Study shows how disruption of spectrin-actin network causes lens cells in the eye to lose shape

Sep 14, 2009
The regular hexagonal arrangement of lens fiber cells is disrupted in the absence of tropomodulin1 (right). Credit: Nowak, R.B., et al. 2009. J. Cell Biol. doi:10.1083/jcb.200905065.

A network of proteins underlying the plasma membrane keeps epithelial cells in shape and maintains their orderly hexagonal packing in the mouse lens, say Nowak et al. The study will appear in the September 21, 2009 issue of the Journal of Cell Biology (online September 14).

Spectrin, F-actin, and associated proteins form a meshwork that supports and shapes the plasma membrane of . A similar network underlies the membranes of other cell types, including lens fiber cells: elongated epithelial cells that encircle vertebrate lenses in concentric layers, appearing in cross section as tightly packed hexagons. Actin filaments within this membrane skeleton are stabilized by their association with members of the tropomyosin and tropomodulin families of actin-binding proteins.

In mice lacking tropomodulin1, gamma-tropomyosin was also lost from the membrane skeleton of lens fiber cells. F-actin and spectrin remained associated with the cell membrane, but gaps appeared in the usually continuous network, suggesting that the two actin-binding proteins stabilize a subset of required to link the network together.

Scanning electron microscopy revealed that fiber cell protrusions, which interlock with neighboring cells, were distorted and irregularly arranged in the absence of tropomodulin1. And although the fiber cells appeared hexagonal when first forming at the lens' equator, they often became misshapen and disorganized as they matured and moved toward the lens' center.

Senior author Velia Fowler thinks that disruption of the spectrin-actin network alters the adhesive interactions between neighboring cells, causing their shapes and packing to become disordered in response to the mechanical stresses associated with lens growth and eye movements.

More information: Nowak, R.B., et al. 2009. J. Cell Biol. doi:10.1083/jcb.200905065.

Source: Rockefeller University (news : web)

Explore further: Life's extremists may be an untapped source of antibacterial drugs

add to favorites email to friend print save as pdf

Related Stories

How actin networks are actin'

Jan 02, 2008

Dynamic networks of growing actin filaments are critical for many cellular processes, including cell migration, intracellular transport, and the recovery of proteins from the cell surface. In this week’s issue of the open-access ...

Fibroblasts invade at a snail's pace

Feb 02, 2009

A transcription factor known to drive the formation of fibroblasts during development also promotes their ability to invade and remodel surrounding tissues, report Rowe et al. in the February 9, 2009 issue ...

Using a light touch to measure protein bonds

Jun 30, 2008

MIT researchers have developed a novel technique to measure the strength of the bonds between two protein molecules important in cell machinery: Gently tugging them apart with light beams.

Recommended for you

Cohesin molecule safeguards cell division

Nov 21, 2014

The cohesin molecule ensures the proper distribution of DNA during cell division. Scientists at the Research Institute of Molecular Pathology (IMP) in Vienna can now prove the concept of its carabiner-like ...

Nail stem cells prove more versatile than press ons

Nov 21, 2014

There are plenty of body parts that don't grow back when you lose them. Nails are an exception, and a new study published in the Proceedings of the National Academy of Sciences (PNAS) reveals some of the r ...

Scientists develop 3-D model of regulator protein bax

Nov 21, 2014

Scientists at Freie Universität Berlin, the University of Tubingen, and the Swiss Federal Institute of Technology in Zurich (ETH) provide a new 3D model of the protein Bax, a key regulator of cell death. When active, Bax ...

Researchers unwind the mysteries of the cellular clock

Nov 20, 2014

Human existence is basically circadian. Most of us wake in the morning, sleep in the evening, and eat in between. Body temperature, metabolism, and hormone levels all fluctuate throughout the day, and it ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.