Induction by hormones

Many of these compounds—puromycin and cycloheximide in particular—are not cfinically useful but have been important in elucidating the role of protein synthesis in the regulation of metabolic processes, particularly enzyme induction by hormones. 

Increased P450 synthesis requires enhanced transcription and translation. A cytoplasmic receptor (termed AhR) for polycyclic aromatic hydrocarbons (eg, benzo[a]pyrene, dioxin) has been identified, and the translocation of the inducer-receptor complex into the nucleus and subsequent activation of regulatory elements of genes have been documented. A pregnane X receptor (PXR), a member of the steroid-retinoid-thyroid hormone receptor family, has recently been shown to mediate CYP3 A induction by various chemicals (dexamethasone, rifampin) in the liver and intestinal mucosa. A similar receptor, the constitutive androstane receptor (CAR) has been identified for the phenobarbital class of inducers (Sueyoshi, 2001 Willson, 2002). 

Savas U, Griffin KJ, Johnson EF. Molecular mechanisms of cytochrome P-450 induction by xenobiotics an expanded role for nuclear hormone receptors. Mol Pharmacol 1999 56 851-857. 

Mohamed, M. and Prestwich, G.D. (1988). Hemolymph juvenile hormone binding proteins of Reticulitermes flavipes induction by methoprene and suppression by pheromones. In Endocrinological frontiers in physiological insect ecology, ed. 

The metabolism of zinc is influenced by hormones, stress situations, lipopolysaccharides, toxins, oxygen radicals, lipid peroxidations, etc. This may lead to fluctuations in the zinc concentration, mainly due to the induction of metallothioneine (MT), which is a transport and intracellular depot protein. One third of this protein consists of cysteine, which binds zinc, copper, cadmium, cobalt and mercury. This protects the body from toxic heavy metal... 

Normal values of y-GT may be the result of cellular moulting or due to regular but still individually differing inductions within the biotransformation process caused by toxins, (s. p. 55) Similarly, normal values of y-GT in women may be brought about by hormonal action (e.g. decline in enzymatic activity through oestro-gens). 

Nakagomi A, Freedman SB, et ai. Interferon-gamma and lipopolysaccharide potentiate monocyte tissue factor induction by C-reactive protein relationship with age, sex, and hormone replacement treatment. Circulation 2000 101 1785-91. 

Larsen, B., Anderson, S., Brockman, A., Essmann, M., and Schmidt, M. (2006) Key physiological differences in Candida albicans CDRl induction by steroid hormones and antifungal drugs. Yeast, 23, 795-802. 

On the other hand, and since alkaloids constitute a defense against certain environmental stresses, it is not surprising that the TIA pathway shows induction by several biotic and abiotic stress factors [6, 133-137], Among those, the induction by fungal elicitors has been particularly well characterized, together with the regulation by the plant stress hormone methyljasmonate [5, 9]. 

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