PubMed · 1198438
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J Greenberg, R Goldstein. 1975-11-15. Proceedings: Prothrombin activation.. https://pubmed.ncbi.nlm.nih.gov/1198438/
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When the temperature of exponential-phase cultures of Saccharomyces cerevisiae was abruptly raised from 28 to 40 degrees C, trehalose immediately accumulated, whereas the activities of trehalase and trehalose-6-phosphate synthase/trehalose-6-phosphate phosphatase complex increased after a lag period of about 10 min. Heat shock also induced a sudden rise in intracellular glucose, simultaneously with a decrease in the concentration of hexose phosphate and fructose 2,6-bisphosphate. The increase of trehalose-metabolizing enzymes, but not the accumulation of glucose and trehalose, was prevented by cycloheximide. Investigation of the kinetic properties of partially purified enzymes showed that both non-activated and cyclic AMP-dependent-protein-kinase-activated forms of trehalase are almost inactive in the absence of Ca2+ and that the concentration of free Ca2+ required for half-maximal activity increased with increasing temperature, being approx. 1 microM at 30 degrees C and 20 microM at 40 degrees C for the activated form of trehalase. In contrast, trehalose-6-phosphate synthase and trehalose-6-phosphate phosphatase were three times more active at 40 degrees C. It is proposed that the rapid accumulation of trehalose induced by heat shock may be in part explained by changes in the kinetic properties of trehalase and trehalose-6-phosphate synthase/trehalose-6-phosphate phosphatase.
The results reported here indicate that activated species of Hageman factor (HF, factor XII), a protein that mediates blood clotting, fibrinolysis, and activation of the complement cascade, induce elaboration of interleukin 1 (IL-1) by human monocytes. Augmentation of IL-1 production in mononuclear cell cultures was observed when HF was present along with lipopolysaccharide (LPS) but was not observed with HF alone. Furthermore, antiserum to HF abrogated the enhancement of IL-1 in cultures containing HF and LPS. Total IL-1 activity, which represents secreted and cell-associated IL-1, was enhanced in LPS-stimulated mononuclear cultures by HF. In the absence of LPS, the initial activation product of HF, HFa, which contains the serine protease enzyme activity and the surface-binding domains of the protein, induced IL-1 beta protein and mRNA. In the presence of LPS, the enzymatic moiety (HFf), which is also contained in HF and HFa, amplified IL-1 production. Induction and amplification of monocyte IL-1 by HF provides further evidence for establishing a role for HF in the acute-phase reaction and the cellular immune response.
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