Human white blood cells swim with molecular "paddles"

researchers report in the September 15 issue of the Journal of Biophysics that human white blood cells, or white blood cells, swim using a new mechanism called molecular stroke. This tiny mechanism of motion can explain how immune cells and cancer cells migrate beneficially or harmfully in a variety of small liquid-filled habitats in the body.
" ability to move live cells autonomously is fascinating and critical to many biological functions, but only part of the cell migration mechanism is understood. "Our findings provide new clues to the mechanisms of migration of amoebud cells, an important topic in immunology and cancer research," said Olivier Theodoly, co-senior author of the paper and a professor at the University of Aix-Marseille in France. The
have evolved different strategies to migrate and explore their environment. For example, sperm cells, microalgae, and bacteria can swim through deformation or with a whip-like appendage called whiplash. Mammal cells, by contrast, migrate by attaching to the surface and crawling. It is generally accepted that white blood cells cannot migrate on two-dimensional surfaces without attachment.
previous study, some white blood cells in the body, called neutral granulocytes, can swim, but there is no evidence of their mechanism. Another study showed that mice could be artificially induced to swim with white blood cells. It is generally accepted that cell movement without whiplash requires a change in cell shape, but the exact mechanism of white blood cell migration has been controversial.
Compared to previous studies, Theodory and co-author Chaouqi Misbah of the University of the Alps in Grenoble provide experimental and computational evidence that human white blood cells can migrate on two-dimensional surfaces without clinging to them, or swim using a mechanism that does not depend on changes in cell shape. "Watching cell movement gives the illusion that cells deform their bodies like swimmers." "Although white blood cells are highly dynamic in shape and appear to swim in breaststroke mode, our quantitative analysis shows that these movements do not drive cells," Misbah said. Instead
cells use transfilm proteins to "scratch water" across the membrane and protrude them outside the cell. The researchers showed that the membrane's "treading motion" -- the back movement of the cell's surface -- pushes white blood cells to migrate in solid or liquid environments, with or without adhesion.
, however, the cell membrane does not move like a uniform treadmill. Some transfilm proteins are connected to the myoglobin microfilaments, which form part of the cytoskeleary and contract to allow the cells to move. The amyoglobin cytoskelete is widely thought to be the molecular engine that drives cell crawls. The new findings suggest that the cross-membrane proteins that bind to the tymodrins move and push the cells forward, and that the freely diffused cross-membrane proteins prevent the cells from moving.
researchers suggest that cells can achieve continuous water-scratching by combining the external "treading motion" driven by the muscle protein and the internal circulation of the trans-membrane protein by combining the movement of the tyrosin, which is transported through the follicles. Specifically, the water-scratching protein located at the back of the cell is encased in a vesicle that is squeezed from the cell membrane and transported to the front of the cell. In contrast, non-scratching transfilm proteins are selected and do not carry out the internal cycle of this vesicle transport.
cycle of the "cytosome" cell membrane is being studied in depth by scientists studying the flow of vesicles in cells, but its role in motion is rarely considered. Theodoly said, "The function of these proteins in the selection and transportation seems to be very complex for swimming." To our surprise, our research spans such far-flung fields as microswimming's physics and the biology of vesicle transportation.
the researchers say that when immune cells move in a liquid-filled ecological position, molecular movement allows immune cells to thoroughly explore all parts of the body, such as swollen body parts, infected bladders, cerebrospinal fluid, or amniotic fluid. Next, the researchers plan to study the function of molecular movement in a variety of environments and assess whether other types of cells use this movement.
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