Gene expression modification

Meng Q, Waters KM, Malard JM, Lee KM, Pounds JG. Gene expression modifications in a mouse emphysema model induced by elastase. Society of Toxicology, 2005. 

In all cell systems the protein turnover is delicately balanced between its synthesis and degradation by different intraeellular proteases. For example, in a growing bacterium, 1-3% of the cell protein is degraded into amino acids every hour. Apart from this, protein turnover is an essential factor in the environmental adaptation of a cell, particularly in an environment lacking in protein or amino acids (Tanaka et al., 1998). There is a plethora of evidence to indicate that proteases are involved in modulation of gene expression, modification of the enzyme and its secretion proeesses and in the control of translation by modification of enzyme associated with ribozyme (Atsumi et al., 1989 Guzzo et al., 1991 Traidej et al., 2003 Peng et al., 2004). 

Long-chain fatty acid synthesis is controlled in the short term by allosteric and covalent modification of euTymes and in the long term by changes in gene expression governing rates of synthesis of enzymes. 

Post-translational modification Maximizing gene expression 5.3 Gene therapy and gene repair... 

Once a gene is cloned it is necessary to convert the information contained in it into a functional protein. There are a number of steps in gene expression (i) transcription of DNA into mRNA (ii) translation of the mRNA into a protein sequence and (iii) in some instances, post-translational modification of the protein. In discussing these steps in more detail, expression of a cloned insulin gene will be used as an example. 

A number of subtle dysfunctions occur at the cellular and molecular levels in the early stages of disease progression associated with the loss of cellular homeostatic functions of endothelial cells, smooth muscle cells and macrophages which constitute the major cell types in the atheroma environment. These events include the modification of the pattern of gene expression, cell proliferation and apoptosis. 

Proteomics, the measurement of the global changes in proteins produced as a result of gene expression, bridges the gap between genome sequence and cellular behaviour and takes into account the post-translational modifications that often result in the functional effect. It has the potential to determine the role of protein-protein complexes in the complex signalling cascades that... 

In the nuclei of all eukaryotic cells, DNA is tightly wrapped around an octamer of histone proteins and is compacted into a dense structure known as chromatin. In order to access the genetic information which is required in numerous essential cellular processes including DNA replication, gene expression and DNA repair, chromatin needs to be partially unwound. One important mechanism to regulate chromatin structure and thus to control the access of the genomic DNA is through histone modifications [1-6]. The histone octamer is composed of two copies of H2A, H2B, H3 and H4 core histone proteins. Their tails, that protrude out of the surface of the... 

There is a broad diversity of heterologous hosts for gene expression, and there is no best or universal host which is suitable for the production of all possible proteins. Nevertheless, many proteins can be expressed cheaply and successfully in Escherichia coli, which is still the most preferred host for heterologous production of proteins without posttranslational modifications. 

The initial approach to gene therapy involved manipulation of gene expression ex vivo. Toward this end, the desired target cells are identified and subsequently removed from the subject, transfected in vitro, then reintroduced into the patient. A number of protocols have been established for the ex vivo transfection of a wide variety of cell types. This method allows specific cell targeting and high transfection efficiency. However, the process is time consuming, complex, and costly. Additionally, the method is not applicable to all situations, such as those in which an immediate modification is required. 

Biochemical modifications of receptors / Modulation of second messaging systems and gene expression / Changes in extracellular ion concentrations... 

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