Fig. 4.
Hypoxia activates LPA1 signaling pathways by potentiating LPA1 activity. The Gαi inhibitor PTX (A–C) and the Rac1 inhibitor NSC23766 (D–F) inhibited hypoxia-induced mitotic displacement, whereas treatment with a Rho-associated kinase inhibitor, Y-27632, (G–I) increased displacement of mitotic cells (n = 10, 6, and 7 matched pairs, respectively) compared with cortices treated with vehicle. (J and K) Representative images of LPA-induced neurite retraction. (L) LPA-induced retraction of TSM1 neurites can be blocked partially by inhibiting LPA1 with Ki16425. Other Ki16425-insensitive LPA receptors are expressed by TSM1 cells. This retraction is potentiated by hypoxia and is Ki16425 sensitive (LPA1 specific). (M) cAMP inhibition assay. B103 cells stably expressing LPA1 were treated with increasing LPA concentrations in hypoxia, showing a maximal inhibition at 250 nM (∼50% over normoxia). cAMP levels are normalized to cell number. *P < 0.05; **P < 0.01; ***P < 0.001. (Scale bar: 50 μm in A, 10 μm in J.)