Investigation of Bax VDAC Interactions and Their Relationship Regarding Apoptosis in Drosophila melanogaster

Sullivan, John (2014) Investigation of Bax VDAC Interactions and Their Relationship Regarding Apoptosis in Drosophila melanogaster. Undergraduate thesis, under the direction of Dr. Bradley Jones from Biology, The University of Mississippi .

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Abstract

Cell mediated death, or apoptosis, is a critical biological process that once fully understood could unlock a potentially new understanding of the mechanisms of both cancer and neurodegenerative diseases. The general mechanism of apoptosis includes cytochrome c being released from the mitochondrial membrane through a channel created by an activated pro-apoptotic BH123 protein. Once the cytochrome c leaves the mitochondrial membrane it goes on to ultimately activate a caspase cascade, which results in cell apoptosis. Similar to BH123 channels, VDACs (voltage-dependent anion channels) are also pore-forming proteins that regulate the intake and output of metabolites from the mitochondrial intermembrane space and cytosol. Dr. Jekabsons has shown in rat granule neurons that the BH123 protein Bax interacts with VDACs. He was able to show that when a Bax VDAC complex forms, Bax is not active. From that, a hypothesis was formed to test whether VDACs inhibit the activation of Bax and therefore restrain apoptosis. To test this, we used Drosophila melanogaster as a genetic platform test the hypothesis that VDAC prevents premature Bax activation by crossing a VDAC mutant with one that ectopically expresses Bax. The extent of Bax-mediated death in this fly strain was compared to a strain functional VDAC and Bax alleles. If the hypothesis was true, the crosses were expected to show that the strain with an inactive VDAC and an active Bax would have a worse visible phenotype due to increased cell death attributed to less restraint from the VDACs on apoptosis. The Gal4 UAS system was used to induce selective activation of the UAS-Bax gene in the eye of Drosophila melanogaster by using the GMR-Gal4 to selectively activate it. The VDAC mutant that was used was porin365, which contains a deletion and therefore inactivates the gene. This porin mutant was crossed through many generations to form a final genotype of porin365 GMR-Gal4/UAS-Bax. The porin36 GMR-Gal4 chromosome was from a recombinant line that was created during the early stages of the genetic crossings. The final results indicated that the eye phenotype in the flies with an activated Bax gene and an inactive porin gene had less apoptosis than flies expressing functional porin. Increased cell death in the eye did not occur and therefore we were not able to lend support for the hypothesis that VDACs negatively impact the function of Bax in apoptosis. In fact the results tend to indicate a possibility that VDAC may have a role in facilitating Bax-dependent apoptosis.

Item Type: Thesis (Undergraduate)
Creators: Sullivan, John
Student's Degree Program(s): B.A. in Biochemistry and Biology
Thesis Advisor: Dr. Bradley Jones
Thesis Advisor's Department: Biology
Institution: The University of Mississippi
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QH Natural history > QH426 Genetics
Depositing User: John Magruder Sullivan
Date Deposited: 08 May 2014 19:35
Last Modified: 08 May 2014 19:35
URI: http://thesis.honors.olemiss.edu/id/eprint/103

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