Distinct and shared roles of β-arrestin-1 and β-arrestin-2 on the regulation of C3a receptor signaling in human mast cells

PLoS One. 2011 May 12;6(5):e19585. doi: 10.1371/journal.pone.0019585.


Background: The complement component C3a induces degranulation in human mast cells via the activation of cell surface G protein coupled receptors (GPCR; C3aR). For most GPCRs, agonist-induced receptor phosphorylation leads to the recruitment of β-arrestin-1/β-arrestin-2; resulting in receptor desensitization and internalization. Activation of GPCRs also leads to ERK1/2 phosphorylation via two temporally distinct pathways; an early response that reflects G protein activation and a delayed response that is G protein independent but requires β-arrestins. The role of β-arrestins on C3aR activation/regulation in human mast cells, however, remains unknown.

Methodology/principal findings: We utilized lentivirus short hairpin (sh)RNA to stably knockdown the expression of β-arrestin-1 and β-arrrestin-2 in human mast cell lines, HMC-1 and LAD2 that endogenously expresses C3aR. Silencing β-arrestin-2 attenuated C3aR desensitization, blocked agonist-induced receptor internalization and rendered the cells responsive to C3a for enhanced NF-κB activity as well as chemokine generation. By contrast, silencing β-arrestin-1 had no effect on these responses but resulted in a significant decrease in C3a-induced mast cell degranulation. In shRNA control cells, C3a caused a transient ERK1/2 phosphorylation, which peaked at 5 min but disappeared by 10 min. Knockdown of β-arrestin-1, β-arrestin-2 or both enhanced the early response to C3a and rendered the cells responsive for ERK1/2 phosphorylation at later time points (10-30 min). Treatment of cells with pertussis toxin almost completely blocked both early and delayed C3a-induced ERK1/2 phosphorylation in β-arrestin1/2 knockdown cells.

Conclusion/significance: This study demonstrates distinct roles for β-arrestins-1 and β-arrestins-2 on C3aR desensitization, internalization, degranulation, NF-κB activation and chemokine generation in human mast cells. It also shows that both β-arrestin-1 and β-arrestin-2 play a novel and shared role in inhibiting G protein-dependent ERK1/2 phosphorylation. These findings reveal a new level of complexity for C3aR regulation by β-arrestins in human mast cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Arrestins / genetics
  • Arrestins / physiology*
  • Cell Degranulation
  • Cell Line
  • Complement C3a / metabolism*
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gene Knockdown Techniques
  • Humans
  • Mast Cells / metabolism*
  • Pertussis Toxin / pharmacology
  • Phosphorylation
  • Protein Isoforms / physiology*
  • Receptors, Complement / metabolism*
  • Signal Transduction*
  • beta-Arrestin 1
  • beta-Arrestin 2
  • beta-Arrestins


  • ARRB1 protein, human
  • ARRB2 protein, human
  • Arrestins
  • Protein Isoforms
  • Receptors, Complement
  • beta-Arrestin 1
  • beta-Arrestin 2
  • beta-Arrestins
  • Complement C3a
  • Pertussis Toxin
  • Extracellular Signal-Regulated MAP Kinases