Genome complexity: Protecting genes during mitosis (Introduction)

by David Turell , Thursday, August 06, 2015, 19:41 (3396 days ago) @ David Turell

The genetic information must be preserved during mitosis. The mechanism is now found condensing the information into the nucleus:-http://phys.org/news/2015-08-scientists-key-proteins-segregate-vital.html-"Now, new research from The Wistar Institute has identified an interaction between proteins that provides a pivotal role in organizing chromosomes so that vital genetic information gets passed on safely.-"To understand how dividing cells protect and faithfully segregate genes that have been transcribed, researchers focused on a protein complex found in human cells called condensin. This set of proteins helps compact more than 20,000 protein-coding genes in the human genome into something that can fit inside the nucleus of each of our cells.-"Previously, Noma's lab showed that many genes are connected to centromeres. Centromeres are sites where two chromatids - copies of newly replicated chromosomes - are positioned to be properly split up during mitosis. Condensin mediates the clustering of RNA polymerase III-transcribed genes (abbreviated Pol III genes) and Pol II-transcribed "housekeeping" genes that are necessary for every cell to function properly. However, scientists did not know exactly how the condensin was being recruited to aid in this process.-"In this study, Noma and his colleagues identified the interactions of proteins that link condensin and mitosis. By studying mitosis in yeast, they were able to identify a subunit of condensin called Cnd2 that binds directly to a protein called the TATA box-binding protein (TBP). TBP is a general transcription factor required for every type of transcription. When Cnd2 binds to TBP, it recruits condensin onto Pol III genes and Pol II-transcribed housekeeping genes. When this happens, condensin tethers these genes to the centromeres so that when mitosis occurs, the genetic information remains protected and intact as the chromatins are split apart."-Comment: As usual highly complex molecular interactions control the process. Note the use of the word 'information'.