ZFIN ID: ZDB-PUB-110823-22
Retina-specific protein fascin 2 is an actin cross-linker associated with actin bundles in photoreceptor inner segments and calycal processes
Lin-Jones, J., and Burnside, B.
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.