#GENE EXPRESSION C ARTOON FULL#

De novo establishment of 3D genome architecture Thus, it is the ideal model system to study the processes underlying the establishment of chromatin structure. In Drosophila, the lab of Nicola Iovino had previously shown that after fertilization chromatin undergoes major restructuring events. Interestingly most of the epigenetic modifications that shape chromatin are erased and have to be established de novo. The resulting totipotent zygote will ultimately give rise to all the different cells of the body. At fertilization, two highly specialized cells – sperm and egg – fuse. We discovered that the reader protein HP1a is required to establish chromatin structure during early embryonic development in Drosophila”, says Fides Zenk, first-author of the study.Įarly embryonic development is a particularly interesting time window to study the processes governing the organization of chromatin. “Proteins that carry out these epigenetic modifications can be thought of as being either writers, erasers or reader of the given epigenetic modification. These are small chemical groups that are installed on the histones. The degree of packaging as well as the corresponding gene activity is influenced by epigenetic modifications. Early embryos as a model to study chromatin reprogramming By combining powerful Drosophila genetics with 3D genome modeling, they discovered that HP1a is required to establish a proper chromatin 3D structure at multiple hierarchical levels during early embryonic development. Now the lab of Nicola Iovino at the MPI in Freiburg, in collaboration with Luca Giorgetti from the Friedrich Miescher Institute in Basel (Switzerland), was able to show the fundamental role of the heterochromatin protein 1a (HP1a) in the reorganization of the 3D chromatin structure after fertilization.

#GENE EXPRESSION C ARTOON FULL#

The full machinery contributing to this 3D chromatin organization remains unexplored. The chromosomes themself occupy distinct positions within the nucleus, known as chromosome territories, that also enable efficient packaging and organization of the genome. This complex of DNA and proteins is called chromatin. As such, chromatin is the fundament for further packaging of the genetic material into chromosomes whose structure is mostly known for its characteristic cross shape. Part of this packaging are histone proteins acting as spools around which DNA is winded and thereby compacted. Instead, it is folded in a very organized way to ensure that different parts of the genome, sometimes several thousand base pairs away from each other, can intercommunicate for appropriate gene functions,” says Nicola Iovino, group leader at the MPI of Immunobiology and Epigenetics in Freiburg. “The DNA thread is not simply stuffed into the cell nucleus. The DNA molecule must be extensively packaged to fit inside the nucleus, the size of which is in the micrometer range. If all chromosomes could be disentangled and linearly aligned, they would be a thin thread of about 2 meters. The information of the human genome is encoded by approximately 3 billion DNA base pairs and packaged into 23 pairs of chromosomes. © MPI of Immunobiology and Epigenetics/ F.

Gene expression c artoon