Tissue dynamics: development, regeneration and failure in human disease
We are interested in the basic problem of organ size control and its implications on human health and disease: how is the proper size of organs determined and maintained? What are the cellular origins of tissues? What are the molecular signals that control tissue mass homeostasis and regeneration?
We study these problems in the context of the developing and adult pancreas, aiming to obtain insights of relevance for diabetes and pancreatic cancer. Most of our work focuses on the biology of insulin-producing beta cells. We wish to understand how beta cells are generated during embryonic development and in postnatal life, what controls beta cell mass in healthy and disease conditions and the mechanisms of beta cell failure in diabetes. Our work utilizes advanced transgenic mouse models allowing for tissue specific and conditional genetic manipulations in vivo, as well as cadaveric human material and human blood samples.
We work in very close collaboration with Ben Glaser (Hadassah medical center, Endocrinology). Additional local collaborators include Ittai Ben-Porath, Aharon Razin and Ruth Shemer (our department), Amir Eden (Hebrew University, Life Sciences), and Gidi Zamir, Adi Vaknin, Marc Gotkine, Aviad Zick, David Planer, Giora Landesbergand Zvi Friedlender (Hadassah medical center).
Our work is generously funded by the Juvenile Diabetes Research Foundation (JDRF), the European Union, the NIH (Human Islet Research Network), the Dutch friends of Hebrew University / DON foundation, the Helmsley Trust, the UK-Israel BIRAX initiative, the Israeli Science Foundation and the Zalman Cowen Universities Fund.
Glucose metabolism as a central regulator of beta cell biology
We have previously shown that glucose, acting via glucose metabolism, is a major physiological driver of beta cell replication and regeneration (Porat et al., Cell Metabolism 2011). More recently, we described how hyper-glycolysis may also be toxic to beta cells, and can specifically cause double strand breaks in the DNA and activation of the tumor suppressor p53 (Tornovsky-Babeay et al., Cell Metabolism 2014). Ongoing efforts are aimed at understanding the significance of DNA damage in beta cells and in diabetes, and the pathways mediating the toxic and mitogenic effects of glucose on beta cells.
Consequences of glucose metabolism in beta cells.The mitogenic effect of glucose mediated by classic GSIS pathway, specifically by calcineurin and insulin receptor controls replication.
The molecular signature of replicating beta cells
What does it mean to be a replicating beta cell in vivo? Which signaling pathways are active when quiescent beta cells enter the cell division cycle? Which genes are expressed in replicating beta cells? Are there any metabolic changes? Are there druggable targets? Answers to these questions require access to a pure population of replicating beta cells. However, beta cell replication is rare and current protocols for isolating these cells via FACS require fixation and processing that destroys sensitive biological material such as RNA. To overcome this problem we have developed a transgenic mouse strain that allows for the isolation of live replicating beta cells for global analysis of gene expression (Klochendler et al., Developmental Cell 2012,Klochendler et al., Diabetes 2016).
The Ccnb1-GFP transgene allows for the isolation of live replicating cells. Although GFP is expressed in all cells, it is rapidly degraded in quiescent (G0) and G1 cells (blue) and accumulates only in S/G2/M (green). In compound transgenic mice expressing Ccnb1-GFP and RipCre-RosaLSLTomato, quiescent (red) and replicating (yellow) beta-cells can be sorted live for RNA purification and transcriptome analysis.
Senescence in pancreas dynamics
We are studyingin collaboration with Ittai Ben-Porathhow cellular senescence affects the function and replication of pancreatic beta cells, and how this powerful tumor suppression mechanism affects tissue dynamics in the exocrine pancreas in the context of early stages of pancreatic cancer.
Effects of p16-induced senescence on beta cell function. Components of the senescence program that contribute to increased insulin secretion are highlighted in red ((Helman et al., Nature Medicine 2016)
Non-invasive detection of cell death in the human body
When cells die in the human body, their broken DNA is released to the circulation. Since each human tissue has a unique DNA methylation signature, analysis of methylation patterns in circulating DNA can in principle identify the tissue origins of cell-free circulating DNA as an indicator of cell death in specific tissues. We have developed a method to identify circulating DNA derived from specific tissues, and applied it to detect tissue-specific cell death in multiple pathologies including type 1 diabetes, cancer, neurodegeneration and trauma. We are working to develop this approach into a universal, minimally invasive methodfor early diagnosis and monitoring of multiple human diseases.
