Biological complexity: intercellular signalling (Introduction)

by David Turell , Tuesday, May 31, 2016, 15:05 (3098 days ago) @ dhw

It is all molecular, purposeful transmembrane reactions:-http://www.the-scientist.com/?articles.view/articleNo/45904/title/Kissing-Cousins/&utm_campaign=NEWSLETTER_TS_The-Scientist-Daily_2016&utm_source=hs_email&utm_medium=email&utm_content=30090040&_hsenc=p2ANqtz-8EZAy2t5EQjdis9kKx3hS-bn0lEAJgoSterbxt4piM3G0mU1qvg3kUvCCJRIBiZ-mrNQictDo6MmUmFim4W6Bob9wdNA&_hsmi=30090040/-"Kirsten Hattermann knows a thing or two about chemokines. A researcher working with Janka Held-Feindt's lab at the University of Kiel in Germany, Hattermann has spent the last decade studying these little proteins, which bind—either as transmembrane (tm) proteins or as soluble (s) equivalents that are shed from the membrane or secreted by the cell—to complementary receptors on target cells. Binding of the s-chemokines can elicit several responses in target cells, including cell migration and proliferation, but scientists are still working out the consequences of tm-chemokine binding.-"Recently, while investigating chemokine signaling in tumor cells from a variety of human cancers, Hattermann and her colleagues found something they couldn't explain. When they exposed glioma and carcinoma cells lacking known chemokine receptors to the soluble form of the chemokines CXCL16 and fractalkine, the researchers assumed there would be no binding and, hence, no signal transduction. But to their surprise, Hattermann says, “we observed intracellular signaling.”-***-"Using immuno-electron microscopy, the researchers showed that s-CXCL16 and s-fractalkine directly bind to their transmembrane equivalents, implicating tm-chemokines as the elusive signal transducers. “If it's correct, it's paradigm-shifting in terms of the way we understand how some of these molecules work,” says Gerry Graham, a professor of molecular and structural immunology at the University of Glasgow. “Binding of a soluble [chemokine] to a membrane-anchored one to transduce a signal is completely new.”-"Transfecting the melanoma cells with tm-CXCL16 and tm-fractalkine partly activated s-chemokine signal transduction, the researchers found, while silencing the tm-chemokines in otherwise responsive, receptor-negative tumor cells abolished the effect. This novel mode of communication, which the team has termed “inverse signaling,” may fine-tune classical signaling mechanisms, Hattermann suggests."-Comment: this exact mechanism is not the important point. It is a good illustration of how cells communicate in organisms, and these various communication techniques are still being found. This may look like the cells are intelligent in signaling, but the opposite view is this is an aspect of intelligent planning in the information that is at the basis of life's processes.