ABSTRACT
Hypoxia-induced changes of rat skeletal muscle were investigated by two-dimensional difference in-gel electrophoresis (2D-DIGE) and mass spectrometry. The results indicated that proteins involved in the TCA cycle, ATP production, and electron transport are down-regulated, whereas glycolytic enzymes and deaminases involved in ATP and AMP production were up-regulated. Up-regulation of the hypoxia markers hypoxia inducible factor 1 (HIF-1alpha) and pyruvate dehydrogenase kinase 1 (PDK1) was also observed, suggesting that in vivo adaptation to hypoxia requires an active metabolic switch. The kinase protein, mammalian target of rapamycin (mTOR), which has been implicated in the regulation of protein synthesis in hypoxia, appears unchanged, suggesting that its activity, in this system, is not controlled by oxygen partial pressure.
Subject(s)
Energy Metabolism , Hypoxia , Muscle, Skeletal , Proteome/analysis , 3-Phosphoinositide-Dependent Protein Kinases , Adenosine Triphosphate/metabolism , Amino Acid Sequence , Animals , Cell Line , Citrate (si)-Synthase/metabolism , Electrophoresis, Gel, Two-Dimensional , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Male , Mass Spectrometry , Mitochondria/metabolism , Molecular Sequence Data , Muscle, Skeletal/chemistry , Muscle, Skeletal/metabolism , Protein Kinases/metabolism , Protein Serine-Threonine Kinases/metabolism , Rats , Rats, Sprague-Dawley , TOR Serine-Threonine KinasesABSTRACT
The absence of triose phosphate isomerase activity causes an accumulation of only one of the two trioses, dihydroxyacetone phosphate, and this produces a shift in the final product of glucose catabolism from ethanol to glycerol (Compagno et al., 1996). Alterations of glucose metabolism imposed by the deletion of the TPI1 gene in Saccharomyces cerevisiae were studied in batch and continuous cultures. The Deltatpi1 null mutant was unable to grow on glucose as the sole carbon source. The addition of ethanol or acetate in media containing glucose, but also raffinose or galactose, relieved this effect in batch cultivation, suggesting that the Crabtree effect is not the primary cause for the mutant's impaired growth on glucose. The addition of an energy source like formic acid restored glucose utilization, suggesting that a NADH/energy shortage in the Deltatpi1 mutant could be a cause of the impaired growth on glucose. The amount of glycerol production in the Deltatpi1 mutant could represent a good indicator of the fraction of carbon source channelled through glycolysis. Data obtained in continuous cultures on mixed substrates indicated that different contributions of glycolysis and gluconeogenesis, as well as of the HMP pathway, to glucose utilization by the Deltatpi1 mutant may occur in relation to the fraction of ethanol present in the media.
Subject(s)
Glucose/metabolism , Saccharomyces cerevisiae/enzymology , Triose-Phosphate Isomerase/metabolism , Bioreactors , Dihydroxyacetone/analysis , Dihydroxyacetone/biosynthesis , Gene Deletion , Glycerol/analysis , Mutagenesis , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/growth & development , Triose-Phosphate Isomerase/deficiency , Triose-Phosphate Isomerase/geneticsABSTRACT
In order to keep subscribers up-to-date with the latest developments in their field, this current awareness service is provided by John Wiley & Sons and contains newly-published material on yeasts. Each bibliography is divided into 10 sections. 1 Books, Reviews & Symposia; 2 General; 3 Biochemistry; 4 Biotechnology; 5 Cell Biology; 6 Gene Expression; 7 Genetics; 8 Physiology; 9 Medical Mycology; 10 Recombinant DNA Technology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted. (4 weeks journals - search completed 7th Mar. 2001)
