Two predominant age-related diseases, non-insulin dependent diabetes (NIDDM) and Alzheimer's disease (AD) are characterized by amyloid formation in the pancreas and brain, respectively, which is associated with cell death. NIDDM and AD affect large populations of Americans (ca. 7.2 and 4.5 million annually) and their combined annual costs exceed $175 billion. We demonstrated that the expression of human islet amyloid precursor protein (hIAPP) in COS-l cells generated intracellular amyloid that was associated with cell death (O'Brien et al., Am J Pathol 147:609-616, 1995). We postulated that: (i) intracellular amyloidogenesis is a primary cause of cell death, and (ii) cells have evolved protective mechanisms to prevent intracellular amyloidogenesis. In preliminary studies we have found that small heat shock proteins (sHsps) prevent in vitro amyloid formation by the Abeta(1-42) peptide, the amyloid precursor in AD. Accordingly, we hypothesize that: (iii) the Hsp/chaperone family plays a role in preventing intracellular amyloidogenesis, and (iv) age-related changes in Hsp/chaperone levels initiate amyloidogenesis in NIDDM and AD. We will test the former hypothesis (iii) by adapting a fluorescent assay to quantitate intracellular amyloid levels in COS-1 cells expressing either hIAPP or Abeta(1-42) and correlate these levels with traditional markers of apoptosis/necrosis, using fluorescence activated cell sorting analyses (FACS). Subsequently, Hsp levels will be manipulated in these cells either by heat shock, or co-expression of wild-type Bip (wtBip) or dominant negative Bip mutants (mtBip), which act in the proximal endoplasmic reticulum, the proposed site of amyloid formation. In accordance with hypothesis iii, heat shock and overexpression of wtBip should protect and mtBip should increase amyloid formation and FACS markers of cell death.
|Effective start/end date||3/1/97 → 2/28/98|
- National Institutes of Health