Genomes and Genes
MOLECULAR MOTORS IN RETINAL CELL MOTILITY
Principal Investigator: MARY BURNSIDE
Affiliation: University of California
Abstract: The ultimate goal of our research is to understand how cytoskeletal motor proteins power motile processes critical to the differentiation and function of the vertebrate photoreceptor. Since photoreceptor survival is jeopardized if the function of specific motors is compromised by mutation or aging, a better understanding of motor protein function in normal photoreceptors will provide insight into mechanisms of photoreceptor degeneration and vision loss. In this application we examine the roles of the cytoskeletal motors kinesin II and myosin VIIA in photoreceptor morphogenesis and outer segment turnover, investigate the contribution of ciliary axoneme-dependent transport to outer segment formation and maintenance, and further characterize a new myosin we have discovered, myosin III, which is a vertebrate homologue of Drosophila ninaC. Our strategy for functional analysis of these motors entails assessing the effects of compromising their function in chick photoreceptors in vitro and in vivo using two complementary strategies: (a) transient knockout of motor protein expression using antisense technology; and (b) retroviral-mediated overexpression of dominant negative tail constructs to inactivate endogenous motor proteins and saturate cargo binding sites. Kinesin II is concentrated at the basal body and axoneme of vertebrate photoreceptors. This motor has been shown to be required for morphogenesis and maintenance of motile and sensory flagella, where it mediates intraflagellar transport (IFT), the movement of rafts of multipeptide particles between the axoneme and plasma membrane. We propose to use degenerate primer PCR to seek vertebrate homologues of IFT particle peptides and investigate the possible roles of kinesin II and axoneme-dependent transport in outer segment morphogenesis and maintenance using the chick photoreceptor assay system. Mutations in the human myosin VIIA gene produce Usher's Syndrome type 1B, a form of retinitis pigmentosa accompanied by deafness. Myosin VIIA has been shown to be concentrated at the photoreceptor connecting cilium but its function is not known. We propose to test the hypothesis that disk morphogenesis is powered by the interaction of myosin VIIA with actin filaments associated with the axoneme at the distal connecting cilium. We have recently found that vertebrate retinas selectively express a homologue of the Drosophila myosin (ninaC). Since flies with null mutations for ninaC exhibit altered phototransduction and light-induced photoreceptor degeneration, we are interested in determining the properties and functions of the vertebrate myosin III. To this end we will use heterologous expression for biochemical characterization and in vitro motility assays, and functional analysis in the chick photoreceptor system.
Funding Period: 1980-12-01 - 2003-11-30
more information: NIH RePORT
- Characterization of peripherin/rds and rom-1 transport in rod photoreceptors of transgenic and knockout animalsEdwin S Lee
Department of Molecular Cell Biology, University of California, Berkeley, USA
Invest Ophthalmol Vis Sci 47:2150-60. 2006..Peripherin/rds and rom-1 trafficking were studied in several knockout and transgenic animal models...
- Kinetic mechanism of human myosin IIIAAndrea C Dose
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
J Biol Chem 282:216-31. 2007..The long lived actomyosin-ADP state may be important for the ability of myosin III to function as a cellular transporter and actin cross-linker in the actin bundles of sensory cells...
- Retina-specific protein fascin 2 is an actin cross-linker associated with actin bundles in photoreceptor inner segments and calycal processesJennifer Lin-Jones
Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California, USA
Invest Ophthalmol Vis Sci 48:1380-8. 2007..To investigate the role of fascin 2 in photoreceptor survival, the authors examined its localization in photoreceptors and characterized its interactions with actin filaments in vitro...
- Identification and localization of myosin superfamily members in fish retina and retinal pigmented epitheliumJennifer Lin-Jones
Department of Molecular and Cell Biology, University of California, Berkeley, California 94720 3200, USA
J Comp Neurol 513:209-23. 2009....
- Myosin IIIa boosts elongation of stereocilia by transporting espin 1 to the plus ends of actin filamentsFelipe T Salles
1 Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA 2 These authors contributed equally to the work
Nat Cell Biol 11:443-50. 2009....
- Cloning and distribution of myosin 3B in the mouse retina: differential distribution in cone outer segmentsChristiana Katti
Department of Neuroscience and Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA
Exp Eye Res 89:224-37. 2009..Myo3B may have diverse roles in retinal neurons. In photoreceptor inner segments Myo3B is positioned appropriately to prevent photoreceptor loss of function caused by Myo3A defects...