Date of Award

12-2008

Level of Access

Campus-Only Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biochemistry and Molecular Biology

Advisor

John P. Sundberg

Second Committee Member

Gregory Cox

Third Committee Member

Harm HogenEsch

Abstract

The "chronic proliferative dermatitis" (cpdm) phenotype was first reported in laboratory mice in 1993. Spontaneous mutations in the mouse Sharpin gene were discovered independently in two different strains of laboratory mice carrying the cpdm mutation by fine mapping and direct sequencing. Subsequent rescue of the mutant phenotype by complementation with a bacterial artifical Chromosome containing the mouse Sharpin gene was successful. The region of mouse Chromosome 15 containing Sharpin is highly conserved and orthologous to human Chromosome 8q24.3. However, little is known about Sharpin, and it has not previously been associated with lymphoid architecture or immune system abnormalities. Preliminary work to elucidate the role of Sharpin in the immune system included histological studies using hematoxylin and eosin stained, paraffin-embedded sections and whole mount immunohistochemistry of the small intestine to establish that Peyer's patch anlagen develops in mutant mice, but normal developmental patterns are lacking and the tissue is rapidly effaced by granulocytic infiltrates. The lymphoid tissue regresses as the mouse matures. Immunofluorescence assays of the spleen and Peyer's patches determined that normal segregation and expansion of B and T cell zones fails in Sharpincpdm mutant mice. Nonablative bone marrow or spleen cell transplantation into neonatal Sharpin-deficient recipient mice resulted in engraftment of donor lymphocytes but did not rescue Peyer's patch development or normal segregation of B and T cells in the secondary lymphoid organs, indicating that the expression of SHARPIN in hematopoietic cells alone is not sufficient to maintain these structures. This work demonstrates the requirement for SHARPIN in the normal development of lymphoid architecture and the maintenance of Peyer's patches. Efforts to elucidate the mechanism by which the Sharpin gene product contributes to the normal development of secondary lymphoid organs, B cell class switching, and control of innate inflammation are ongoing. Future plans include identifying the specific molecular pathways in which Sharpin plays a role, by co-immunoprecipitation and identification of its binding partners in lymphoid tissues and the epidermis.

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