A new study shows how cell membranes curve to form the “mouths” that allow cells to consume things that surround them.
“Just as our eating habits basically affect everything in our bodies, the way cells ‘eat’ is important to cell health,” said Comert Kural, associate professor of physics at Ohio State University and lead author of the Study. “And scientists haven’t understood how that happened until now.”
The study, which was published in the journal last month Development cell, found that the intercellular machinery of a cell merges into a highly curved, basket-like structure that eventually grows into a closed cage. Scientists had previously believed the structure started out as a flat lattice.
The curvature of the membrane is important, said Kural: It controls the formation of the pockets that transport substances in and out of a cell.
The pockets trap substances around the cell and form around the extracellular substances before turning into vesicles – tiny vesicles that are one millionth the size of a red blood cell. Vesicles transport important things for the health of a cell – for example proteins – into the cell. But they can also be hijacked by pathogens that can infect cells.
But the question of how these pockets were formed from membranes previously thought to be flat has bothered researchers for almost 40 years.
“It was a controversy in cellular studies,” said Kural. “And with super-resolution fluorescence imaging we were actually able to observe how these pockets form in living cells, and so we were able to answer the question of how they arise.
“Simply put, unlike the previous studies, we made high-resolution films of cells instead of taking snapshots,” said Kural. “Our experiments have shown that protein scaffolds begin to deform the underlying membrane as soon as they are recruited at the sites of vesicle formation.”
This is in contrast to previous hypotheses that the protein framework of a cell would have to go through an energy-intensive reorganization in order for the membrane to bend, said Kural.
The way cells consume and secrete vesicles is key to living organisms. The process helps remove bad cholesterol from the blood; it also transmits neural signals. The process is known to break down in several diseases, including cancer and Alzheimer’s.
“Understanding the origin and dynamics of membrane-bound vesicles is important – they can be used to deliver drugs for medical purposes, but at the same time they can be abducted by pathogens such as viruses to invade and infect cells,” said Kural. “Our results are important, not only for our understanding of the fundamentals of life, but also for developing better therapeutic strategies.”
Emanuele Cocucci, Assistant Professor at Ohio State’s College of Pharmacy, co-authored this study with researchers from UC Berkeley, UC Riverside, Iowa State University, Purdue University, and the Chinese Academy of Sciences.
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Nathan M. Willy et al., De novo endocytic clathrin envelopes develop a curvature in the early stages of their formation, Development cell (2021). DOI: 10.1016 / j.devcel.2021.10.019
Ohio State University
High-resolution laboratory experiments show how cells “eat” (2021, December 30th)
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