DNA methylation in pancreas development
The insulin gene promoter is unmethylated in beta cells but is heavily methylated elsewhere, providing a classic example of gene regulation by DNA methylation. We are studying how this pattern of methylation is established and what are the implications for developmental biology of the pancreas and for cellular plasticity in islets.
Dr. Mushira Abudia
Dr. Samir Abu Gazala
Dr. Shira Anzi
Dr. Noa Corem-Weinberg
Dr. Daniela Dadon
Dr. Avigail Dreazen
Dr. Tsufit Gonen-Gross
Dr. Ronny Helman
Dr. Abed Khalaileh
Dr. Tomer Nir
Dr. Shay Porat
Dr. Seth Salpeter
Dr. Rachel Schyr
Dr. Yaron Suissa
Dr. Batsheva Werman
Dr. Sharon Yagur
Dr. Oren Ziv
94661 Selected Research Projects in Bio Med. Sciences
94668 Biochemistry - Gene structure and Expression
94673 Metabolic and Physiologic Biochemistry
75215 Problem-Based Learning
Malakar P., Chartarifsky L., Hija A., Leibowitz G., Glaser B., Dor Y., and Karni R. (2016) Insulin receptor alternative splicing is regulated by insulin signaling and modulates beta cell survival. Sci Rep, 6:31222. doi: 10.1038/srep31222.
Lehmann-Werman R., Neiman D., Zemmour H., Moss J., Magenheim J., Vaknin-Dembinsky A., Rubertsson S., Nellg?rd B., Blennow K., Zetterberg H., Spalding K., Haller MJ., Wasserfall CH., Schatz DA., Greenbaum CJ., Dorrell C., Grompe M., Zick A., Hubert A., Maoz M., Fendrich V., Bartsch DK., Golan T., Ben Sasson SA., Zamir G., Razin A., Cedar H., Shapiro AM., Glaser B., Shemer R. and Dor Y. (2016) Identification of tissue-specific cell death using methylation patterns of circulating DNA. Proc Natl Acad Sci U S A 113(13):E1826-34.
Klochendler A., Caspi I., Corem N., Moran M., Friedlich O., Elgavish S., Nevo Y., Helman A., Glaser B., Eden A., Itzkovitz S. and Dor Y. (2016). The genetic program of pancreatic beta-cell replication in vivo. Diabetes 65(7):2081-93.
Helman, A., Klochendler, A., Azazmeh, N., Gabai, Y., Horwitz, E., Anzi, S., Swisa, A., Condiotti, R., Granit, R.Z., Nevo, Y., Fixler, Y., Shreibman, D., Zamir, A., Tornovsky-Babeay, S., Dai, C., Glaser, B., Powers, A.C., Shapiro, A.M., Magnuson, M.A., Dor, Y. and Ben-Porath, I. (2016). p16-induced senescence of pancreatic beta cells enhances insulin secretion. Nat Med 22(4):412-20.
Wittenberg, A.D., Azar, S., Klochendler, A., Stolovich-Rain, M., Avraham, S., Birnbaum, L., Binder Gallimidi, A., Katz, M., Dor, Y. and Meyuhas, O. (2016). Phosphorylated Ribosomal Protein S6 Is Required for Akt-Driven Hyperplasia and Malignant Transformation, but Not for Hypertrophy, Aneuploidy and Hyperfunction of Pancreatic beta-Cells. PLoS One 11, e0149995.
Swisa, A., Granot, Z., Tamarina, N., Sayers, S., Bardeesy, N., Philipson, L., Hodson, D.J., Wikstrom, J.D., Rutter, G.A., Leibowitz, G., Glaser, B. and Dor, Y. (2015). Loss of Liver Kinase B1 (LKB1) in Beta Cells Enhances Glucose-stimulated Insulin Secretion Despite Profound Mitochondrial Defects. J Biol Chem 290, 20934-20946.
Stolovich-Rain, M., Enk, J., Vikesa, J., Nielsen, F.C., Saada, A., Glaser, B. and Dor, Y. (2015). Weaning triggers a maturation step of pancreatic beta cells. Dev Cell 32, 535-545.
Tornovsky-Babeay, S., Dadon, D., Ziv, O., Tzipilevich, E., Kadosh, T., Schyr-Ben Haroush, R., Hija, A., Stolovich-Rain, M., Furth-Lavi, J., Granot, Z., Porat, S., Philipson, L.H., Herold, K.C., Bhatti, T.R., Stanley, C., Ashcroft, F.M., In't Veld, P., Saada, A., Magnuson, M.A., Glaser, B. and Dor, Y. (2014). Type 2 diabetes and congenital hyperinsulinism cause DNA double-strand breaks and p53 activity in beta cells. Cell Metab 19, 109-121.
