The cell nucleus houses the genome, and thus, it must robustly resist and respond to intra- and extracellular forces. Micromanipulation experiments by my collaborator Andrew Stephens (Marko lab) show that the nucleus responds to forces in a surprising manner that depends on to major nuclear components: the outer protein shell (the lamina) and the chromatin contained within the nucleus (the genome itself).
These results can be explained by a conceptually simple simulation model. Our model, depicted below, is that the lamina is a polymeric shell that encapsulates a polymer gel — the genome.
For small deformations, the polymer shell is somewhat floppy, so it does not contribute much to mechanical response. Instead, the genome provides rigidity against small deformations.
This page is under construction. There’s more to come about how chromatin impacts nuclear morphology and my current research analyzing Hi-C genome contact maps and developing a polymer molecular dynamics model to probe the biophysics of genome structure.
References
- AD Stephens, EJ Banigan, SA Adam, RD Goldman, and JF Marko (2017) Chromatin and lamin A determine two different mechanical response regimes of the cell nucleus. Mol. Biol. Cell 28: 1984.
- EJ Banigan, AD Stephens, and JF Marko (2017)Mechanics and buckling of biopolymeric shells and cell nuclei. Biophys. J. 113: 1654.
- AD Stephens, PZ Liu, EJ Banigan, LM Almassalha, V Backman, SA Adam, RD Goldman, and JF Marko (2018) Chromatin histone modifications and rigidity affect nuclear morphology independent of lamins. Mol. Biol. Cell, In press.
- AD Stephens, EJ Banigan, and JF Marko (2017) Separate roles for chromatin and lamins in nuclear mechanics. Nucleus, In press.