Altered protein synthesis

W.G. Tatton, J.S. Wadia, W.Y. Ju, R.M. Chalmers-Redman, N.A. Tatton, (-)-Deprenyl reduces neuronal apoptosis and facilitates neuronal outgrowth by altering protein synthesis without inhibiting monoamine oxidase, J. Neural. Transm. Suppl. 48 (1996) 45-59. 

Glucocorticoids affect various cells in a manner that is characteristic of steroid hormones (see Chapter 28, Fig. 28-3). In general, steroids alter protein synthesis in responsive cells through a direct effect on the cell s nucleus. These hormones alter the transcription of specific DNA genes, which results in subsequent changes in RNA synthesis and the translation of RNA into cellular proteins.6,73... 

TRANSLATIONAL CONTROL Eukaryotic cells can respond to various stimuli (e.g., heat shock, viral infections, and cell cycle phase changes) by selectively altering protein synthesis. The covalent modification of several translation factors (nonribosomal proteins that assist in the translation process) has been observed to alter the overall protein synthesis rate and/or enhance the translation of specific mRNAs. For example, the phosphorylation of the protein eIF-2 affects the rate of hemoglobin synthesis in rabbit reticulocytes (immature red blood cells). 

ROS can lead to more than 20 oxidized base variations, which can cause DNA strand breaks, DNA—DNA and DNA—protein cross-links, and to sister—chromatid exchange leading to replication faults, including mutations that could ultimately alter protein synthesis (Cooke et al., 2003). In addition, DNA bases may be modified by 4-HNE and acrolein, leading to the formation of exocyclic adducts. 

One of the cultures is subjected to physiological conditions that may alter protein synthesis, e.g., heat, lack of a key nutrient. 

Most of the common immunological techniques (nephelometry, turbidimetry, etc.) can be used to determine the concentration of transferrin directly. Generally, enhanced turbidimetric assays are now used for transferrin measurements on automated analyzers. Transferrin is decreased in disorders involving reduced or altered protein synthesis (e.g., liver disease) and increased in iron deficiency anemia. A rare condition of near complete absence of plasma transferrin (atransferrinemia) has been reported. 

Hepatic triglyceride is increased by agents that alter protein synthesis. 

It is not clear as to how T-2 toxin inhibited initial germination in these seeds, although the fact that T-2 toxin is a potent inhibitor of protein synthesis in all biological systems studied to date provides a possible explanation (Dashek et al., 1986). However, AFB has been shown to alter protein synthesis at the transcriptional level (Goldblatt, 1969), but it did not inhibit seed germination in our studies to the same extent as did the T-2 toxin. In fact, in Atriplex canescans, AFB actually caused a slight increase in hypocotyl eruption, while in Hordeum vulgare, AFB decreased epicotyl eruption. This was concomitant with increased hypocotyl eruption and a decrease in time until hypocotyl eruption. 

Both RBP and TTR have a relatively short half-life ( 0.5 and 2-3 days, respectively) and, therefore, they must be synthesized continuously to maintain normal plasma levels. Plasma retinol, RBP, and TTR are reduced in states of impaired protein synthesis, which may be due to an inadequate intake of protein or energy or to impairments in metabolism. Plasma RBP and TTR are sometimes used as clinical indicators of visceral protein synthesis. During infection and/or inflammation, plasma retinol, RBP, and TTR fall transiently, even though liver vitamin A reserves are adequate, due to altered protein synthesis during the acute-phase response. Because multiple nutritional and metabolic disturbances can lead to a similar decrease in plasma retinol, RBP, and TTR, laboratory values must be interpreted with caution. 

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