An international research team led by scientists at Karolinska Institutet, Sweden, has discovered a new structure in human cells — a new type of protein complex that the cell uses to attach to its surroundings and proves to play a key part in cell division.

Cells in a tissue are surrounded by a net-like structure called the extracellular matrix.

To attach itself to the matrix the cells have receptor molecules on their surfaces, which control the assembly of large protein complexes inside them.

These so-called adhesion complexes connect the outside to the cell interior and also signal to the cell about its immediate environment, which affects its properties and behavior.

The newly-discovered type of adhesion complex — named ‘reticular adhesions’ — has a unique molecular composition that sets it apart from those already known.

“Reticular adhesions can provide answers to an as-yet unanswered question: how the cell can remain attached to the matrix during cell division? The previously known adhesion complexes dissolve during the process to allow the cell to divide, but not this new type,” the study authors said.

“We’ve shown that this new adhesion complex remains and attaches the cell during cell division,” said Karolinska Institutet’ Professor Staffan Strömblad, senior author of the study.

The team also found that reticular adhesions control the ability of daughter cells to occupy the right place after cell division.

This memory function was interrupted when the researchers blocked the adhesion complex.

The study was done on human cell lines mainly using confocal microscopy and mass spectrometry.

Further research is now needed to examine the new adhesion complex in living organisms.

“Our findings raise many new and important questions about the presence and function of these structures,” Professor Strömblad said.

“We believe that they’re also involved in other processes than cell division, but this remains to be discovered.”

The findings are published in the journal Nature Cell Biology.

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John G. Lock et al. 2018. Reticular adhesions are a distinct class of cell-matrix adhesions that mediate attachment during mitosis. Nature Cell Biology 20: 1290-1302; doi: 10.1038/s41556-018-0220-2