The Role of DNase2𝛃 in the Nuclear DNA Degradation of Chickens

Abigail Lorden, Samuel Graves, Rebekah Saint Germain, and Luciano Crespo

Abstract:
Programmed death, or apoptosis, of damaged and aging cells is required for normal development of many organisms. Acid endonucleases called Deoxyribonuclease 2 (DNase2) have enzymes that degrade DNA. There are two variants of DNase2- DNase2α and DNase2β. DNase2α is expressed in all cells; it’s necessary to digest DNA of apoptotic cells. In mouse studies, when DNase 2α is not expressed, it results in early death due to accumulation of undigested DNA from apoptotic cells. DNase2β is selectively expressed and essential for proper lens cell differentiation. While most vertebrates have both DNase2 genes, chickens only have DNase2β. This bears the question of how chickens survive the loss of DNase2α. Our working hypothesis is that chicken DNase2β may be able to compensate for the loss of DNase2α. The DNase2β gene has an original transcript and two newly discovered transcripts, X1 and X2. These transcripts may produce enzymes with activities similar to the DNase2α enzyme, therefore compensating for the loss of the DNase2α gene. The first step in this work is to confirm the existence of X1 and X2 transcripts in chickens. RNA in chicken eye and spleen tissue was used to generate cDNA, using reverse transcription. Using X1- and X2-specific primers, PCR was conducted to amplify the cDNA products of the X1 and X2 transcripts. Gel electrophoresis was performed to confirm the presence of the X1 and X2 transcripts. This work will help us understand how organisms who lack the DNase2α gene survive given its importance for proper development and survival.