The broad, long-term objective is to elucidate the mechanisms for recovery of the dark state through increase in cytoplasmic cGMP concentration in vertebrate retina rod outer segments (ROS). Biochemical and electrophysiological studies have shown that cGMP plays a key role in the system that converts a light signal into electric signa's in ROS. Little is known about the regulatory mechanism of cGMP synthesis by retinal guanylate cyclase (retGC) in ROS. Other mechanisms for the increase of free cGMP concentration have never been revealed. This proposal is based upon our recent progress in the basic characterization of vertebrate retGC, finding of possible multiple signaling pathways in ROS, and elucidation of unexpected involvement of cGMP phosphodiesterase (PDE) in increase of free cGMP concentration in ROS. Further characterization of the molecular mechanism for the increase of cytoplasmic cGMP concentration with or without cGMP metabolism will provide new aspects to the mechanism of abnormal regulation of cGMP concentration found in retinal cell degeneration, although the proposed research is based on basic biochemical and molecular biological experiments. The proposed research is also expected to provide broad applicability in studies about cellular regulation of second messengers in other cells.
Specific Aims i n the proposals are: l. To characterize retGC in vertebrate ROS. We have purified retGC from vertebrate ROS and provided basic characterization of retGC. During our study, we found that retGC has special characteristics which are different from other GCs. We also suggested unexpected localization of retGC. Polymorphism of retGC, and its post-translational modifications which may result in the polymorphism of retGC, have also been suggested. The molecular bases and biological significance of these retGC properties will be investigated using biochemical, molecular biological and histochemical methods. 2. To elucidate regulatory mechanisms of retGC in vertebrate ROS. We suggested complex regulatory mechanism of retGC in ROS. Molecular mechanisms and physiological significance of these regulations remain basically unclear. Exploration of new retGC regulatory mechanisms is possible by our progress in preparation of various retGC samples, and purification of Ca binding proteins and transducin isoforms. 3. To explore the direct, positive involvement of PDE in the recovery process of ROS to the dark condition. We recently found the Ca-sensitive cGMP release from PDE by GTP/transducin, retinal G-protein, complex. The unexpected finding allows us to investigate the mechanism of increase of cGMP concentration without cGMP metabolism. These phenomena suggest that the components involved in the reduction of cGMP level may also be involved in the increase of cGMP level in ROS. Molecular mechanism of the regulation will be studied using biochemical and molecular biological methods.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY007546-10
Application #
2684533
Study Section
Visual Sciences C Study Section (VISC)
Project Start
1991-08-01
Project End
2000-03-31
Budget Start
1998-04-01
Budget End
2000-03-31
Support Year
10
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Wayne State University
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
City
Detroit
State
MI
Country
United States
Zip Code
48202
Yamazaki, Akio; Hayashi, Fumio; Matsuura, Isao et al. (2011) Binding of cGMP to the transducin-activated cGMP phosphodiesterase, PDE6, initiates a large conformational change involved in its deactivation. FEBS J 278:1854-72
Yamazaki, Akio; Tatsumi, Masahiro; Bondarenko, Vladimir A et al. (2010) Mechanism for the regulation of mammalian cGMP phosphodiesterase6. 2: isolation and characterization of the transducin-activated form. Mol Cell Biochem 339:235-51
Yamazaki, Akio; Bondarenko, Vladimir A; Matsuura, Isao et al. (2010) Mechanism for the regulation of mammalian cGMP phosphodiesterase6. 1: identification of its inhibitory subunit complexes and their roles. Mol Cell Biochem 339:215-33
Yamazaki, Akio; Moskvin, Oleg; Yamazaki, Russell K (2002) Phosphorylation by cyclin-dependent protein kinase 5 of the regulatory subunit (Pgamma) of retinal cgmp phosphodiesterase (PDE6): its implications in phototransduction. Adv Exp Med Biol 514:131-53
Matsuura, I; Bondarenko, V A; Maeda, T et al. (2000) Phosphorylation by cyclin-dependent protein kinase 5 of the regulatory subunit of retinal cGMP phosphodiesterase. I. Identification of the kinase and its role in the turnoff of phosphodiesterase in vitro. J Biol Chem 275:32950-7
Hayashi, F; Matsuura, I; Kachi, S et al. (2000) Phosphorylation by cyclin-dependent protein kinase 5 of the regulatory subunit of retinal cGMP phosphodiesterase. II. Its role in the turnoff of phosphodiesterase in vivo. J Biol Chem 275:32958-65
Kachi, S; Yamazaki, M; Tanaka, Y et al. (2000) Structural change of bovine retinal cGMP phosphodiesterase by release of its gamma subunit: direct imaging by improved low angle rotary shadowing. J Electron Microsc (Tokyo) 49:699-708
Kachi, S; Nishizawa, Y; Olshevskaya, E et al. (1999) Detailed localization of photoreceptor guanylate cyclase activating protein-1 and -2 in mammalian retinas using light and electron microscopy. Exp Eye Res 68:465-73
Bondarenko, V A; Yamazaki, M; Hayashi, F et al. (1999) Suppression of GTP/T alpha-dependent activation of cGMP phosphodiesterase by ADP-ribosylation by its gamma subunit in amphibian rod photoreceptor membranes. Biochemistry 38:7755-63
Yu, H; Olshevskaya, E; Duda, T et al. (1999) Activation of retinal guanylyl cyclase-1 by Ca2+-binding proteins involves its dimerization. J Biol Chem 274:15547-55

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