title: Mechanical force effect on the two-state equilibrium of the hyaluronan-binding domain of CD44 in cell rolling.
abstract: CD44 is the receptor for hyaluronan (HA) and mediates cell rolling under fluid shear stress. The HA-binding domain (HABD) of CD44 interconverts between a low-affinity, ordered (O) state and a high-affinity, partially disordered (PD) state, by the conformational change of the C-terminal region, which is connected to the plasma membrane. To examine the role of tensile force on CD44-mediated rolling, we used a cell-free rolling system, in which recombinant HABDs were attached to beads through a C-terminal or N-terminal tag. We found that the rolling behavior was stabilized only at high shear stress, when the HABD was attached through the C-terminal tag. In contrast, no difference was observed for the beads coated with HABD mutants that constitutively adopt either the O state or the PD state. Steered molecular dynamics simulations suggested that the force from the C terminus disrupts the interaction between the C-terminal region and the core of the domain, thus providing structural insights into how the mechanical force triggers the allosteric O-to-PD transition. Based on these results, we propose that the force applied from the C terminus enhances the HABD-HA interactions by inducing the conformational change to the high-affinity PD transition more rapidly, thereby enabling CD44 to mediate lymphocyte trafficking and hematopoietic progenitor cell homing under high-shear conditions.
authors.affiliation: Division of Physical Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Division of Physical Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Division of Physical Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Ogino
authors.affiliation: Division of Physical Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Umemoto
authors.affiliation: Division of Physical Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Nishida
authors.affiliation: Division of Physical Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan shimada@iw-nmr.f.u-tokyo.ac.jp.
authors.forename: Ichio
authors.initials: I
authors.lastname: Shimada
mesh_terms: D001696:Biomechanical Phenomena; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000378:metabolism*; D008954:Models, Biological; D056004:Molecular Dynamics Simulation; D017434:Protein Structure, Tertiary; D013997:Time Factors
chemical_list: D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid
keywords: CD44; allosteric regulation; cell adhesion; hyaluronan; mechanical force