Regulatory targeting of Matrix Metalloproteinase 2 by βftz-f1 in Drosophila melanogaster fat body remodeling

Abstract

Tissue remodeling is involved in multiple functions in the animal body, as the process through which cells dissociate and detach from each other. Tissue remodeling is the driving force behind wound healing and cancer metastasis, and is carried out partially by Matrix Metalloproteinases (MMPs). MMPs are proteases that degrade the extracellular matrix (ECM) between cells, which then allows them to move freely from one another. The expression of Mmps is highly regulated. To study Mmp regulation and tissue remodeling, Drosophila melanogaster makes for a highly useful model organism due to a process called larval fat body remodeling. Larval fat body remodeling occurs when Drosophila go from larva to adult fly, a highly regulated process thought to involve Matrix Metalloproteinase 2 (MMP2). MMP2 is believed to be the mechanism of ECM fat cell cleaving, which allows for cells to detach from each other and move around freely during larval fat body remodeling. Research suggests that the expression of Mmp2 in Drosophila is 20-hydroxyecdysone (ecdysone) hormonal cascade regulated, mediated by ßFTZ-F1 (Bond et al., 2011). Bond et al. (2011) showed that both ßftz-f1 and Mmp2 are necessary and sufficient for larval fat body remodeling in Drosophila. The hypothesis of this study is that Mmp2 is a downstream target of ßFTZ-F1 in the ecdysone hormonal cascade, more specifically that Mmp2 expression is induced by ßFTZ-F1. Levels of Mmp2 expression were relatively quantified compared to a control gene, in wild type Drosophila and transgenic Drosophila in which expression of ßftz-f1 was reduced in the larval fat body. To fully sustain my hypothesis, I expect to see reduced expression of Mmp2 in ßftz-f1 reduced larval fat body compared to wild type larval fat body. This is because if expression of Mmp2 is induced by ßftz-f1 expression, by reducing ßftz-f1 it comes that there will be a reduction of Mmp2 expression as well. The findings of this study show a reduction of Mmp2 at 10 hours after puparium formation (APF) in ßftz-f1 reduced larval fat body, which is consistent with the hypothesis. At 8 and 12 hours APF, the study found increased expression of , which does not support the hypothesis, however it might be explained by individual variances in biological samples, as well as a quickly shifting level of Mmp2 expression at these time points. Future studies using the Western blot technique might serve as a tool to more precisely study expression levels at these time points.