Date of Award

5-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Biological Sciences

Committee Member

Charles D. Rice, Ph.D., Committee Chair

Committee Member

Yanzhang Wei, Ph.D

Committee Member

Thomas R. Scott, Ph.D.

Abstract

Cellular vaults are ubiquitous 13 mega Da multi-subunit structures that may have a role in nucleo-cytoplasmic transport. Seventy percent of the vault's mass consists of a ≈100 kDa protein, the major vault protein (MVP). Elevated MVP was first recognized as lung resistance protein (LRP) because metastatic lymphoid tumor cells in the lung over-expressed this protein following acquired resistance to traditional chemotherapy. Previous work in our lab screened a cDNA library constructed from channel catfish monocytes (42TA cells), whereby MVP was sequenced and found to be highly conserved compared to other vertebrates. This sequence was recently expressed as a recombinant protein for generating a panel of specific monoclonal antibodies (mAbs), resulting in hybridoma 3F9 secreting a mAb that recognizes MVP in all fish examined to date, as well as mammalian cells. Using immunohistochemical (IHC) approaches, mAb 3F9 staining indicates that MVP, and presumably intact vaults, is highly expressed in epithelial cells, cells of the immune system, and endothelial cells in various organs. Quantitative RT-PCR primers for channel catfish MVP were designed and used to show that gene expression can be easily detected and quantified in the well-characterized channel catfish ovarian (CCO) cell line following treatment with different classes of pharmacological agents. Using mAb 3F9, we show that MVP protein levels, and presumably intact vaults, reflect high levels of MVP gene expression in catfish. In another study, we examined MVP protein expression in tissues from Atlantic killifish collected at the Atlantic Wood (AW) site on the southern branch of the Elizabeth River of VA - a US-EPA Superfund site. Killifish from the AW site are adapted to high concentrations of PAHs, display a PAH-resistant phenotype, and have a high incidence of liver lesions and neoplasia. MVP expression is highly variable in AW fish compared to a relatively clean reference site, and many advanced neoplastic liver lesions in AW killifish show high expression, and even nuclear location in the most advanced lesions. The true function of cellular vaults remains unknown, but the results of this study support a role in acquired resistance to intracellular toxic compounds and/or metabolites, and may be a shuttle between the cytoplasm and nucleus.

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