Jun Signaling During Drosophila Development

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Publication Type dissertation
School or College School of Medicine
Department Human Genetics
Author Jud, Molly Christine
Title Jun Signaling During Drosophila Development
Date 2016-05
Description Jun N-terminal kinase (JNK) signaling is a key modulator of development and disease in all multicellular organisms. One process in which the consequences of both gain and loss of JNK signaling can be monitored is embryonic dorsal closure (DC) in the fruit fly, Drosophila melanogaster. DC occurs midway through embryogenesis; it is the process by which the lateral epidermis expands bilaterally to meet and fuse at the dorsal midline, thereby encasing the entire embryo in epidermis. JNK signaling in leading edge (LE) cells (the dorsal-most row of epidermis) initiates closure. My studies of a novel but conserved JNK signaling antagonist, Raw, have provided several unique insights into: 1) Jun function as a component of the AP-1 transcription factor, and 2) the role of the epidermis as a signaling template mediating development of the epidermis and adjacent tissues. My graduate work has built upon the demonstration that raw is required to prevent promiscuous JNK signaling in the embryonic epidermis just prior to DC. I have shown that raw is necessary for proper accumulation of Jun in LE cells required to define the LE, which functions as a signaling center required for epidermal closure as well as for underlying heart development. I have gone on to show that Jun accumulates at previously unrecognized sites in the embryonic epidermis, including tracheal pits and solitary epidermal cells lying directly above the peripheral nervous system (PNS). Jun activity is required for tracheal and nervous system defects observed in mutants of two JNK signaling antagonists, raw and rib, and indicates that cell signals within and to an adjacent tissue are integral to proper development. I have found that the epidermis iv plays an instructive role during development, and results from my work have led to insights into how JNK signaling centers in the epidermis coordinate morphological processes. As Raw is a novel but conserved JNK signaling antagonist, I have built and tested models of its molecular mechanism of action as well. Bolstering conclusions of previous studies of mammalian c-Jun in cell culture, my data indicate that N-terminal phosphorylation is not an on/off switch, but rather it increases Jun stability for its activity as a component of the AP-1 transcription factor. raw mutants exhibit both high levels of Jun protein and an accumulation of phosphorylated Jun (P-Jun), and my data point to a role for Raw in effecting the Jun:P-Jun ratio via mediation of Jun degradation. In deciphering the mechanism of Raw function, we are gaining significant new insights into previously unrecognized mechanisms of JNK signaling regulation. Understanding these mechanisms will be important for dissecting the etiology of developmental abnormalities and diseases, such as cancer, which hinge on the Goldilocks effect, having just the right amount of signaling at just the right time.
Type Text
Publisher University of Utah
Subject MESH Drosophila melanogaster; Mitogen-Activated Protein Kinases; Drosophila; Drosophila Proteins; Epidermis; JNK Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinases; Embryonic Development; Embryonic Structures; Embryonic Induction; Gene Expression Regulation, Developmental; Morphogenesis; Mitogen-Activated Protein Kinase Phosphatases; MAP Kinase Signaling System; Transcription Factors; Signal Transduction
Dissertation Institution University of Utah
Dissertation Name Doctor of Philosophy
Language eng
Relation is Version of Digital reproduction of Jun Signaling During Drosophila Development
Rights Management Copyright © Molly Christine Jud 2016
Format Medium application/pdf
Format Extent 31,150,089 bytes
Source Original in Marriott Library Special Collections
ARK ark:/87278/s6187xw2
Setname ir_etd
Date Created 2019-10-08
Date Modified 2019-10-30
ID 1468112
Reference URL https://collections.lib.utah.edu/ark:/87278/s6187xw2
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