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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Identification, isolation and characterization of proinsulin producing thymic cells

Palumbo, Michael O. January 2007 (has links)
The finding that more than 152 tissue-restricted antigens are expressed by thymic medullary epithelial cells is redefining the importance of thymic central tolerance induction in the prevention of autoimmune diseases. One of the tissue-restricted antigens in the thymus is proinsulin, and in both mice and humans, reduced thymic proinsulin levels have been shown to predispose to Type 1 diabetes. Using transgenic mice expressing a functional beta-Galactosidase gene under the regulation of the Ins2 promoter we have determined that between 1-3% of all medullary thymic epithelial cells express proinsulin and that these cells are frequently part of the Hassall's Corpuscles like structures in mice. Using a cross between the beta-Galactosidase expressing mice and Immortomice (expressing SV40 large T Antigen under the regulation of the MHC I promoter), we have isolated and cultured two proinsulin and two non-proinsulin producing medullary epithelial cell lines. Microarray analysis and RT-PCR analysis of the cell lines revealed the over-expression of approximately 50 genes (>4 fold or more) in the proinsulin producing lineage, versus the non proinsulin producing lineage, and approximately half the over-expressed genes can be considered tissue-restricted antigens. We do not find any evidence for chromosomal clustering of the over-expressed genes nor do we report the expression of any other pancreatic n-cell antigens or specific pancreatic proinsulin regulatory proteins (Pdx-1, Glut-2 or GCK) within the proinsulin producing cell lines but we do detect their expression in whole thymus. Our results suggest that chromosomal clustering is not a phenomenon associated with thymic tissue-restricted antigen expression and that the mechanisms allowing for thymic tissue-restricted antigen expression are not related to the expression mechanisms of such antigens in peripheral tissues.
2

Identification, isolation and characterization of proinsulin producing thymic cells

Palumbo, Michael O. January 2007 (has links)
No description available.

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