Alzheimers' disease (AD) is characterized by the selective loss of cognitive function, including memory, accompanied by characteristic pathological changes in affected brain tissue. In the course of an initial characterization of the molecular changes that are associated with the genetically programmed, complete degeneration of cerebellar Purkinje cells that occurs in the mouse mutant pcd, we have identified a segment of a cDNA that encodes a novel polypeptide sequence, that we term hsp70B1. Strikingly, the mRNA that encodes this protein is found to be expressed selectively at high levels not only in Purkinje cells, but most intriguingly, in large cortical neurons and in hippocampal neurons, predominantly in are CA3, regions that are known to be involved in the Alzheimers' disease process. We now have enough sequence information to know that the full-length polypeptide, when completely cloned and analyzed, will reveal a brain-specific, new member of the heat shock protein 70 (hsp70) family of molecules. Knowledge about-hsps in the nervous system is very limited, but from studies in other tissues, certain generalizations about he function of these proteins can be made. Synthesis of these proteins, which is now known to occur under a variety of pathological conditions, is protective in response to various stresses on cells. Furthermore, it is now clear that the hsps are present in tissues even at normal temperatures and are actually crucial for the normal physiological functioning of cells, and are even thought to be essential for cell viability. The sensitive up- regulation of some hsp70s under conditions of physiological stress and cell death due to the dysfunction of these genes indicate their importance in normal cells. In fact, the hsp70 series is important for protein folding and unfolding, protein translocation across the endoplasmic reticulum membrane, and the assembly of macromolecular complexes within cells. Since the novel hsp70B1 seems to be neuron and region-specific, it is interesting to consider the possibility that this protein may be directly involved in the neurological degeneration that accompanies AD. To begin to address this point, we propose in this pilot project to (1) complete the sequence analysis of this novel protein, (2) raise antibodies to the recombinant polypeptide, and using these tools, (3) examine the distribution of the cognate mRNA for hsp70B1 and it's encoded polypeptide in normal and AD affected brain tissue. All human brain tissue will be obtained from the neuropathology Core that is integral to this proposal.
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