UT Chem/Biochem Dept

The 2010-2011 Beckman Scholars: Aaron Seo

Faculty Mentor: Professor Andy Ellington Length of term: Summer 10, Fall 10, Spring 11 Honors & Awards:University Honors (Fall 07, Spring 08, Fall 08, Spring 09, Fall 09, Spring 10, Fall 10, Spring 11); College of Natural Sciences Summer Undergradaute Research Fellowship (2009); Unrestricted Endowed Presidential Scholarship (2009); Undergraduate Research Fellowship (2009); Dean's Honored Graduate (2011) Publications: Hall, B., Arshad, S., Seo, K., Bowman, C., Corley, M., Jhaveri, S.D., Ellington, A.D. In vitro selection of RNA aptamers to a protein target by filter immobilization. Curr Protoc Nucleic Acid Chem. 2010 Mar; Chapter 9: Unit 9.3, 1-27; Hall, B., Arshad, S., Seo, K., Bowman, C., Corley, M., Jhaveri, S.D., Ellington, A.D. In vitro selection of RNA aptamers to a protein target by filter immobilization. Curr Protoc Mol. Biol. 2009 Oct; Chapter 24: Unit 24.3. Where is he now? Graduated with Bachelor of Science (Biology) with Honors, with Special Departmental Honors in Biology, May 2011, and with a Bachelor of Arts (Plan II Honors), May 2011. Aaron is currently in the MD/PhD program at the University of Washington in Seattle. How can I contact him? aaronseo at gmail.com

Beckman research project in the Ellington group

Targeting the RNA binding protein Musashi for therapy in tumors of neural origin

Musashi1 (Msi1) is an RNA binding protein (RBP) that contributes to the development of neural tumors and maintenance of the neural stem cell state. This protein regulates post-transcriptional expression of several genes and orchestrates complex signaling networks. Studies in the Penalva lab (UTHSC-SA) indicate that Msi1 interacts with gene transcripts influencing cell proliferation, apoptosis, cycle and differentiation. Knockdown of Msi1 prevents tumor growth of medulloblastoma and glioblastoma cells as xenographs. ¹ Consequently, the knockdown of Msi1 activity is a potentially promising avenue for tumor therapy. The overarching goal of this project is to inhibit Msi1 function in vivo with functional nucleic acid known as aptamers.

This project has three specific aims. The first is to express and purify a full-length Musashi1 protein in vitro. Secondly, several aptamer candidates against Msi1 will be developed. Finally, the therapeutic efficacy of these aptamers will be tested in an in vivo model. The first aim of this project has already been achieved. A maltose binding protein (MBP) and Msi1 fusion construct was constructed to produce a readily soluble form of Msi1. The MBP also served as a protein-purifying marker to separate the desired Msi1 protein from the cell expression lysate. Western blots and RNA-binding assays were then performed to assess proper folding and function. Tests were then performed to assess this protein's binding ability. The main work of the project will begin with the second aim. The purified Msi1 protein will be used in a process known as Systematic Evolution of Ligands by EXponential enrichment (SELEX) to produce a library of candidate 'aptamers'. This iterative process will be performed using 2'-O-methyl modified RNA to enhance stability and protect against in vivo nuclease digestion. The aptamers with the strongest affinity in vitro for the Msi1 target will then go on for further development in vivo.

Finally, in vivo tissue culture models with U251 (human glioma) and Daoy (medulloblastoma) cell lines will be used to determine if targeting Msi1 with RNA aptamers will promote tumor regression. A successfully selected aptamer against Msi1 will knockdown Msi1 activity. In turn, neural tumors requiring Msi1 will be negatively affected. Therefore, an anti-Msi1 aptamer possesses great therapeutic value. In coordination with Dr. Magnus Bergkvist (UAlbany), various modalities for in vivo delivery of the anti-Msi1 aptamer will be pursued in the future. Aptamer selections against Msi1 will also potentially elucidate more specific binding motifs of Msi1 than currently known. Thus, future work can also screen for native sequences that Msi1 binds to. In doing so, a more defined understanding of Msi1's biological mechanisms and cellular functions can be established.

¹Sanchez-Diaz, P.; Burton, T.; Burns, S.; Hung, J.; Penalva, L. Musashi1 modulates cell proliferation genes in the medulloblastoma cell line Daoy. BMC Cancer: 2008, 8, 80.