title: Identification of Ser/Thr phosphorylation sites in the C2-domain of phospholipase C γ2 (PLCγ2) using TRPM7-kinase.
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.
authors: Department of Immunology, University of Colorado Denver, National Jewish Health, Denver, CO 80206, USA.
authors: Francina
authors: F
authors: Deason-Towne
authors: Anne-Laure
authors: AL
authors: Perraud
authors: Carsten
authors: C
authors: Schmitz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002645:Chickens; D006801:Humans; D008274:Magnesium / Q000378:metabolism; D008969:Molecular Sequence Data; D051966:Phospholipase C gamma / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D050053:TRPM Cation Channels / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism
chemical_list: D011947:Receptors, Antigen, B-Cell; D050053:TRPM Cation Channels; D013912:Threonine; D012694:Serine; D017346:Protein Serine-Threonine Kinases; C486583:TRPM7 protein, human; D051966:Phospholipase C gamma; D008274:Magnesium; D002118:Calcium