Helena (Elena) Parfenova, Ph.D.
Department of Physiology
The University of Tennessee Health Science Center
894 Union Avenue
Memphis, TN 38163
Phone: (901) 448-8319
Fax: (901) 448-7126
Lab: 305 Nash Research Building
Email: Helena (Elena) Parfenova
- Ph.D. Institution: University of Uruguay, Montevideo, Uruguay
The general goal of my research program is to understand the cellular and molecular mechanisms controlling mammalian organ development in health and disease by focusing in two homedomain-containing transcription factors (Six3 and Prox1). During the last few years, we generated a number of valuable animal models that have been critical in the progress of our research. The detailed characterization of many of these animal models highlighted the important roles of these two genes in mammalian embryonic development and disease. We gathered valuable information about how these genes control basic aspects of brain, visual system and lymphatic development and generated a number of animal models of disease aimed to better understand the role of these genes in a variety of human disorders.
The detailed characterization of generated Six3 standard and conditional knock-out mouse strains revealed the critical function of this gene during brain formation and regionalization as we previously demonstrated that Six3 directly represses Wnt1 expression in the anterior neuroectoderm and that this step is essential for forebrain development. Using a generated Six3 conditional mouse strain we also determined that conditional deletion of Six3 in the presumptive lens ectoderm affected lens induction and specification positioning Six3 at the top of the regulatory pathway leading to lens formation. Using a similar conditional deletion approach we identified Six3 as the first gene whose activity is required to initiate neuroretina specification.
In relationship with Prox1, our previous work revealed that in mammals, Prox1 activity is critical for the development of many organs and tissues, such as lymphatic vasculature, dentate gyrus, lens, retina, and heart. Our initial work identified Prox1 as the first specific marker for lymphatic endothelial cells (LECs) and described the first mouse model devoid of a lymphatic vasculature. Subsequently, we demonstrated that blood endothelial cells (BECs) are the default condition from which a LEC fate is induced by Prox1. In a surprising twist, we also demonstrated that a defective lymphatic vasculature promotes late-onset obesity in Prox1 heterozygous mice, a result that could have important implications in public health. Later by using a lineage tracing approach, we showed that in mammals the lymphatic vasculature is exclusively venous derived, an issue that has been debated for over a century. More recently, we demonstrated that the LEC phenotype is plastic and requires constant expression of Prox1 to maintain its differentiated state.
- Johnson P, Thorman Hartig M, Frazier R, Clayton M, Oliver G, Nelson BW, Williams-Cleaves BJ. Engaging faith-based resources to initiate and support diabetes self-management among African Americans: a collaboration of informal and formal systems of care. Health Promot Pract. 2014 Nov;15(2 Suppl):71S-82S. doi: 10.1177/1524839914543012. PubMed PMID: 25359253.
- Srinivasan RS, Escobedo N, Yang Y, Interiano A, Dillard ME, Finkelstein D, Mukatira S, Gil HJ, Nurmi H, Alitalo K, Oliver G. The Prox1-Vegfr3 feedback loop maintains the identity and the number of lymphatic endothelial cell progenitors. Genes Dev. 2014 Oct 1;28(19):2175-87. doi: 10.1101/gad.216226.113. PubMed PMID: 25274728; PubMed Central PMCID: PMC4180978.
- Wiener Z, Högström J, Hyvönen V, Band AM, Kallio P, Holopainen T, Dufva O, Haglund C, Kruuna O, Oliver G, Ben-Neriah Y, Alitalo K. Prox1 promotes expansion of the colorectal cancer stem cell population to fuel tumor growth and ischemia resistance. Cell Rep. 2014 Sep 25;8(6):1943-56. doi: 10.1016/j.celrep.2014.08.034. Epub 2014 Sep 18. PubMed PMID: 25242330.
- Lavado A, Oliver G. Jagged1 is necessary for postnatal and adult neurogenesis in the dentate gyrus. Dev Biol. 2014 Apr 1;388(1):11-21. doi: 10.1016/j.ydbio.2014.02.004. Epub 2014 Feb 13. PubMed PMID: 24530424; PubMed Central PMCID: PMC4009513.
- Yang Y, Oliver G. Transcriptional control of lymphatic endothelial cell type specification. Adv Anat Embryol Cell Biol. 2014;214:5-22. doi: 10.1007/978-3-7091-1646-3_2. Review. PubMed PMID: 24276883.
- Yang Y, García-Verdugo JM, Soriano-Navarro M, Srinivasan RS, Scallan JP, Singh MK, Epstein JA, Oliver G. Lymphatic endothelial progenitors bud from the cardinal vein and intersomitic vessels in mammalian embryos. Blood. 2012 Sep 13;120(11):2340-8. doi: 10.1182/blood-2012-05-428607. Epub 2012 Aug 2. PubMed PMID: 22859612; PubMed Central PMCID: PMC3447786.