Dorsky Lab

Wintrobe 4th Floor

20 North 1900 East
Room 401 MREB
Salt Lake City, Utah 84132
(801) 581-4529 - Lab / (801) 581-6073 - Office


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In the vertebrate central nervous system (CNS), neural progenitor cells are influenced by their environment to differentiate and adopt specific fates. These environmental signals are crucial for the generating the correct number and type of neurons during development, and for continued neurogenesis throughout life to facilitate plasticity and repair. Our laboratory is studying the role of the Wnt signaling pathway in CNS neurogenesis. We use zebrafish as a model organism, focusing on the regulation of Wnt target genes in the CNS by a family of transcription factors called Tcf proteins. Tcfs can act as repressors or activators of target genes depending on the state of Wnt signaling.

Our current work focuses on two sites of neurogenesis that are conserved throughout vertebrates – in the spinal cord and the hypothalamus. In both regions, we are studying the roles of Tcf-mediated transcription in embryonic neurogenesis as well as in post-embryonic homeostasis and regeneration. We are investigating specific functions for Wnt/Tcf signaling in CNS development by addressing three important questions.

1) Which cells require Wnt/Tcf signaling? Using transgenic zebrafish that express fluorescent reporters under the control of Wnt-responsive promoters, we are characterizing reporter-expressing cell populations in the CNS and determining whether transgene expression in these regions also requires specific Tcf molecules. We are also systematically examining the expression of all Tcf genes in zebrafish during CNS development and maintenance.

2) What is the function of Tcf proteins in responsive cells? We have generated transgenic lines that express inducible modulators of Tcf target genes. Following conditional activation of these transgenes, we are analyzing misexpressing cells in vivo to identify essential Tcf functions in CNS development. In addition, we are examining mutant phenotypes for each Tcf gene, alone and in combination.

3) What are the target genes? Tcf function can lead to the repression or activation of downstream genes, but specific targets in the CNS are unknown. We are using chromatin immunoprecipitation (ChIP) with specific Tcf antibodies to identify and directly analyze candidate gene promoters as potential targets of Tcfs in the CNS. We are also performing microarray analysis of loss-of-function mutants to identify functionally regulated genes in CNS progenitors.

Spinal Cord Neurogenesis

We are interested in the functions of Wnt signaling and Tcf3 function in embryonic spinal cord development and regeneration. In addition to the roles of Wnt/Tcf-mediated transcription in spinal cord patterning and proliferation (Bonner, et al., Dev Biol, 2008), Tcf3 acts as a transcriptional repressor to prevent progenitor differentiation (Gribble et al., Development, 2009), indicating that it may function to maintain a stable population of multipotent progenitor cells.

One current project in the lab focuses on the cellular and molecular characterization of spinal progenitors following loss of Tcf3. We have generated tcf3 mutant zebrafish and are analyzing the phenotypes of spinal progenitors, and using gene expression analysis to identify Tcf3 targets. This work is testing the hypothesis that Tcf3 acts as a master regulator of the CNS progenitor state, similar to the known function for this protein in epidermal development.

A second project is investigating spinal progenitor response to injury. Zebrafish have a remarkable ability to fully regenerate their spinal cord following complete transection. We are using a transgenic approach to label spinal radial glia, and determining whether these cells undergo neurogenesis following injury, and if this response depends on Wnt/Tcf function.


Hypothalamic Neurogenesis

This work focuses on the role of Wnt and Lef1 activity in post-embryonic neurogenesis. We previously identified a requirement for Lef1 in the formation of neural progenitors in the posterior hypothalamus (Lee et al., Development, 2006). This region of the brain maintains Wnt activity and continues to produce GABAergic neurons throughout life (Wang et al., Zebrafish, 2009), suggesting that Wnt-regulated neurogenesis plays an important role in the adult brain.

We are testing the hypothesis that post-embryonic hypothalamic neurogenesis regulated by Wnt signaling is important in feeding behavior. We are transgenically labeling newly-born GABAergic neurons to determine whether they integrate into feeding circuitry. We will also genetically manipulate these cells in vivo and test whether there are resulting behavioral effects. Evolutionary conservation of this cell population suggests that mammalian hypothalamic function may also be regulated by Wnt signaling.

To determine the functional role of Wnt signaling and Lef1 in the hypothalamus, we are using a conditional transgenic approach to modulate the pathway in vivo. These experiments will test whether Wnt signaling is required to promote neurogenesis in progenitor cells, regulating the rate of GABAergic neuron production. We are identifying Lef1 target genes in neural progenitors using whole-genome ChIP analysis and expression profiling in lef1 mutants.

