Mammalian cells, response

Although we will stick to the IL-6 gene, it should be mentioned at the side that two other RNA polymerases exist in mammalian cells responsible for the synthesis of RNA molecules, which are not translated into proteins ribosomal (rRNA), transfer (tRNA), small nuclear (snRNA), small nucleolar (snoRNA), and some of the recently discovered microRNAs and piRNAs. These RNA molecules act in the process of translation and mRNA turnover. Micro and piRNAs are probably extremely important in the definition of stem cells and of differentiation programs. Some of them are synthesized by RNA polymerase II. 

Another major second messenger in cells is calcium ion. Virtually any mammalian cell line can be used to measure transient calcium currents in fluorescence assays when cells are preloaded with an indicator dye that allows monitoring of changes in cytosolic calcium concentration. These responses can be observed in real time, but a characteristic of these responses is that they are transient. This may lead to problems with hemi-equilibria in antagonist studies whereby the maximal responses to agonists may be depressed in the presence of antagonists. These effects are discussed more fully in Chapter 6. 

All mammalian cells are virtually capable of producing CO with heme as the main substrate (Fig. 1) [5]. Enzymatic heme metabolism in vivo is mainly catalyzed by heme oxygenase (HO). In the presence of HO, the porphyrin ring of heme is broken and oxidized at the a-methene bridge, producing equimolar amounts of CO, ferrous iron, and biliverdin. Three isoforms of HO have been identified. Inducible HO-1 (32 kDa) is mostly recognized for its upregulation in response... 

Devary, Y., Gottlieb, R.A., Smeal, T., Karin, M. (1992). The mammalian ultraviolet response is triggered by activation of Src tyrosine kinases. Cell 71, 1081-1091. 

Li, G. Laszio, A. (1985). Thermotolerance in mammalian cells A possible role for the heat shock proteins. In Changes in Eukaryotic Gene Expression in Response to Environmental Stress (Atkinson, B.G. Walden, D.B. eds.), pp. 349-371, Academic Press, Orlando. 

Bridge AJ, Pebernard S, Ducraux A, Nicoulaz AL, Iggo R (2003) Induction of an interferon response by RNAi vectors in mammalian cells, Nat Genet 34 263-264 BrummeUcamp TR, Bernards R, Agami R (2002) A system for stable expression of short interfering RNAs in mammahan cells. Science 296 550-553... 

Note that both acetogenins and styryl-lactones are cytotoxic for mammalian cells, as the result of distinct biochemical pathways, which, however, have their molecular origin near or in the mitochondrial membrane and/or the mitochondrial respiratory system (61,62). Acetogenins were first characterized as the active principles responsible for... 

Talorete T, Limam A, Kawano M, Jenhani ABR, Ghrabi A, Isoda H (2008) Stress response of mammalian cells incubated with landfill leachate. Environ Toxicol Chem 27 1084-1092... 

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