Thrombin promotes sustained signaling and inflammatory gene expression through the CDC25 and Ras-associating domains of phospholipase Cϵ.
Phospholipase C-epsilon (PLCϵ) plays a critical role in G-protein-coupled receptor-mediated inflammation. In addition to its ability to generate the second messengers inositol 1,4,5-trisphosphate and diacylglycerol, PLCϵ, unlike the other phospholipase C family members, is activated in a sustained manner. We hypothesized that the ability of PLCϵ to function as a guanine nucleotide exchange factor (GEF) for Rap1 supports sustained downstream signaling via feedback of Rap1 to the enzyme Ras-associating (RA2) domain. Using gene deletion and adenoviral rescue, we demonstrate that both the GEF (CDC25 homology domain) and RA2 domains of PLCϵ are required for long term protein kinase D (PKD) activation and subsequent induction of inflammatory genes. PLCϵ localization is largely intracellular and its compartmentalization could contribute to its sustained activation. Here we show that localization of PLCϵ to the Golgi is required for activation of PKD in this compartment as well as for subsequent induction of inflammatory genes. These data provide a molecular mechanism by which PLCϵ mediates sustained signaling and by which astrocytes mediate pathophysiological inflammatory responses.
From the Department of Pharmacology, School of Medicine and Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, California 92093 and.
Stephanie S
SS
Dusaban
From the Department of Pharmacology, School of Medicine and.
Maya T
MT
Kunkel
Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642.
Alan V
AV
Smrcka
From the Department of Pharmacology, School of Medicine and jhbrown@ucsd.edu.
Joan Heller
JH
Brown
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002451:Cell Compartmentation; D031541:Fluorescence Resonance Energy Transfer; D005786:Gene Expression Regulation; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D007249:Inflammation; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D054801:Phosphoinositide Phospholipase C / Q000235:genetics / Q000378:metabolism*; D061251:Primary Cell Culture; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D013917:Thrombin / Q000378:metabolism / Q000494:pharmacology*; D020827:rap1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020666:ras-GRF1 / Q000235:genetics / Q000378:metabolism*
D020666:ras-GRF1; D015544:Inositol 1,4,5-Trisphosphate; C089212:protein kinase D; D011493:Protein Kinase C; D054801:Phosphoinositide Phospholipase C; C423320:phospholipase C epsilon; D013917:Thrombin; D020827:rap1 GTP-Binding Proteins
G protein-coupled receptor (GPCR); Phospholipase C; Ras-related protein 1 (Rap1); astrocyte; cyclooxygenase (COX); diacylglycerol; guanine nucleotide exchange factor (GEF); protein kinase D (PKD); thrombin