Doctor of Philosophy

dissertationAntigen receptor-encoding lymphocytes (i.e., B and T cells) are key mediators of the adaptive immune response. Hence, the developmental and functional programs of these cells are crucial to the sustained viability of metazoans such as mouse and man. One strategy to ensure these cellular programs is through the use of tightly orchestrated networks of gene expression. To preserve these networks, a myriad of proteins function to activate or repress particular sets of genes. The Snail family of transcription factors consists of three members: Snai1 (Snail), Snai2 (Slug), and Snai3 (Smuc). These proteins are conserved throughout evolution and share a high degree of protein sequence homology. While best known for roles in developmental biology and malignancy, members of the family (i.e., Snai2) have been shown to function in hematopoietic progenitor biology. Additionally, the overlapping expression of Snail genes is evident in a multitude of hematopoietic cell types. To test whether Snai2 and Snai3 functioned redundantly in hematopoiesis, germline double knockout animals were generated. Analysis of Snai2/Snai3 germline double knockouts demonstrated imbalances in the development of lymphoid and myeloid lineages, which absolutely required the deletion of both Snai2 and Snai3. These animals were iv also affected nonhematopoietically as evidenced by the almost complete absence of female double knockout progeny and accelerated thymic atrophy. Furthermore, one allele of either Snai2 or Snai3 rescued all phenotypes to a similar degree suggesting that both gene products were haplo sufficient in the ability to compensate for the loss of the other three alleles. Snai2/3 conditional double knockout mice were generated in an effort to better ascertain the hematopoietic cell intrinsic roles of Snai2 and Snai3. Snai2/3 conditional double knockout animals expired at approximately one month of age due to rampant autoimmunity inclusive of both IgM and IgG autoantibodies. Adoptive transfer of wildtype regulatory T cells halted autoimmune pathology, autoantibody production, and rescued animals from death. Importantly, autoimmunity was generated in Snai2 sufficient Rag2-/- animals receiving double knockout bone marrow. These data supported a cell intrinsic role for Snai2 and Snai3 in regulating immune tolerance

Thymus antibody-secreting cells: once forgotten but not lost

Antibody-secreting cells are essential contributors to the humoral response. This is due to multiple factors which include: 1) the ability to secrete thousands of antibodies per second, 2) the ability to regulate the immune response and 3) the potential to be long-lived. Not surprisingly, these cells can be found in numerous sites within the body which include organs that directly interface with potential pathogens (e.g., gut) and others that provide long-term survival niches (e.g., bone marrow). Even though antibody-secreting cells were first identified in the thymus of both humans and rodents in the 1960s, if not earlier, only recently has this population begun to be extensively investigated. In this article, we provide an update regarding the current breath of knowledge pertaining to thymus antibody-secreting cells and discuss the potential roles of these cells and their impact on health

EFEMP1 suppresses malignant glioma growth and exerts its action within the tumor extracellular compartment

<p>Abstract</p> <p>Purpose</p> <p>There are conflicting reports regarding the function of EFEMP1 in different cancer types. In this study, we sought to evaluate the role of EFEMP1 in malignant glioma biology.</p> <p>Experimental Design</p> <p>Real-time qRT-PCR was used to quantify <it>EFEMP1 </it>expression in 95 glioblastoma multiforme (GBM). Human high-grade glioma cell lines and primary cultures were engineered to express ectopic EFEMP1, a small hairpin RNA of EFEMP1, or treated with exogenous recombinant EFEMP1 protein. Following treatment, growth was assayed both <it>in vitro </it>and <it>in vivo </it>(subcutaneous (s.c.) and intracranial (i.c.) xenograft model systems).</p> <p>Results</p> <p>Cox regression revealed that EFEMP1 is a favorable prognostic marker for patients with GBM. Over-expression of EFEMP1 eliminated tumor development and suppressed angiogenesis, cell proliferation, and VEGFA expression, while the converse was true with knock-down of endogenous EFEMP1 expression. The EFEMP1 suppression of tumor onset time was nearly restored by ectopic VEGFA expression; however, overall tumor growth rate remained suppressed. This suggested that inhibition of angiogenesis was only partly responsible for EFEMP1's impact on glioma development. In glioma cells that were treated by exogenous EFEMP1 protein or over-expressed endogenous EFEMP1, the EGFR level was reduced and AKT signaling activity attenuated. Mixing of EFEMP1 protein with cells prior to s.c. and i.c. implantations or injection of the protein around the established s.c. xenografts, both significantly suppressed tumorigenicity.</p> <p>Conclusions</p> <p>Overall, our data reveals that EEFEMP1 suppresses glioma growth <it>in vivo</it>, both by modulating the tumor extracellular microenvironment and by altering critical intracellular oncogenic signaling pathways.</p