[Cabantchik Ioav]CABANTCHIK, Z. IOAV

Born 1942, Buenos Aires, Ph.D.(cum laude)  1973 (Medical Sciences and Biophysics), Univ. of Rochester School of Medicine and Dentistry; Senior Lecturer 1981; Associate Professor 1983; Professor 1987.

E-mail:  ioav@cc.huji.ac.il

Tel: 972-2-658-5420; Fax: 972-2-658-6974

Prizes and Awards

Recipient Metzger's Award for Distinguished MD Ph.D. Thesis (Rochester, 1974); E.D. Bergmann Research Prize, 1992; Nachmias Research Prize 1999

Research Interests:

The biochemistry and physiology of iron metabolism in health and disease : a. basic molecular mechanisms of iron handling by cells ; b. novel diagnostic and therapeutic approaches for treating diseases of dysfunctional iron handling (iron overload of systemic or local nature); c. novel experimental tools for tracing iron and other metals in the compartments of living cells by fluorescence microscope imaging.

Research Projects (2006-):

  1. Labile iron pools : biological and medical implications. (Israel Scien ce Foundation).
  2. Genetic basis of iron disorders: European Community FP6
  3. Treating Friedereich ataxia: AFM, Asoc. Franc. Contre la Myotonie

 

Abstracts of Current Research:

Animal cells have developed intricate mechanisms for handling iron, an essential nutrient and yet a potentially hazardous species. The cellular traffic of the metal is associated with various forms of labile or chelatable iron that constitute the so called labile iron pool (LIP). This pool serves as a crossroads for metal transit between different cell components and between cell and medium. It includes the chemical forms of iron required for integration into macromolecules and for the coordinated regulation of cell iron levels by iron responsive proteins (IRPs). However, LIP can also mediate oxidative damage, especially in conditions of iron overload, systemically such as in hereditary and transfusional haemachromatosis or locally as in neurodegenerative disorders (selected areas of the brain) or anemia of chronic inflammation (reticuloendothelial system).


This “Labile Iron Pool” (LIP) must be constantly and tightly controlled, and its deregulation is thought to initiate oxidative events that are regarded as important determinants of iron-dependent tissue damage. This occurs in many iron-related diseases such as hemochromatosis, dysmetabolic hemosiderosis, the anemia of chronic disease, various forms of ataxia, some neurodegenerative disorders, ischemia-reperfusion damage, and cardiac toxicity of some widely used antitumor drugs. The development of new therapeutic interventions requires a better understanding of how precisely iron homeostasis is disrupted in such diseases, and how the LIP is regulated. This knowledge can be obtained by designing and optimising cellular models that express genes involved in the regulation of LIP, and by refining analytical tools that assess the functions of specific genes at molecular and cellular levels. For that purpose it is necessary to combine the complementary expertise of (a) designing cellular models of gene expression and assessing the molecular and cellular functions of the expressed genes, (b) developing analytical tools that define the status of iron in the same cells and its movements across distinct organelles.

We have developed sensitive probes that detect and quantify the LIP in living cells and their compartments with profiles of high sensitivity and specificity. These probes, called FMS or fluorescent metal sensors are used as tools to trace the LIP in investigational models of diseases which share iron de-compartmentalization as a common causative factor (hereditary hemochromatosis, genetic ataxias, neurodegeneration, sideroblastic anemia, cardiotoxicity of anticancer anthracyclines, ischemia-reperfusion damage). The approaches we are using have the analytical power to identify the factors that perturb the dynamics and size of LIPs in distinct cell compartments, and offer the opportunity to accommodate iron-related diseases in a unifying patho-physiological picture. On the long run our research effort aims at devising new therapeutic approaches for iron-dependent diseases. For that purpose our (translational research) projects address also basic questions that are currently unanswered in this field : what are the regulatory mechanisms that enable the LIP to reconstitute iron-requiring enzymes without exposing cells to the damaging effects of metal-triggered formation of reactive O species?; and further, is the LIP involved in the iron-mediated transcriptional regulation of central proteins of iron metabolism such as ferritin and transferrin receptors (via IRPs) or the hormone hepcidin?

