Two-step cellular development
For nearly 30 years, scientists thought cells develop into specific cell types nerve, skin, or liver cells, for instance in exactly the same way. But researchers Robert Tjian of Berkeley and Maria Divina E. Deato of the California Institute for Regenerative Medicine, working with skeletal muscle cells, are throwing this basic premise into doubt.
Traditional wisdom was that certain proteins are essential components for cell transcription from start to finish. But Tjian and Deato suggest these so-called essential proteins are disassembled during cell differentiation (the process by which a universal stem cell becomes a skeletal muscle cell). Instead, entirely different proteins take over the task of directing the expression of muscle-specific genes to create a muscle cell. It’s as if a key software program on your computer were taken apart and replaced by another program mid-task. “We’ve been trying to figure out how this software works,” says Tjian. And what’s true for skeletal muscle cells is also likely to be true for other cell types, he says.
The implications of the research five years in the making are profound. Scientists worldwide are racing to figure out how to grow specific cell types to combat diabetes, Parkinson’s, and spinal cord injuries. So they need to know the mechanics of how these cells are created. Does this mean Tjian and Deato now can grow human muscle? Not quite, Tjian says with a laugh. “It will eventually lead us to a better understanding of how to build muscle,” he says. “We want to know why something works, not just whether it will work.”