Factor activation

S6K1 (also known as p70S6 kinase) is a serine/ threonine protein kinase which is involved in the regulation of translation by phosphorylating the 40S ribosomal protein S6. Insulin and several growth factors activate the kinase by phosphorylation in a PI 3-kinase dependent and rapamycin-sensitive manner. Phosphorylation of S6 protein leads to the translation of mRNA with a characteristic 5 polypyrimidine sequence motif. 

Goldenbetg, C.J., Luo, Y., Fenna, M., Baler, R., Weinmann, R., Voellmy, R. (1988). Purified human factor activates heat shock promoter in a HeLa cell free transcription system. J. Biol. Chem. 263, 19734-19739. 

Zimarino, V., Tsai, C., Wu, C. (1990a). Complex modes of heat shock factor activation. Mol. Cell. Biol. 10, 752-759. 

The effect of prolonged antioxidant therapy in relation to normal physiological processes (for example, redox cycling, cell-cell signalling, transcription factor activation) must be assessed. It is conceivable that the overload of one antioxidant by dietary supplementation (for example, a-tocopherol) may shift the levels of other antioxidants (for example, by decreasing ascorbate and /3-carotene concentrations), with unknown consequences. To assess the potential for lipid-soluble antioxidant treatment in inflammatory diseases such as RA, further investigations into these questions will be needed. 

Sotsios Y, Whittaker GC, Westwick J, Ward SG. The CXC chemokine stromal cell-derived factor activates a Gi-coupled phosphoinositide 3-kinase in T lymphocytes. J Immunol 1999 163(11) 5954—5963. 

C9. Carson, S. D and Johnson, D. R., Consecutive enzyme cascades Complement activation at the cell surface triggers increased tissue factor activity. Bloodl6,361-367 (1990). 

Daar, I., Paules, R. S and Vande Woude, G. F. (1991). A characterization of cytostatic factor activity from Xenopus eggs and c-mor-transformed cells. J. Cell Biol. 114 329-335. 

Gomez, N., and Cohen, P. (1991). Dissection of the protein kinase cascade by which nerve growth factor activates MAP kinases. Nature 353 170-173. 

Morla, A. 0., Schreurs, J.,Miyajima, A., and Wang, J. H. J. (1988). Hematopoietic growth factors activate the tyrosine phosphorylation of distinct sets of proteins in interleukin-3-dependent murine cell lines. Mol. Cell. Biol. 8 2214-2218. 

Murray, A. W., Solomon, M. J., and Kirschner, M. W. (1989). The role of cyclin synthesis and degradation in the control of maturation promoting factor activity. Nature 339 280-286. 

Bhatt RR, Ferrell JE Jr 1999 The protein kinase p90Rsk as an essential mediator of cytostatic factor activity. Science 286 1362—1365... 

The metaphase arrest in vertebrate oocytes is maintained by cytostatic factor activity (CSF Masui Markert 1971). CSF was first demonstrated in amphibian oocytes by transferring cytoplasm from metaphase II (M II)-arrested oocytes into one blastomere of a two-cell embryo. The injected blastomere was arrested in M phase while the non-injected blastomere continues to cleave (Masui Markert... 

Asselineau, J., H, Bloch and E. Lederer Synthesis of Cord-Factor active... 

Shaywitz, A.J., Greenberg, M.E. CREB a stimulus-induced transcription factor activated by a diverse array of extracellular signals. Annu. Rev. Biochem. 68 821, 1999. 

In animal studies, high levels of cortisol have been shown to induce (increase) the activity of the enzyme tryptophan 2,3-dioxygenase in the liver, thereby decreasing the bioavailability of tryptophan to the brain. It is interesting to note that low acute doses of a number of different antidepressants inhibit the activity of this enzyme and, as a result, increase brain tryptophan concentrations, thus stimulating 5-HT synthesis (Badawy and Evans, 1982). In this way a link between the two key monoamine neurotransmitters and the hormone may be seen namely, reduced brain NA activity leads to decreased inhibition of the HPA axis, while increased levels of cortisol reduce 5-HT activity in the brain. Activation of the HPA axis has also been shown to result in tissue atrophy, in particular of the limbic system s hippocampus, and a reduction in the levels of neurotrophic factors responsible for the maintenance and optimal function of brain neurons (Manji et al., 2001). In conclusion, manipulation of the HPA axis (Nemeroff, 2002) and stimulation of neurotrophic factor activity (Manji et al., 2001) might open up new avenues for the treatment of affective disorders. 

Uyttenhove, C., Simpson, R.J. and van Snick, J. (1988) Functional and structural characterisation of P40, a mouse glycoprotein with T cell growth factor activity. Proceedings of the National Academy of Sciences USA 85, 6934—6938. 

Fig. 4.14. The polymers (X) acting on DNA are transcription factors activated frequently by small molecules or ions with a wide variety of time constants. E is an enzyme. Instructions are passed to a polymer (X) or directly to DNA. Energy requirements not shown (see also Fig. 3.13). Note. All these cycles are element neutral, non-polluting.

Methods for Studying Signal-Dependent Regulation of Translation Factor Activity... 

Another barnacle species, Elminius modestus, was found to produce mono and trihydroxy fatty acids [146]. Analysis of the extract of whole animal homogenates by TLC provided two hatching factor active bands. The more polar band was tentatively identified as a trihydroxy fatty acid (THFA) band. The less polar band had an / r value similar to a 5-HETE standard. The compounds from this latter band were eluted from the TLC plate, methylated, and trimethylsilylated. GC-MS analysis detected several HEPE s and small amounts of monohydroxy derivatives of Ci8 1, C18 2, and C22 fatty acids. Hydrogenation and subsequent GC-MS analysis allowed identification of the major compound as 8-HEPE (ca. 70%). Five to ten percent of 9-, 11-, and 15-HEPE and minor amounts of 5-, 6-, 12-, and 13-HEPE were also detected. No stereochemical features of these oxylipins were determined. 

Ten barnacle species, including the two above, were assayed for hatching factor activity and the presence of monohydroxy fatty acids (MHFA) and THFA bands [147]. The other eight species were Balanus crenatus, B. balanus, B. hameri, B. amphitrite, B. perforatus, Chthalamus montagui, Pollicipes pollicipes, and Lepas anatifera. All ten showed both MHFA and THFA bands. 

In contrast, some cytokines (e.g. some CSFs and EPO) appear to be expressed constitutively. In yet other instances cytokines such as PDGF and TGF-P are stored in cytoplasmic granules and can be rapidly released in response to appropriate stimuli. Other cytokines (mainly ones with growth factor activity, e.g. TGF-P, FGF and IL-1) are found bound to the extracellular matrix in connective tissue, bone and skin. These are released, bringing about a biological response upon tissue injury. 

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