In research published today in Nature Cell Biology, scientists present a new structure that exists in human cells. The new structure is a type of protein complex with a unique molecular composition that is used for cell adhesion, even during cell division.
"It's incredibly surprising that there's a new cell structure left to discover in 2018," says principal investigator Staffan Strömblad, professor at the Department of Biosciences and Nutrition, Karolinska Institutet. "The existence of this type of adhesion complex has completely passed us by."
In tissue, cells are surrounded by a net-like structure called the extracellular matrix. In order to attach themselves to the matrix, cells have receptor molecules on their surfaces that control the assembly of large protein complexes inside them. These so-called adhesion complexes connect the outside to the cell's interior, and they also signal to the cell about its immediate environment, affecting cell properties and behavior.
Scientists call the newly discovered cell structures “reticular adhesions” to reflect their net-like form. Most importantly, these structures provide answers to an as-yet unanswered question: How can the cell 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.
"We've shown that this new adhesion complex remains and attaches the cell during cell division," says Strömblad.
The newly discovered structures also help daughter cells occupy the right location after cell division. When the researchers blocked the adhesion complex, this memory function was interrupted.
"Our findings raise many new and important questions about the presence and function of these structures," Strömblad says. "We believe that they're also involved in other processes than cell division, but this remains to be discovered."
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.