The nuances of the economy are nothing compared with the nuances throughout biology, yet we don’t see our scientists screaming at each other on TV (instead we see researchers versus Jenny McCarthy…ugh!). Researchers take their arguments and evidence to respectable journals and state the facts, which aren’t always in black and white. Today’s stunning image is from a paper that clarifies how actin can prevent AND promote secretion.
Cells use regulated secretion to release certain material outside of the cell at specific times. This multi-stage process involves the production and packaging of the material into secretory granules, trafficking of the material around the cell, and exocytosis (release) of the material out of the cell. Past research complicated the understanding of how important actin is in regulated secretion—some indicates that actin prevents it, while some indicates that actin promotes it. Recently, a research group dove right into the cell to look at regulated secretion in one specific cell type, and clarified the nuances of actin’s prevention/promoting roles. Nightingale and colleagues found that secretory granules are anchored to actin filaments to prevent premature secretion. However, actin later supports secretion by forming a ring-like structure at the site of the secretory granule’s fusion at the plasma membrane. This ring then contracts to help the release of material out of the cell. In the images above, actin (green) is found on the secretory granules (red). The higher magnification images (right) of the boxed region show the actin rings (bottom) found on fused secretory granules (middle).
Nightingale, T., White, I., Doyle, E., Turmaine, M., Harrison-Lavoie, K., Webb, K., Cramer, L., & Cutler, D. (2011). Actomyosin II contractility expels von Willebrand factor from Weibel-Palade bodies during exocytosis originally published in The Journal of Cell Biology, 194 (4), 613-629 DOI: 10.1083/jcb.201011119