• Ph.D., Louisiana State University, Baton Rouge, LA, 1997, Biochemistry
  • B.S.N., University of Alabama at Birmingham, Birmingham, AL, 1977, Nursing

Research Interests

Dr. Floyd has a general interest in protein turnover mediated by the ubiquitin-proteasome system. In particular, her laboratory is interested in understanding how the ubiquitin-proteasome pathway affects adipose tissue biology. Research in the laboratory is currently focused on how ubiquitin and ubiquitin-like modifications regulate the activity of the peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear hormone receptor required for the formation and maintenance of adipocytes. Our studies show that the ubiquitin ligase Siah2 selectively regulates PPARgamma activity in adipose tissue while also acting to control obesity-related adipose tissue inflammation, the balance between adipose tissue expansion via hyperplasia or hypertrophy and the link between adipocyte hypertrophy and obesity-induced insulin resistance.

Another area of interest in the laboratory is the impact of botanical supplementation on insulin sensitivity. These studies explore the effects of extracts from Russian Tarragon and Bitter Melon, plants with a long history of ameliorating the symptoms of type 2 diabetes. The studies currently focus on identifying the bioactive components of the botanical extracts that enhance insulin signaling in skeletal muscle and improve glucose metabolism.

Department(s) : John S. McIlhenny Botanical Research Laboraotry and Ubiquitin Biology Laboratory

Selected Publications

  1. Vandanmagsar, B., Yu, Y., Simmler, C., Dang, T.N., Kuhn, P., Poulev, A., Ribnicky, D.M., Pauli, G.F., Floyd, Z.E. (2021)  Bioactive compounds from Artemisia dracunculus, activate AMPK signaling in skeletal muscle. Biomedicine and Pharmacotherapy, 143:112188  PMCID: PMC8516709 doi: 10.1016/j.biopha.2021.112188.
  2. Dang, T.N., Taylor, J.L., Kilroy, G., Yu, Y., Burk, D.H., Floyd, Z.E. (2021) Siah2 is expressed in adipocyte precursor cells and interacts with Ebf1 and Zfp521 to promote adipogenesis. Obesity. 29(1): 98-107 PMCID: PMC7902405 doi: 10.1002/oby.23013
  3. Vaithiyanathan M, Yu Y, Rahnama A, Pettigrew JH, Safa N, Liu D, Gauthier TJ, Floyd ZE, Melvin AT. (2021) Characterization of PMI-5011 on the Regulation of Deubiquitinating Enzyme Activity in Multiple Myeloma Cell Extracts. Biochem Eng J. 166:107834 doi: 10.1016/j.bej.2020.107834.
  4. Burke SJ, Taylor JL, Batdorf HM, Noland RC, Burk DH, Yu Y, Floyd ZE, Collier JJ. (2020) The Ubiquitin Ligase SIAH2 Negatively Regulates Glucocorticoid Receptor Activity and Abundance. Biomedicines Dec 30;9(1):22. PMCID: PMC7823448 doi: 10.3390/biomedicines9010022. 
  5. Yu, Y., Simmler, C., Kuhn, P., Poulev, A., Raskin, I., Cefalu, W. T., Ribnicky, D., Floyd, Z.E., Pauli, G.F. (2019) The DESIGNER approach helps decipher the hypoglycemic bioactive principles of Artemisia dracunculus (Russian Tarragon). Journal of Natural Products. December 27; 82 (12): 3321-3329. PMCID: PMC7076913 doi: 10.1021/acs.jnatprod.9b00548
  6. Ghosh, S., Taylor, J.L., Mendoza, T.M., Dang, T., Burk, D.H., Yu, Y., Kilroy, G., Floyd, Z.E. (2019) Siah2 exerts sex-dependent effects on metabolic and inflammatory remodeling in adipose tissue. BMC Biology of Sex Differences. April 15; 10(1):19. PMCID: PMC6466809 doi: 10.1186/s13293-019-0233-y 
  7. Xu B, Allard C, Alvarez-Mercado AI, Kim JH, Hewitt SC, Urano R, Korach KS, Levin ER, Arvan P, Floyd, ZE, Mauvais-Jarvis F. Estrogens promote misfolded proinsulin degradation to protect insulin production and delay diabetes. 2018; Cell Reports. July 3; 24:181-196. PMCID: PMC6092934 doi: 10.1016/j.celrep.2018.06.019.
  8. Kilroy G, Burk DH, Floyd, ZE. Siah2 mediates early events in commitment to an adipogenic pathway. Journal of Biological Chemistry. 2016; Dec 30; 291(53): 27289-27297. PMCID PMC5207155 doi: 10.1074/jbc.M116.744672
  9. Kilroy G, Carter LE, Newman S, Burk DH, Manuel J, Moller A, Bowtell DD, Mynatt RL, Ghosh S, Floyd ZE. The ubiquitin ligase Siah2 regulates obesity-induced adipose tissue inflammation. Obesity 2015; 23: 2223-2232. PMCID: PMC4633373 doi: 10.1002/oby.21220.
  10. Kilroy SG, Kirk-Ballard H, Carter LE, Floyd ZE. The ubiquitin ligase Siah2 regulates PPARgamma activity in adipocytes. Endocrinology 2012; 153 (3): 1206-1218. PMCID: PMC3281538. doi: 10.1210/en.2011-1725
  11. Floyd ZE and Stephens JM. Controlling a master switch of adipocyte development and insulin sensitivity: Covalent modification of PPARgamma. Biochem Biophys Acta 2012; 1822: 1090-1095. PMCID: PMC3355475 doi: 10.1016/j.bbadis.2012.03.014
  12. Kilroy SG, Burk DH, Floyd ZE. High efficiency siRNA transfection of adipocytes using “reverse transfection”. PLoS One 2009; 4(9) e6940. PMCID: PMC2736387 doi: 10.1371/journal.pone.0006940
  13. Kilroy SG, Zhang X, Floyd ZE. PPARgamma AF-2 domain functions as a component of a ubiquitin-dependent degradation signal. Obesity 2009; (4): 665-73. PMCID: PMC2585986 doi: 10.1038/oby.2008.616

Complete list of publications: