The multi-scale structure of chromatin in the nucleus
Biomedical Engineering Faculty,Technion
The DNA in a human cell which is ~3 meters long is packed in a ~10 μmradius nucleus. The DNA is immersed in a condensed soup of proteins, RNA andenzymes and it is highly dynamic while taking part in many nuclear processessuch as protein expression and cell division.
Nevertheless, it must stay organized to prevent chromosomeentanglement and for genome expression control. Studying this nanometer –micrometer scale structure is difficult, as it requires to use both highspatial and temporal resolutions for studying its characteristics.
Studying the nucleus organization is complex and we developed variousmethods, including live-cell imaging, time-resolved spectroscopy, chromosomeconformation capture (3C), FISH, spectral karyotyping and single moleculemethods such as AFM. The results are followed by biophysical modeling and allowedus to identify that a single protein, lamin A, is the most important player inthe chromatin organization mechanism. It forms chromatin loops therebyrestricting the chromatin dynamics in the whole nucleus volume. Other proteinshave a secondary effect.
We conclude that the organization of the DNA in the nucleus is basedon a “chromatin network”, a structure that we describe here for the first time.
Host: Sagi Levy