Investigating The Roles of The P63 Isoforms In The Microrna Biogenesis Pathway

<p>MicroRNAs play roles in various biological processes like development, tumorigenesis, metastasis and pluripotency. My thesis work has demonstrated roles for <em>p63, </em>a <em>p53</em> family member, in the upstream regulation of microRNA biogenesis. The <em>p63</em> gene has a complex gene structure and has multiple isoforms. The <em>TAp63</em> isoforms contain an acidic transcription activation domain. The <em>ΔNp63</em> isoforms, lack the TA domain, but have a proline rich region critical for gene transactivation. To understand the functions of these isoforms, the Flores lab generated <em>TAp63</em> and <em>ΔNp63 </em>conditional knock out mice. Using these mice and tissues and cells from these mice we have found that <em>TAp63</em> transcriptionally regulates <em>Dicer</em> while <em>ΔNp63</em> transcriptionally regulates <em>DGCR8</em>. <em>TAp63^-/-</em> mice are highly tumor prone. These mice develop metastatic mammary adenocarcinomas, squamous cell carcinomas, and lung adenocarcinomas to distant sites including the liver, lungs, and brain. I found that <em>TAp63</em> suppresses metastasis by transcriptionally activating <em>Dicer. TAp63</em> and <em>Dicer</em> levels were very low or lost in high grade human tumors like mammary adenocarcinomas, squamous cell carcinomas, and lung adenocarcinomas. Expression of <em>Dicer</em> in these tumor cell lines reduced their invasiveness. Using <em>ΔNp63 ^-/-</em> mice, I found that <em>ΔNp63</em> transcriptionally activates <em>DGCR8,</em> resulting in a miRNA profile that is critical to reprogram cells to pluripotency. Analysis of epidermal cells derived from <em>ΔNp63 ^-/- </em>mice revealed that these cells expressed markers of pluripotency, including Sox2, Oct 4 and Nanog; however, genome-wide analysis revealed a novel profile of genes that are common between <em>ΔNp63 ^-/- </em>epidermal cells and embryonic stem cells. I also found that mouse cells depleted of <em>ΔNp63</em> form chimeric mice and teratomas in SCID mice, demonstrating that <em>ΔNp63 </em>deficient cells are pluripotent. Further, I found that restoration of DGCR8 in <em>ΔNp63 ^-/- </em>epidermal cells reduces their pluripotency and induces terminal differentiation. I also demonstrated that iMS (induced multipotent stem) cells could be generated using human keratinocytes by knockdown of ∆<em>Np63 </em>or <em>DGCR8.</em> Taken together, my work has placed <em>p63</em> and its isoforms at a critical node in controlling miRNA biogenesis.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation (PhD)

Year dc:date.available

2013

Author dc:creator

• Chakravarti, Deepavali

Contributors dc:contributor

• Dr. Elsa Flores
• Dr. Jeffrey Rosen
• Dr. Pierre McCrea

• microRNA
• p63
• tumorigeneis
• iPS cells
• Dicer
• DGCR8
• Biology
• Cancer Biology
• Cell Biology
• Other Cell and Developmental Biology

Repository record dc:identifier

https://digitalcommons.library.tmc.edu/utgsbs_dissertations/370

OAI identifier oai:identifier

oai:digitalcommons.library.tmc.edu:utgsbs_dissertations-1405