Date of Award

6-1-2013

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Alexey Veraksa

Second Advisor

Linda Huang

Third Advisor

Richard Kesseli

Abstract

Kurtz (Krz) is the only Drosophila homolog of mammalian beta-arrestins. We have already implicated Krz in regulation of Toll, receptor tyrosine kinase (RTK) and mitogen activated protein kinase (MAPK) pathways. As a multifunctional adaptor, how does Krz coordinate different signaling pathways and carry out well-orchestrated duties? I hypothesize that a possible strategy for Krz is to dynamically reorganize its core interaction complexes in response to the given physiological status. I systematically tested this hypothesis by analyzing in vivo Krz signaling networks dynamics. I also performed an in vivo structure-function analysis of Krz by biochemistry and genetic analysis. I successfully identified the in vivo core Krz interaction complexes, which include: Ulp1, Dos, shep, CG10289 and CG3797; my results suggested phosphoinositide binding elements (KRK motif) in Krz was important for normal fertility of flies, which may due to combined defects of RTK and Toll. As a case study, I also investigated molecular mechanism of Krz/Ulp1 interaction: I found that they may synergistically limit SUMOylation of Dorsal and other substrates in cells. Combined with Saima Anjum's genetic data, this analysis showed that the proper balance of SUMOylation was critical for Toll signaling, which was otherwise up-regulated, leading to an inappropriate inflammatory response.

Notch is important for normal pattern of cell differentiation. Tissue specificity and endocytosis mediated control of Notch signaling components complicate the study of this pathway. To understand Notch signaling dynamics and mechanism, it will be beneficial to investigate in vivo proteomes and live trafficking events of both Notch receptor and its ligand Delta. Based on previous work of Dr. Marla Tipping, I successfully made SBP or fluorescent tagged genomic transgenes for Notch and Delta. Using those transgenic flies, I analyzed the in vivo Notch/Delta signaling complexes and also collaborated with Dr. S. Artavanis-Tsakonas lab on fluorescent live imaging of Notch/Delta dynamics.

Krz has been shown as a regulator of Notch; the resulting networks of the Krz and Notch will deepen our understanding of their interplay and potentially uncover some unknown points of signaling cross-talks among Notch and other pathways, in which Krz may act as a signaling hub.

Comments

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