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  • Dioleoyl phosphatidic acid increases intracellular Ca2+ through endogenous LPA receptors in C6 glioma and L2071 fibroblasts.

Dioleoyl phosphatidic acid increases intracellular Ca2+ through endogenous LPA receptors in C6 glioma and L2071 fibroblasts.

Prostaglandins & other lipid mediators (2007-05-15)
Young-Ja Chang, Yu-Lee Kim, Yun-Kyung Lee, Santosh J Sacket, Kyeok Kim, Hyo-Lim Kim, Mijin Han, Yoe-Sik Bae, Fumikazu Okajima, Dong-Soon Im
ABSTRACT

Phosphatidic acid (PA) increased intracellular Ca(2+) concentration ([Ca(2+)](i)) in C6 rat glioma and L2071 mouse fibroblast cells. Dioleoyl PA (PA, 18:1) was the most efficacious, followed by dipalmitoyl PA (16:0 PA) and dimyristoyl PA (14:0 PA). Lysophosphatidic acid (LPA) also increased the [Ca(2+)](i) in the both cells. PA desensitized LPA-induced Ca(2+) response completely in C6 cells, but partly in L2071 cells. Treatment of pertussis toxin (PTX), a specific inhibitor of G(i/o)-type G proteins, completely ameliorated LPA- and PA-induced Ca(2+) response in C6 cells. However, in L2071 cells, PTX inhibited PA-induced Ca(2+) increase by 80% and LPA-induced one by 20%. Ki16425, a specific inhibitor of LPA(1)/LPA(3) receptors, completely inhibited both LPA- and PA-induced Ca(2+) responses in C6 cells. On the other hand, in L2071 cells, Ki16425 completely inhibited PA-induced Ca(2+) response, but partly LPA-induced one. VPC32183, another specific inhibitor of LPA(1)/LPA(3) receptors, completely inhibited LPA- and PA-induced Ca(2+) responses in both C6 and L2071 cells. Therefore, PA and LPA appear to increase [Ca(2+)](i) through Ki16425/VPC32183-sensitive LPA receptor coupled to PTX-sensitive G proteins in C6 cells. In L2071 cells, however, LPA increases [Ca(2+)](i) through Ki16425-insensitive LPA receptor coupled to PTX-insensitive G proteins and Ki16425-sensitive LPA receptor coupled to PTX-sensitive G protein, whereas PA utilized only the latter pathway. Our results suggest that PA acts as a partial agonist on endogenous LPA receptors, which are sensitive to Ki16425 and coupled to PTX-sensitive G protein, but not on LPA receptors, which are not sensitive to Ki16425 and coupled to PTX-insensitive G protein.

MATERIALS
Product Number
Brand
Product Description

Avanti
18:0 PA, Avanti Research - A Croda Brand
Avanti
10:0 PA, 1,2-didecanoyl-sn-glycero-3-phosphate (sodium salt), powder
Avanti
10:0 PA, 1,2-didecanoyl-sn-glycero-3-phosphate (sodium salt), chloroform
Avanti
08:0 PA, 1,2-dioctanoyl-sn-glycero-3-phosphate (sodium salt), chloroform