In the course of thymocyte development, progenitor T cells from the bone marrow migrate to the thymus where they are positively or negatively selected depending on specific molecular interactions. This selection process takes place at a developmental stage where immature thymocytes are exquisitely sensitive to glucocorticoid exposure and they readily succumb in a process referred to as apoptosis. Glucocorticoid-induced thymocyte apoptosis has been shown to require RNA and protein synthesis, which indicates an active death-inducing process. One molecular event that occurs in immature thymocytes during this process is the rapid and high induction of a glucocorticoid-induced gene called GIG18. Within this dissertation, I identify a GIG18 open reading frame (ORF), that encodes a ∼50KDa protein, that is 93% conserved between mouse and human. By expressing this ORF with a 6X-Histidine tag, I was able to purify the GIG18 protein on a nickel affinity column to generate a rabbit polyclonal antibody. The western blot showed glucocorticoid-regulated induction of two protein bands, a mildly induced band at the predicted size (50KDa) and a highly induced band at ∼68KDa. Further analysis of mouse and human expressed sequence tags (ESTs) indicated that alternate transcripts produced from this gene, are likely account for the 68KDa band. The mouse GIG18 ORF identified in our lab maps to human chromosome 7 and contains 8 exons covering ∼250 Kb. This region of human chromosome 7 corresponds to homologous sequence on mouse chromosomes 5 and 6. I also show that GIG18 belongs to family of three genes encoded in the human genome with two extensive regions of conserved sequence. Expression analysis of the GIG18 ORF in thymocytes and HeLa cells did not reveal any obvious cellular morphological variations or functions induced by this gene. I conclude this dissertation with a discussion of potential roles that GIG18 may play within the context of thymocyte development.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/280642 |
| Date | January 2001 |
| Creators | Leptich, Thomas David |
| Contributors | Miesfeld, Roger L. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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