Berlin 2015 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 16: Posters: Cell adhesion, mechanics and migration
BP 16.7: Poster
Montag, 16. März 2015, 17:30–19:30, Poster A
Unique mechanical properties of cell nuclei regulated by chromatin — •Chii Jou Chan1,2, Wenhong Li2, Jana Scholze2, Mirjam Schürmann2, and Jochen Guck1,2 — 1Cavendish Laboratory, Department of Physics, University of Cambridge, UK — 2Biotechnology Center, TU Dresden, Dresden, Germany
Nuclear mechanics could affect gene regulation and gene expression. Chromatin, a major component of cell nuclei, could play an important role in maintaining nuclear integrity and their mechanical properties. Previous studies on nuclear mechanical properties focused largely on the role of the nuclear lamina, using techniques such as AFM and micropipette aspiration. In this work, we explicitly address the contributions of chromatin to nuclear rheology after isolation from the cell using a microfluidic optical stretcher. We find that isolated nuclei swell under uniaxial stress and exhibit significant softening with increased nuclear size, which can be described by a filtration model for the nuclear membrane encasing a cortical layer of chromatin. Changes to the state of chromatin condensation via histone modifications or chromatin remodeling processes (ATP, topoisomerase II) can strongly impact nuclear morphology and compliance. Moreover, isolated nuclear mechanics is sensitive to ionic conditions: nuclei stiffen with increasing ionic strength of the buffer and contract during optical stretching in the presence of multivalent ions. The presented work establishes a quantitative link between nuclear mechanical properties and the compaction state of chromatin, which can be modulated by osmotic stress, chromatin remodeling or electrochemical environment.