Baeyens, L., Lemper, M., Leuckx, G., De Groef, S., Bonfanti, P., Stange, G., Shemer, R., Nord, C., Scheel, D.W., Pan, F.C., Ahlgren, U., Gu, G., Stoffers, D.A., Dor, Y., Ferrer, J., Gradwohl, G., Wright, C.V., Van de Casteele, M., German, M.S., Bouwens, L. and Heimberg, H. (2014). Transient cytokine treatment induces acinar cell reprogramming and regenerates functional beta cell mass in diabetic mice. Nat Biotechnol 32, 76-83.
Hija, A., Salpeter, S., Klochendler, A., Grimsby, J., Brandeis, M., Glaser, B. and Dor, Y. (2014). G0-G1 transition and the restriction point in pancreatic beta-cells in vivo. Diabetes 63, 578-584.
Suissa, Y., Magenheim, J., Stolovich-Rain, M., Hija, A., Collombat, P., Mansouri, A., Sussel, L., Sosa-Pineda, B., McCracken, K., Wells, J.M., Heller, R.S., Dor, Y. and Glaser, B. (2013). Gastrin: a distinct fate of neurogenin3 positive progenitor cells in the embryonic pancreas. PLoS One 8, e70397.
Ziv, O., Glaser, B. and Dor, Y. (2013). The plastic pancreas. Dev Cell 26, 3-7.
Salpeter, S.J., Khalaileh, A., Weinberg-Corem, N., Ziv, O., Glaser, B. and Dor, Y. (2013). Systemic regulation of the age-related decline of pancreatic beta-cell replication. Diabetes 62, 2843-2848.
Dor, Y. and Glaser, B. (2013). beta-cell dedifferentiation and type 2 diabetes. N Engl J Med 368, 572-573.
Khalaileh, A., Dreazen, A., Khatib, A., Apel, R., Swisa, A., Kidess-Bassir, N., Maitra, A., Meyuhas, O., Dor, Y. and Zamir, G. (2013). Phosphorylation of ribosomal protein S6 attenuates DNA damage and tumor suppression during development of pancreatic cancer. Cancer Res 73, 1811-1820.
Boj, S.F., van Es, J.H., Huch, M., Li, V.S., Jose, A., Hatzis, P., Mokry, M., Haegebarth, A., van den Born, M., Chambon, P., Voshol, P., Dor, Y., Cuppen, E., Fillat, C. and Clevers, H. (2012). Diabetes risk gene and Wnt effector Tcf7l2/TCF4 controls hepatic response to perinatal and adult metabolic demand. Cell 151, 1595-1607.
Klochendler, A., Weinberg-Corem, N., Moran, M., Swisa, A., Pochet, N., Savova, V., Vikesa, J., Van de Peer, Y., Brandeis, M., Regev, A., Nielsen, F.C., Dor, Y. and Eden, A. (2012). A transgenic mouse marking live replicating cells reveals in vivo transcriptional program of proliferation. Dev Cell 23, 681-690.
Cleaver, O. and Dor, Y. (2012). Vascular instruction of pancreas development. Development 139, 2833-2843.
Stolovich-Rain, M., Hija, A., Grimsby, J., Glaser, B. and Dor, Y. (2012). Pancreatic beta cells in very old mice retain capacity for compensatory proliferation. J Biol Chem 287, 27407-27414.
Magenheim, J., Ilovich, O., Lazarus, A., Klochendler, A., Ziv, O., Werman, R., Hija, A., Cleaver, O., Mishani, E., Keshet, E. and Dor, Y. (2011). Blood vessels restrain pancreas branching, differentiation and growth. Development 138, 4743-4752.
Magenheim, J., Klein, A.M., Stanger, B.Z., Ashery-Padan, R., Sosa-Pineda, B., Gu, G. and Dor, Y. (2011). Ngn3(+) endocrine progenitor cells control the fate and morphogenesis of pancreatic ductal epithelium. Dev Biol 359, 26-36.
Salpeter, S.J., Klochendler, A., Weinberg-Corem, N., Porat, S., Granot, Z., Shapiro, A.M., Magnuson, M.A., Eden, A., Grimsby, J., Glaser, B. and Dor, Y. (2011). Glucose regulates cyclin D2 expression in quiescent and replicating pancreatic beta-cells through glycolysis and calcium channels. Endocrinology 152, 2589-2598.