Cell iron dynamics and regulation:

a.  Design, development and application novel iron assays based on FMS for the quantitative definition of LIP in healthy and diseased cells from various origins. In conjunction with online fluorimetry or confocal microscope fluorescence cell imaging, the novel approaches provide continuous and spatial information about iron traffic through the LIP of living cells.

b.  Targeted delivery of probes to organelles such as mitochondria and lysosomes has opend the road for exploring the relationship between the cytosolic LIP and organellar iron pools, which are key components of iron maintenance in cells.

c.  Assessment of the cells' ability to adjust LIP levels in response to iron loads and correlate them with the known regulatory activities of IRPs and cell ferritin. The studies are carried out in primary and established lines of liver parenchymal cells and human monocytes, in genetically manipulated cells to express iron-handling proteins (ferritin) and carriers (transporters) or anti-sense fragments of genes as specific repressors of their expression.

d.  Evaluation of the hypothesis that the ability of certain cells (hepatocytes, monocytes) to respond to immunological factors such as cytokines and to inducers of oxidative stress, is associated with changes in LIP levels. Those studies are conducted also in cells derived from normal and transgenic mice with variable ability to handle oxidative stress (catalase and superoxide dismutase deficient or over expressing variants). The studies are meant to furnish essential information for assessing LIP's role in the physiology of iron in health and disease.

e.  The overexpression or repression of key genes of iron metabolism such as ferritin or frataxin generates a gamut of cellular responses in metabolism, cell cycle, oxidative stress and cell survival.

Revealing labile iron pools in cells 

The lab has until recently been concerned primarily with diseases of systemic iron overload (Thalassemia and hemochromatosis), with emphasis on defining labile forms of iron plasma (LPI) that lead to extra-hepatic iron overload, especially in the heart, with the delineation of the mechanisms whereby LPI permeates into cardiac cells and raises labile cell iron pools (LCIP) in different cell organelles, and with the evaluation of novel oral iron chelators as therapeutic agents for conditions of iron overload (Glickstein et. 2005; Cabantchik et al. 2004). A new methodology was developed for dyamically tracing labile iron forms (as targets of chelators) in the compartments of living cells and in plasma, with clinical implications for diagnosis of iron overload and quality control of existing chelation therapies (Esposito et al 2002; Breuer et al. 2001). The methodologies referred as FDI (Fig. 1) fluorescence detection of iron, are applied in solution and in living cells using fluorescent probes designed to specifically target organelles as exemplified in the following figures (Fig. 2).

 

Fig.2. A. Fluorescent metal sensors FMS (e.g. calcein) are targeted to cell compartments by coupling them to carrier molecules endowed with organellar addresses such as NLS peptide sequences in histones (for the nucleus), a hydrophobic-cationic moiety (for mitochondria) or dendrimeric structures that are used as scaffold to build the targeted FMS, while histones H-derived sequences and other organellar leader peptides are used as pilot units for organellar delivery.

The picture in B represents the red fluorescent FMS rhodamine-hydroxybenzoic acid targeted to mitochondria of cardiac H9C2 cells.

C represents a macromolecular FMS calcein-dendrimer  conjugate taken up into endosomes (yellow-green fluorescence) by   macrophage cells J774. D  depicts the yellow-green fluorescent FMS  calcein-histone targeted to the nucleus of cardiac H9C2 cells. The FMS are used to assess the level of labile iron in each compartment by revealing the quenched fluorescence with a permeant iron chelator. All these studies are aided by examination  with an epifluorescence microscope or confocal microscope and image recording devices that allow both spatial and temporal monitoring of changes in fluorescence in cells.

 

 

Extracellular iron pools in human pathology:

In healthy individuals virtually “all” of the circulating iron is bound to the iron-carrier protein transferrin (Tf) and thus it is shielded from pro-oxidants. This is apparently not the case in individuals with iron overload (thalassemia, hemochromatosis), patients under iv iron maintenance, patients undergoing chemotherapy, heart bypass operations and other conditions where large amounts of iron, such as from hemoglobin catabolism, are released into the plasma. In all those cases, the iron binding capacity of Tf is generally overwhelmed. This results in the appearance of non Tf-bound iron=NTBI, of which the redox-active and chelatable forms are referred as labile plasma iron (LPI), which is toxic because of its redox-activity and because it acts as an-unregulated source of iron supply whose uptake leads to iron overload, particularly in the liver. Moreover, as plasma LPI poses an immediate threat to the heart and thefore demands appropriate therapies (iron chelation or phlebotomy, depending on the disease in question).

