TitleC-rel deficiency and its effect on proliferation and survival in immunodeficient lymphoblastic B cells
NameValentin Acevedo, Anibal J. (author), Covey, Lori (chair), Werlen, Guy (internal member), Jacinto, Estela (internal member), Gelinas, Celine (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectCell and Developmental Biology,
Immunological deficiency syndromes,
DescriptionThe analysis of lymphocytes from immunodeficient patients has provided valuable insights into understanding the development and function of the immune system. In particular, studies of patients with Hyper IgM syndrome, a rare immunodeficiency resulting from defects in both CD40L in activated CD4+ T cells and components of the CD40 signaling pathway in B cells have been crucial for the elucidation of molecular pathways involved in the activation, proliferation and differentiation of B lymphocytes. Previously our lab generated EBV transformed lymphoblastic cells with inducible LMP1 from a female patient diagnosed with non-X-linked HIGM (Pt1-LCLtet cells, Pt1). Analysis of these cells revealed a CD40-specific activation defect associated with low c-Rel levels. To broaden our understanding of the Pt1 phenotype we analyzed c-Rel expression and found that low c-Rel levels were the outcome of depressed transcriptional activation of the c-rel promoter. In-vivo analysis revealed that low transcription was coincident with increased p65 activity at the c-rel promoter although this was insufficient to induce normal c-Rel expression. Further investigations of the Pt1-LCLtet cells uncovered a proliferation and survival defect characterized by reduced c-Myc transcription and increased levels of caspase-4. This defect was complemented after c-Rel overexpression, supporting a causative role for c-Rel deficiency in the observed phenotype of the Pt1-LCLtet cells. The LCLtet cells were further utilized as a model system for the independent analysis of LMP1 and CD40 signaling. These studies revealed several outcomes of LMP1 signaling in the biology and function of CD40. Specifically, LMP1 signaling induced a unique pattern of CD40 phosphorylation as well as the expression of several novel CD40 isoforms. Moreover, when CD40 and LMP1 were activated simultaneously a synergistic effect was observed towards p65 and p38 phosphorylation suggesting a functional interaction that might occur during early stages of EBV infection or malignant transformation where both LMP1 and CD40 are co-expressed in the infected cell. Collectively, our results demonstrate that a majority of the defects displayed in the Pt1-LCLtet cells are a result of reduced c-Rel expression. Importantly, these results ascribe c-Rel a novel function as a negative regulator of caspase-4 expression and a putative key player in the control of cell survival in EBV-immortalized B cells.
NoteIncludes bibliographical references
Noteby Anibal J. Valentin Acevedo
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.