Biological complexity: maintaining cell shape (Introduction)

by David Turell , Monday, February 17, 2020, 19:13 (1523 days ago) @ David Turell

Expansion and contraction forces have to be balanced to maintain cell shape:

https://phys.org/news/2020-02-protein-function-protrusive-contractile-cell.html

"In a healthy cell, there is a fine balance between the protrusive structures that make the cell more migratory, and the contractile structures that maintain the cell's shape and its association with the environment. A disturbance in this balance leads to several diseases, such as invasive cancers.

"The most important component of both protrusive and contractile machineries is a protein called actin. This means that the proper distribution of actin between these structures is essential for the normal function of the cell. Nevertheless, the mechanisms that ensure that actin is distributed correctly between the protrusive and contractile machineries have remained elusive.

"Researchers at the University of Helsinki, Finland, and the University of Pennsylvania, Philadelphia, U.S., have now identified a protein called tropomodulin as a key player that maintains the balance between the protrusive and contractile actin-filament machineries within a cell.

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"'We have now revealed that tropomodulins stabilise the actin filaments of the contractile structures in non-muscle cells through interacting with specific proteins within these actin filament bundles. The depletion of tropomodulins led to a loss of contractile structures, accompanied by an excess of protrusive structures, and thus to severe problems in a cell's shape and force production," says Academy Professor Pekka Lappalainen from the HiLiFE—Institute of Biotechnology, University of Helsinki.

"Researchers were surprised to see that the depletion of one protein can have such drastic effects on the balance of the actin machinery.

"'Another exciting and unexpected finding of this study was the notion that the same protein can have a different function depending on the tissue or cell type."

Comment: I don't know why the research team is surprised at a single protein showing differing protein functions in different cells, when differing cells have differing DNA code expressions. This system requires careful balances to work correctly. Life is a symphony of balanced protein reactions. It cannot have come together by chance.