PALLD Regulates Phagocytosis by Enabling Timely Actin Polymerization and Depolymerization

J Immunol. 2017 Sep 1;199(5):1817-1826. doi: 10.4049/jimmunol.1602018. Epub 2017 Jul 24.


PALLD is an actin cross-linker supporting cellular mechanical tension. However, its involvement in the regulation of phagocytosis, a cellular activity essential for innate immunity and physiological tissue turnover, is unclear. We report that PALLD is highly induced along with all-trans-retinoic acid-induced maturation of myeloid leukemia cells, to promote Ig- or complement-opsonized phagocytosis. PALLD mechanistically facilitates phagocytic receptor clustering by regulating actin polymerization and c-Src dynamic activation during particle binding and early phagosome formation. PALLD is also required at the nascent phagosome to recruit phosphatase oculocerebrorenal syndrome of Lowe, which regulates phosphatidylinositol-4,5-bisphosphate hydrolysis and actin depolymerization to complete phagosome closure. Collectively, our results show a new function for PALLD as a crucial regulator of the early phase of phagocytosis by elaborating dynamic actin polymerization and depolymerization.

MeSH terms

  • Actins / metabolism*
  • Animals
  • Cell Differentiation
  • Cell Line, Tumor
  • Cell Self Renewal
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • Dendritic Cells / immunology*
  • Humans
  • Immunity, Innate
  • Leukemia, Myeloid, Acute / immunology*
  • Mice
  • Mice, Inbred C57BL
  • Neoplastic Stem Cells / physiology*
  • Oculocerebrorenal Syndrome / immunology*
  • Phagocytosis*
  • Phagosomes / metabolism
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Phosphoric Monoester Hydrolases / metabolism
  • Polymerization
  • Receptor Aggregation
  • Tretinoin / metabolism


  • Actins
  • Cytoskeletal Proteins
  • PALLD protein, human
  • Phosphoproteins
  • Tretinoin
  • Phosphoric Monoester Hydrolases
  • phosphoinositide 5-phosphatase