Despite the importance attributed to LPBI in the pathophysiology and therapy of iron overload, there has been a lack of reliable methods for assesing its levels in human plasma (serum). A methodological advance by the author has recently managed to bridge the gap. It is based on the principle of FDI, fluorescence detection of iron. The latter comprises FMS probes that monitor changes in iron levels either within or without cells, both quantitatively/ This paved the road for assessing the levels of LPI and the pathological role of toxic forms of iron appearing in the serum of iron overloaded patients such as in thalassemia and hemochormatosis and end stage renal disease (dialysis patients). The new methodologies serve as a basis for a survey of hundreds of such patients in in Israel and Europe with the aim of assessing the adequacy of presently used therapies in iron overload and in iron supplementation, primarily in chronic conditions such as Thalassemia and hemochromatosis.

Can chelation of accumulated toxic iron be of therapeutic value in neurological diseases?  An example of transitional research  In collaboration with Prof. Arnold Munnich (HN, Paris).

Cardiac and neuronal cells are the targets of iron accumulation in various disorders of metabolic or genetic origin. Friedreich ataxia (FRDA), the most common inherited ataxia, affecting 1:30.000 people, is a progressive disorder with significant morbidity: loss of ambulation typically occurs 15 years after disease onset with the majority suffering also from cardiac disease, diabetes and other complications. The cause of the disease is a mutation in the form of a GAA triplet that repeats 10-30 times more in patients than in normal, drastically reducing the production of a protein (frataxin) that handles iron needed for the formation of essential iron-sulfur cluster proteins. A reduced expression of frataxin leads to accumulation of iron in mitochondria and ensuing oxidative damage, especially in brain and cardiac tissue.

Can iron accumulation in brain mitochondria be prevented when frataxin under-expressed and can thereby ensuing oxidative damage be overcome?  At Jerusalem and Paris we jointly advanced the concept of selective chelation as a corrective or preventive strategy for reducing neuronal (and cardiac) damage associated with disease-related iron accumulation. It is based on an agent designed ideally to: 1. gain access to the brain and “safely” scavenge iron accumulated in defined areas; 2. redistribute the chelated iron in a way that will not compromise brain functions ; 3. overcome frataxin deficiency by supporting (!) the otherwise defective S-cluster protein formation machinery and 4. evoke no systemic iron deficiency.

The search for such “magic agent” relied on our original development of novel fluorescent iron sensors that can be placed in various compartments of the cell and bioimage the presence of labile or toxic iron. Bioimaging iron in living cardiac cells and neuronal cells allowed us to screen for agents capable of removing iron accumulated in mitochondria and redistributing it within the cell or outside to safe sanctuaries for metabolic reutilization. The first agent answering the above criteria was serendipitously found to be one already in clinical use for iron overload diseases. This paved the road for an expeditious design of a pilot clinical trial with 10 Friedreich ataxia patients in the Clinical Genetics Unit at Hopital-Necker-Enfants headed by Prof. A. Munnich. The experimental treatment showed progressive reduction of accumulated iron in the cerebellum of all  patients and totally unanticipated neurological benefits as early as 6-8 weeks of the onset of treatment. Parallel to the submission of the work for publication and the design of large prospective study, the search for improved agents has continued and expanded to other neurological conditions in which toxic iron has been implicated.

 

Key Words:

Iron, metabolism, toxicity, chelation, fluorescence, thalassemia, hemochromatosis, anemia of chronic inflammation, neurodegenerative disorders, Friedreich ataxia

Publications (since 1995):

Vieira, L., Slotki, I.N. and Cabantchik, Z.I. (1995). Chloride conductive pathways which support electrogenic H-pumping in Leishmania major promastigotes. J. Biol. Chem. 270:5299-5304

Vieira, L. and Cabantchik, Z.I. (1995). Bicarbonate ions and pH regulation of Leishmania major promastigotes. FEBS Lett. 36:123-126.

