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Characterization of C/EBPs in Mammary Epithelial Cell Biology

Dearth, Lawrence
http://rave.ohiolink.edu/etdc/view?acc_num=osu1038840268

Abstract Details

2002, Doctor of Philosophy, Ohio State University, Molecular, Cellular, and Developmental Biology.
Work from this dissertation has demonstrated that C/EBPbeta is the predominant C/EBPbeta isoform expressed in the normal mouse mammary gland and mouse mammary tumors in vivo. Specific analysis of the C/EBPbeta isoforms demonstrated that LIP protein levels are directly influenced by the protein isolation procedure, indicating that LIP levels are modulated by protein isolation induced proteolysis. C/EBPbeta LIP was not detected in the normal mammary gland, but was detected in mammary tumors. Analysis of the affect of C/EBPbeta LIP overexpression on mammary epithelial cell proliferation and differentiation demonstrated that LIP did not have a significant effect on proliferation, but abrogated differentiation by an extracellular matrix-independent mechanism. This work has lead to the model that disruption of the differentiation program by LIP allows mammary epithelial cells to undergo continued proliferation, which may result in breast cancer. In addition, we demonstrated for the first time that C/EBPdelta mRNA exhibits a relatively short half-life in G0 growth arrested mouse and human mammary epithelial cells. Results of oligo/RNase H cleavage analysis and RACE-PAT revealed a short C/EBPdelta mRNA half-life in addition to demonstrating that the C/EBPdelta mRNA poly(A) tail is relatively short. The poly(A) tail length is not modulated during C/EBPdelta mRNA degradation, which suggests a deadenylation-independent pathway. The C/EBPdelta protein also exhibited a short half-life in G0 growth arrested mouse and human mammary epithelial cells. Results of ubiquitination inhibitor studies demonstrated that C/EBPdelta protein is degraded in an ubiquitin-dependent manner, exclusively in the nucleus during G0 growth arrest. Finally, replacement of the C/EBPdelta 3’ untranslated region (UTR) with the bovine growth hormone 3’ UTR increased C/EBPdelta mRNA half-life, implying a role for the 3’ UTR in the regulation of C/EBPdelta mRNA stability. Analysis of the C/EBPdelta 3’ UTR identified two potential AREs. RNA electromobility shift assays (REMSAs) demonstrated that the C/EBPdelta mRNA 3’ UTR binds a trans-acting factor(s) present in G0 growth arrested, but not growing mammary epithelial cell lysates. Competition analysis revealed that the 5’ ARE is necessary for trans-acting factor binding. UV-binding analysis revealed that the specific RNA/protein complex observed upon REMSA analysis had a mass of approximately 35 kDa.
James DeWille (Advisor)
181 p.
Biology, Molecular
C/EBPs; mammary epithelial cells; posttranscriptional regulation; posttranslational regulation

Recommended Citations

Citations

  • Dearth, L. (2002). Characterization of C/EBPs in Mammary Epithelial Cell Biology [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1038840268

    APA Style (7th edition)

  • Dearth, Lawrence. Characterization of C/EBPs in Mammary Epithelial Cell Biology. 2002. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1038840268.

    MLA Style (8th edition)

  • Dearth, Lawrence. "Characterization of C/EBPs in Mammary Epithelial Cell Biology." Doctoral dissertation, Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1038840268

    Chicago Manual of Style (17th edition)

osu1038840268
787
© 2002, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.