Life begins with the movement of a single cell. Guided by signals from proteins and enzymes, the cell starts contracting, pinching, and dividing. This sets off a cascade where new cells grow, specialize, and eventually form a complete organism.
MIT scientists have now discovered a way to control these cellular movements using light. They studied egg cells from starfish, a long-standing model for understanding how cells grow and develop. By honing in on a crucial enzyme that drives these movements, they engineered a version of the enzyme that responds to light.
The researchers observed that light activated the enzyme, causing predictable cell movements. For example, specific light patterns could make cells pinch or contract, while targeted light beams could reshape cells from a circle to a square.
These findings introduce a tool for manipulating cell shapes at early developmental stages. This breakthrough could help create synthetic cells, such as light-activated cells for healing wounds or delivering drugs. It also offers new insights into how life begins at its earliest stages.
The study’s senior author, Nikta Fakhri, an associate professor of physics at MIT, said, “By revealing how a light-activated switch can reshape cells in real time, we’re uncovering basic design principles for how living systems self-organize and evolve shape. The power of these tools is that they guide us to decode all these processes of growth and development, helping us understand how nature does it.”
Researchers have studied the mechanisms behind how starfish egg cells move and shape themselves. A key part of this process is a “circuitry” involving the enzyme GEF, which circulates in a cell’s cytoplasm.
When GEF is activated, it works with a protein called Rho, which plays a crucial role in cell mechanics. GEF prompts Rho to attach to the cell membrane instead of floating freely. This attachment triggers the growth of tiny muscle-like fibers on the membrane, allowing the cell to twitch, contract, and move.
Fakhri’s team previously showed they could manipulate cell movement by adjusting GEF levels: more GEF led to more cell contractions. This inspired the idea of “hacking” the system to alter movement and alter movement and achieve specific mechanical responses.
Fakhri said, “This whole idea made us think whether it’s possible to hack this circuitry, not just to change a cell’s pattern of movements but get a desired mechanical response.”
Researchers used optogenetics, which uses light to activate genetically engineered proteins and enzymes, to control cell movement precisely. They developed a light-sensitive version of the GEF enzyme, extracted its mRNA (the blueprint for producing it), and injected it into starfish egg cells. These cells then began generating their own light-sensitive GEF enzymes.
Under a microscope, the team exposed the enzyme-infused cells to specific light patterns, recording the cells’ movements in response. When light was shone on particular spots, the GEF enzyme activated, attracting Rho protein to those areas.
This triggered the formation of muscle-like fibers, enabling the cell to pinch, pull, or even transform into shapes like a square. The researchers found that shining light in one spot caused the cell to contract sweepingly beyond a specific enzyme concentration.
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This “excitable system” enables small, precise light signals to cause dramatic changes in cell shape and movement. The researchers created a theoretical model to predict these changes, paving the way for designing programmable synthetic cells.
These could be designed for tasks like wound healing or delivering drugs at light-specific locations, offering new possibilities in biomedical applications.
Fakhri said, “We realized this Rho-GEF circuitry is an excitable system, where a small, well-timed stimulus can trigger a large, all-or-nothing response. So we can either illuminate the whole cell or just a tiny place on the cell, such that enough enzyme is recruited to that region so the system gets kickstarted to contract or pinch on its own.”
The researchers compiled their observations and derived a theoretical framework to predict how a cell’s shape will change, given how it is stimulated with light. The framework, Fakhri says, opens a window into “the ‘excitability’ at the heart of cellular remodeling, which is a fundamental process in embryo development and wound healing.”
She adds: “This work provides a blueprint for designing ‘programmable’ synthetic cells, letting researchers orchestrate shape changes at will for future biomedical applications.”
Journal Reference
- Liu, J., Burkart, T., Ziepke, A., Reinhard, J., Chao, Y., Tan, T. H., Swartz, S. Z., Frey, E., & Fakhri, N. (2025). Light-induced cortical excitability reveals programmable shape dynamics in starfish oocytes. Nature Physics, 1-10. DOI: 10.1038/s41567-025-02807-x
Source: Tech Explorist
