DNA Damage and Oxidative Stress in Dyskeratosis Congenita: Analysis of Pathways and Therapeutic Strategies Using CRISPR and iPSC Model Systems
Abstract
Every cell of our body has regulatory elements that control its survival and growth, and when they get "too old," there are signals that direct them to die. The aging process transpires due to a number of reasons, but is the culmination of cellular and environmental factors. One key factor that controls aging is the length of telomeres, which are found at the end of each chromosome. The telomere is a simple DNA sequence, repeated thousands of times; however, this sequence shortens with every cell division and thus acts as a molecular clock. Once at a critically shortened length, telomeres will initiate a cellular program to begin cell death. Patients with the disease Dyskeratosis Congenita (DC) carry mutations within their cells that prevent telomeres from becoming fully elongated and thus accelerate the molecular clock that leads to premature cell death. These patients have three typical disease presentations that include spots on the tongue (leukoplakia), irregular skin pigmentation, and malformed, wrinkled fingernails (nail dystrophy). However, none of these particular symptoms are ominous. What typically brings these patients to a clinician s attention is when they acquire low blood counts or aplastic anemia. Aplastic anemia arises due to a severe decrease in blood stem cells that give rise to all the different cells types in the blood (red blood cells, white blood cells, platelets). The only way to cure this disease is by bone marrow transplantation (stem cell transplant), but a contributing problem is the fact that DC patients do not tolerate chemotherapy, which is required for transplant. In our previous research, we have found that cells from these patients do not grow as well as normal cells in cell culture but can be significantly improved if we experimentally elongate the telomeres or disrupt the pathway that communicates to the cell to enter cell death because of shortened telomeres. We believe that one contributing factor that promotes cell death due to short telomeres is overproduction of reactive oxygen species (ROS). ROS are found in normal cells but can act as a cellular poison and cause cell damage if not detoxified. ROS are significantly increased in DC cells compared to normal cells, and we believe they carry out the marching orders sent from short telomeres to help facilitate cell death. We have uncovered evidence of key genes that can help to detoxify ROS are turned off when cells telomeres are short but are turned back on when telomeres are experimentally elongated. This indicates to us that cells with short telomeres turn off ROS-detoxifying genes to promote conditions favoring cell death. The primary objective of our research is to investigate this and apply this knowledge to DC blood stem cells in the hope to improve symptoms associated with DC. The innovation found in experiments we are proposing lies within the collection of cells we have acquired from DC patients that will allow us to perform large-scale experiments. In these studies, we will individually manipulate genes and ROS levels that could help us understand detoxifying pathways, which ultimately can be applied to patients to improve their health. In addition, we are also proposing to acquire a library of drugs currently approved for clinical use for the purpose of finding new cell targets that can decrease ROS and improve disease symptoms. Finally, blood stem cells are difficult to acquire in DC, but our lab specializes in the creation of cells that can be used towards producing any cell type of interest (induced pluripotent stem cells, iPSCs). All of the proposed experiments are well within the scope of what our lab is currently performing and do not require the development of any new or difficult-to-learn techniques. The impact of these studies will benefit not only DC patients, but other patients with similar bone marrow failure problems. In the short term, characterization of these pathways and the role ROS pla
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 04, 2016
- Source ID
- W81XWH1510099
Entities
People
- Frederick Goldman
Organizations
- United States Army
- University of Alabama at Birmingham