Identification of Ser/Thr phosphorylation sites in the C2-domain of phospholipase C γ2 (PLCγ2) using TRPM7-kinase

Cell Signal. 2012 Nov;24(11):2070-5. doi: 10.1016/j.cellsig.2012.06.015. Epub 2012 Jul 1.

Abstract

PLC-isozymes are central elements of cellular signaling downstream of numerous receptors. PLCγ2 is a pivotal component of B cell receptor (BCR) signaling. The regulation of PLCγ2-dependent signaling functions by Tyr-phosphorylation is well characterized, however, the potential role of Ser/Thr phosphorylation events remains undefined. TRPM7 is the fusion of a Ser/Thr kinase with an ion channel, and an essential component of Mg(2+)-homeostasis regulation. Although the interaction between the C2 domain of several PLC-isozymes and TRPM7 is well established, previous studies have focused on the effect of PLC-activity on TRPM7. Here, we investigated whether Ser/Thr phosphorylation sites in the C2 domain of PLCγ2 could be identified using TRPM7-kinase. We show that TRPM7-kinase phosphorylates PLCγ2 in its C2-domain at position Ser1164 and in the linker region preceding the C2-domain at position Thr1045. Using a complementation approach in PLCγ2(-/-) DT40 cells, we found that the PLCγ2-S1164A mutant fully restores BCR mediated Ca(2+)-responses under standard growth conditions. However, under hypomagnesic conditions, PLCγ2-S1164A fails to reach Ca(2+)-levels seen in cells expressing PLCγ2 wildtype. These results suggest that Mg(2+)-sensitivity of the BCR signaling pathway may be regulated by Ser/Thr phosphorylation of PLCγ2.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Calcium / metabolism
  • Cell Line
  • Chickens
  • Humans
  • Magnesium / metabolism
  • Molecular Sequence Data
  • Phospholipase C gamma / chemistry
  • Phospholipase C gamma / metabolism*
  • Phosphorylation
  • Protein-Serine-Threonine Kinases
  • Receptors, Antigen, B-Cell / metabolism
  • Serine / metabolism
  • Signal Transduction
  • TRPM Cation Channels / metabolism*
  • Threonine / metabolism

Substances

  • Receptors, Antigen, B-Cell
  • TRPM Cation Channels
  • Threonine
  • Serine
  • Protein-Serine-Threonine Kinases
  • TRPM7 protein, human
  • Phospholipase C gamma
  • Magnesium
  • Calcium