Joyce A. Lloyd

Education

• B.S. Biological Sciences (1982) University of Connecticut, Storrs
• Ph.D. Molecular Biology and Biochemistry (1987) Wesleyan University, Middletown, CT
• Postdoctoral Training (1987 through 1991) University of Cincinnati College of Medicine, mentor: Dr. Jerry Lingrel, Department of Molecular Genetics, Biochemistry and Microbiology

Professional experience

• 2001 to present: Associate professor with tenure, Department of Human Genetics, Virginia Commonwealth University, Richmond
•  2004 to present:  Director for Planning and Operations, Department of Human Genetics
• 1991 to 2001: Assistant professor, Department of Human Genetics, VCU

Honors

• 2002: Certificate Award for teaching Human Genetics for first-year medical students
• 1999: Outstanding Teacher Award, Department of Human Genetics, VCU
• 1988 to 1991: National Institutes of Health Postdoctoral Fellow, General Medical Sciences Institute
• 1986: Peterson Fellowship, Wesleyan University
• 1982: Summa Cum Laude B.S., University of Connecticut

Funded and recently completed research

• R01DK074694: Role of KLF2 in Erythropoiesis and Globin Expression
• Jeffress Memorial Trust: Roles of EKLF and KLF2 in Embryonic Erythropoiesis and Globin Gene Regulation

Research interests

Developmental Regulation of Erythopoiesis and Globin Gene Expression

The laboratory is interested in the developmental regulation of the globin genes in erythroid cells, and in the genes controlling erythroid development. Although we do basic science research, these projects have important clinical relevance to the future treatment of sickle cell anemia and beta-thalassemia.

Human beta-like globin expression switches from the embryonic (epsilon-) to the fetal (gamma-) to the adult (beta-) globin genes. Epsilon- and gamma-globin have an ameliorating effect on sickle cell anemia and beta-thalassemia, so a basic understanding of how switching occurs will lead to novel therapeutic strategies. The major focus of this research project has been to identify the DNA regulatory elements and transcription factors involved in globin gene switching. We have shown using knock-out/transgenic mice that KLF2, a zinc finger transcription factor, regulates epsilon-globin gene expression and is required for the maturation or stability of embryonic (primitive) erythroid cells. Recently, we have determined that KLF2 works coordinately with the related protein, EKLF/KLF1, in these functions. Interestingly, embryos with a double knockout for EKLF and KLF2 are severely anemic and die earlier than either single knockout. The EKLF/KLF2 knockout embryos have abnormal endothelial cells at an early time point, suggesting a link between erythropoiesis and development of the vascular system. KLF2 may be a good candidate for use in gene therapy strategies. The current questions which we are addressing include:

• Is the role of KLF2 carried out directly in erythroid cells or are surrounding cells involved?
• Does KLF2 bind directly to the epsilon globin promoter?
• By what mechanism do KLF2 and EKLF act together and compensate for each other?
• How do EKLF and KLF2 interact with each other in endothelial cells?

As an extension of the work above, we made a double knockout mouse model for KLF2 and KLF4. Although we have not observed affects on erythroid cells in these embryos, this double knockout is also more severe than either single knockout, showing that there are interactions between the KLF2 and KLF4 genes. Interestingly, KLF2/KLF4 knockout embryos have a cardiovascular phenotype, again suggesting links between erythroid and vascular development. This is a relatively new area of research, which we plan to follow-up.

We have also developed a technique to isolate erythroid cells from the developing mouse embryo, using laser capture microdissection (LCM). Primitive erythroid cells that express embryonic globins are being isolated from the yolk sac, and definitive erythroid cells are being isolated from the fetal liver and adult bone marrow. The goal is to generate a genetic profile of the RNAs expressed in erythropoiesis throughout development, using microarray assays. We will also identify the genes which are down-regulated in EKLF, KLF2 and EKLF/KLF2 knockout mice to learn more about how these genes affect primitive erythropoiesis. Using this top-down approach, we hope to learn more about how globin gene regulation is controlled, and apply this to increasing the expression of the embryonic and fetal globin genes in adults with hemoglobinopathies.

Teaching assignments at VCU

• HGEN 614 Human Biochemical and Molecular Genetics
• M-1 Human Genetics
• HGEN 501 Introduction to Human Genetics
• BIOC/MICR 504 Biochemistry, Cell and Molecular Biology

Publications

Names in bold are current or former graduate students or postdoctoral fellows from the Lloyd laboratory team.

