Ubiquitin Biology


Elizabeth Floyd, Ph.D.

Z. Elizabeth Floyd, PhD


Laboratory Members

pradip panta, PhD

Pradip Raj Panta, PhD

Candida Rebello, PhD, RD

Matthew C. Scott, PhD

Jacob Mey, PhD, RD

Jennifer Doucet, BS

Wagner Dantas, PhD

Emily O'Quin, student

Research Focus

Our laboratory is focused on understanding how the ubiquitin-proteasome pathway affects adipose tissue biology and the role of adipose tissue in obesity-related diseases such as insulin resistance and type 2 diabetes.

About this Lab

The Ubiquitin Biology Laboratory explores how ubiquitin and ubiquitin-like posttranslational protein modifications affect adipose tissue responses to the metabolic challenge of obesity.  In earlier studies, we explored how ubiquitin-dependent modifications regulate the activity of the peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear hormone receptor required for the formation and maintenance of adipocytes. In a series of studies, we found that the ubiquitin ligase Siah2 selectively regulates PPARgamma activity in adipose tissue while also acting to control obesity-related adipose tissue inflammation and the link between adipocyte hypertrophy and obesity-induced insulin resistance. Our current studies focus on the role of Siah2-mediated regulation of PPARγ in adipose tissue macrophage to more broadly understand how the ubiquitin-proteasome system affects the link between adipose tissue inflammation and insulin resistance.  
In other studies, we found that Siah2 participates in the early steps that determine commitment of preadipocytes to adipocyte formation. That finding has led to an interest in understanding how Siah2 may affect the balance between fat and bone formation.  We also collaborate with colleagues at the Louisiana State University Health Science Center in New Orleans and the Our Lady of the Lake Regional Medical Center to explore the role of Siah2 in the ability of tumors that arise in adipose tissue (liposarcomas) to form mature fat cells as a potential therapeutic target in those cancers.

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. In collaboration with colleagues at the University of Illinois at Chicago, we are identifying the bioactive components present in an ethanolic extract from Russian tarragon that enhance insulin signaling in skeletal muscle and improve glucose metabolism. Additional studies carried out in collaboration with colleagues in the LSU School of Engineering focus on how botanically-derived compounds affect the activity of the ubiquitin-proteasome system deubiquitinases in multiple myeloma.


Laboratory Member Bios

  • BSN Nursing
    University of Alabama at Birmingham, 1977
  • PhD  Biochemistry
    Louisiana State University, 1977
  • Postdoctoral Fellow
    Washington University School of Medicine, 1997-2000
  • Postdoctoral Fellow, Louisiana State University, 2000-2004

Dr. Floyd is the principal investigator of the Ubiquitin Biology Laboratory.  After working in university and community hospital settings as a critical care nurse and clinical coordinator, Dr. Floyd returned to school to obtain a PhD in biochemistry. She is interested in the mechanistic biology that underlies the physiological role of adipose tissue with a specific focus on regulation of adipose tissue biology by the ubiquitin-proteasome system. In her free time, she enjoys spending time with her husband and friends, gardening, reading fiction, and dabbling in photography. 

  • BS Biochemisry, Louisiana State University, 2012
  • PhD Biochemistry, Louisiana State University, 2021
  • John S. McIlhenny Postdoctoral Fellow, 2021-22

Dr. Panta is interested in understanding how a ubiquitin ligase, Siah2, is regulating adipose tissue inflammation in high-fat diet induced-obesity models. Siah2 deletion in macrophages increases lipid accumulation in adipose tissue macrophages, inflammation in adipose tissue, glucose intolerance, and insulin resistance without affecting adiposity in mice fed with high-fat diets. His current work is focused on determining whether Siah2 deletion in macrophages causes macrophage mitochondrial dysfunction. Pradip is also interested in understanding the link between gut microbiota and immunometabolism. Dr. Panta is supported by a John S. McIlhenny Endowed Postdoctoral Fellowship. He likes to enjoy his free time playing musical instruments, singing, and spending time with family and friends

  • BS Kinesiology, Louisiana State University, 2012
  • MS Kinesiology, Louisiana State University, 2014
  • PhD Kinesiology, Louisiana State University, 2021

Dr. Scott is a postdoctoral fellow in the Ubiquitin Biology Lab and is funded by a NIH Botanical T32 Fellowship. He is currently working on bone marrow cell differentiation, with a focus on describing a potential role of Siah2 in the balance between osteogenesis and adipogenesis and exploring how botanical compounds may impact osteogenesis or osteoclastogenesis. Broadly, Dr. Scott is interested in bone metabolism in the context of lifestyle modifications such as diet and exercise. Dr. Scott also finds purpose in spending time with his wife, raising his two children, exercising, and doing household chores. 

  • BS Biological Sciences, Southeastern Louisiana University, 2019

Jennifer Doucet is a research associate in the Ubiquitin Biology laboratory. She earned her BS in Biological Sciences from Southeastern Louisiana University in 2019. During her free time, she enjoys spending time with her son, exercising, and being outdoors.

  • Premed student, Louisiana State University

Emily has always loved science and learning about how cells work.  She became interested in working at Pennington because she wanted to gain experience in working in a lab and applying the concepts that she is currently learning in the classroom to the “real lab world”.  For example, working with mice and genotyping has taught her about the hard work of troubleshooting and given her a deeper understanding of genetics. When not in the lab, Emily is interested in political science and is a huge LSU football fan. She also represents her college as an LSU College of Science Ambassador and as a chemistry tutor for the LSU Center of Academic Success. After graduating LSU, Emily hopes to attend medical school and become a surgeon.

Research In Focus

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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