Cellular activity is governed by a complex system of communication that involves the cell membrane. For the first time, a multidisciplinary team of researchers has been able to observe, in real-time, the cellular process that organizes this microscopic traffic. Turns out that actin, a natural fractal, may be the ideal cellular scaffolding.CSU scientists used photoactivated localization microscopy or PALM to understand how a fractal influences cellular communication.Click To Tweet
The cell membrane is a double-layer cellular structure that separates the inside of the cell from the extracellular environment, playing a vital role in numerous cellular functions: cell signaling, the transport and adherence of molecules across and on the membrane, and ionic conductivity and molecular circulation inside and on the cell.
Real-time Observation of the Cell Membrane in Action
A team of biophysicists and biochemists from Colorado State University elucidated the interaction of the cell membrane with its cellular environment, and especially with the cortical actin cytoskeleton that serves as a scaffold underneath it.
For the first time, CSU scientists have been able to observe the, until now, misunderstood cellular process: the cytoskeleton acts as a barrier to proteins on the surface of the cell and organizes their circulation.
For the study, which will appear in Physical Review X, the team used photoactivated localization microscopy (PALM), a fluorescence microscopy that overcomes the diffraction limit of light to achieve super-resolutions (for images and videos of biological processes) of nanometric order. The method was invented in 2006 by Eric Betzig and his team and won them the Nobel Prize in Chemistry 2014.
The researchers examined the movement of ion channels of potassium, a protein that interacts with the cortical actin cytoskeleton.
Far out Fractal Actin a Fool
The cytoskeleton, or cellular skeleton, is a complex network of filaments beneath the membrane, giving the cell its mechanical properties, shape, mobility, and internal organization. Scientists already understood the critical role of the cytoskeleton in the functioning of the cell membrane but were not able to visualize this action.
Using PALM, the researchers recorded the precise moments when the potassium ion hit the actin filaments. Then they analyzed these movements to provide evidence of the structure of actin, which is a natural fractal. Researchers showed that the random movements of proteins on the cell membrane follow sophisticated patterns. For example, proteins tend to bounce in spots they had previously visited,
Thanks to PALM, and CSU teamwork, which involved biochemistry, biomedical engineering, and computer technology, we were offered the first statistical and visual evidence that movement of proteins on the cell membrane is directly linked to the natural fractal, actin.
“The fractal nature of the actin network explains our measurements,” said Sanaz Sadegh, a Ph.D. student in Krapf’s lab. “It leads us to question why we see so many fractals in nature. Is it an efficient way to organize functions? It’s an interesting question for future studies.”