Induction of Prostaglandin I2 Receptor in Murine Osteoblastic Cell

Prostanoids are important paracrine bioregulators for many animal tissues in physiological and pathological conditions. They are synthesized in the cyclooxygenase pathway, and released out of cells immediately. There are five basic types of prostanoid receptor linked to specific G proteins and these receptors show various biological activities [1]. MC3T3-El cloned from newborn mouse calvaria is an osteogenic cell line, which differentiated into an osteoblast [2]. Earlier we demonstrated production of PGE2 as a major arachidonate metabolite in this cell line [3], and our later studies with MC3T3-E1 cells have shown the transcriptional regulation by TNFα of cyclooxygenase-2 induction [4]. In consideration of a possible function of the produced PGE2 as an autocrine mediator, we attempted to detect prostanoid receptors in the plasma membrane of MC3T3-E 1 cells. Previous papers reported the presence in this cell line of EP1, EP2, and EP4 [5], and FP [6], but their dynamic behaviors remained unclarified. In the present work, we will discuss an induction of IP rather than its constitutive expression in MC3T3-E1 cells [7].