The objective of this study was to further determine the distribution of
selenoprotein W (SeW) in tissues from rats and sheep fed different selenium levels and to
search for the possible functions of this protein. In the rat study a total of 28 rat tissues
were examined and SeW was found in all of the tissues except for liver, thyroid,
pancreas, pituitary and eyes regardless of the level of Se fed. SeW was not detected in
heart, lungs, prostate, esophagus, small intestine, tongue, skin diaphragm and skeletal
muscle from selenium deficient rats, but was present in these tissues when the two higher
levels of selenium (0.1 and 4.0 mg/kg) were fed. SeW has the highest expression in
muscle, brain, testis and spleen when selenium is adequate. Interestingly, selenium
deficiency resulted in undetectable SeW levels in heart and muscle from deficient sheep
and rats, but the content in brain was unaffected by selenium status. Second generation
selenium depleted and repleted rats indicated that the expression of SeW in cortex and
cerebellum was not significantly affected by selenium, but selenium increased its levels
in thalamus. Cortex had the highest SeW expression among the three parts of the rat
brain. SeW levels in muscle, spleen, skin and testis were undetectable in weanling rats,
but became detectable after 6 weeks of selenium repletion. Studies with various brain cell
cultures indicated that Se appears to be metabolized differently by different brain cell types. As demonstrated in neuroblastoma and glial cells, glutathione peroxidase (GPX)
activity decreased at a faster rate than SeW with neuroblastoma cells whereas SeW
decreased at a faster rate than GPX activity in glial cells when selenium was removed
from the media. Since other work showed that glutathione was bound to SeW, it was
speculated that it has antioxidant function similar to other selenoproteins. SeW
overexpressed and underexpressed cell lines were established by DNA recombinant
techniques. There was a greater survival rate of overexpressed cells when incubated with
2,2'-Azobis (2-amidinopropane) dihydrochloride (AAPH) than control cells, suggesting
SeW possibly has an antioxidant function. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33538 |
| Date | 27 May 1998 |
| Creators | Sun, Yu, 1963- |
| Contributors | Whanger, Philip D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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