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microtubules

A Look Inside a Beating Heart Cell

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Caption: Microtubules (blue) in a beating heart muscle cell, or cardiomyocyte. Credit: Lab of Ben Prosser, Ph.D., Perelman School of Medicine, University of Pennsylvania

You might expect that scientists already know everything there is to know about how a healthy heart beats. But researchers have only recently had the tools to observe some of the dynamic inner workings of heart cells as they beat. Now an NIH-funded team has captured video to show that a component of a heart muscle cell called microtubules—long thought to be very rigid—serve an unexpected role as molecular shock absorbers.

As described for the first time recently in the journal Science, the microtubules buckle under the force of each contraction of the muscle cell before springing back to their original length and form. The team also details a biochemical process that allows a cell to fine-tune the level of resistance that the microtubules provide. The findings have important implications for understanding not only the mechanics of a healthy beating heart, but how the abnormal stiffening of heart cells might play a role in various forms of cardiac disease.


Snapshots of Life: Cell Skeleton on the Move

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Keratinocyte

Credit: Torsten Wittmann, University of California, San Francisco

Cells are constantly on the move. They shift, grow, and migrate to new locations—for example, to heal a wound or to intercept an infectious agent as part of an immune response. But how do cells actually move?

In this image, Torsten Wittmann, an NIH-funded cell biologist at the University of California, San Francisco, reveals the usually-invisible cytoskeleton of a normal human skin cell that lends the cell its mobility. The cytoskeleton is made from protein structures called microtubules—the wispy threads surrounding the purple DNA-containing nucleus—and filaments of a protein called actin, seen here as the fine blue meshwork in the cell periphery. Both actin and microtubules are critical for growth and movement.


“OMG” Microscope Lives Up To Its Name

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Photo of an epithelial cell in metaphase with microtubules stained red, kinetochores stained green, DNA stained blue

Courtesy of Indiana University

The scientists at the IU School of Medicine-Bloomington nicknamed their new microscope the “OMG” for good reason—the images it produces are showstoppers. The DeltaVision OMX imaging system (its official title) is a $1.2 million dollar microscope that can peek inside a cell and image fluorescent proteins in unprecedented detail.

Jane Stout, a researcher in the NIH-funded lab, used the OMG to create this spectacular image that won her first place in the high- and super-resolution microscopy category of the 2012 GE Healthcare Life Sciences Cell Imaging Competition.

What you’re looking at is a cell in the midst of dividing into two identical copies—a process called mitosis. Here, the chromosomes (in blue) are aligned at the cell’s equator. Microtubules (red) from opposite poles of the cell attach to the chromosomes using the kinetochores (green) and pull them to opposite ends of the cell, which then splits in half. But sometimes cells do not divide properly—a common problem in cancer. Understanding the mechanics of cell division could help us correct this process when it goes wrong.

Jane Stout’s prize: her mitosis image will light up a billboard in Times Square in New York City in April. That is a wonderful celebration of science!

NIH support: the National Institute of General Medical Sciences

 


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