The primary goal of this application is to isolate a caspase inhibitory factor induced by 17-beta-estradiol in primary cultures of human neurons. A group of mammalian cysteinyl caspases is activated in a cell-, insult- and species-specific manner during apoptosis of various cell types. In human neurons, caspase-6 is active during serum deprivation-mediated neuronal apoptosis. We have previously shown that caspase-6 activity is lethal to human neurons in culture. Now, we find that 17 -beta-estradiol but not 17-alpha-estradiol, testosterone, or epitestosterone delay caspase-6 mediated neuronal cell death (Zhang et al. 2001). 17-beta-estradiol-treated neuronal extracts directly inhibit recombinant active caspase-6 in an in vitro assay. In contrast, 17-beta-estradiol does not induce CIF nor prevent caspase-mediated cell death in astrocytes. We conclude that 17-beta-estradiol induces a caspase inhibitory factor (CIF) that is preventing neuronal apoptosis. CIF is induced through estrogen receptors via a non-genomic pathway. We show that CIP is a broad spectrum caspase inhibitor between 10 and 14 kDa in size that is fairly resistant to boiling and proteinase K in neuronal extracts. Our results indicate that 17-beta-estradiol induces a novel inhibitor of active caspases and provide an additional mechanism for the neuroprotective action of 17-beta-estradiol. In this proposal, the primary goal is to identify CIF and determine its role in neuronal survival and cell death.
In aim #1, we will biochemically isolate and sequence CIF.
In aim #2, we will clone CIF cDNA and obtain antibodies. We will then confirm the role of CIF in neuronal survival and against caspases (aim #3), and determine the mode of activation of CIF (aim #4) and inactivation of caspase-6 (aim #5). Finally, we will study the regulation of CIF expression in normal and AD brains (aim #6). Given the strong epidemiological link of estrogen against Alzheimer's disease and its possible prophylactic role in neuroprotection, our results suggest a novel mechanism of action of 17-Beta-estradiol that could be exploited to promote neuroprotection in injury or neurodegenerative diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS040965-01A2
Application #
6470798
Study Section
Special Emphasis Panel (ZRG1-MDCN-2 (01))
Program Officer
Murphy, Diane
Project Start
2002-04-15
Project End
2006-03-31
Budget Start
2002-04-15
Budget End
2003-03-31
Support Year
1
Fiscal Year
2002
Total Cost
$128,250
Indirect Cost
Name
Mcgill University
Department
Type
DUNS #
City
Montreal
State
PQ
Country
Canada
Zip Code
H3 0-G4
Guo, H; Petrin, D; Zhang, Y et al. (2006) Caspase-1 activation of caspase-6 in human apoptotic neurons. Cell Death Differ 13:285-92
LeBlanc, Andrea C (2005) The role of apoptotic pathways in Alzheimer's disease neurodegeneration and cell death. Curr Alzheimer Res 2:389-402
Guo, Huishan; Albrecht, Steffen; Bourdeau, Martine et al. (2004) Active caspase-6 and caspase-6-cleaved tau in neuropil threads, neuritic plaques, and neurofibrillary tangles of Alzheimer's disease. Am J Pathol 165:523-31