During DNA replication, all the information in the mother cell must be transmitted to the daughter cells. The DNA must be faithfully copied, of course, but also properly organized within the cell. DNA is wrapped around proteins called histones, to form chromatin.
This complex structure contains so-called epigenetic information, which governs gene expression and gives each cell its specific identity. The histone chaperone, Asf1, coordinates the removal of histones from the chromatin to allow the replication machinery to move along the DNA, with the supply of new histones to reform the chromatin once the replication machinery has passed. This discovery sheds new light on the transmission of epigenetic information in cells, and was published in the 21 December 2007 issue of Science.
DNA inherited from both parents is copied during each cell division and transmitted to all cells. Each of our cells therefore contains the same genetic information. So, what is the difference between a neuron and a white blood cell? The difference lies in the fact that although every cell in our body has the same number of genes, only some of these genes are active in any given cell. Depending on cell type, certain genes are “locked” to prevent their expression. Information on the locking and unlocking of genes is essential for cell function, and is not carried in the genes themselves but by epigenetic factors. These can be chemical modifications(2) or the organization of the DNA within the cell. The DNA double helix (diameter 2 nanometers) is wrapped around histones, proteins that facilitate its compaction, to form nucleosomes, which are strung along the DNA like beads on a string. This bead necklace then folds on itself to form a fiber—chromatin.
When a cell divides to give rise to two daughter cells, the DNA-replicating machinery unfolds the chromatin as it moves along the DNA strands. Once the so-called replication fork (the structure that forms during DNA replication) has passed, both the DNA and the epigenetic factors must be repositioned. The “Chromatin Dynamics” team of Geneviève Almouzni (UMR 218 CNRS/Institut Curie) has now shown that the histone chaperone, the protein ASF-1, regulates the progression of the replication fork, and handles the supply and demand of histones during this process essential to cell life. Asf1 oversees the removal of old histones upstream of the replication fork, and their recycling, together with the supply of newly synthesized histones to the DNA daughter strands. In so doing, Asf1 collaborates with MCM2-7, a protein complex that opens the DNA strands to allow the replication fork to advance. Asf1 therefore plays a key role in replication during cell division by coordinating the recycling of old histones and the incorporation of newly synthesized histones.
This discovery clarifies the relation between duplication of the genetic material and transmission of information carried by the histones during cell division. Any alterations occurring in the DNA or chromatin may compromise the development of an organism or play a part in cell aging, or even in the occurrence of cancer. This discovery sheds new light on the role of epigenetics in cancer development.
Protein interaction helps Yersinia cause disease
21.08.2018 | Schwedischer Forschungsrat - The Swedish Research Council
Nanobot pumps destroy nerve agents
21.08.2018 | American Chemical Society
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
21.08.2018 | Power and Electrical Engineering
21.08.2018 | Life Sciences
21.08.2018 | Medical Engineering