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NDR1-Dependent Regulation of Kindlin-3 Controls High-Affinity LFA-1 Binding and Immune Synapse Organization

Naoyuki Kondo1, Yoshihiro Ueda1, Toshiyuki Kita1

  • 1Department of Molecular Genetics, Institute of Biomedical Science, Kansai Medical University, Hirakata, Osaka, Japan.

Molecular and Cellular Biology
|February 1, 2017
PubMed

Insights

Rap1 signaling is crucial for T cell adhesion by recruiting kindlin-3 to the immunological synapse (IS). This process, involving NDR1 kinase, ensures proper T cell-APC interactions and IS organization for effective immune responses.

Area of Science:

  • Immunology
  • Cell Biology
  • Molecular Biology

Background:

  • T cell adhesion to antigen-presenting cells (APCs) is vital for initiating adaptive immunity.
  • The formation of the immunological synapse (IS) involves specific molecular interactions, including LFA-1 and ICAM-1.
  • Understanding the molecular regulation of IS formation is key to deciphering immune cell communication.

Purpose of the Study:

  • To investigate the single-molecule dynamics of LFA-1/ICAM-1 interactions during IS formation.
  • To elucidate the roles of Rap1 signaling, Mst1/Mst2, and NDR1 kinase in regulating T cell adhesion and IS organization.
  • To identify the mechanisms by which kindlin-3 is recruited to the IS.

Main Methods:

  • Single-molecule force spectroscopy on supported lipid bilayers to measure LFA-1/ICAM-1 binding.
  • Genetic manipulation to study the function of Rap1, Mst1/Mst2, and NDR1 kinase.
  • Immunofluorescence microscopy to assess the localization of key proteins and regulators within the IS.

Main Results:

  • High-affinity LFA-1/ICAM-1 binding was observed in the inner SMAC zone, associated with activated Rap1 and kindlin-3.
  • Rap1 signaling, through NDR1 kinase and Mst1/Mst2, was essential for recruiting kindlin-3 to the IS.
  • Deficiency in Mst1/Mst2 impaired high-affinity binding, abrogated cSMAC formation, and disrupted kindlin-3 localization, leading to defective T cell-APC interactions.

Conclusions:

  • Rap1 signaling is indispensable for T cell attachment and IS organization.
  • NDR1 kinase acts as a critical mediator in the Rap1 cascade, facilitating kindlin-3 recruitment to the IS.
  • Proper recruitment of kindlin-3 and IS organization are essential for high-affinity LFA-1/ICAM-1 binding and effective T cell-APC interactions.

Keywords:
ICAM-1LFA-1NDR1Rap1immunological synapsesingle-molecule measurementvesicular transport

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