Characterization of the transient receptor potential channels mediating lysophosphatidic acid-stimulated calcium mobilization in B lymphoblasts.
Altered 1-oleoyl-lysophosphatidic acid (LPA, 100 microM)-stimulated calcium responses occur in B-lymphoblast cell lines from bipolar disorder patients, but the mechanism(s) involved is uncertain. Lysophosphatidic acid shares a structurally similar fatty acid side chain with the diacylglycerol analogue, 1-oleoyl-2-acetyl-sn-glycerol (OAG), a known activator of subtypes 3, 6 and 7 of the canonical transient receptor potential (TRPC) cation channel subfamily. Accordingly, the objective of this study was to determine whether the LPA-stimulated calcium response in B-lymphoblasts is mediated, in part, through this TRPC channel subfamily. Divalent cation selectivity in response to thapsigargin, LPA and OAG were used to distinguish TRPC-like character of the responses to these agents in BLCLs. The sensitivity to gadolinium, an inhibitor of capacitative calcium channels, was used to determine the store-operated nature of the responses. The TRPC isoforms that are present in BLCLs as identified by immunoblotting and/or PCR include TRPC1, 3 and 5. Minimal barium influx in calcium-free buffer was observed following thapsigargin stimulation. However, LPA stimulated barium influx of a magnitude similar to that induced by OAG. Thapsigargin-provoked calcium influx was completely inhibited by gadolinium (10 microM), whereas LPA and OAG-stimulated responses were partially inhibited and potentiated, respectively. The results suggest that 100 microM LPA stimulates calcium entry through channels with characteristics similar to TRPC3, as TRPC6 and 7 are absent in B-lymphoblasts.
Roedding
Angela S
AS
Laboratory of Cellular and Molecular Pathophysiology, Centre for Addiction and Mental Health, Toronto, ON, Canada M5T 1R8.
Li
Peter P
PP
Warsh
Jerry J
JJ
D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D001464:Barium / Q000378:metabolism; D001714:Bipolar Disorder / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002460:Cell Line; D004075:Diglycerides / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D008246:Lysophospholipids / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D050052:TRPC Cation Channels / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology
D004075:Diglycerides; D008246:Lysophospholipids; D050052:TRPC Cation Channels; D001464:Barium; D019284:Thapsigargin; C038237:1-oleoyl-2-acetylglycerol; C032881:lysophosphatidic acid