title: Role of actin filaments in correlating nuclear shape and cell spreading.
abstract: It is well known that substrate properties like stiffness and adhesivity influence stem cell morphology and differentiation. Recent experiments show that cell morphology influences nuclear geometry and hence gene expression profile. The mechanism by which surface properties regulate cell and nuclear properties is only beginning to be understood. Direct transmission of forces as well as chemical signalling are involved in this process. Here, we investigate the formal aspect by studying the correlation between cell spreading and nuclear deformation using Mesenchymal stem cells under a wide variety of conditions. It is observed that a robust quantitative relation holds between the cell and nuclear projected areas, irrespective of how the cell area is modified or when various cytoskeletal or nuclear components are perturbed. By studying the role of actin stress fibers in compressing the nucleus we propose that nuclear compression by stress fibers can lead to enhanced cell spreading due to an interplay between elastic and adhesion factors. The significance of myosin-II in regulating this process is also explored. We demonstrate this effect using a simple technique to apply external compressive loads on the nucleus.
authors.affiliation: Soft Condensed Matter group, Raman Research Institute, Bangalore, Karnataka, India.
authors.forename: Renu
authors.initials: R
authors.lastname: Vishavkarma
authors.affiliation: Soft Condensed Matter group, Raman Research Institute, Bangalore, Karnataka, India.
authors.forename: Swetavalli
authors.initials: S
authors.lastname: Raghavan
authors.affiliation: Soft Condensed Matter group, Raman Research Institute, Bangalore, Karnataka, India.
authors.forename: Chandrashekar
authors.initials: C
authors.lastname: Kuyyamudi
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine, National Centre for Biological Sciences (TIFR), Bangalore, Karnataka, India.
authors.forename: Abhijit
authors.initials: A
authors.lastname: Majumder
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine, National Centre for Biological Sciences (TIFR), Bangalore, Karnataka, India.
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Dhawan
authors.affiliation: Soft Condensed Matter group, Raman Research Institute, Bangalore, Karnataka, India.
authors.forename: Pramod A
authors.initials: PA
authors.lastname: Pullarkat
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D000199:Actins / Q000032:analysis / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D002448:Cell Adhesion; D053144:Cell Nucleus Shape; D002478:Cells, Cultured; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D051379:Mice
chemical_list: D000199:Actins