Document Type

Dissertation

Date of Degree

Fall 2011

Degree Name

PhD (Doctor of Philosophy)

Degree In

Anatomy and Cell Biology

First Advisor

John D. Colgan

Abstract

B and T lymphocytes are critical to the adaptive immune response against invading microorganisms. B and T cells develop in the bone marrow and thymus, respectively, and initiate a series of proliferative responses once they encounter their cognate antigen in the peripheral lymphoid organs. These developmental and functional processes are controlled by different networks of transcriptional regulators that repress and activate gene expression. Identifying proteins that activate or repress specific genes and integrating these proteins into their transcriptional networks is critical to understanding lymphocyte development and function. The study of B lymphopoiesis and CD4+ T cell functional responses has greatly increased our understanding of how transcriptional regulators and other proteins cooperate to specify cell fates and responses. While many of the key components of these protein networks have been defined, several factors have yet to be described.

Chemically induced random mutagenesis is a powerful tool for identifying genes that have critical biological functions. Justy mutant mice were generated by injecting wild-type mice with of N-Ethyl-N-Nitrosourea (ENU), a mutagen, which generated a unique point mutation in the mouse Gon4-like (Gon4l) gene. This mutation was found to specifically blunt B cell development and impair the functional responses of CD4+ T cells. Given that the Gon4l protein contains domains implicated in transcriptional regulation and B lymphopoiesis and T cell responses are regulated transcriptionally, the aim of this project was to characterize T and B lymphocyte populations from Justy mice and provide insights into the mechanisms underlying the regulation of gene expression during these biological processes. The work presented in this dissertation demonstrates that the protein encoded by Gon4l is essential for B lymphopoiesis, likely through the repression of alternate lineage genes. This work also shows that in CD4+ T cells, decreased Gon4l protein expression results in reduced levels of proliferation in response to exogenous IL-2 or T cell receptor (TCR) engagement. Additionally, Justy mutant CD4+ T cells display a reduced ability to generate IFNγ-producing cells in response to Th1 polarization in vitro. Collectively, these defects correlate with elevated levels of genes known to specifically inhibit the above developmental and functional processes. Thus, this dissertation proposes that Gon4l acts as a transcriptional repressor within the protein networks controlling B lymphopoiesis and CD4+ T cell responses.

Keywords

B cell, Cell signaling, Development, Lymphocyte, T cell, Transcription factor

Pages

xiv, 149 pages

Bibliography

Includes bibliographical references (pages 132-149).

Comments

This thesis has been optimized for improved web viewing. If you require the original version, contact the University Archives at the University of Iowa: http://www.lib.uiowa.edu/sc/contact/.

Copyright

Copyright 2011 Isaiah Luke Hankel

Included in

Cell Anatomy Commons

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