Adult and pluripotent stem cell research not only has huge potential for the future of regenerative medicine, but also holds promise to elucidate pathways altered in malignant transformation due to parallels between stem cells and cancer. Embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC) exhibit the rare characteristics that they can contribute to all three germ layers in vivo and are capable of self-renewal in vitro. Where as, one example of adult stem cell, the hematopoietic stem cell (HSC), maintains hematopoiesis throughout life and has the potential to both self-renew and differentiate to the multiple cell lineages of the hematopoietic system. An intimate balance between self-renewal, differentiation and quiescence is required to maintain hematopoiesis. Disruption of this balance can result hematopoietic malignancy, including acute myeloid leukemia (AML). Both intrinsic and extrinsic molecular mechanisms such as cytokine signaling and transcription factors play a key role in stem cell fate decisions. However recent studies by our lab and others have suggested that ubiquitin proteasome system (UPS), a key modulator of protein stability and function, also regulates self-renewal, lineage specification, and malignant transformation adding an additional layer to molecular mechanisms regulating stem cells.

The research interest of the lab centers on the molecular mechanisms regulating stem cell fate decisions that may also be linked to cancer. My goal is to utilize genomic and proteomic approaches to identify key ubiquitin ligases and their substrates that regulate mechanisms of pluripotency, self-renewal, differentiation, and hematopoietic malignant transformation. The dynamic reversibility of the ubiquitin modification (by kinases, phosphatases, E3 ligases and de-ubiquitinases) and recent success of a UPS inhibitor (Velcade) for the treatment of multiple myeloma and mantle cell lymphoma proves the translational importance of the UPS system. The UPS is amenable to molecule targeting, opening the way for possible future therapeutics. This suggests that targeting of specific elements of the UPS could lead to future breakthroughs in both basic research and cancer therapy by leading to more efficient generation of induced pluripotent stem cells, promoting lineage differentiation for cell therapy, and provide potential targets for drug discovery.


Shannon Buckley

Assistant Professor

University of Nebraska Medical Center

Department of Genetics, Cell Biology and Anatomy


Samantha Swenson

Postdoctoral Fellow

University of Nebraska Medical Center

Department of Genetics, Cell Biology and Anatomy


Tyler Gilbreath

Graduate Student

University of Nebraska Medical Center

Department of Genetics, Cell Biology and Anatomy


Karli Wittorf

Graduate Student

University of Nebraska Medical Center

Department of Genetics, Cell Biology and Anatomy


Alyssa Castle

Masters Student

University of Nebraska Medical Center

Department of Genetics, Cell Biology and Anatomy


Mika Caplan

Undergraduate Student

University of Nebraska Medical Center

Department of Genetics, Cell Biology and Anatomy



1. Swenson, SA., Gilbreath, TJ., Vahle, H., Hynes-Smith, RW., Law, HCH., Woods, NT., Green, MR.,Buckley, SM. E3 Ligase UBR5 HECT domain mutations in lymphoma control maturation of B cells via alternative splicing. bioRxiv 732180; doi:

2. Hynes-Smith, RW., Swenson, SA., Vahle, H., Wittorf, KJ., Caplan, Amador, C., Hyde, RK., Buckley, SM. Loss of FBXO9 enhances proteasome activity and promotes aggressiveness in acute myeloid leukemia. Cancers 2019, 11(11), 1717;

3. Quadros, R, Miura, H, Harms, DW, Akatsuka, H, Sato, T, Aida, T, Redder, R, Richardson, GP, Inagaki, Y, Sakai, D, Buckley, SM, Seshacharyulu, P, Batra, SK, Behlke, MA, Zeiner, SA., Jacobi, AM, Izu, Y, Thoreson, WB, Urness, LD, Mansour, SL, Ohtsuka, M, and Gurumurthy, CB. A robust method for the one-step generation of mice carrying conditional and insertion alleles using long ssDNA donors and CRISPR ribonucleoproteins. Genome Biology. Genome Biology. 2017; 18:92.

4. Strikoudis, A, Lazaris, C, Trimarchi, T, Galvao Neto, AL, Yang, Y, Ntziachristos, P, Rothbart, S, Buckley, S, Dolgalev, I, Stadtfeld, M, Strahl, BD, Dynlacht, BD. Tsirigos, A, and Aifantis, I. Regulation of transcriptional elongation in pluripotency and cell differentiation by the PHD-finger protein Phf5a. Nature Cell Biology. 2016 Oct 17.

