Scientists at St. Jude Children's Research Hospital have demonstrated that a key event during apoptosis (cell suicide) occurs as a single, quick event, rather than as a step-by-step process. Apoptosis eliminates extraneous cells from the developing body; and disposes of cells that sustain irreparable harm to their DNA or are infected with microorganisms. The researchers photographed individual cells undergoing that process, allowing investigators to observe the release of certain proteins from pores in the membranes of mitochondria. These cellular structures contain enzymes that extract energy from food molecules, and the space within the membrane surrounding them holds a variety of proteins that are released during apoptosis.
Results of the study indicate the formation of pores in the mitochondrial membranes is a rapid process that allows a nearly simultaneous rather than a sequential release of many apoptosis proteins, according to Douglas Green, Ph.D., chair of the St. Jude Department of Immunology. Green is senior author of a report on this work that appears in the August 1 issue of Proceedings of the National Academy of Sciences. The process of pore formation, called mitochondrial outer membrane permeabilization (MOMP), allows apoptosis proteins stored underneath the membrane to escape and orchestrate the cell's destruction.
MOMP is controlled by a family of proteins called Bcl-2; some of these support apoptosis and others interrupt the process. The pro- and anti-apoptotic Bcl-2 proteins cooperate to weigh and balance cell signals that promote survival or death, in this way determining the final outcome. During apoptosis, these proteins are either already on the mitochondrial membranes or migrate to the membranes, where they trigger MOMP.
"The slow, continuous release of one of the proteins, apoptosis-inducing factor (AIF), suggests that the pore formed during MOMP remains open for many hours," Green said. "Our finding of nearly simultaneous rather than sequential release of the mitochondrial membrane proteins helps to explain the timing of the movement of these apoptosis proteins following MOMP. The findings also suggest that release of these proteins is not controlled by multiple levels of regulators, but rather occurs as a single event."
The study also highlights the importance of the Bcl-2 family in regulating the formation of pores in the mitochondrial membrane and emphasizes how critical the formation of these pores is to the regulation of apoptosis, Green said.
The team found that after cells were treated with a chemical that triggers apoptosis, it took three to 10 minutes for several proteins, cytochrome c, Smac, Omi and adenylate kinase-2 to escape together immediately following MOMP.
However, the AIF protein escaped from the mitochondrial membrane much more slowly and incompletely, starting with the release of cytochrome c but continuing during the next few hours. The St. Jude researchers concluded that while AIF is known to regulate other cellular processes, the protein itself is not involved in triggering apoptosis. The researchers made the movement of the proteins visible by attaching fluorescent tags to make them glow when observed under a special microscope equipped with a laser that scanned the cells.
Bonnie Kourvelas | EurekAlert!
At last, butterflies get a bigger, better evolutionary tree
16.02.2018 | Florida Museum of Natural History
New treatment strategies for chronic kidney disease from the animal kingdom
16.02.2018 | Veterinärmedizinische Universität Wien
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).
Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
16.02.2018 | Information Technology
16.02.2018 | Health and Medicine
16.02.2018 | Physics and Astronomy