Jerry Kaplan

Professor of Pathology

B.S. State University of New York, Stony Brook

Ph.D. Purdue University

Diane McVey Ward

Associate Professor of Pathology

Kaplan & Ward

B.S. Brigham Young University

Ph.D. University of Utah

Research

References

 

 

Research

Our research focuses on two major areas.  First, we are interested in iron metabolism.  Iron is an element required by virtually all organisms.  The facile ability of iron to gain and loose electrons renders this metal an essential cofactor in redox reactions.  Organisms as disparate as prokaryotes and mammals have developed a variety of mechanisms to obtain iron and regulate its storage and utilization.  We utilize yeast as a model system to study iron metabolism because of the relative ease of genetic manipulation.  We have utilized a variety of genetic screens to identify yeast genes required for iron transport across the plasma membrane for iron storage in the yeast vacuole.  We have also identified molecules that respond to both high and low iron and regulate the transcription of iron transporters.  Our studies in yeast have led to the identification of both plant and mammalian iron transporters.

We have also identified the mechanisms underlying both the regulation and malregulation of mammalian iron-linked disorders.  We determined that entry of iron from cells into plasma is dependent upon the interaction of the iron exporter ferroportin with the peptide hormone hepcidin.  Hepcidin is synthesized by the liver in response to inflammation and iron stores and is a negative regulator of plasma iron.  We determined that hepcidin binds to ferroportin inducing its internalization and degradation.  Mammalian iron overload disease is the result of either inadequate hepcidin production or mutations in ferroportin that lead to hepcidin resistance.  Our current studies have identified the mechanism of hepcidin-mediated ferroportin internalization and degradation.

Our second area of research is the study of membrane trafficking.  We are interested in identifying molecules that regulate the fusion and fission of endocytic vesicles.  Many human diseases result from alterations vesicle trafficking and delivery to the lysosomes.  One such disease is Chediak-Higashi syndrome in which lysosomes are abnormally large.  We have identified the gene responsible for this disorder and have ongoing studies to identify the biochemical defect responsible for the enlargement of lysosomes. 

Kaplan Figure

 

References

1. Troadec MB, Warner D, Wallace J, Thomas K, Spangrude GJ, Phillips J, Khalimonchuk O, Paw BH, Ward DM, Kaplan J (2011) Targeted deletion of the mouse Mitoferrin1 gene: from anemia to protoporphyria. Blood, Epub ahead of print

2. Kaplan J, Ward DM, De Domenico I (2011) The molecular basis of iron overload disorders and iron-linked anemias. Int J Hematol (1):14-20

3. De Domenico I, Vaughn MB, Paradkar P, Lo E, Ward DM, Kaplan J (2011) Decoupling ferritin synthesis from free cytosolic iron results in ferritin secretion. in response to a deficiency in free cytosolic iron. Cell Metab 13(1):57-6

4. Lin H, Li L, Jia X, Ward DM, Kaplan J (2010) Genetic and biochemical analysis of high iron toxicity in yeast: Iron toxicity is due to the accumulation of cytosolic iron and occurs under both aerobic and anaerobic conditions. J Biol Chem 286:3851-62

5. Troadec MB, Ward DM, Lo E, Kaplan J, De Domenico I (2010) Induction of FPN1 transcription by MTF-1 reveals a role for ferroportin in transition metal efflux. Blood 116(22):4657-64

6. De Domenico I, Zhang TY, Koening1 C, Branch2 RW, London N, Lo E, Daynes R, Kushner JP, Li D, Ward DM, Kaplan J (2010) Binding of Hepcidin Alters Transcription and Modulates Acute Cytokine-Induced Inflammatory Responses in Mice. J Clin Invest 120(7):2395-405

7. Li L, Murdock G, Bagley D, Jia X, Mc Vey Ward D, Kaplan J (2010) Genetic dissection of a mitochondria to vacuole signaling pathway in yeast reveals a link between chronic oxidative stress and vacuolar iron transport. J Biol Chem 285(14):10232-42

8. De Domenico I, Lo E, Ward DM, Kaplan J (2010) Human Mutation D157G in Ferroportin Leads to Hepcidin-Independent Binding of Jak2 and Ferroportin Downregulation. Blood 115(14):2956-9

9. Morrissey J, Baxter IR, Lee J, Li L, Lahner B, Grotz N, Kaplan J, Salt DE, Guerinot ML (2009) The ferroportin metal efflux proteins function in iron and cobalt homeostasis in Arabidopsis. Plant Cell. 2009 Oct;21(10):3326-38

10. Kaplan CD, Kaplan J (2009) Iron acquisition and transcriptional regulation. Chem Rev 109(10):4536-52

11. Koening CL, Mu HH, Van Schelt A, Lo E, Ward DM, Kaplan J, De Domenico I (2009) Hepcidin is elevated in mice injected with Mycoplasma arthritidis. J Inflamm (Lond) 6:33

12. Lin H, Burton D1, Li L, Warner DE, Phillips J, Ward DM, Kaplan J (2009) Gain of function mutations identify amino acids within transmembrane domains of the yeast vacuolar transporter Zrc1 that determine metal specificity. Biochem J 422(2):273-83

 

 

Updated 06/15/2011