Biological complexity: signal pathways (Introduction)

by David Turell , Thursday, July 30, 2015, 15:31 (3404 days ago) @ David Turell

Signal pathways controlled by enzymes dictate cellular functions and migration abilities. Another illustration of cell complexity and automaticity:-http://phys.org/news/2015-07-mystery-akt-cytosol-cell-membrane.html-"Using a state-of-the-art imaging tracking system, they discovered that a small protein called Ub14A can help to build "bridges," called actin branches, that bring Akt directly to the cell membrane, where it gets activated. Their findings are published in an article in the July 20 issue of the Proceedings of the National Academy of Sciences -"Akt is one of the key components in the cell-signaling network and has been a major target for therapeutic intervention, especially for anticancer drug development, for decades. To perform as a signaling molecule, Akt must move from the cytosol to the cell membrane so it can be activated by its upstream components. After it is activated, it then quickly moves back to the cytosol so that it can direct its downstream "workers" in other cellular actions, such as cell growth, proliferation, energy metabolism, and even resistance to cancer. -"'For years, scientists were puzzled as to how Akt 'moves' from the cytosol to the cell membrane," said Xiang. "There is a 'creek' flowing underneath the cell membrane, and Akt is unable to 'swim' across by itself. Using both super resolution imaging and genetic approaches, we found that Ubl4A builds 'bridges' or actin branches that bring Akt directly to the cell membrane, where it gets activated." -"Mice deficient in Ubl4A show significant impairment in Akt signaling, resulting in, for example, high neonatal birth mortality and delay in growth. Actin branches also are important for many other cellular events, such as cell migration and wound healing. "For example, white blood cells normally migrate towards bacteria during infection, but white blood cells where Ub14A is absent get so confused in the direction that they cannot effectively reach the infection site," Xiang said.-"The study therefore both fills in a missing link in the Akt signaling pathway and uncovers a novel function of actin branching."-
 Comment: All cells have actin fibers which act as pathways along which molecules travel