- Dean, FAES (Foundation for Advanced Education in the Sciences, Inc.) Graduate School at the NIH, 1999-present
- Chief, Molecular Cell Biology Section, Molecular Medicine Branch, NIDDK, 1994-present
- Research Physicist, Laboratory of Chemical Biology, NIDDK, 1985-present
- NRSA Fellowship, National Institute of General Medical Sciences, Laboratory of Chemical Biology, NIAMDD, 1975-1977
- Ph.D., the George Washington University, 1975
- B.A., University of California, Berkeley, 1970
Induction of erythropoietin production by low oxygen enables erythropoietin to act as a protective hormone against hypoxic stress. Elevated erythropoietin stimulates survival, proliferation, and differentiation of blood stem cells/progenitor cells to form mature red blood cells. Erythropoietin activity in other tissues including cardiovascular, brain, muscle, and fat suggests the potential for erythropoietin to act as a pleiotropic hypoxia responsive hormone to facilitate tissue repair and wound healing. Erythropoietin stimulation of nitric oxide production in vascular endothelium contributes to increased oxygen delivery. Erythropoietin activity in non-erythroid tissue complements its function in erythroid and endothelial tissue to increase oxygen delivery by promoting oxygen consumption.
The purpose of these studies on erythropoietin biology is to determine endogenous erythropoietin activity in erythroid and non-erythroid tissue, including response to hypoxia, and the action of erythropoietin treatment to regulate red blood cell production, oxygen delivery, and other tissue responses.
Our lab investigates the role of cytokines in maintaining stem/progenitor cell characteristics. Molecular structure and processing related to cellular function, differentiation, and development are studied using molecular and cell biology, biochemical, and biophysical approaches. Emphasis is on transcriptional regulation of proliferation and differentiation and animal models. We are particularly interested in the function of the erythropoietin receptor and metabolic and stress response to erythropoietin in hematopoietic, neuronal, muscle, endothelial, bone, gender-specific regulation of fat mass and other stem/progenitor cells. Other studies include erythroid differentiation, globin gene expression and related pathophysiology of sickle cell disease and other hemoglobinopathies.
Applying our Research
Erythropoietin has been available as hormone treatment to increase red blood cell production for treatment of anemia in conditions such as chronic kidney disease for three decades. Demonstration of erythropoietin protective activity in animal models of brain and heart injury suggested potential use in stroke and cardiovascular disease. However, efforts to increase clinical applications of erythropoietin, including high dose erythropoietin treatment in anemic patients to increase hematocrit to normal levels in kidney disease and select cancers, led to awareness of adverse effects associated with high dose treatment. It also led to a requirement to reduce the recommended dose for erythropoietin therapy.
Full characterization of endogenous erythropoietin activity and erythropoietin response in tissues beyond red blood cell production will provide insight on its use to treat anemia and associated risks and possible related adverse events. It will also provide the potential application of erythropoietin administration for stroke, cardiovascular, metabolic and other diseases, or tissue injury.
Need for Further Study
Erythropoietin activity in animal models and cultured cells has been useful in identifying erythropoietin action in various erythroid and other tissues. Areas for further study include endothelial response to erythropoietin to facilitate oxygen delivery and to promote tissue repair. Erythropoietin stimulation of nitric oxide production suggests a link between nitric oxide and erythropoietin activity. The manner in which erythropoietin regulated oxygen delivery acts with tissue-specific response to provide erythropoietin protective activity to injury in brain, heart, muscle and other tissues will clarify erythropoietin activity in tissue repair. Erythropoietin response in non-erythroid tissues such as white fat and brain contributes to regulation of metabolism, glucose level, insulin sensitivity, fat mass, and oxygen consumption. In addition, regulation of energy expenditure, food intake and fat mass by erythropoietin treatment suggests some sexual dimorphism in metabolic response and particular contributions from adipose tissue and hypothalamus/neural response contributing to specific erythropoietin metabolic activity. The potential role of erythropoietin in bone remodeling to promote bone repair or bone loss suggested by animal models and the implications for human health require clarification.
Understanding these aspects of erythropoietin action in addition to the response of blood cells and regulation of red blood cell production will clarify the role of stem cell/progenitor cell response to erythropoietin during development and tissue maintenance and repair. This gives rise to potential beneficial or adverse response to erythropoietin treatment for anemia including chronic kidney disease and for specific tissue injury or disease.
- Sex-specific brain erythropoietin regulation of mouse metabolism and hypothalamic inflammation.
- Dey S, Cui Z, Gavrilova O, Zhang X, Gassmann M, Noguchi CT.
- JCI Insight (2020 Mar 12) 5. Abstract/Full Text
- Erythropoietin modulates bone marrow stromal cell differentiation.
- Suresh S, de Castro LF, Dey S, Robey PG, Noguchi CT.
- Bone Res (2019) 7:21. Abstract/Full Text
Research in Plain Language
Stem cells and progenitor cells have the remarkable ability to develop into different cell types. They offer the potential to provide a renewable source of replacement cells to treat diseases, conditions, and disabilities. We use molecular and cell biology, biochemical, and biophysical approaches to learn how these cells work. We are also particularly interested in the role of cytokines and hormones that trigger the initial development of stem and progenitor cells into different cell types. Our research allows us to build models of how these processes work.
One focus of our lab’s research is on the way in which a stem cell produces a red blood cell offspring. Erythropoietin, produced in the kidney, is the hormone that regulates the daily production of 200 billion new red blood cells. These red blood cells are important because they carry oxygen from the lungs to tissues. In our lab we investigate many roles of erythropoietin such as the following:
- When oxygen levels are low, erythropoietin is triggered to increase red blood cell formation. As more red blood cells are formed, more oxygen can be moved from the lungs to tissues. This increases overall oxygen levels in the body.
- Erythropoietin stimulates endothelial cells to produce increased nitric oxide production; this regulates blood flow and contributes to increasing oxygen delivery. We relate this activity to a protective effect in a mouse model of heart ischemic injury (blocked blood flow).
- Erythropoietin can stimulate muscle progenitor cells to promote wound healing in a mouse model of skeletal muscle injury.
- In the brain, erythropoietin can stimulate the proliferation of neural progenitor cells and the survival of neurons to provide protection in mouse models of ischemic injury. Erythropoietin activity in brain also contributes to improved glucose metabolism and protection against diet-induced obesity.
- Erythropoietin contributes to fat tissue metabolic response. Erythropoietin treatment, especially in obese mice, improves glucose metabolism and insulin sensitivity, increases energy expenditure and activity, and in male mice reduces food intake and fat mass. Female mice exhibit erythropoietin regulation of fat mass after disruption of the anti-obesity effect of estrogen.
- Erythropoietin stimulates bone forming cells in the bone marrow to regulate bone and bone marrow fat, an activity required for normal bone formation in mice. Erythropoietin treatment to increase red blood cell production is accompanied by decrease in bone marrow fat and a direct response of bone forming progenitor cells resulting in bone loss.
Other studies in our lab focus on the activity of the globin gene family. Globin genes are components of hemoglobin, the molecule that carries oxygen. These genes make up 98 percent of the protein in red blood cells that transport oxygen in the bloodstream. In particular, we want to understand the changes in hemoglobin function observed in sickle cell disease and other diseases related to hemoglobin abnormalities.