Temporal expression of Dmp53 and SNAMA isoforms and their relation to genotoxic stress.

Nweke, Ekene Emmanuel
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RBBP6 is an E3 Ubiquitin ligase protein with a U-box motif. It interacts with p53 and Rb and is linked to several cellular functions. SNAMA is the Drosophila RBBP6 homolog, but is less characterized than its vertebrate counterparts. Gene expression studies on Drosophila have a potential to advance the knowledge on molecular mechanism underlying genotoxic stress. Previous studies have shown that SNAMA plays a critical role as an apoptosis suppressor and possibly in responses to genotoxic stress. The molecular basis for this is, however, unknown. Initially, two isoforms were identified by bioinformatics and one (Snama A) experimentally as well. Here, we confirm experimentally the existence of the second isoform (Snama B). We also show that these are differentially expressed during development and when the organism undergoes genotoxic stress. Total RNA samples were used to demonstrate gene expression by using Reverse Transcriptase Polymerase Chain Reaction. Using samples collected at different stages of development and from adult flies treated with the DNA damaging agent, irinotecan, it is shown that these isoforms are differentially expressed throughout development and upon genotoxic stress. This knowledge may help to understand the functional role SNAMA plays in normal physiology and in response to genotoxic stress. Furthermore, the results show that SNAMA is involved in a potentially beneficial intervention whereby the glycolytic pathway is bypassed by the addition of methyl pyruvate.
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2015.