PgmNr D1412: Functional analyses of the transposable element-derived genes DPLG1 and DPLG4 in Drosophila melanogaster.

Authors:
D. Jangam 1 ; C. Feschotte 2 ; E. Betrán 1


Institutes
1) University of Texas at Arlington, Arlington, TX; 2) University of Utah, Salt Lake City, UT.


Keyword: evolution and development

Abstract:

Our laboratory has described several domesticated transposases from PIF/Harbinger DNA transposable elements (TEs) in Drosophila (Casola et al. 2007). Although, the exact functions of these genes are still unknown, these transposase-derived genes appear to have their DNA binding domain conserved but not their catalytic domain and we hypothesize that they might be regulatory proteins. Their regulatory function might include the regulation of TE activity. Here, we present work aimed to elucidate the function of two of the PIF/Harbinger derived transposases named Drosophila PIF like gene 1 (DPLG1) and DPLG4. Taking advantage of the UAS/GAL4 system, these two DPLGs were knocked down ubiquitously and the effects on the viability and fertility were studied. Using light microscopy and fluorescent microscopy, defects in the testis of knock-down (KD) flies were identified. In situ hybridization was used to ascertain the level of transcript reduction in KD testis, and RNA-seq analyses were performed for KD testis and controls to quantify differentially expressed genes and TEs. KD of DPLG1 does not affect viability in D. melanogaster; however, it resulted in male sterility. We observe that the elongated spermatids do not individualize into mature sperms and the seminal vesicles are empty. The testis of these KD males show increased activity of LINE TEs including all three telomeric elements. In addition, DPLG4 came out in a screen designed to detect genes involved in TE control (Handler et. al 2013). KD of DPLG4 reduces viability of D. melanogaster. This result has been independently validated using a DPLG4 mutant line. DPLG4 KD males showed a phenotype analogous to DPLG1 KD males. Taken together, these results support that DPLG4 might play a role in the viability of D. melanogaster, and DPLG1 and DPLG4 might be needed during spermatogenesis and could potentially have been recruited from PIF/Harbinger TEs to defend against the detrimental activities of other parasitic elements. We are in the process of generating resilient transgenes for DPLG1 and DPLG4 which will be used to rescue the defects resulting from the KD and KO experiments. To further advance our understanding of the functional importance of these genes, we are generating null mutants of DPLG1 and DPLG4 using CRISPR-Cas9 which will be used to further investigate the role of these genes. This will help us validate the results from our experiments. Additionally, the resilient constructs are HA tagged and will be used to test the nuclear localization of these genes and their interactions with chromatin remodeling proteins.    .