Conserved signaling mechanisms in the D. melanogaster cellular immune response 公开

Brantley, Susanna Elizabeth (2013)

Permanent URL: https://etd.library.emory.edu/concern/etds/41687h73r?locale=zh
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Abstract

The model organism Drosophila melanogaster provides a system and excellent genetic tools for studying highly conserved innate immune responses. Numerous screens and mutant fly strains have implicated conserved signaling pathways, including Toll, JAK/Stat, and JNK, in the fly cellular immune response against parasitic wasps (Zettervall, 2004; Avet-Rochex, 2010; Irving, 2005; Braun, 1997). This study was conducted to better understand the tissue specific activity of Toll, JAK/Stat, and JNK signaling pathways in the differentiation of a specialized blood cell type, the lamellocyte, which is actively involved in encapsulation of wasp pathogens. The pro-immune activity of Toll, JAK/Stat, and JNK signaling in Drosophila indicates that conserved signaling pathways could be the targets of wasp virulence strategies. Many wasps are successful pathogens of D. melanogaster, but the mechanisms of wasp virulence, such as the action of wasp venom components, are not well studied. It is not known if or how wasps use virulence mechanisms specifically targeting conserved signaling pathways implicated in lamellocyte differentiation. This study will investigate the effect of parasitism by diverse wasp species on JAK/Stat activity in D. melanogaster. By better understanding the precise mechanisms of conserved signaling and the ways in which parasites affect the pathways involved in immune responses, we may gain insight into how signaling pathways implicated in mammalian development, immunity, and disease can be controlled and modulated.

Table of Contents

CHAPTER 1: Introduction……………………………………………………………. 1

Figure 1.1 D. melanogaster hemocytes …………………………………………………. 7

CHAPTER 2: The role of conserved signaling pathways in the D. melanogaster cellular immune response to parasitic wasps ………………………………………… 8

ABSTRACT ……………………………………………………………………………... 9

INTRODUCTION ……………………………………………………………………... 10

MATERIALS and METHODS ………………………………………………………... 11

RESULTS ……………………………………………………………………………… 13

Table 2.1 Candidate Genes

Table 2.2 Overexpression of Toll, JAK/Stat, and JNK signaling pathway components alters hemocyte composition in a tissue specific manner

Figure 2.1 He-Gal4>UAS-hep leads to lamellocyte differentiation

Figure 2.2 Effect of knockdown on encapsulation rate of LcNet

Figure 2.3 Defective capsule

DISCUSSION ………………………………………………………………………….. 22

CHAPTER 3: Interaction of parasitic wasps with JAK/Stat pathway activity in the D. melanogaster cellular immune response ………………………………………….. 24

ABSTRACT ……………………………………………………………………………. 25

INTRODUCTION ……………………………………………………………………... 26

MATERIALS and METHODS ………………………………………………………... 27

RESULTS ……………………………………………………………………………… 30

Figure 3.1 JAK/Stat activity is required for melanotic encapsulation

Figure 3.2 Stat activity following wasp attack

Table 3.1 10XStatGFP activity in fat body following wasp attack

Figure 3.3 Wasp virulence strategies target lamellocytes downstream of JAK activation

Table 3.2 Wasp attack induces changes in circulating host hemocytes

Figure 3.4 Hemocyte composition altered by wasps is associated with changes in HopTum-l tumor phenotype penetrance

DISCUSSION ………………………………………………………………………….. 43

CHAPTER 4: Discussion …………………………………………………………….. 47

REFERENCES ………………………………………………………………………... 51

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