• *Basu, P., *Lung, T., Lemsaddek, W., Giang Sargent, T., Williams, D.C. Jr., Basu, M., Redmond, L.C., Lingrel, J. B, Haar, J.L. and J. A. Lloyd. (2007) EKLF and KLF2 have compensatory roles in embryonic b-globin gene expression and primitive erythropoiesis. Blood 110:3417-3425 *The first two authors contributed equally to this work.
• Rupon, J., Wang, S.Z., Gaensler, K., Lloyd, J.A. and G.D. Ginder. (2006) Methyl binding domain protein 2 mediates gamma-globin gene silencing in adult human ßYAC transgenic mice. Proceedings of the National Academy of Sciences USA 103(17):6617-22
• *Chervenak, A.P., *Basu, P., Shin, M., Redmond, L.C., Sheng, G. and J.A. Lloyd. (2006) Identification, characterization and expression pattern of the chicken EKLF gene. Developmental Dynamics 235:1933-40 *The first two authors contributed equally to this work.
• Redmond, L.C., Haar, J.L., Giebel, M. L., Dumur, C.I., Basu, P., Ware, J.L. and J.A. Lloyd (2006) Isolation of Erythroid Cells from the Mouse Embryonic Yolk Sac by Laser Capture Microdissection and Subsequent Microarray Hybridization. Blood Cells, Molecules, and Diseases 37:27-32
• Zhang, P., Basu, P., Redmond, L.C., Morris, P., Rupon, J.  Ginder, G.D. and Lloyd, J.A. (2005) A functional screen for Krüppel-like factors that regulate the human gamma-globin gene through the CACCC promoter element. Blood Cells, Molecules and Diseases 35:227-35
• Basu, P., Morris P., Haar, J.L., Wani, M.A., Lingrel, J.B, Gaensler, K.M.L., and Lloyd J.A. (2005) KLF2 is essential for primitive erythropoiesis and regulates the human and murine embryonic beta-like globin genes. Blood 106:2566-7 (Commentary by J. Bieker “An unexpected entry into the globin real estate market” Blood 106:2230-2231)

• Basu, P., Giang Sargent, T., Redmond, L.C., Aisenberg, J.C., Kransdorf, E.P., Wang, S.Z., Ginder, G.D. and Lloyd, J.A. (2004) Evolutionary conservation of KLF transcription factors and functional conservation of human gamma-globin gene regulation in chicken. Genomics 84:311-319
• Giang Sargent, Lloyd JA (2001) The human gamma-globin TATA and CACCC elements have key, distinct roles in surpressing beta-globin gene expression in embryonic/fetal development. J Biol Chem 276: 41817-41824
• Buller AM, Elford HL, Meyer JM, DuBois CC, Lloyd JA (1999) A combination of hydroxyurea and isobutyramide to induce fetal hemoglobin in transgenic mice is more hematotoxic than the individual agents. Blood Cells, Molecules, and Diseases 25 (16):255-269
• Case SS, Huber P, Lloyd JA (1999) The gammaPE complex contains both SATB1 and HOXB2 and has positive and negative roles in gamma-globin gene regulation. DNA and Cell Biology 18:805-817
• Giang Sargent T, DuBois CC, Buller AM, Lloyd JA (1999) The roles of 5'HS2, 5'HS3, and the gamma-globin TATA, CACCC and SSE elements in suppression of beta-globin expression in early development. Journal of Biological Chemistry 274:11229-11236
• Giang Sargent T, Buller AM, Teachey DT, McCanna KS, Lloyd JA (1999) The gamma-globin promoter has a major role in competitive inhibition of beta-globin gene expression in early erythroid development. DNA and Cell Biology 18:293- 303
• Pandya A, Xia XJ, Landa B, Arnos K, Israel J, Lloyd J, James AL, Diehl S, Blanton S and Nance W (1996) Phenotypic variation in Waardenburg syndrome:mutational heterogeneity, modifier genes or polygenic background? Human Molecular Genetics 5:497 -502
• Lloyd JA, Case, SC, Ponce E, Lingrel JB (1994) Positive transcriptional regulation of the human gamma-globin gene: gammaPE is a novel nuclear factor with multiple binding sites near the gene. Journal of Biological Chemistry 269:19385-1 9393
• Anderson K, Lloyd J, Ponce E, Crable S, Neumann J, Lingrel J (1993) Regulated expression of the human beta-globin gene in transgenic mice requires an upstream globin or non-globin promoter. Molecular Biology of the Cell 4:1077-1085
• Lloyd JA, Krakowsky JM, Crable SC, Lingrel JB (1992) Human gamma- to beta-globin gene switching using a mini construct in trangenic mice. Molecular and Cellular Biology 12:1561-1567
• Ponce E, Lloyd JA, Pierani A, Roeder RG and Lingrel JB (1991) Transcription factor OTF-1 interacts with two distinct elements in the A gamma globin gene promoter. Biochemistry 30:2961-2967
• Lloyd JA, Lee RF, and Lingrel JB (1989) Mutations in two regions upstream of the A gamma globin gene canonical promoter affect gene expression. Nucleic Acids Res 17:4339-4352
• Lloyd JA and Potter SS (1988) Distinct subfamilies of primate L1Gg retroposons, with some elements carrying tandem repeats in the 5' region. Nucleic Acids Res 16:6147-6156

• Potter SS and Lloyd JA (1987) pPyLT1 does not always dictate the formation of autonomously replicating elements in transgenic mice. Nucleic Acids Res 15:5482
• Lloyd JA, Lamb AN and Potter SS (1987) Phylogenetic screening of the human genome: Identification of evolutionarily variable repetitive sequence families. Molecular Biology and Evolution 4:85-98