These mechanisms can provide a signal transduction pathway linking eukaryotic cellular stress responses to alterations in the control of gene expression at the translational level. Extensive phosphorylation of eIF2 alpha and strong inhibition of eIF2B activity can result in the downregulation of the overall rate of protein synthesis less marked changes may lead to alterations in the selective translation of alternative open reading frames in polycistronic mRNAs, as demonstrated in yeast. Left ventricular hypertrophy (LVH) may be due to a physiologic response to increased load, pathologic hypertrophy due to hypertrophic cardiomyopathy (HCM) or be mimicked by myocardial infiltration. Induced by factors such as hypertension or. A cell can adapt to a certain point, but if the stimulus continues beyond that point, failure of the cell, and. Pathological cardiac hypertrophy is a maladaptive growth response of the heart to a variety of disease stimuli. These adaptations include hyperplasia, hypertrophy, atrophy, and metaplasia, and can be physiologic or pathologic, depending upon whether the stimulus is normal or abnormal. Phosphorylated eIF2 acts as a dominant inhibitor of the guanine nucleotide exchange factor eIF2B and prevents the recycling of eIF2 between successive rounds of protein synthesis. In such situations, cells must adapt to the new environment. Physiological conditions which result in eIF2 alpha phosphorylation include virus infection, heat shock, iron deficiency, nutrient deprivation, changes in intracellular calcium, accumulation of unfolded or denatured proteins and the induction of apoptosis. The alpha subunit of polypeptide chain initiation factor eIF2 can be phosphorylated by a number of related protein kinases which are activated in response to cellular stresses.
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