Author ORCID Identifier
0000-0002-5121-5234
Date of Graduation
5-2021
Document Type
Dissertation (PhD)
Program Affiliation
Immunology
Degree Name
Doctor of Philosophy (PhD)
Advisor/Committee Chair
R. Eric Davis, M.D.
Committee Member
Michael Curran, Ph.D.
Committee Member
Michael Green, Ph.D.
Committee Member
Pierre McCrea, Ph.D.
Committee Member
Shao-Cong Sun, Ph.D.
Abstract
Diffuse Large B Cell Lymphoma (DLBCL) is the most common aggressive hematologic malignancy in adults, but despite recent advances in treatment, many patients today still face poor outcomes. Of the two types of DLBCL, activated B-cell (ABC) and germinal center B-cell (GCB), patients diagnosed with the ABC subtype especially face a lack of effective treatment options. Unlike GCB-DLBCL, ABC-DLBCL is characterized by chronic antigen-driven signaling by the B-cell receptor (BCR), indicating an escape from immunologic tolerance mechanisms that normally regulate self-reactive B cells. While recent therapies have focused on inhibiting the kinases that propagate BCR signaling with mixed success, we believe that investigation into restoration of immunological tolerance may provide significant scientific and biological knowledge and lead to the development of novel therapies. Here, we identified the gene PAG1, which is expressed in normal B cells and GCB-, but not ABC-DLBCL, as a potential regulator of BCR signaling and mediator of immunological tolerance. We investigated the role of PAG1 in DLBCL cells and found that PAG1 regulates BCR signaling in both GCB and ABC contexts, and further that the forced expression of PAG1 is highly toxic to ABC-DLBCL lines, triggering reduction in constitutive antigen signaling and reorganization of the BCR. These results hint at a novel role for PAG1 in the maintenance of B cell tolerance and in the pathogenesis of ABC DLBCL. In the course of studying the role of PAG1 in BCR signaling, we also developed methods to catalog the activity of key mediators of BCR activation through the use of a Förster resonance energy transfer (FRET) based assay in living cells, measuring time-course, dose-response, and kinetic assays by flow cytometry. Together, these studies lay the groundwork for further exploration into the role of PAG1 in B cell biology and for future work to develop therapies which target the toxicity mechanisms that PAG1 activates.
Keywords
PAG1, CBP, DLBCL, BCR, ABC-DLBCL