Dorsky Lab Members

  Name
Email
Position Research

Lisa
Benko

lisa.benko@neuro.utah.edu

Graduate
Student

Characterization of Multipotent Spinal Cord Progenitors

Rob Duncan

rob.duncan@neuro.utah.edu

Graduate
Student

Identification of Neural Stem Cells in the Zebrafish Hypothalamus

Hyung-Seok Kim

hskim@neuro.utah.edu

Postdoctoral
Fellow

Tcf3 Targets in Spinal Cord Development

Adam McPherson

adam.mcpherson@neuro.utah.edu

Graduate
Student

Functional Analysis of Post-Embryonic Hypothalamic Neurogenesis

Xu
Wang

wangxu@neuro.utah.edu

Graduate
Student

Wnt Signaling and Post-Embryonic Hypothalamic Neurogenesis

 

Xin
Wu

xin.wu@neuro.utah.edu

Lab Manager

 

 

Lab Alumni

Name
Email
Current Postion

Jennifer Bonner

jbonner@skidmore.edu

Assistant Professor, Skidmore College, NY

Suzanna Gribble

slgribble@gcc.edu

Assistant Professor, Grove City College, PA

Junji Lin

junji.lin@pharm.utah.edu

Pharmacotherapy Outcomes Research Center (PORC), University of Utah

Eric Veien

eric.veien@umassmed.edu

Postdoctoral Fellow, U Mass Medical Center

Search Pubmed for Richard Dorsky's lab publications

  • Wang X, Lee JE, Dorsky RI.  Identification of Wnt-responsive cells in the zebrafish hypothalamus.  Zebrafish 6, (2009), 49-58.
  • Gribble SL, Kim HS, Bonner J, Wang X, Dorsky RI.  Tcf3 inhibits spinal cord neurogenesis by regulating sox4a expression.  Development, 136 (2009) 781-9.
  • Veien ES, Rosenthal JS, Kruse-Bend RC, Chien CB, Dorsky RI.  Canonical Wnt signaling is required for the maintenance of dorsal retinal identity.  Development, 135 (2008) 4101-11.
  • Bonner, J, Gribble SL, Veien ES, Nikolaus OB, Weidinger G, Dorsky RI. Distinct pathways mediate patterning and proliferation in the dorsal spinal cord downstream of canonical Wnt signaling, Developmental Biology, 313 (2008) 398-407.
  • Gribble SL, Nikolaus OB, Dorsky RI. Regulation and function of Dbx genes in the zebrafish spinal cord. Developmental Dynamics, 236 (2007), 3472-83.
  • Nyholm MK, Wu SF, Dorsky RI, Grinblat Y. The zebrafish zic2a-zic5 gene pair acts downstream of canonical Wnt signaling to control cell proliferation in the developing tectum. Development, 134 (2007), 735-46.
  • Lee J, Wu S, Goering, LM, Dorsky, RI. Canonical Wnt signaling through Lef1 is required for hypothalamic neurogenesis. Development, 133 (2006), 4451-61.
  • Veien ES, Grierson MJ, Saund RS, Dorsky RI. The Expression Pattern of Zebrafish tcf7 Suggests Unexplored Domains of Wnt/ß-Catenin Activity. Developmental Dynamics, 233 (2005). 233-239.
  • Lewis JL, Bonner J, Modrell M, Ragland JW, Moon RT, Dorsky RI, Raible DW. Reiterated Wnt signaling during zebrafish neural crest development. Development, 131(2004), 1299-308.
  • Dorsky RI, Itoh M, Moon RT, Chitnis A. Two tcf3 genes cooperate to pattern the zebrafish brain. Development, 130 (2003), 1937-1947.
  • Dorsky RI, Sheldahl LC, Moon RT. A Transgenic Lef1/ß-catenin-Dependent Reporter is Expressed in Spatially-Restricted Domains Throughout Zebrafish Development Developmental Biology, 241 (2001), 229-237.
  • Dorsky RI, Raible DW, Moon RT. Direct regulation of nacre, a zebrafish MITF homolog required for pigment cell formation, by the Wnt pathway. Genes and Development 14 (2000), 158-162.
  • Dorsky RI, Moon RT, Raible DW. Control of neural crest cell fate by the Wnt signalling pathway. Nature 396 (1998), 370-373.
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