(Applicant 's abstract) Tyrosine-specific protein kinases are abundant in synaptic layers of the vertebrate neural retina but their function remains a central unanswered question in vision research. We recently made the important discovery that tyrosine (Tyr) phosphorylation of specific proteins (106, 78, 40 Kd and others) associated with terminals of retinal neurons and surrounding Muller glial processes in the chick neural retina is dramatically stimulated in response to illumination. The response is rapid, nontransient, and readily reversible. Our immediate goal is to define the proximal components of the pathway of signal transduction mediated by Tyr kinases in response to light (the neurotransmitter signals, the Tyr kinases activated by light, and the substrates of kinase action) with the long range goal of elucidating their function in the photic response. Our working hypothesis is that Tyr dephosphorylation of substrates is related to neurotransmitter signalling or reuptake in retinal neurons or glia. We will apply a new tool, phosphotyrosine (PTyr) antibodies to analyze the PTyr response in the chick retina by immunocytochemical, biochemical, and molecular biological techniques. We will (1) determine the optimal illumination conditions pathways, (2) use immunoelectron microscopy to localize the subcellular sites of the substrates and to test the postulate that the PTyr response is related to coated vesicle dynamics involved in membrane recycling, (3) identify specific neurotransmitters as signals for Tyr dephosphorylation or phosphorylation in the outer and inner plexiform layers, (4) generate monolconal antibodies to study the structure and function of retinal substrates, and (5) identify novel Tyr kinases responsible for light-dependent phosphorylation of substrates in the retina by PTyr antibody screening of a retinal cDNA library. This research investigates an unexplored areas of protein modification in the retina, which will contribute to our understanding of normal retinal function and vision.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY008975-02
Application #
3266336
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1991-01-01
Project End
1993-12-31
Budget Start
1992-01-01
Budget End
1992-12-31
Support Year
2
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Type
Schools of Medicine
DUNS #
078861598
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Biscardi, J S; Denhez, F; Buehler, G F et al. (1996) Rek, a gene expressed in retina and brain, encodes a receptor tyrosine kinase of the Axl/Tyro3 family. J Biol Chem 271:29049-59
Biscardi, J S; Cooper, N G; Maness, P F (1993) Phosphotyrosine-modified proteins are localized in Muller cells of the chick neural retina. Exp Eye Res 56:281-9
Ingraham, C A; Cooke, M P; Chuang, Y N et al. (1992) Cell type and developmental regulation of the fyn proto-oncogene in neural retina. Oncogene 7:95-100
Biscardi, J S; Shores, C G; Maness, P F (1991) Elevated protein tyrosine phosphorylation in the optic tract of the chick embryo. Curr Eye Res 10:1121-8