5. Gao, J*, Buckley, SM*, Cimmino L, Guillamot M, Strikoudis A, Cang Y, Goff SP, Aifantis I. The CUL4-DDB1 ubiquitin ligase complex controls adult and embryonic stem cell differentiation and homeostasis. Elife. 2015 Nov 27;4. pii: e07539. doi: 10.7554/eLife.07539. PubMed PMID: 26613412. (*contributed equally to the manuscript)

6. Reavie, LR.*, Buckley, SM.*, Loizou, E, Takeishi, S., Abdel-Wahab, O., Aranda-Orgilles, B., Ndiaye-Lobry, D., Ibrahim, S., Nakayama, KI., and Aifantis, I. Regulation of c-Myc ubiquitination controls chronic myelogenous leukemia initiation and progression. Cancer Cell. 2013; 23(3):362-375. (*contributed equally to the manuscript)

7. Khurana, S., Margamulijana, L., Joseph C., Schouteden, S., Buckley, SM., and Verfaillie CM. Glypican-3 mediated inhibition of CD26 by TFPI: a novel mechanism in hematopoietic stem cell homing and maintenance. Blood. 2013; 121(14):2587-95.

8. Khurana, S., Buckley, S., Schouteden, S., Ekker, S., Petryk, A., Delforge, M., Zwijsen, A., and Verfaillie CM. A novel role of BMP4 in adult hematopoietic stem and progenitor cell homing via Smad independent regulation of Integrin-α4 expression. Blood. 2013; 121(5):781-790.

9. Buckley, SM., Aranda-Orgilles, B., Strikoudis, A., Apostolou, E., Loizou, E., Moran-Crusio, K., Farnsworth, CL., Koller, AA., Dasgupta, R., Silva, JC., Stadtfeld, M., Hochedlinger, K., Chen, EI., and Aifantis, I. Regulation of pluripotency and cellular reprogramming by the ubiquitin-proteasome system. Cell Stem Cell. 2012; 11(6):783-798. Comment in: Cell Stem Cell. 2013; 11(6):728-730. UPS Delivers Pluripotency. Okita, Y. and Nakayama, K.

10. Buckley, S. and Verfaillie, C. Regulation of Hematopoiesis. In: Blood and Bone Marrow Pathology, 2nd ed. Elsevier, 63-76, 2011.

11. Buckley, SM., Ulloa-Montoya, F., Abts, D., Oostendorp, R., Dzierzak, E., Ekker, SC. and Verfaillie, CM. Maintenance of HSC by Wnt5a secreting AGM-derived stromal cell line. Experimental Hematology. 2011; 39(1):114-123.

12. Reavie, L., Della Gatta, G., Crusio, K., Aranda-Orgilles, B., Buckley, SM., Thompson, B., Lee, E., Gao, J., Bredemeyer, AL., Helmink, BA., Zavadil, J., Sleckman, BP., Palomero, T., Ferrando, A., and Aifantis, I. Regulation of Hematopoietic Stem Cell Differentiation by a Single Ubiquitin Ligase-Substrate Complex. Nature Immunology. 2010; 11(3):207-15.

13. Sahin, B., Schwartz, RE., Buckley, SM., Heremans, Y., Hu, W., Verfaillie, CM. Isolation and Characterization of Liver Derived Stem Cells from Unmanipulated Rat Liver. Liver Transplantation. 2008; 14(3):333-45.

14. Serafini, M., Dylla, S., Oki, M., Heremans, Y., Jiang, Y., Buckley, SM., Pelacho, B., Burns, T., Frommer, S., Rossi, D., Bryder, D. Panoskaltsis-Mortari, A., O’Shaughnessy, M., Nelson-Holte, M., Weissman, IL., Blazar, BR., Verfaillie, CM. Complete Lymphohematopoietic Reconstitution by Multipotent Adult Progenitor Cells. Journal of Experimental Medicine. 2007; 204(1):129-39.

15. Lakshmipathy, U., Buckley, S., Verfaillie C. Gene transfer via nucleofection into adult and embryonic stem cells. Stem Cell Assays, Methods Molecular Biology. 2007; 407:115-126.

16. Liu B, Buckley SM, Lewis ID, Goldman AI, Wagner JE, van der Loo JC. Homing defects of cultured human hematopoietic cells in the NOD/SCID mouse is mediated by Fas/CD95. Experimental Hematology. 2003; 31(9):824-32.

17. Van der Loo JC, Liu BL, Goldman AI, Buckley SM, Chrudimsky KS. Optimization of Gene Transfer into Primitive Human Hematopoietic Cells of Granulocyte-Colony Stimulating Factor-Mobilized Peripheral Blood Using Low-Dose Cytokines and Comparison of a Gibbon Ape Leukemia Virus Versus an RD114-Pseudotyped Retroviral Vector. Human Gene Therapy. 2002; 13(11):1317-30.


We are looking for graduate students, and postdoctoral fellows interested in studying the role of the ubiquitin proteasome systems in regulating stem cell fate decisions and hematopoietic malignancies. If interested in our research please email me at with your CV and statement of research interests.


Buckley Lab
University of Nebraska Medical Center
Fred and Pamela Buffet Cancer Center, 10-12416
985805 Nebraska Medical Center
Omaha, NE 68198

P: (402) 559-6082
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