Early vertebrate development and pattern formation, Wnt signaling, chromatin and epigenetic regulation of early development, hematopoietic stem cell biology, neuropharmacology of bipolar disorder, lithium and glycogen synthase kinase-3 (GSK-3).
Wnt, embryo, signal transduction, developmental biology, lithium, chromatin, epigenetic, hematopoiesis, stem cell, GSK-3, behavior, affective disorders.
Description of Research
This lab studies patterning in early vertebrate development, the regulation of stem cell self-renewal in the hematopoietic system, and the molecular mechanisms in the pathogenesis and treatment of neuropsychiatric disorders. Areas of current research include:
1) Wnt signaling modifies chromatin architecture to control early development: We have found that Wnt signaling through ß-catenin establishes poised chromatin architecture at Wnt target promoters in the early embryo. We have identified Prmt2 as a histone H3 arginine-8 methyltransferase and shown that it is recruited by ß-catenin to Wnt target gene promoters and is required for dorsal-ventral patterning. We are currently examining the requirement for Prmt2 in other Wnt-regulated contexts in development and in somatic stem cell populations. We are also exploring the regulation of zygotic gene expression before the midblastula transition, focusing on the role of preMBT transcription in germ layer specification. These experiments are being carried out in Xenopus laevis embryos and in mouse hematopoietic stem cells, and involve microinjection, microsurgical procedures, molecular analysis of chromatin structure and gene expression, and biochemical analysis of the Wnt signaling pathway.
2) Wnt and GSK-3 regulation of hematopoietic stem cell (HSC) self-renewal: We are studying the roles of GSK-3 and Wnt signaling in HSC homeostasis in vivo and in primary HSC culture. We are exploring novel ex vivo culture techniques to define the signaling pathways required for and the gene expression profile associated with HSC self-renewal. In collaboration with Wei Tong at CHOP, we are also studying how JAK/STAT signaling interacts with GSK-3 and Wnts to regulate HSC renewal. These experiments are being carried out with mouse and human hematopoietic stem cells, using novel ex vivo culture techniques and stem cell transplantation assays in mice. These experiments also involve flow cytometry and cell sorting, RNA interference, and biochemical analysis of transmembrane signaling pathways. Our long-term interest is to adapt these findings to clinical applications including hematopoietic stem cell transplantation in humans and treatment of bone marrow failure disorders.
3) Neuronal signaling pathways that mediate the response to mood stabilizing drugs, with a focus on lithium, GSK-3, and Wnt signaling in the adult central nervous system, in order to understand the molecular pathogenesis and pharmacotherapy of bipolar disorder. This laboratory identified GSK-3 as a direct target of lithium, the most widely used and effective treatment for bipolar disorder. We are currently investigating the downstream molecular targets and the neuronal cell populations within the brain that mediate the response to mood stabilizing drugs. For these experiments, we use neural specific gene knockout and transgenic mice, multiple behavioral assays in adult mice, and in vivo analysis of neural stem cell proliferation and differentiation. In collaboration with Celeste Simon, we are examining interaction between hypoxia inducible factors, GSK-3, and the Wnt pathway in regulating neuronal stem/progenitor cells and the potential role of this cell population in mood disorders.
4) Molecular mechanisms of Wnt signaling: We are also investigating the molecular mechanisms of Wnt signaling, with a focus on how GSK-3 activity is suppressed in response to Wnts and other upstream signals. We have found that GSK-3 is positively regulated by the tumor suppressor APC and are exploring the hypothesis that GSK-3 is functionally inhibited by dissociation of APC from GSK-3 containing complexes, such as the axin degradation complex.
1. Molecular analysis of hematopoietic stem cell signaling in vivo and in ex vivo culture.
2. Role of hypoxia in HSC maintenance and proliferation ex vivo.
3. Chromatin modifications in response to Wnt signaling in HSCs.
4. PreMBT regulation of dorsal-ventral patterning and Wnt signaling in Xenopus embryos.
5. Identify components of the Wnt regulated ß-catenin/Prmt2 complex.
6. Role of chromatin modifications in developmental plasticity and the response to developmental signals during early embryogenesis.
7. Use of microarray and RNA-seq to identify novel preMBT genes; characterization of function of genes expressed before MBT.
Alex Valvezan, graduate student
Jian Huang, postdoctoral fellow
Michelle Nguyen-McCarty, graduate student
Mansi Shinde, graduate student
Kelsey Speer, graduate student (Lemmon and Klein labs)
Aseem Upadhyay, graduate student (master's program)
Shawn Kelley, undergraduate
Matthew Dong, undergraduate
Jessica Manlove, lab manager
Huang J, Nguyen-McCarty M, Hexner EO, Danet-Desnoyers G, and PS Klein, : Maintenance of Hematopoietic Stem Cells through regulation of Wnt and mTOR Pathways. Nature Medicine 18: 1778-1785, Nov 11 2012 Notes: doi: 10.1038/nm.2984.
Valvezan AJ, Zhang FS, Diehl JA, and PS Klein: Adenomatous Polyposis Coli (APC) regulates multiple signaling pathways by enhancing glycogen synthase kinase-3 (GSK-3) activity. Journal of Biological Chemistry 287: 3823-3832, 2012.
O’Brien WT, Huang J, Buccafusca R, Garskof J, Valvezan AJ, Berry GT, and PS Klein: Glycogen synthase kinase-3 is essential for β-arrestin-2 complex formation and lithium-sensitive behaviors in mice. Journal of Clinical Investigation 121: 3756-3762, 2011.
Skirkanich J, Luxardi G, Yang J, Kodjabachian L, and PS Klein: An essential role for transcription before the MBT in Xenopus laevis. Developmental Biology 357: 478-491, 2011.
Blythe SA and Klein PS: Prepatterning embryonic development: tabula scripta? Developmental Cell 21: 977-978, 2011.
Blythe SA, Cha SW, Tadjuidje E, Heasman J, Klein PS,: beta-Catenin primes organizer gene expression by recruiting a histone H3 arginine 8 methyltransferase, Prmt2. Developmental Cell 19(2): 220-231, Aug 2010.
Mazumdar J, O'Brien WT, Johnson RS, LaManna JC, Chavez JC, Klein PS, Simon MC: O2 regulates stem cells through Wnt/β-catenin signalling. Nature Cell Biology 12(10): 1007-13, Oct 2010.
Huang J, Zhang Y, Bersenev A, O'Brien WT, Tong W, Emerson SG, Klein PS: Pivotal role for glycogen synthase kinase-3 in hematopoietic stem cell homeostasis in mice. Journal of Clinical Investigation 119(12): 3519-29, Dec 2009.
Yin, L, Wang, J, Klein, PS, and Lazar, MA. : Nuclear receptor Rev-erbα is a Critical Lithium-Sensitive Component of the Circadian Clock. Science 311(5763): 1002-5. Feb 2006.
Wu J, O’Donnell M, Gitler AD, and PS Klein: Kermit-2/XGIPC, an IGF1R interacting protein, is required for IGF signaling in Xenopus eye development. Development 133: 3651-3660, 2006.
O'Brien, W.T., Harper,A.D., Jove, F., Woodgett, J.R., Maretto, S., Piccolo, S., and P.S. Klein: Glycogen synthase kinase-3ß haploinsufficiency mimics the behavioral and molecular effects of lithium. Journal of Neuroscience 24: 6791– 6798, 2004.
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Last updated: 03/14/2014
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