Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085631 (agitation)
 12,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously reported that a microcarrier-attached human hepatoma (Hep G2) cell line responds to hydrodynamic shear upon transfer to an agitated, clean, autoclaved spinner flask with a transient increase in cytochrome P450IA1 (CYPIA1) activity. Physiological changes induced by hydrodynamic stress could be problematic in the scaleup of microcarrier cultures. A better understanding of how stress alters cell physiology may assist in reactor scaleup. The induction of CYPIA1 activity was dependent on the agitation level of the cultures, and the level of CYPIA1 induction was comparable to that obtained with exposure to approximately 0.1 nM TCDD (2, 3, 7, 8-tetrachlorodibenzo-p-dioxin). It has been well documented that hydrodynamic shear stress can cause alterations in the metabolism of phospholipid membrane-bound arachidonic acid (AA) in adherent cells in a parallel plate system. The present study was carried out to determine if either AA or a metabolite of AA was involved in the induction of CYPIA1 activity in the microcarrier cultures of Hep G2 cells. Addition of exogenous AA followed by initiation of the stress resulted in an increase in the level of CYPIA1 activity. Pretreatment of the cultures with quinacrine, an inhibitor of phospholipase A2, reduced the stress-induced CYPIA1 activity. Furthermore, addition of propranolol, an inhibitor of phosphatidic acid phosphohydrolase, resulted in an increase in the response in addition to sustaining the induced enzyme activity. Pretreatment with the cyclooxygenase inhibitor, indomethacin, or the lipoxygenase inhibitor, caffeic acid, had no effect on the response, suggesting that the cyclooxygenase and lipoxygenase pathways were not involved in generating AA metabolites that alter CYPIA1 activity. The agent, nordihydroguaiaretic acid, blocks the monooxygenase pathway and blocks CYPIA1 activity increases. These observations suggest a possible mechanism where the stress on the cells induces phospholipase D, resulting in the formation of phosphatidic acid which then activates phospholipase A2, resulting in the release of AA. Further, these results are consistent with a mechanism in which the metabolism of AA, most likely through the monooxygenase pathway, results in a metabolite that by a yet unknown mechanism induced CYPIA1.
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PMID:Possible role of arachidonic acid in stress-induced cytochrome P450IA1 activity. 898 9

We show that differentiation of zoospores of the late blight pathogen Phytophthora infestans into cysts, a process called encystment, was triggered by both phosphatidic acid (PA) and the G-protein activator mastoparan. Mastoparan induced the accumulation of PA, indicating that encystment by mastoparan most likely acts through PA. Likewise, mechanical agitation of zoospores, which often is used to induce synchronized encystment, resulted in increased levels of PA. The levels of diacylglycerolpyrophosphate (DGPP), the phosphorylation product of PA, increased simultaneously. Also in cysts, sporangiospores, and mycelium, mastoparan induced increases in the levels of PA and DGPP. Using an in vivo assay for phospholipase D (PLD) activity, it was shown that the mastoparan-induced increase in PA was due to a stimulation of the activity of this enzyme. Phospholipase C in combination with diacylglycerol (DAG) kinase activity also can generate PA, but activation of these enzymes by mastoparan was not detected under conditions selected to highlight 32P-PA production via DAG kinase. Primary and secondary butanol, which, like mastoparan, have been reported to activate G-proteins, also stimulated PLD activity, whereas the inactive tertiary isomer did not. Similarly, encystment was induced by n- and sec-butanol but not by tert-butanol. Together, these results show that Phytophthora infestans contains a mastoparan- and butanol-inducible PLD pathway and strongly indicate that PLD is involved in zoospore encystment. The role of G-proteins in this process is discussed.
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PMID:Phospholipase D in Phytophthora infestans and its role in zoospore encystment. 1223