Tsafack, A., Golenser,J., Libman, J., Shanzer, A. and Cabantchik, Z.I. (1995). Mode of action of iron(III) chelators as antimalarials. Overadditive effects in the combine action of hydroxamate-based agents on in vitro growth of Plasmodium falciparum. Mol. Pharmacol. 47:403-409.

Cabantchik, Z.I. (1995). Iron chelators as antimalarials.The biochemical basis of cytotoxicity. Parasitol. Today 11:74-78. (invited review).

Breuer, V.W., Epstejn, S., Milgram, P. and Cabantchik, Z.I. (1995). Transport of iron and other related metals into cells as revealed by a fluorescent probe. Am. J. Physiol (Cell)268:1354-1361.

Golenser, J., Chevion, M. and Cabantchik, Z.I. (1995). Malaria, iron and oxidant stress. In Parasitology for the 21st century: ICOPA VIII. M.A. Ozcel and Alkan (editors). pp 89-102, CAB International, Wallingford, Oxon, UK. (invited review).

Vieira, L and Cabantchik, Z.I. (1995). Amino acid uptake and intracellular accumulation Leishmania major promastigotes are largely determined by a H-pump generated membrane potential. Mol. Biochem. Parasitol. 75:15-23.

Cabantchik, Z.I., Milgram, P. Glickstein,H. and Breuer, W., (1995) A method for assessing iron chelation in membrane model systems and in living mammalian cells. Anal. Biochem. 233:221-227.

Breuer VW, Epsztejn S, Cabantchik ZI. (1995) Iron acquired from transferrin by K562 cells is delivered into a cytoplasmic pool of chelatable iron. J. Biol. Chem. 270:24209-16.

Glickstein,H, Loyevsky, M. ,Konijn, A., Libman, J., Shanzer, A. and Cabantchik, Z.I. (1996) Differential cytotoxicity of iron chelators in proliferation of malaria infected cells versus mammalian cells. Blood. 87:4871-4878

Cabantchik Z.I., Golenser J, Loyevsky M, Tsafack A.(1996) Iron chelators. Mode of action as antimalarials. Acta Haematol 95:70-77.

Tsafack, A., Golenser, J. and Cabantchik, Z.I. (1996). Antimalarial action of iron chelators. In Molecular Biology of Hematopoiesis. N. Abrams, Editor.

Breuer, W., Epsztejn, S. and Cabantchik, Z.I.,(1996) The dynamics of the labile iron pool of mammalian cells. FEBS Letters 382:304-308.

Tsafack, A., Loyevsky, M., Ponka, P. and Cabantchik, Z.I. (1996). Mode of action of iron chelators as antimalarials. The combined action of desferrioxamine and aryl-isonicotynoyl-hydrazones. J. Lab. Clin. Med. 127:574-582.

Vieira, L. and Cabantchik, Z.I. (1996). An amino acid channel activated by hypotonically swelling of Leishmania major promastigotes. Biochem. J. 319: 691-697.

Tsafack, A., Libman, J. Shanzer, A. and Cabantchik, Z.I. (1996). Chemical determinants of the antimalarial activity of reversed siderophores. Antimicrob. Ag. Chemother. 40(9): 2160-2166.

Epsztejn, S., Kakhlon, O., Breuer, W. Glickstein, H.and Cabantchik, Z.I.,(1997) A fluorescence assay for the labile iron pool (LIP) of mammalian cells. Anal. Biochem. 248:31-40.

Breuer, W., Greenberg, E. and Cabantchik, Z.I. (1997). The role of newly delivered transferrin iron in oxidative cell injury. FEBS Lett. 403:213-219.

Zanninelli, G., Brissot, P., Hider, R.R., Konijn, A.P., Shanzer, A. and Cabantchik, Z.I. (1997). Chelation and mobilization of cellular iron by different classes of iron chelators. Mol. Pharmacol. 51: 842-852.

Vieira, L. and Cabantchik, Z.I. (1997). Modulation of the swelling-activated amino acid channel of Leishmania major promastigotes by protein kinases. Mol. Biochem.Parasitol.. 90: 449-461.

