The long-term goal of this research is to elucidate mechanisms by which cell-extrinsic signals influence progenitor cell fate specification and neuronal differentiation. The proposed study focuses on mechanisms by which ciliary neurotrophic factor (CNTF)-like cytokines act in the mouse retina. During development, CNTF affects the differentiation of photoreceptor cells, bipolar cells, and Muller glia; while in the mature retina, CNTF enhances retinal ganglion cell survival and prevents photoreceptor degeneration in various mammalian models. We have demonstrated that CNTF differentially activates intracellular signaling pathways in proliferating progenitors and postmitotic neurons in the neonatal retina; CNTF-dependent inhibition of rod photoreceptor differentiation requires STAT function, whereas CNTF-enhanced production of Muller glia involves both STAT and ERK activities. We hypothesize that STAT and ERK signaling play distinct roles in retinal progenitor cells and in postmitotic cells. To test this hypothesis, we will perturb cytokine signaling pathways using cell type-specific promoters and mutant signaling proteins in the postnatal retina. We have also observed that persistent CNTF signals trigger only transient retinal signal transduction, which correlates with an up-regulation of the cytokine signaling inhibitor SOCS3. We hypothesize that the negative regulation of cytokine signals by SOCS3 is critical for proper retinal development. To elucidate the function of SOCS3, we will misexpress SOCS3 and inhibit SOCS3 expression by RNA interference-mediated gene inhibition. It has been shown that viral mediated CNTF expression in the rds mutant retina rescues photoreceptor cell death, but causes abnormal cell morphology and retinal function. We will characterize signaling events in CNTF treated rds retina and test if the survival of photoreceptors is mediated by cytokine activated Muller glia. We have also begun to screen for cytokine target genes in the postnatal retina by microarray analyses. Potential candidate target genes will be validated by RT-PCR, in situ hybridization, Western blot, and promoter sequence analyses. Interactions between STAT transcription factors and target gene promoters will be examined by promoter binding assays. These proposed studies will advance our understanding of cytokine signaling mechanisms in the normal developing retina and in a mutant model of photoreceptor degeneration.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY012270-06
Application #
7124287
Study Section
Biology and Diseases of the Posterior Eye Study Section (BDPE)
Program Officer
Mariani, Andrew P
Project Start
2000-05-01
Project End
2009-07-31
Budget Start
2006-08-01
Budget End
2007-07-31
Support Year
6
Fiscal Year
2006
Total Cost
$377,173
Indirect Cost
Name
University of California Los Angeles
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Rhee, K-D; Yu, J; Zhao, C Y et al. (2012) Dnmt1-dependent DNA methylation is essential for photoreceptor terminal differentiation and retinal neuron survival. Cell Death Dis 3:e427
Sakagami, Kiyo; Chen, Bryan; Nusinowitz, Steven et al. (2012) PTEN regulates retinal interneuron morphogenesis and synaptic layer formation. Mol Cell Neurosci 49:171-83
Rhee, Kun Do; Yang, Xian-Jie (2010) Function and mechanism of CNTF/LIF signaling in retinogenesis. Adv Exp Med Biol 664:647-54
Sakagami, Kiyo; Gan, Lin; Yang, Xian-Jie (2009) Distinct effects of Hedgehog signaling on neuronal fate specification and cell cycle progression in the embryonic mouse retina. J Neurosci 29:6932-44
Yang, Xin; Zhang, Hua; Zhang, Yingchun et al. (2008) Two new diterpenoid acids from Pinus koraiensis. Fitoterapia 79:179-81
Goureau, Olivier; Rhee, Kun Do; Yang, Xian-Jie (2004) Ciliary neurotrophic factor promotes muller glia differentiation from the postnatal retinal progenitor pool. Dev Neurosci 26:359-70
Yang, Xian-Jie (2004) Roles of cell-extrinsic growth factors in vertebrate eye pattern formation and retinogenesis. Semin Cell Dev Biol 15:91-103
Rhee, Kun Do; Goureau, Olivier; Chen, Shiming et al. (2004) Cytokine-induced activation of signal transducer and activator of transcription in photoreceptor precursors regulates rod differentiation in the developing mouse retina. J Neurosci 24:9779-88
Hashimoto, Takao; Zhang, Xiang-Mei; Yang, Xian-Jie (2003) Expression of the Flk1 receptor and its ligand VEGF in the developing chick central nervous system. Gene Expr Patterns 3:109-13
Rhee, Kun Do; Yang, Xian-Jie (2003) Expression of cytokine signal transduction components in the postnatal mouse retina. Mol Vis 9:715-22

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