Defense Date

2004

Document Type

Thesis

Degree Name

Doctor of Philosophy

Department

Biology

First Advisor

John J. Ryan

Abstract

Mast cells have long been appreciated as the primary effector cells in allergy and asthma, and recently have been implicated in other inflammatory diseases. Using high density oligonucleotide probe arrays, we assessed genome-wide transcriptional profiles after FcεRI aggregation for 90 minutes, 5 hours and 24 hours. We describe novel gene regulation in response to FcεRI signaling, including altered expression of CD44, Pari, osteopontin, Nur77, E4BP4, and NDRG 1. In addition, the gene encoding FcεRI β was downregulated 5 hours after mast cell activation according to both microarray analysis and RPA, and western blotting confirmed the downregulation of the beta subunit protein. Moreover, this downregulation of beta mRNA correlated with the decreased FcεRI surface expression after mast cell activation. Very little is known about the transcriptional regulation of the beta subunit of FcεRI. These transcriptome profiling experiments are revealing novel and clinically relevant insight into how FcεRI signaling may be controlled.

Continuing with our focus on how mast cell activation is regulated, we examined the effects of Th2 cytokines on expression of important surface receptors. Murine mast cells co-express the activation receptor FcγRIII and the inhibitory receptor FcγRIIb and can be activated by lgG immune complexes. Using mouse bone marrow-derived mast cells, we report that IL-4 selectively increases FcγRIII expression without altering FcγRIIb. This enhanced expression could be induced by Stat6 activation alone, and appeared to be mediated in part by increased FcγRIIIα protein synthesis without significant changes in transcription. The increase in FcγRIII expression was functionally significant, as it was matched by enhanced FcγR-mediated degranulation and cytokine production. Selective regulation of mast cell FcγR by IL-4 could alter inflammatory lgG responses and subsequently disease severity and progression. Collectively, our studies have used genome-wide screening and reductionist studies to demonstrate mechanisms by which mast cell function is regulated.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

8-9-2016

Included in

Biology Commons

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