Golenser, J., Domb, A., Teomim, B., Tsafack, A., Nissim, O. Ponka, P., Eling, W. and Cabantchik, Z.I. (1997). The treatment of animal models of malaria with iron chelators using a novel polymeric device for slow drug release. J. Pharmacol. Exp. Ther. 281:1127-1135.

Picard, V , Epsztejn, S.., Santambrogio, P.Cabantchik, Z.I. and Beaumont C. (1998). Role of ferritin in the control of the labile iron pool in murine erythroleukemic cells. J. Biol. Chem. 273:15382-15386.

Konijn, A.M., Vaisman, B., Glickstein, H., Meyron-Holtz, E., Slotki, I.N. and Cabantchik, Z.I. (1999). The cellular labile iron pool (lip) and intracellular ferritin in K562 cells. Blood. 94,2128-2134.

Epsztejn, S. Picard. V, Breuer, W.V., Glickstein, H. Slotki, I.N., Beaumont C. and Cabantchik, Z.I. (1999). Functional consequences of H-ferritin over-expression in transfected cells. Blood. 94:3593-3603.

Cabantchik, Z.I. (1999). Erythrocyte membrane transport. In “Novartis Foundation Symposium 226- Jan. 1999 on Transport and trafficking in the malaria-infected erythrocyte. J. Wiley & Sons. Chichester pp.6-19

Cabantchik, Z.I., Moody-Haupt, S. and Gordeuk, V. (1999). Iron chelators as anti-infectives. Malaria as a paradigm. FEMS. 26:289-298.

Cabantchik, Z.I., Slotki, I.N., Beaumont, C. and Breuer, W. (1999) Development and Application of Fluorescent Assays for Probing Labile Iron Pools in Biological Systems. In : “Iron Chelators: New Development Strategies” (D. Badman, R.J. Bergeron and G.M. Brittenham, eds), Saratoga Publishing Group, Ponte Vedra, Florida ).

Publications (since 2000):

Breuer, W., and Cabantchik, Z.I. (2000). The importance of non-transferrin bound iron in disorders of iron metabolism. Transf. Sci. 23:185-1

Breuer, W., Ronson, A, Slotki, I.N., Abramov, A., and Cabantchik, Z.I. (2000). The application of a novel method for assessing non transferrin bound iron (NTBI) in pathological conditions. Blood 95:2975-2982.

Breuer, W.V. and Cabantchik, Z.I (2001). A fluorescence-based one-step assay for serum non-transferrin bound iron (NTBI). Anal. Biochem. 299:194-202.

Kakhlon, O. Gruenbaum. Y. and Cabantchik, Z.I (2001). Repression of the heavy ferritin chain increases the labile iron pool of human K562 cells Biochem. J. 356: 311-316.

Kakhlon, O. Gruenbaum. Y. and Cabantchik, Z.I (2001). Repression of ferritin expression increases the labile iron pool and ,oxidative stress ,and short-term growth of human erythroleukemia cells. Blood. 97:2863-2871.

Esposito, B.P, Breuer, V.W., Slotki, I.N. and Cabantchik, Z.I. (2002). Labile iron in parenteral iron formulations and its potential for generating plasma non-transferrin bound iron (NTBI) in dialysis patients. Eur. J. Clin. Inv. 1:42-9.

Espósito, B.P., Epsztejn, S. Breuer, W. Cabantchik, Z.I. (2002) A review of fluorescence methods for assessing labile iron in cells and biological fluids. Anal. Biochem. 1;304(1):1-18.

Cabantchik ZI, Kakhlon O, Epsztejn S, Zanninelli G, Breuer W.(2002). Intracellular and extracellular labile iron pools. Adv Exp Med Biol. 509:55-75. Review

Esposito BP, Breuer W, Cabantchik ZI. (2002). Design and applications of methods for fluorescence detection of iron in biological systems. Biochem Soc Trans. 30(4):729-32.

Kakhlon O, Cabantchik ZI.  (2002) The labile iron pool: characterization, measurement, and participation in cellular processes . Free Radic Biol Med. 3(8):1037-46. Review.

Meijler MM, Arad-Yellin R, Cabantchik ZI, Shanzer A.  (2002). Synthesis and evaluation of iron chelators with masked hydrophilic moieties. J Am Chem Soc. 124:12666-12667.

