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. Paradkar P, De Domenico I, Durchfort N, Zohn I, Kaplan J, Ward DM (2008) Iron-depletion limits intracellular bacterial growth in macrophages. Blood, In Press (Epub ahead of print)

2. Kumánovics A, Chen OS, Li L, Bagley D, Adkins EM, Lin H, Dingra NN, Outten CE, Keller G, Winge D, Ward DM, Kaplan J (2008) Identification of FRA1 and FRA2 as Genes Involved in Regulating the Yeast Iron Regulon in Response to Decreased Mitochondrial Iron-Sulfur Cluster Synthesis. J Biol Chem 283(16):10276-86 (Epub 2008 Feb 15)

3. Li L, Bagley D, Ward DM, Kaplan J (2008) Yap5 is an iron-responsive transcriptional activator that regulates vacuolar iron storage in yeast. Mol Cell Biol 28(4):1326-37 (Epub 2007 Dec 10)

4. Keel SB, Doty RT, Yang Z, Quigley JG, Chen J, Knoblaugh S, Kingsley PD, De Domenico I, Vaughn MB, Kaplan J, Palis J, Abkowitz JL (2008) A heme export protein is required for red blood cell differentiation and iron homeostasis. Science 319(5864):825-8

5. De Domenico I, McVey Ward D, Kaplan J (2008) Regulation of iron acquisition and storage: consequences for iron-linked disorders. Nat Rev Mol Cell Biol 9(1):72-81 Review

6. Kaplan J, De Domenico I, Ward DM (2008) Chediak-Higashi syndrome. Curr Opin Hematol 15(1):22-9 Review

7. De Domenico I, Vaughn MB, Yoon D, Kushner JP, Ward DM, Kaplan J (2007) Zebrafish as a model for defining the functional impact of mammalian ferroportin mutations. Blood 110(10):3780-3 (Epub 2007 Aug 28)

8. Wang F, Paradkar PN, Custodio AO, McVey Ward D, Fleming MD, Campagna D, Roberts KA, Boyartchuk V, Dietrich WF, Kaplan J, Andrews NC (2007) Genetic variation in Mon1a affects protein trafficking and modifies macrophage iron loading in mice. Nat Genet 39(8):1025-32 (Epub 2007 Jul 15)

9. De Domenico I, Ward DM, di Patti MC, Jeong SY, David S, Musci G, Kaplan J (2007) Ferroxidase activity is required for the stability of cell surface ferroportin in cells expressing GPI-ceruloplasmin. EMBO J 26(12):2823-31 (Epub 2007 May 31)

10. De Domenico I, Ward DM, Langelier C, Vaughn MB, Nemeth E, Sundquist WI, Ganz T, Musci G, Kaplan J (2007) The molecular mechanism of hepcidin-mediated ferroportin down-regulation. Mol Biol Cell 18(7):2569-78 (Epub 2007 May 2)