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VASP Regulates NK Cell Lytic Granule Convergence

Katelynn M Wilton1,2, Daniel D Billadeau3,4

  • 1Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN 55905.

Journal of Immunology (Baltimore, Md. : 1950)
|October 5, 2018
PubMed

Insights

Vasodilator-stimulated phosphoprotein (VASP) is crucial for natural killer (NK) cell killing. VASP maintains lytic granule convergence at the microtubule-organizing center (MTOC) for effective target cell elimination.

Area of Science:

  • Immunology
  • Cell Biology
  • Cytoskeletal Dynamics

Background:

  • Natural killer (NK) cells eliminate infected and malignant cells via directed release of cytotoxic granules.
  • This process requires the convergence of granules at the microtubule-organizing center (MTOC) before delivery to the immunological synapse.
  • Actin dynamics and cytoskeletal rearrangements are critical for NK cell cytotoxicity.

Purpose of the Study:

  • To investigate the role of vasodilator-stimulated phosphoprotein (VASP) in NK cell-mediated cytotoxicity.
  • To determine VASP's function in lytic granule trafficking and convergence at the MTOC.

Main Methods:

  • Immunofluorescence microscopy to visualize VASP, lytic granules, and MTOC.
  • VASP depletion using siRNA in human NK cells.
  • Assessment of conjugate formation, synaptic actin accumulation, and MTOC polarization.
  • Analysis of lytic granule convergence and spreading using KHYG-1 cell line.

Main Results:

  • VASP localizes to the cytolytic synapse and copurifies with lytic granules.
  • VASP is required for NK cell killing but does not affect conjugate formation or MTOC polarization.
  • VASP depletion impairs lytic granule convergence at the MTOC.
  • Disruption of VASP or F-actin leads to spreading of converged granules in KHYG-1 cells.

Conclusions:

  • VASP plays a novel role in maintaining lytic granule convergence during NK cell cytotoxicity.
  • Actin polymerization regulated by VASP is essential for stabilizing lytic granules at the MTOC.
  • VASP is a key regulator of granule trafficking dynamics critical for NK cell effector function.

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