Retina-specific protein fascin 2 is an actin cross-linker associated with actin bundles in photoreceptor inner segments and calycal processes
- Authors
- Lin-Jones, J., and Burnside, B.
- ID
- ZDB-PUB-110823-22
- Date
- 2007
- Source
- Investigative ophthalmology & visual science 48(3): 1380-1388 (Journal)
- Registered Authors
- Burnside, Beth, Lin-Jones, Jennifer
- Keywords
- none
- MeSH Terms
-
- Actin Cytoskeleton/metabolism*
- Amino Acid Sequence
- Animals
- Animals, Genetically Modified
- Blotting, Western
- Cloning, Molecular
- Eye Proteins/chemistry
- Eye Proteins/metabolism*
- Gene Expression
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Microfilament Proteins/chemistry
- Microfilament Proteins/metabolism*
- Microscopy, Fluorescence
- Molecular Sequence Data
- Phosphorylation
- Photoreceptor Cells, Vertebrate/metabolism*
- Recombinant Fusion Proteins
- Serine/metabolism
- Transgenes
- Xenopus laevis
- Zebrafish
- PubMed
- 17325187 Full text @ Invest. Ophthalmol. Vis. Sci.
purpose. Fascin 2 is a retinal-specific member of the fascin family of actin filament-bundling proteins. Fascin 2 mutation in humans results in autosomal dominant retinitis pigmentosa or macular degeneration. 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.
methods. Fascin 2 localization was determined by immunohistochemistry and transgenic expression of green fluorescent protein (GFP)–tagged fascin 2 in Xenopus laevis rods. Fascin 2 actin-binding and actin-bundling activity were examined in sedimentation assays using bacterially expressed fusion proteins and polymerized actin. To assess the role of phosphorylation of a conserved serine (amino acid 39) in fascin 2 on subcellular localization and actin-binding, effects of serine mutants were also examined in transgenic Xenopus and in in vitro assays.
results. Fascin 2 is localized to actin filament bundles of the photoreceptor inner segment and calycal processes. Like fascin 1, fascin 2 binds and cross-links actin filaments. Mutation of serine 39 to an aspartic acid reduced fascin 2 binding of actin filaments and abolished fascin 2 bundling of actin filaments in vitro but produced no detectable effect on GFP-tagged fascin 2 localization in transgenic Xenopus.
conclusions. These observations suggest that fascin 2 plays a role in the assembly or stabilization of inner segment and calycal process actin filament bundles in photoreceptors and that serine 39 phosphorylation reduces actin-binding and cross-linking activity and, thus, is likely to regulate the inner segment actin cytoskeleton.