The goal of my lab is to utilize genomic and proteomic approaches in normal and malignant hematopoietic cells as well as mouse models to study molecular mechanisms regulating cell fate decisions. Our research specially focuses on studying posttranslational modifications by ubiquitin E3 ligases in self-renewal, differentiation, and transformation. Adult hematopoiesis is maintained throughout life by the hematopoietic stem cell (HSC), which are self-renewing population capable of generating all hematopoietic lineages. Within the bone marrow (BM) the HSCs are quiescent and can signaled to replenish the hematopoietic system in times of stress. Both intrinsic and extrinsic molecular mechanisms such as cytokine signaling and transcription factors play a key role in quiescence, self-renewal, and differentiation. In addition, the ubiquitin proteasome system (UPS), a key modulator of protein stability and function, regulates cell fate decisions adding an additional layer to molecular mechanisms regulating hematopoiesis. Ubiquitin E3 ligases are the substrate-recognizing component of the UPS that target specific proteins, tags them with polyubiquitin chains, and promotes their degradation through the proteasome. One family of E3 ligases is the FBOX family of proteins, which contains about 71 E3 ligases. To date only 15 of the 71 FBOX proteins have a known role in normal or malignant hematopoiesis. We are currently studying a number of FBOX proteins to understand their role in HSC maintenance, differentiation, and malignant transformation.
We also are studying the ubiquitin E3 ligase UBR5. UBR5 is mutated in ~18% of patients with Mantle Cell Lymphoma (MCL). Our work has demonstrated a key role of UBR5 in maturation and activation of B cells, and our future goal is to decipher the molecular mechanism of UBR5 in B cell activation and lymphoma. In addition, we have utilized proteomic approaches to identify key proteins expressed in MCL patients with the goal of identifying potential therapeutic targets. 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. Building from our current projects we aim to further explore the role of ubiquitin proteasome system in regulating self-renewal, differentiation, and malignant transformation by utilizing both proteomic and genomic approaches in normal and malignant hematopoietic populations.
(Selected Publications Since 2010)
1. Hynes-Smith, RW, Wittorf KJ, Buckley, SM. Regulation of normal and malignant hematopoiesis by FBOX ubiquitin E3 ligases. Trends in Immunology. 2020.
2. Swenson, SA., Gilbreath, TJ., Vahle, H., Hynes-Smith, RW., Law, HCH., Woods, NT., Green, MR., Buckley, SM. UBR5 HECT domain mutations identified in mantle cell lymphoma control maturation of B cells. Blood. 2020;136(3):299-312. doi:10.1182/blood.2019002102.
3. 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; https://doi.org/10.3390/cancers11111717
4. 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.
5. 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.
6. 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)
7. 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)
8. 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.
9. 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.
10. 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.
11. Buckley, S. and Verfaillie, C. Regulation of Hematopoiesis. In: Blood and Bone Marrow Pathology, 2nd ed. Elsevier, 63-76, 2011.
12. 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.
13. 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.
(July) Tyler and Karli are awarded UNMC graduate fellowships
(May) Mika graduates with honors at UNL and is off to start her PhD at UCSD
(April) Sam and Tyler's manuscript is accepted in Blood!
(December) Willow defends her thesis. Congrats, Dr. Hynes-Smith!
We are looking for graduate students, and postdoctoral fellows interested in studying the role of the ubiquitin proteasome systems in regulating normal and maliganant hematopoiesis. If interested in our research please email me at Shannon.Buckley@unmc.edu with your CV and statement of research interests.