Phospholipase C-η1 is activated by intracellular Ca(2+) mobilization and enhances GPCRs/PLC/Ca(2+) signaling.
Phospholipase C-η1 (PLC-η1) is the most recently identified PLC isotype and is primarily expressed in nerve tissue. However, its functional role is unclear. In the present study, we report for the first time that PLC-η1 acts as a signal amplifier in G protein-coupled receptor (GPCR)-mediated PLC and Ca(2+) signaling. Short-hairpin RNA (shRNA)-mediated knockdown of endogenous PLC-η1 reduced lysophosphatidic acid (LPA)-, bradykinin (BK)-, and PACAP-induced PLC activity in mouse neuroblastoma Neuro2A (N2A) cells, indicating that PLC-η1 participates in GPCR-mediated PLC activation. Interestingly, ionomycin-induced PLC activity was significantly decreased by PLC-η1, but not PLC-η2, knockdown. In addition, we found that intracellular Ca(2+) source is enough for PLC-η1 activation. Furthermore, the IP(3) receptor inhibitor, 2-APB, inhibited LPA-induced PLC activity in control N2A cells, whereas this effect was not observed in PLC-η1 knockdown N2A cells, suggesting a pivotal role of intracellular Ca(2+) mobilization in PLC-η1 activation. Finally, we found that LPA-induced ERK1/2 phosphorylation and expression of the downstream target gene, krox-24, were significantly decreased by PLC-η1 knockdown, and these knockdown effects were abolished by 2-APB. Taken together, our results strongly suggest that PLC-η1 is activated via intracellular Ca(2+) mobilization from the ER, and therefore amplifies GPCR-mediated signaling.
Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.
Jung Kuk
JK
Kim
Jung Woong
JW
Choi
Seyoung
S
Lim
Ohman
O
Kwon
Jeong Kon
JK
Seo
Sung Ho
SH
Ryu
Pann-Ghill
PG
Suh
D000818:Animals; D020013:Calcium Signaling; D002460:Cell Line; D051766:Early Growth Response Protein 1 / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology; D051379:Mice; D054801:Phosphoinositide Phospholipase C / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D034622:RNA Interference; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism*
D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D008246:Lysophospholipids; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins; D048049:Extracellular Signal-Regulated MAP Kinases; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; C506061:Plch1 protein, mouse; C503884:Plch2 protein, mouse; C032881:lysophosphatidic acid