Research Could Lead To Gene Therapy Approach For Treating Sickle Cell Anemia And Beta-Thalassemia

Virginia Commonwealth University researchers studying hemoglobin genes, mutations of which play a role in genetic blood disorders like sickle cell anemia and beta-thalassemia, have identified two proteins that are responsible for regulating overlapping groups of genes during the development of red blood cells.

The findings may point researchers to future gene therapies for patients with sickle cell anemia and beta-thalassemia.

In an article pre-published online as a First Edition Paper in the journal Blood, the journal of the American Association for Hematology, researchers reported that a protein called KLF2 coordinates with a related and well-studied transcription factor, EKLF, in the regulation of embryonic globin genes responsible for the development of mouse embryonic red blood cells.

EKLF plays a central role in the developmental regulation of the adult beta-globin gene, and is essential for the maturation and stability of adult red blood cells. KLF2 is a protein crucial for making embryonic red blood cells.

“If EKLF and KLF2 can turn on the embryonic globin genes in adult cells — we don’t know if this is true yet — then these findings may provide a gene therapy approach for treating sickle cell anemia and beta-thalassemia. It is well-established that the expression of embryonic globin genes can help ameliorate these diseases,” said Joyce A. Lloyd, Ph.D., associate professor of human genetics at the VCU Massey Cancer Center, and corresponding author for this study.

Lloyd’s team studied gene expression and red blood cell development in the mouse embryo. They used mouse embryos missing both the KLF2 and EKLF genes to show that embryonic globin expression is severely reduced, and that the embryos therefore are anemic, compared to mice missing KLF2 or EKLF alone.

“This likely means that EKLF and KLF2, which are related transcription factors, regulate overlapping groups of genes in developing red blood cells. In the absence of both factors, they cannot compensate for each other, causing more serious defects in red blood cell development,” Lloyd said.

According to Lloyd, the production of blood cells involves a complex differentiation pathway with interactions between many molecular players and proteins.

In humans, there are four globin genes clustered on chromosome 11 in the order in which they are ‘turned on’ or expressed. These genes include the epsilon-globin gene, two gamma-globin genes and the beta-globin gene. Lloyd said that during fetal development, the embryonic epsilon-globin gene is active first, followed by the gamma-globin genes, and finally the adult form, beta-globin takes control following birth.

Understanding how genes are regulated or turned on and off is critical. In gene therapy, a normal gene can be inserted into cells to correct a genetic defect. However, according to Lloyd, in this case, the goal would be to insert a transcription factor into adult cells that would turn on an existing, silenced embryonic gene.

This research was supported by a grant from the National Institutes of Health.

Lloyd collaborated with Jack Haar, Ph.D., professor of anatomy and neurobiology in the VCU School of Medicine; Priyadarshi Basu, Ph.D., a former postdoctoral fellow at VCU; and Tina Lung, who recently earned her masters degree. Additionally, colleagues from the Department of Molecular Genetics, Biochemistry and Microbiology at the University of Cincinnati also contributed to this work.

About VCU and the VCU Medical Center: Virginia Commonwealth University is the largest university in Virginia and ranks among the top 100 universities in the country in sponsored research. Located on two downtown campuses in Richmond, VCU enrolls more than 30,000 students in nearly 200 certificate and degree programs in the arts, sciences and humanities. Sixty-three of the programs are unique in Virginia, many of them crossing the disciplines of VCU’s 15 schools and one college. MCV Hospitals and the health sciences schools of Virginia Commonwealth University compose the VCU Medical Center, one of the nation’s leading academic medical centers. For more, see vcu/.

About the VCU Massey Cancer Center: The VCU Massey Cancer Center is one of 61 National Cancer Institute-designated institutions that leads and shapes America’s cancer research efforts. Working with all kinds of cancers, the Center conducts basic, translational and clinical cancer research, provides state-of-the-art treatments and clinical trials, and promotes cancer prevention and education. Since 1974, Massey has served as an internationally recognized center of excellence. It offers more clinical trials than any other institution in Virginia, serving patients in Richmond and in four satellite locations. Its 1,000 researchers, clinicians and staff members are dedicated to improving the quality of human life by developing and delivering effective means to prevent, control and ultimately to cure cancer. Visit Massey online at massey.vcu/.

Source: Sathya Achia-Abraham

Virginia Commonwealth University

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