Snapshots of Life: Cell Skeleton on the Move

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.

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Snapshots of Life: Wild Outcome from Knocking Out Mobility Proteins

Spiky fibroblast cell

Credit: Praveen Suraneni and Rong Li, Stowers Institute for Medical Research

When biologists disabled proteins critical for cell movement, the result was dramatic. The membrane, normally a smooth surface enveloping the cell, erupted in spiky projections. This image, which is part of the Life: Magnified exhibit, resembles a supernova. Although it looks like it exploded, the cell pictured is still alive.

To create the image, Rong Li and Praveen Suraneni, NIH-funded cell biologists at the Stowers Institute for Medical Research in Kansas City, Missouri, disrupted two proteins essential to movement in fibroblasts—connective tissue cells that are also important for healing wounds. The first, called ARPC3, is a protein in the Arp2/3 complex. Without it, the cell moves more slowly and randomly [1]. Inhibiting the second protein gave this cell its spiky appearance. Called myosin IIA (green in the image), it’s like the cell’s muscle, and it’s critical for movement. The blue color is DNA; the red represents a protein called F-actin.

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