Role of prostaglandin I2 in the gene expression induced by mechanical stress in spinal ligament cells derived from patients with ossification of the posterior longitudinal ligament.
Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic bone formation in the spinal ligaments, and mechanical stress has been suggested to play an important role in the progression of OPLL. To identify the genes that participate in OPLL, the differential display reverse transcription-polymerase chain reaction (RT-PCR) method was used. A 283-base pair cDNA fragment corresponding to prostaglandin I2 (PGI2) synthase was highly expressed in OPLL cells compared with non-OPLL cells. To examine the effect of mechanical stress on the expression of PGI2 synthase, cells were subjected to uniaxial cyclic stretch (0.5 Hz, 20% stretch), and PGI2 synthase mRNA expression was assessed by quantitative RT-PCR. Cyclic stretch induced an increase in PGI2 synthase in OPLL cells in a time-dependent manner, whereas no change was observed in non-OPLL cells. Cyclic stretch for 9 h also induced a 2.86x increase in PGI2 production. Beraprost (a stable PGI2 analog) and dibutyryl cAMP (a membrane-permeable cAMP analog) increased the mRNA expression of alkaline phosphatase (ALP) as a marker for osteogenic differentiation up to 240 and 200%, respectively, in OPLL cells, whereas no change was observed in non-OPLL cells. The increases in ALP mRNA induced by beraprost and cyclic stretch were both inhibited by SQ22536, a potent adenylate cyclase inhibitor. These data suggest that the increase in PGI2 synthase induced by mechanical stress plays a key role in the progression of OPLL, at least in part through the induction of osteogenic differentiation in spinal ligament cells via the PGI2/cAMP system.
Ohishi
Hirotaka
H
Department of Orthopaedic Surgery, Hirosaki University School of Medicine, Hirosaki 036-8562, Japan.
Furukawa
Ken-Ichi
K
Iwasaki
Koei
K
Ueyama
Kazumasa
K
Okada
Akihiro
A
Motomura
Shigeru
S
Harata
Seiko
S
Toh
Satoshi
S
D000067956:Adenylyl Cyclase Inhibitors; D000469:Alkaline Phosphatase / Q000096:biosynthesis; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D001483:Base Sequence; D003994:Bucladesine / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000502:physiology*; D018076:DNA, Complementary / Q000032:analysis; D011464:Epoprostenol / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000096:biosynthesis / Q000502:physiology*; D017846:Longitudinal Ligaments; D008969:Molecular Sequence Data; D017887:Ossification of Posterior Longitudinal Ligament / Q000473:pathology*; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000819:agonists / Q000037:antagonists & inhibitors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013314:Stress, Mechanical
D000067956:Adenylyl Cyclase Inhibitors; D000893:Anti-Inflammatory Agents; D018076:DNA, Complementary; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin; D018078:Receptors, Prostaglandin E; C048081:beraprost; D003994:Bucladesine; D003577:Cytochrome P-450 Enzyme System; D011464:Epoprostenol; D000469:Alkaline Phosphatase; D019746:Intramolecular Oxidoreductases; C022461:prostacyclin synthetase