Nanomechanical Characterization of the Stiffness of Eye Lens Cells: A Pilot Study

Hozić, Amela; Rico, Félix; Colom, Adai; Buzhynskyy, Nikolay; Scheuring, Simon

doi:10.1167/iovs.11-8676

Cited by 16 publications

(13 citation statements)

References 44 publications

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“…Such a model is analogous to biomechanical characterization of articular cartilage, in which the depth-dependence of the compressive modulus and its correlation with aging and biochemical composition have been studied in detail [48], [61], [62]. Additional support for this model comes from our measurements of the whole-lens tangent moduli of wild-type lenses (∼500 Pa at zero compression and ∼3000 Pa at 20% compression), which fall between the individual moduli of isolated sheep lens cortical fiber cells (∼220 Pa) and nuclear fiber cells (∼4800 Pa) determined by atomic force microscopy [63]. Our tangent moduli are also comparable to the moduli of pig, cow, and monkey lenses determined using a variety of techniques, including whole-lens compression, microindentation, and atomic force microscopy [64], [65], [66].…”

Section: Discussionmentioning

confidence: 58%

Tmod1 and CP49 Synergize to Control the Fiber Cell Geometry, Transparency, and Mechanical Stiffness of the Mouse Lens

et al. 2012

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The basis for mammalian lens fiber cell organization, transparency, and biomechanical properties has contributions from two specialized cytoskeletal systems: the spectrin-actin membrane skeleton and beaded filament cytoskeleton. The spectrin-actin membrane skeleton predominantly consists of α2β2-spectrin strands interconnecting short, tropomyosin-coated actin filaments, which are stabilized by pointed-end capping by tropomodulin 1 (Tmod1) and structurally disrupted in the absence of Tmod1. The beaded filament cytoskeleton consists of the intermediate filament proteins CP49 and filensin, which require CP49 for assembly and contribute to lens transparency and biomechanics. To assess the simultaneous physiological contributions of these cytoskeletal networks and uncover potential functional synergy between them, we subjected lenses from mice lacking Tmod1, CP49, or both to a battery of structural and physiological assays to analyze fiber cell disorder, light scattering, and compressive biomechanical properties. Findings show that deletion of Tmod1 and/or CP49 increases lens fiber cell disorder and light scattering while impairing compressive load-bearing, with the double mutant exhibiting a distinct phenotype compared to either single mutant. Moreover, Tmod1 is in a protein complex with CP49 and filensin, indicating that the spectrin-actin network and beaded filament cytoskeleton are biochemically linked. These experiments reveal that the spectrin-actin membrane skeleton and beaded filament cytoskeleton establish a novel functional synergy critical for regulating lens fiber cell geometry, transparency, and mechanical stiffness.

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Section: Discussionmentioning

confidence: 58%

Tmod1 and CP49 Synergize to Control the Fiber Cell Geometry, Transparency, and Mechanical Stiffness of the Mouse Lens

et al. 2012

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“…Lens cells have been prepared from sheep lens as previously described 29 . Briefly, lenses from healthy sheep 5 ± 2 years old were obtained from UCEA INRA (Unité Commune d'Expérimentation Animale, Jouy-En-Josas, Institut National de la Recherché Agronomique, France).…”

Section: Methodsmentioning

confidence: 99%

“…Although relatively slow, this method assures gentle and controlled separation of different layers of cells from lens tissue. Resulting cells feature native transparency and elasticity 29 .…”

Section: Methodsmentioning

confidence: 99%

A hybrid high-speed atomic force–optical microscope for visualizing single membrane proteins on eukaryotic cells

et al. 2013

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High-speed atomic force microscopy is a powerful tool for studying structure and dynamics of proteins. So far, however, high-speed atomic force microscopy was restricted to well-controlled molecular systems of purified proteins. Here we integrate an optical microscopy path into high-speed atomic force microscopy, allowing bright field and fluorescence microscopy, without loss of high-speed atomic force microscopy performance. This hybrid high-speed atomic force microscopy/optical microscopy setup allows positioning of the high-speed atomic force microscopy tip with high spatial precision on an optically identified zone of interest on cells. We present movies at 960 ms per frame displaying aquaporin-0 array and single molecule dynamics in the plasma membrane of intact eye lens cells. This hybrid setup allows high-speed atomic force microscopy imaging on cells about 1,000 times faster than conventional atomic force microscopy/optical microscopy setups, and allows first time visualization of unlabelled membrane proteins on a eukaryotic cell under physiological conditions. This development advances high-speed atomic force microscopy from molecular to cell biology to analyse cellular processes at the membrane such as signalling, infection, transport and diffusion.

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“…Thus, the optical function of the lens is closely tied to its mechanical function. The biomechanical stiffness of soft-tissues (Candiello et al, 2010;Tsujii et al, 2017;Lampi and Reinhart-King, 2018), including the lens (Baradia et al, 2010;Hozic et al, 2012;Cheng et al, 2016a) increase with age. Increased biomechanical tissue stiffness in the aging lens diminishes its ability to change shape, resulting in presbyopia and the need for reading glasses (Heys et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

The effects of mechanical strain on mouse eye lens capsule and cellular microstructure

Parreno

Cheng

Nowak

et al. 2018

Preprint

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The understanding of multiscale load transfer within complex soft tissues is incomplete. The eye lens is ideal for multiscale tissue mechanics studies as its principal function is to fine focus light at different distances onto the retina via mechanical shape changes. The biomechanical function, resiliency, and intricate microstructure of the lens make it an excellent non-connective soft tissue model. We hypothesized that compressive strain applied onto whole lens tissue leads to deformation of specific microstructures and that this deformation is reversible following removal of load. For this examination, mouse lenses were compressed by sequential application of increasing load. Using confocal microscopy and quantitative image analysis, we determined that axial strain ≥10% reduces capsule thickness, expands epithelial cell area, and separates fiber cell tips at the anterior region of the lenses. At the equatorial region, strain ≥6% increases fiber cell widths. The effects of strain on lens epithelial cell area, capsule thickness, and equatorial fiber cell widths are reversible following the release of lenses from strain. However, although fiber cell tip separation following the removal of low loads is reversible, the separation becomes irreversible with application of higher loads. This irreversible separation between fiber cell tips leads to incomplete bulk lens resiliency. The lens is an accessible biomechanical model system that provides new insights on multiscale transfer of loads in soft tissues.

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Nanomechanical Characterization of the Stiffness of Eye Lens Cells: A Pilot Study

Cited by 16 publications

References 44 publications

Tmod1 and CP49 Synergize to Control the Fiber Cell Geometry, Transparency, and Mechanical Stiffness of the Mouse Lens

Tmod1 and CP49 Synergize to Control the Fiber Cell Geometry, Transparency, and Mechanical Stiffness of the Mouse Lens

A hybrid high-speed atomic force–optical microscope for visualizing single membrane proteins on eukaryotic cells

The effects of mechanical strain on mouse eye lens capsule and cellular microstructure

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