TY - JOUR
T1 - Different signaling pathway between sphingosine-1-Phosphate and lysophosphatidic acid in Xenopus occytes
T2 - Functional coupling of the sphinggosine-1-phosphate receptor to PLC-xβ in Xenopus oocytes
AU - Noh, Seung Jae
AU - Kim, Myung Jun
AU - Shim, Sangwoo
AU - Han, Jin Kwan
PY - 1998/8
Y1 - 1998/8
N2 - In Xenopus occytes, both sphingosine-1-phosphate (SIP) and lysophosphatidic acid (LPA) activate Ca2+-dependent oscillatory CL- currents by acting though membrane-bound receptors. External application of 50 μ S1P elicited a long-lasting oscillatory current that continued over 30 min from the beginning of oscillation, with 300 nA (n = 11) as a usual maximum peak of current, whereas 1-μ LPA treatment showed only transiently oscillating but more vigorous current responses, with 2,800 nA (n = 18) as a maximum peak amplitude. Both phospholipid-induced Ca2+-dependent Cl- currents were observed in the absence of extra-cellular Ca2+, were blocked by intracellular injection of the Ca2+ chelator, EGTA, and could not be elicited by treatment with thapsigargin, and inhibitor of endosplasmic reticulum (ER) Ca2+ ATPase. Intracellular Ca2+-release appeared to be from inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ store, because CI- currents were blocked by heparin injection. Pretreatment with the aminosteroid, U-73122, an inhibitor of G protein-mediated phospholipase C (PLC) activation, to oocytes inhibited the current responses evoked both by S1P and LPA. However, when they were injected with 10 ng of antisense oligonucleotide (AS-ODN) against Xenopus phospholipase C (plc-xβ), occytes could not respodn to S1P application, whereas they responded normally to LPA, indicating that the S1P signaling pathway goes through PLC-Xβ, whereas LPA signaling goes through another unknown PLC. To determine the types of G proteins involved, we introduced AS-ODNs against four types of G-protein α subunits that were identified in Xenopus laevis; G(qα), G11α, G0α, and G11α. Among AS-ODNs against the Gαs tested, AS-G(qα) and AS-G11α to S1P and AS-G(qα) and AS-G11α to LPA specifically reduced current responses, respectively, to about 20-30% of controls. These results demonstrate that LPA and S1P, although they have similar structural features, release intracellular Ca2+ from the IP3-sensitive pool, use different components in their signal transduction pathways in Xenopus oocytes.
AB - In Xenopus occytes, both sphingosine-1-phosphate (SIP) and lysophosphatidic acid (LPA) activate Ca2+-dependent oscillatory CL- currents by acting though membrane-bound receptors. External application of 50 μ S1P elicited a long-lasting oscillatory current that continued over 30 min from the beginning of oscillation, with 300 nA (n = 11) as a usual maximum peak of current, whereas 1-μ LPA treatment showed only transiently oscillating but more vigorous current responses, with 2,800 nA (n = 18) as a maximum peak amplitude. Both phospholipid-induced Ca2+-dependent Cl- currents were observed in the absence of extra-cellular Ca2+, were blocked by intracellular injection of the Ca2+ chelator, EGTA, and could not be elicited by treatment with thapsigargin, and inhibitor of endosplasmic reticulum (ER) Ca2+ ATPase. Intracellular Ca2+-release appeared to be from inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ store, because CI- currents were blocked by heparin injection. Pretreatment with the aminosteroid, U-73122, an inhibitor of G protein-mediated phospholipase C (PLC) activation, to oocytes inhibited the current responses evoked both by S1P and LPA. However, when they were injected with 10 ng of antisense oligonucleotide (AS-ODN) against Xenopus phospholipase C (plc-xβ), occytes could not respodn to S1P application, whereas they responded normally to LPA, indicating that the S1P signaling pathway goes through PLC-Xβ, whereas LPA signaling goes through another unknown PLC. To determine the types of G proteins involved, we introduced AS-ODNs against four types of G-protein α subunits that were identified in Xenopus laevis; G(qα), G11α, G0α, and G11α. Among AS-ODNs against the Gαs tested, AS-G(qα) and AS-G11α to S1P and AS-G(qα) and AS-G11α to LPA specifically reduced current responses, respectively, to about 20-30% of controls. These results demonstrate that LPA and S1P, although they have similar structural features, release intracellular Ca2+ from the IP3-sensitive pool, use different components in their signal transduction pathways in Xenopus oocytes.
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U2 - 10.1002/(SICI)1097-4652(199808)176:2<412::AID-JCP20>3.0.CO;2-3
DO - 10.1002/(SICI)1097-4652(199808)176:2<412::AID-JCP20>3.0.CO;2-3
M3 - Article
C2 - 9648929
AN - SCOPUS:0031850772
SN - 0021-9541
VL - 176
SP - 412
EP - 423
JO - Journal of cellular physiology
JF - Journal of cellular physiology
IS - 2
ER -