Electronic Thesis and Dissertation Repository


Master of Science




Dr. Sean Cregan


Apoptosis is known to contribute to the loss of neurological function in brain injury and several neurodegenerative diseases. The Bcl-2 family of proteins consist of pro-apoptotic and anti-apoptotic members that interact physically and functionally to regulate apoptosis in a cell type and stimulus specific manner. We have previously demonstrated that the Bcl-2 family member Puma plays a key role in triggering neuronal apoptosis under diverse stress conditions. However, the mechanism by which Puma mediates apoptosis remains unclear. Here we found that Puma contains two domains required for its apoptotic function: the BH3 domain and a region in the c-terminus that regulates its localization to the mitochondria. We found that the BH3 domain is required to bind both the anti-apoptotic protein, Bcl-xl, and the pro-apoptotic protein, Bax. However, we found that the BH3 domain of the protein is not required for its mitochondrial-localization. Instead, we identified a region within the c-terminus of Puma that is essential for both mitochondrial-localization and apoptotic function of the protein. Although we found that the c-terminus of Puma is not required to bind Bcl-xl or Bax in vitro, it is required for co-localization and likely interaction with these proteins in the cellular context. In summary, we determined that Puma requires both its c-terminal mitochondrial-localization sequence and its BH3 domain to co-localize and bind to both the anti-apoptotic protein, Bcl-xl, and the pro-apoptotic protein, Bax and to induce neuronal cell death.