Porat, S., Weinberg-Corem, N., Tornovsky-Babaey, S., Schyr-Ben-Haroush, R., Hija, A., Stolovich-Rain, M., Dadon, D., Granot, Z., Ben-Hur, V., White, P., Girard, C.A., Karni, R., Kaestner, K.H., Ashcroft, F.M., Magnuson, M.A., Saada, A., Grimsby, J., Glaser, B. and Dor, Y. (2011). Control of pancreatic beta cell regeneration by glucose metabolism. Cell Metab 13, 440-449.
Melkman-Zehavi, T., Oren, R., Kredo-Russo, S., Shapira, T., Mandelbaum, A.D., Rivkin, N., Nir, T., Lennox, K.A., Behlke, M.A., Dor, Y. and Hornstein, E. (2011). miRNAs control insulin content in pancreatic beta-cells via downregulation of transcriptional repressors. EMBO J 30, 835-845.
Sand, F.W., Hornblad, A., Johansson, J.K., Loren, C., Edsbagge, J., Stahlberg, A., Magenheim, J., Ilovich, O., Mishani, E., Dor, Y., Ahlgren, U. and Semb, H. (2011). Growth-limiting role of endothelial cells in endoderm development. Dev Biol 352, 267-277.
Salpeter, S.J., Klein, A.M., Huangfu, D., Grimsby, J. and Dor, Y. (2010). Glucose and aging control the quiescence period that follows pancreatic beta cell replication. Development 137, 3205-3213.
Gur, C., Porgador, A., Elboim, M., Gazit, R., Mizrahi, S., Stern-Ginossar, N., Achdout, H., Ghadially, H., Dor, Y., Nir, T., Doviner, V., Hershkovitz, O., Mendelson, M., Naparstek, Y. and Mandelboim, O. (2010). The activating receptor NKp46 is essential for the development of type 1 diabetes. Nat Immunol 11, 121-128.
Granot, Z., Swisa, A., Magenheim, J., Stolovich-Rain, M., Fujimoto, W., Manduchi, E., Miki, T., Lennerz, J.K., Stoeckert, C.J., Jr., Meyuhas, O., Seino, S., Permutt, M.A., Piwnica-Worms, H., Bardeesy, N. and Dor, Y. (2009). LKB1 regulates pancreatic beta cell size, polarity, and function. Cell Metab 10, 296-308.
Nir, T., Melton, D.A. and Dor, Y. (2007). Recovery from diabetes in mice by beta cell regeneration. J Clin Invest 117, 2553-2561.
Weinberg, N., Ouziel-Yahalom, L., Knoller, S., Efrat, S. and Dor, Y. (2007). Lineage tracing evidence for in vitro dedifferentiation but rare proliferation of mouse pancreatic beta-cells. Diabetes 56, 1299-1304.
Murtaugh, L.C., Law, A.C., Dor, Y. and Melton, D.A. (2005). Beta-catenin is essential for pancreatic acinar but not islet development. Development 132, 4663-4674.
Stanger, B.Z., Stiles, B., Lauwers, G.Y., Bardeesy, N., Mendoza, M., Wang, Y., Greenwood, A., Cheng, K.H., McLaughlin, M., Brown, D., Depinho, R.A., Wu, H., Melton, D.A. and Dor, Y. (2005). Pten constrains centroacinar cell expansion and malignant transformation in the pancreas. Cancer Cell 8, 185-195.
Stanger BZ, Stiles B, Lauwers GY, Bardeesy N, Mendoza M, Wang Y, Greenwood A, McLaughlin M, Brown D, DePinho RA, Wu H, Melton DA, Dor Y (2005). Pten constrains centroacinar cell expansion and malignant transformation in the pancreas. Cancer Cell 8(3):185-95.
Dor, Y, Brown J, Martinez O, Melton D (2004). Adult pancreatic beta cells are formed by self-duplication rather than stem cell differentiation. Nature 429:41-46.
Dor, Y, Djonov V, Abramovitch R, Itin A, Fishman GI, Carmeliet P, Goelman G, Keshet E (2002). Conditional switching of VEGF provides new insights into adult neovascularization and pro-angiogenic therapy. EMBO J 21:1939-47.
Dor, Y, Camenisch T, Itin A, Fishman G, McDonald J, Carmeliet P, Keshet E (2001). A novel role for VEGF in endocardial cushion formation and its potential contribution to heart septation defects. Development 128:1531-1538.