Actomyosin contractility rotates the cell nucleus.
The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells.
1] Mechanobiology Institute and Department of Biological Sciences, NUS, Singapore 117411 [2].
Abhishek
A
Kumar
1] Department of Physics, Indian Institute of Science, Bangalore 560012, India [2].
Ananyo
A
Maitra
Mechanobiology Institute and Department of Biological Sciences, NUS, Singapore 117411.
Madhuresh
M
Sumit
1] Department of Physics, Indian Institute of Science, Bangalore 560012, India [2] TIFR Centre for Interdisciplinary Sciences, Hyderabad 500075, India.
Sriram
S
Ramaswamy
Mechanobiology Institute and Department of Biological Sciences, NUS, Singapore 117411.
G V
GV
Shivashankar
D008841:Actin Cytoskeleton / Q000187:drug effects* / Q000378:metabolism; D000199:Actins / Q000737:chemistry; D000205:Actomyosin / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects*; D003599:Cytoskeleton / Q000187:drug effects* / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D041681:NIH 3T3 Cells; D059008:Time-Lapse Imaging
D000199:Actins; D006576:Heterocyclic Compounds, 4 or More Rings; C472645:blebbistatin; D000205:Actomyosin