highly malignant strain of Ehrlich ascites tumor cells were determined at different days after tumor transplantation. Kidney glutaminase mRNA steadily increased, reaching maximum values at day 10 of tumor growth, while those of glutamine synthetase did not change, resulting in a sustained decrease of the GS/PAG ratio in the kidneys of tumor-bearing animals compared with controls. However, the GS/PAG ratio in the liver significantly increased, mainly due to a strong decrease in PAG, whereas GS mRNA levels remained almost unaffected. These results, combined with those previously reported on enzymatic activities and glutamine concentrations in the host-tumor system, suggest a long-term regulation of the host glutaminase enzymes in order to increase the circulating glutamine levels needed for tumor growth.

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