Translocation induction

Should there be no evidence of translocation induction in treated spermatogonia, one would have to conclude either that there are some major physiological differences between pre- and postmeiotic germ cells that lead to differential sensitivities to, or differential recoveries from, chemically... 

Fig. 69. a Eye phenotypes in flies with intact chromosomes 1 and 4. b The translocation induction between chromosomes 1 and 4 by Rentgen treatment, c The effect of translocations on eye phenotypes. (After Becker, 1966)... 

Cyclosporine A (CsA) is a water-insoluble cyclic peptide from a fungus composed of 11 amino acids. CsA binds to its cytosolic receptor cyclophilin. The CsA/cyclophilin complex reduces the activity of the protein phosphatase calcineurin. Inhibition of this enzyme activity interrupts antigen receptor-induced activation and translocation of the transcription factor NEAT to the nucleus which is essential for the induction of cytokine synthesis in T-lymphocytes. 

Fig. 8. Inhibition of bacterial translocation by rifaximin in the rat. Results of bacteriological culture (for aerobic and anaerobic bacteria) of tissues and biological fluids obtained from rats with taurocholate-induced ANP. Bars represent the percentage of positive biological samples. Horizontal lines are standard errors. Animals of group A received no treatment, while those of group B were given an enema of 30 ml warmed saline containing rifaximin (20 mg/kg) 1 h prior the induction of ANP (from Marotta et al. [196]).

The hemopexin heme transport system thus acts as an early warning system for cells by activating signaling pathways (including the N-terminal c-Jun kinase, kinases to release RbIA/NFkB family members for nuclear translocation) and transcription of the HO-1 and MT-1 genes. The details of this aspect of hemopexin function with redox-active copper as an initial event in the coordinated induction of HO-1 and MT-1 by heme-hemopexin have recently been reviewed (89) and are not presented in detail here. 

Fig. 11.4. Model of signal transduction via the IL-2 receptor. Binding of IL-2 to the IL-2 receptor initiates activation of the Janus kinases Jakl and Jak3. These phosphorylate tyrosine residues in the P-chain of the IL-2 receptor and in the transcription factor StatS. SH2 domains or PTB domains of adaptor proteins can bind to the Tyr phosphate residues of the P-chain and, as shown in the figure for the Shc/Grb2/Sos complex, can transmit a signal in the direction of the Ras pathway. The phosphorylated transcription factor StatS is translocated into the nucleus and activates the transcription of corresponding gene sections. Another signaling pathway starting from the activated IL-2 receptor involves the Lck and Syk tyrosine kinases (see Chapter 8). The pathway leads to induction of genes for transcription factors such as c-Myc and c-Fos.

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