Esposito, BP., Breuer, W., Sirankapracha, P. Pootrakul, P., Hershko, C. and Cabantchik, Z.I. (2003). Labile plasma iron in iron overload: redox activity and susceptibility to chelators. Blood. 2003;102: 2670-2677.

Pootrakul, P., Breuer, W., Sametband, M., Sirankapracha P., Hershko, C. and Cabantchik, Z.I. (2004) Labile plasma iron (LPI) as an indicator of chelatable plasma redox activity in iron overloaded beta-thalassaemia/HbE patients treated with an oral chelator. Blood 104: 1504 – 1510 .

Sulieman M, Asleh R, Cabantchik ZI, Breuer W, Aronson D, Suleiman A, Miller-Lotan R, Hammerman H, Levy AP. (2004), Serum chelatable redox-active iron is an independent predictor of mortality after myocardial infarction in individuals with diabetes. Diabetes Care. 2004 Nov;27(11):2730-2.

Zheng H, Weiner LM, Bar-Am O, Epsztejn S, Cabantchik ZI, Warshawsky A, Youdim MB, Fridkin M.(2005). Design, synthesis, and evaluation of novel bifunctional iron-chelators as potential agents for neuroprotection in Alzheimer's, Parkinson's, and other neurodegenerative diseases. Bioorg Med Chem. 13):773-83.

Cabantchik ZI  and Breuer, W. (2005). LPI-Labile plasma in iron overload. Best Practice & Research in Clinical Haematology Vol. 18, No. 2, pp. 277–287.

Hershko, C., Konijn, A.M. and Cabantchik, Z.I. (2005). Iron chelation therapy. Current Hematol. Reports Vol. 18, No. 2, pp. 277–287.

Le Lan, c ,  O Loréal T Cohen, M Ropert, H Glickstein, M Pouchard, Y Deugnier, A Le Treut,W Breuer,  ZI Cabantchik, P Brissot (2005). Association between hepatic damage, iron overload and incidence of redox-active iron in the plasma.  Blood. 105: 4527-4531

Glickstein, H, Ben El , R., Shvartsman M. and and Z. Ioav Cabantchik (2005). Intracellular labile iron pools as direct targets of iron chelators. A fluorescence study of chelator action in living cells. Blood. 106: 3242-3250

Hershko, C, Link, G , Konijn AM  and Cabantchik. Z.I. (2005). Iron Chelation Therap.  Curr, Hematol. 4:110-116

van der A, D.J.; Marx, JJM, Grobbee, DE, Kamphuis, MH; Georgiou, N; van Kats-Renaud, JH; Breuer, W., Cabantchik, Z.I.; Roest, M, Voorbij, HAM; van der Schouw, YH (2006) Non–Transferrin-Bound Iron and Risk of Coronary Heart Disease in Postmenopausal Women Circulation. 113:1942-1949.

Rachmilewitz E.A, Weizer-Stern, O., Adamsky, K., Amariglio, N., Rechavi, R., Brda, L., Rivella S.and  Cabantchik, Z.I. (2005). Role of Iron in Inducing Oxidative Stress in Thalassemia: Can It Be Prevented by Inhibition of Absorption and by Antioxidants? Ann. N.Y. Acad. Sci. 1054: 118–123.

Boddaert, N., Le-Quan-Sang, K.H., Rötig, A., Leroy-Willig, A., Gallet, S., Brunelle, F., Sidi, D., Thalabard, J.C., Cabancthik, Z.I. and Munnich, A. (2006). Iron chelation treatment evokes a reduction of MRI R2* values in a brain area implicated in Fiedereich’s ataxia (submitted)

Glickstein H, Ben El R, Link G, Breuer W, Konijn AM, Hershko, C, Nick H and Cabantchik ZI (2006). Action of chelators in iron-loaded cardiac cells: accessibility to intracellular labile iron and functional consequences. Blood (in Press)

Patents:(since 1995):

Novel chelators as therapeutic agents for malaria and for siderosis (jointly with A. Shanzer) (1995)

Novel means for drug administration using subcutaneous polymeric patches: application to malaria and siderosis (jointly with A. Domb and J. Golenser).(1996).

The assay of non-transferrin iron (NTBI) and other metals in metal overload (together with W. Breuer) (1998).

 


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