MSCs become fat cells (red) if RhoA is inactive (left) or osteoblasts (blue) if RhoA is active (right).

Chen/Elsevier

Too many fat cells make us round. But on a molecular level, roundness makes fat cells, based on results from Rowena McBeath, Christopher Chen, and colleagues (Johns Hopkins University, Baltimore, MD).

Fat cells derive from mesenchymal stem cells (MSCs), which are also the precursors of bone-depositing osteoblasts. Chen's group shows that the shape of an MSC determines which of these two cell types it will become.

MSCs that were spread out on a matrix formed osteoblasts, but round cells with only a small matrix-attached surface became fat cells. Changing the cell's surroundings after commitment did not alter the outcome, so the decision must be made at commitment, before differentiation.

Shape is detected via myosin- generated tension in the actin cytoskeleton. Levels of the RhoA GTPase effector...

The Rockefeller University Press
2004
The Rockefeller University Press
2004
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