A network of interactions enables CCM3 and STK24 to coordinate UNC13D-driven vesicle exocytosis in neutrophils

Dev Cell. 2013 Oct 28;27(2):215-226. doi: 10.1016/j.devcel.2013.09.021.


Neutrophil degranulation plays an important role in acute innate immune responses and is tightly regulated because the granule contents can cause tissue damage. However, this regulation remains poorly understood. Here, we identify the complex of STK24 and CCM3 as being an important regulator of neutrophil degranulation. Lack of either STK24 or CCM3 increases the release of a specific granule pool without affecting other neutrophil functions. STK24 appears to suppress exocytosis by interacting and competing with UNC13D C2B domain for lipid binding, whereas CCM3 has dual roles in exocytosis regulation. Although CCM3 stabilizes STK24, it counteracts STK24-mediated inhibition of exocytosis by recruiting STK24 away from the C2B domain through its Ca(2+)-sensitive interaction with UNC13D C2A domain. This STK24/CCM3-regulated exocytosis plays an important role in the protection of kidneys from ischemia-reperfusion injury. Together, these findings reveal a function of the STK24 and CCM3 complex in the regulation of ligand-stimulated exocytosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis Regulatory Proteins
  • Cell Degranulation / genetics
  • Cell Degranulation / immunology
  • Exocytosis
  • Immunity, Innate
  • Intracellular Signaling Peptides and Proteins / deficiency
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Kidney / metabolism
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neutrophils / immunology*
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / deficiency
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Reperfusion Injury / metabolism


  • Apoptosis Regulatory Proteins
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • PDCD10 protein, mouse
  • Unc13d protein, mouse
  • Stk24 protein, mouse
  • Stk25 protein, mouse
  • Protein-Serine-Threonine Kinases