Neurons in autonomic ganglia share many features but can be distinguished by their ganglionic morphology, location and neurotransmitter. Autonomic neurons are derived from the neural crest, a transitory population of precursor cells. The generation of neuronal diversity involves integration of extrinsic and intrinsic instructive cues that result in the neuron subtype-specific expression of transcriptional regulators. For autonomic noradrenergic (NE) neurons, bone morphogenetic 4 (BMP4) is an essential extrinsic cue. BMP4- mediated signaling recruits the basic helix-loop-helix DMA binding protein HAND2, in an NE cell type-specific manner, to a core network of transcriptional regulators expressed by autonomic neuron precursor cells. Both gain-of-function and loss-of-function studies demonstrated a necessary role for HAND2 in neurogenesis and cell type-specific gene expression required for the generation of NE neurons. The underlying mechanisms of HAND2 function remain unknown. The goals of this proposal are to: 1) unravel the mechanisms by which HAND2 contributes to neurogenesis of NE neurons, and 2) determine the mechanism by which HAND2 links expression of pan-neuronal genes to cell type-specific genes. We will use targeted deletion of HAND2 at early and late stages of neurogenesis to reveal the consequences to differentiation as neurons and expression of NE neurotransmitter due to loss of HAND2. Next, we will ectopically express HAND2 in precursor cells and identify target genes by expression profiling. Using promoter reporter constructs in transient transfection assays, we will examine functional interactions of HAND2 with identified target genes. Finally, we will examine intracellular signaling pathways downstream of BMP4 and dependent upon Smad1/4 translocation, MapK and PKA to understand how BMP4-mediated signaling influences the expression and function of HAND2. These studies are particularly compelling because HAND2 is markedly overexpressed in neuroblastoma, a solid pediatric tumor derived from neural crest cells destined to give rise to sympathetic ganglion neurons or adrenal medullary cells. These tumors are heterogeneous in their phenotype and can regress or lead to death. Since we will provide a detailed analysis of fundamental mechanisms underlying neuron cell fate choice and sub-type identity, our studies have the potential for development of novel treatment strategies for neuroblastoma based on genetic regulation of neurogenesis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS040644-08
Application #
7544456
Study Section
Special Emphasis Panel (ZRG1-MDCN-J (02))
Program Officer
Owens, David F
Project Start
2000-07-01
Project End
2010-12-31
Budget Start
2009-01-01
Budget End
2009-12-31
Support Year
8
Fiscal Year
2009
Total Cost
$324,406
Indirect Cost
Name
University of Toledo
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
807418939
City
Toledo
State
OH
Country
United States
Zip Code
43614
Jayakar, Selwyn S; Pugh, Phyllis C; Dale, Zack et al. (2014) PACAP induces plasticity at autonomic synapses by nAChR-dependent NOS1 activation and AKAP-mediated PKA targeting. Mol Cell Neurosci 63:1-12
VanDusen, Nathan J; Vincentz, Joshua W; Firulli, Beth A et al. (2014) Loss of Hand2 in a population of Periostin lineage cells results in pronounced bradycardia and neonatal death. Dev Biol 388:149-58
Newgreen, Donald F; Dufour, Sylvie; Howard, Marthe J et al. (2013) Simple rules for a ""simple"" nervous system? Molecular and biomathematical approaches to enteric nervous system formation and malformation. Dev Biol 382:305-19
Vincentz, Joshua W; Firulli, Beth A; Lin, Andrea et al. (2013) Twist1 controls a cell-specification switch governing cell fate decisions within the cardiac neural crest. PLoS Genet 9:e1003405
Vincentz, Joshua W; VanDusen, Nathan J; Fleming, Andrew B et al. (2012) A Phox2- and Hand2-dependent Hand1 cis-regulatory element reveals a unique gene dosage requirement for Hand2 during sympathetic neurogenesis. J Neurosci 32:2110-20
Barron, Francie; Woods, Crystal; Kuhn, Katherine et al. (2011) Downregulation of Dlx5 and Dlx6 expression by Hand2 is essential for initiation of tongue morphogenesis. Development 138:2249-59
Lei, Jun; Howard, Marthe J (2011) Targeted deletion of Hand2 in enteric neural precursor cells affects its functions in neurogenesis, neurotransmitter specification and gangliogenesis, causing functional aganglionosis. Development 138:4789-800
Holler, Kristen L; Hendershot, Tyler J; Troy, Sophia E et al. (2010) Targeted deletion of Hand2 in cardiac neural crest-derived cells influences cardiac gene expression and outflow tract development. Dev Biol 341:291-304
Schmidt, Mirko; Lin, Shengyin; Pape, Manuela et al. (2009) The bHLH transcription factor Hand2 is essential for the maintenance of noradrenergic properties in differentiated sympathetic neurons. Dev Biol 329:191-200
Hendershot, Tyler J; Liu, Hongbin; Clouthier, David E et al. (2008) Conditional deletion of Hand2 reveals critical functions in neurogenesis and cell type-specific gene expression for development of neural crest-derived noradrenergic sympathetic ganglion neurons. Dev Biol 319:179-91

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