Date of Award

8-1-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Field of Study

Biomedical Sciences

Department

Graduate School of Biomedical Sciences

First Advisor

Johnny J. He

Second Advisor

Geoffrey Guttmann

Third Advisor

Khalid Timani

Abstract

HIV-1 Tat-interacting protein of 110 kDa, Tip110, has roles in tumor antigen presentation, pre-mRNA splicing, transcription of viral and host genes, and protein degradation. Tip110 is also known to be up-regulated in a variety of cancers and to regulate and/or interact with a variety of transcription factors, oncogenes, and pluripotency factors. As such, Tip110 has been shown to effect pluripotency, proliferation, apoptosis, and the cell cycle when knocked down in vitro. However, the function of Tip110 in embryonic development remains largely uncharacterized.

One early study has shown that loss of a Tip110 ortholog leads to embryonic lethality in zebrafish. Our studies have shown that transgenic mouse embryos lacking expression of a functional Tip110 protein die several days post-implantation in vivo. In the present study, we determined how Tip110 knockout affects mouse embryonic development and investigated the underlying molecular mechanisms. We found that Tip110 loss did not impair embryo growth from the zygote to the blastocyst stage nor did it impair the blastocysts ability to implant into the uterine lining in vivo. Extended culture of blastocysts in vitro revealed that Tip110 loss impaired both blastocyst outgrowth formation and derivation of mouse embryonic stem cells from blastocysts. In vivo embryos could survive until the post-implantation stage where they eventually perished. The premature death of these embryos was characterized by a clear retardation in embryonic development resulting in underdeveloped or more commonly, completely resorbed mouse embryos around 8.5 or 9.5 days post coitum. Microarray analysis of Tip110-/- cells derived from mouse blastocysts revealed that Tip110 loss favored differentiation but not self-renewal, pluripotency, or cell cycling through a complex regulatory network of stem cell factors. Tip110-/- cells also had perturbations in many other signaling and cellular processes including mRNA processing and proteasome degradation. Taken together, these findings document for the first time the lethal effects of complete loss of Tip110 on mammalian embryonic development and suggest that Tip110 is an important regulator of not only embryonic development but also stem cell factors.

Comments

Whitmill, Amanda J., Tip110 is Required for Embryonic Stem Cell Survival and Embryonic Development. Doctor of Philosophy (Biomedical Sciences), June, 2016, 171 pp., 3 tables, 36 illustrations, bibliography, 119 titles.

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