title: Intermediate filaments regulate tissue size and stiffness in the murine lens.
abstract: OBJECTIVE
  To define the contributions of the beaded filament (BF), a lens-specific intermediate filament (IF), to lens morphology and biomechanics.
  
  
  METHODS
  Wild-type and congenic CP49 knockout (KO) mice were compared by using electrophysiological, biomechanical, and morphometric approaches, to determine changes that occurred because of the absence of this cytoskeletal structure.
  
  
  RESULTS
  Electrophysiological assessment established that the fiber cells lacking the lens-specific IFs were indistinguishable from wild-type fiber cells. The CP49 KO mice exhibited lower stiffness, and an unexpected higher resilience than the wild-type lenses. The absence of these filaments resulted in lenses that were smaller, and exhibited a higher ratio of lens:lens nucleus size. Finally, lens shape differed as well, with the CP49 KO showing a higher ratio of axial:equatorial diameter.
  
  
  CONCLUSIONS
  Previous work has shown that BFs are necessary in maintaining fiber cell and lens structural phenotypes with age, and that absence of these filaments results in a loss of lens clarity. This work demonstrates that several tissue-level properties that are critical to lens function are also dependent, at least in part, on the presence of these lens-specific IFs.
authors.affiliation: Department. of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Fudge
authors.forename: John V
authors.initials: JV
authors.lastname: McCuaig
authors.forename: Shannon
authors.initials: S
authors.lastname: Van Stralen
authors.forename: John F
authors.initials: JF
authors.lastname: Hess
authors.forename: Huan
authors.initials: H
authors.lastname: Wang
authors.forename: Richard T
authors.initials: RT
authors.lastname: Mathias
authors.forename: Paul G
authors.initials: PG
authors.lastname: FitzGerald
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D004548:Elasticity / Q000502:physiology*; D017097:Electric Impedance; D005136:Eye Proteins / Q000502:physiology*; D007381:Intermediate Filament Proteins / Q000502:physiology*; D007908:Lens, Crystalline / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009929:Organ Size
chemical_list: D005136:Eye Proteins; D007381:Intermediate Filament Proteins; C079098:filensin; C084808:phakinin