Graduation Date

Fall 2018

Document Type

Thesis

Program

Master of Science degree with a major in Biology

Committee Chair Name

Dr. Amy Sprowles

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. John W. Steele

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Jacob P. Varkey Punnamkuzhyil

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Dr. Bruce A. O’Gara

Fourth Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Biology

Abstract

cJun is a transcription factor associated with proliferation and growth. Recent evidence has shown it plays a role in cell fate decision making of embryonic stem cells and correlates with changes in Oct4 expression, an important marker for pluripotency. There are multiple Oct4 isoforms that arise from alternative splicing and alternative translation. Oct4A is the variant most frequently associated with pluripotency, while evidence suggests that Oct4B variants have roles in potency as well as stress responses.

We aimed to study the effect of cJun over expression in murine embryonic stem cells on Oct4 gene expression through two methods: transient transfection of a pLVX cJun plasmid and treatment with nocodazole. We hypothesized that cJun expression would be increased with both of these methods and that these increases would affect Oct4 gene expression, which would affect the expression of the potency markers Nanog and Sox2 and possibly the expression of germ layer markers Brachyury, Sox1, Gata6, and Gata4. The unphosphorylatable cJun mutant L40/42A was also transfected to assess the role of cJun transcriptional activity on these processes. Our results revealed a trend where increased cJun correlated with changes in Oct4 variant expression that correlate with cJun transcriptional activity. Nanog expression appeared unaffected by transfection, but decreased with nocodazole treatment. Sox2 expression appeared to increase slightly with transfection, but remained relatively unaffected by nocodazole treatment. cJun overexpression through transfection increased endoderm markers Gata6 and Gata4, which correlates from other data in our laboratory that shows overexpression of cJun increases cardiomyocyte differentiation of mES cells (Brewer 2017). Further studies will better elucidate the relationship between cJun, the Oct4 variants, and their effect on potency and cell fate.

Citation Style

Council of Science Editors (CSE)

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