Cutting-edge microscopy reveals nanoscale architecture and dynamics of bone remodelling by human osteoclasts
Remodelling is complicated, whether it's your house or your bones. Bone remodelling happens when your bones are damaged, whether that's a fracture or everyday strain. Cells called osteoclasts jump into action to break down old bone so new bone can form. Anchoring themselves to the bone, they form a ring-like structure called the sealing zone, into which bone-degrading substances are released without leaking away. Projections made of actin – podosomes – help form the sealing zone, but their organisation at the nanoscale level is unclear. Researchers use super-resolution microscopy to investigate. Human osteoclasts, containing fluorescently tagged actin, were live imaged adhering to bone (pictured). This revealed densely packed actin cores, which form the centre of podosomes, in the sealing zone. Further analysis revealed the activity of these cores was synchronised locally, with groups of cores surrounded by adhesion proteins. This shines a light on the nanoscale lives of podosomes in bone remodelling.
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