Induction of prostacyclin receptor expression in human erythroleukemia cells

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Abstract
We have identified both high‐affinity (KD = 36±3 nM) and low‐affinity (KD = 2.1±0.8 μM) prostacyclin (PGI2)‐receptor sites on human erythroleukemia (HEL) cells using the radiolabelled prostacyclin analogue, [3H]iloprost. The addition of the phorbol ester, TPA, to the culture medium caused a 5–10‐fold increase in the number of both the low‐ and the high‐affinity sites, without any change in their affinity constants. Iloprost stimulated HEL cell membrane adenylate cyclase activity 5‐fold. This stimulation was potentiated in the presence of GTP, indicating a conventional PGI2 receptor‐Gs‐adenylate cyclase system. HEL cells represent a source of prostacyclin receptor mRNA which may be of value in expression cloning of this receptor.