Current Genomics - Volume 4, Issue 6, 2003

Hsp70 molecular chaperones play a variety of functions in every organism, cell type and compartment, and their activities have been implicated in a number of disease states. Hsp70 activity relies on ATP binding and hydrolysis by the N-terminal domain, which modulates peptide binding and release by the C-terminal domain. In Escherichia coli, the Hsp70 family member DnaK is regulated by DnaJ, which stimulates its ATPase activity, and by GrpE, a nucleotide exchange factor that promotes ADP release. In eukaryotic cells, Hsp70 regulation is far more complex and many families of positive and negative regulators have been characterized, such as Bag-1 that was first identified as an anti-apoptotic Bcl2-binding protein. Whereas eukaryotic DnaJ homologs have extensively been studied, GrpE homolog are found only in the mitochondria or chloroplasts. In fact, until the discovery of Bag-1 in mammalian cells, nucleotide exchange factors were presumed absent from the eukaryotic cytosol and organelles that comprise the secretory pathway, such as the endoplasmic reticulum (ER). However, members of a novel class of nucleotide exchange factors in the ER and in the cytoplasm have recently been identified that act on the ER lumen and cytoplasmic Hsp70 proteins, respectively. Although first uncovered in yeast and named Sls1p and Fes1p, we report here that the class of Hsp70 nucleotide exchange factors defined by Sls1p and Fes1p is conserved from yeast to humans.

Learning and memory is a property of central importance in the nervous system, yet many of the molecular mechanisms for this behavior remain enshrouded in mystery. Despite the daunting nature of the problem, a number of complementary strategies have been employed to unravel the complexities of learning and memory, ranging from genetics to biochemistry. One of the most recent tools brought to bear in this area is genomics. Here, we review some of the most significant insights that have been so far obtained in learning and memory, and we suggest possible areas of future progress.

The decipherment of the human and yeast as well as numerous pathogen genomes has resulted in an explosion of DNA sequence data. Additionally, a plethora of expressed sequences from various tissues and cells are available that cover much more than the estimated actual number of genes within a eukaryotic genome. Although the homology between the mammalian chromosomes, genomes and genes is well conserved simplifying genome analysis in livestock, the latter may be considered as in statu nascendi when compared to the state of development in humans or the mouse. However, this situation is not a surprise, as it has never been the aim of genome analysis projects in livestock to sequence all economical important species completely. The development of genome analysis of the major livestock species also shows that there is not an exponential increase in data. This again, is in contrast to human genome analysis and has mainly two reasons. Firstly, genome analysis in livestock so far has focused on the molecular identification and characterization of major economical important traits (ETLs=economic trait loci, QTL=quantitative trait loci). As the majority of these traits presumably are regulated by a large number of genes, it is conceivable that up to now QTL mapping has only resulted in the isolation of very few traceable major genes. Secondly, there are not many disorders that are of general importance for animal breeding, e.g. stress susceptibility in swine caused by a point mutation in the skeletal muscle ryanodine receptor gene or bovine leukocyte adhesion deficiency caused by a point mutation in the CD18 gene. As a consequence, financial support by breeding organizations or industry is still limited and scientists find it often difficult to convince public funding authorities that genome analysis in livestock as well as the development and implementation of DNA-based diagnosis in breeding programs is not only for the improvement of livestock production but also a contribution to animal welfare. This review summarizes the current state of genome analysis in the major livestock and domestic species, i. e. cattle, pig, sheep, goat, horse and chicken. Special emphasis will be placed on the comparison of availability and development of high-resolution marker maps which facilitate QTL mapping and rapid gene localization. One of the long-term aims of genome analysis in livestock as well as other domestic animals is to obtain genetic screening tests that will improve the health and welfare by selective breeding. There is a great and justifiable optimism that the efforts in genome analysis in livestock will provide new opportunities to identify genes causative for a number of disorders and will improve our understanding of complex traits for the benefit of livestock, livestock production and last but not least the consumer.

The leukocyte integrins are essential membrane receptors that mediate leukocyte adhesion to various cells during immune and inflammatory responses including tumor cell killing, leukocyte migration from the bloodstream into inflamed tissues, and phagocytosis of bacteria. The importance of these receptors is underscored in humans with leukocyte adhesion deficiency (LAD), that is caused by the absence or greatly reduced expression of the leukocyte integrins on leukocytes, and which leads to recurrent life-threatening infections and impaired wound healing. These receptors can also exacerbate the diseased state when excessive accumulation of leukocytes occurs at the site of inflammation because of overexpression or increased activation of the leukocyte integrins on these cells. These receptors are involved in a variety of pathological conditions in the vascular system including ischemic reperfusion injury, stroke, and atherosclerosis. The leukocyte integrins augment tissue damage that occurs in autoimmune diseases including rheumatoid arthritis, multiple sclerosis, Crohn's disease, and ulcerative colitis. This review will focus on the molecular mechanisms that regulate activation of the leukocyte integrins including transcriptional control of leukocyte gene expression and the role these receptors play in normal and pathological inflammatory processes. Their potential use as markers for disease diagnosis and the prospects for anti-adhesion therapy to ameliorate disease as indicted in a number of animal models will be discussed.

During the last few years, high throughput RNA profiling technologies have become nearly indispensable tools in biomedical research. Optimization strategies for the different technologies and bioinformatics tools to mine the wealth of data have developed rapidly to meet the researcher's need calling for more sophisticated clinical and pharmaceutical applications and a more integrated view of the cell's primary molecules DNA, RNAs and proteins. Integrative network analyses based on quantitative expression data, and the integration of data gained from genome analysis defining the relationships between the cell's transcriptome and proteome, are becoming the focus of current research. Key issues to resolve include method developments to optimize analysis of small amounts of tissue or cells and low-abundance messages, and minimize biological noise. DNA microarray technology, oligonucleotide-based microarrays in particular, holds much promise, but may still be largely unexploited. In the wake of experience gathered during expression profiling of human prostate tumors, tissues from human infectious disease models and experimental rodent systems, we discuss here a number of novel DNA microarray-based approaches that may be used in the near future to conduct hypothesis-driven transcriptome research aiming at quantitative models of genetic networks and at narrowing the gap between the transcriptome and the proteome. Such research may also establish microarray technology as indispensable for clinical research near the patient's bedside.