[Regulation of receptor activator of nuclear factor kappaB ligand and osteoprotegerin expression by prostaglandin E2 in osteoblastic-like cells].
OBJECTIVE
To investigate the regulation of receptor activator of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) mRNA expression by prostaglandin E2 (PGE2) in osteoblastic-like cells and involved signaling pathways.


METHODS
Rat UMR106 osteoblast-like cells were cultured and treated with various dose of PGE2 or regulators of different signaling pathways such as protein kinase A, protein kinase C, ERK-MAPK and calcium/calmodulin pathways for different period of time,the cells were then harvested at indicated time points, total RNA were isolated and RANKL/OPG mRNA expression were studied by real-time PCR.


RESULTS
PGE2, Forskolin and db-cAMP increased RANKL mRNA by 2.8 times (P = 0.002), 2.2 times (P = 0.006) and 2.1 times (P = 0.005) respectively, and inhibited OPG mRNA expression by 12% (P < 0.01), 85% (P = 0.005) and 70% (P = 0.013) respectively, while RANKL and OPG mRNA expression were down-regulated by A23187 by 58% (P = 0.002) and 53% (P = 0.017) respectively. As for inhibitory experiments, the stimulatory effects of PGE2 on RANKL mRNA expression could be inhibited only by KT-5720 by 53% (P < 0.01), while the other inhibitors did not have any effect at all. The inhibitory effects of PGE2 on OPG mRNA expression were partially blocked by KT-5720 by 47% (P = 0.01), verapamil by 38% (P = 0.029) and W7 by 43% (P < 0.01) respectively, while KN-62, chelerythrine and PD98059 had no effects.


CONCLUSIONS
PGE2 can up-regulate the expression of RANKL but down-regulate the expression of OPG. The up-regulation of RANKL mRNA expression by PGE2 was mediated through the activation of PKA signaling pathway while PGE2 induced down-regulation of OPG mRNA expression was predominantly mediated via PKA as well as the Ca2+ /Calmodulin signaling pathways.
Wang
Bao-li
BL
Division of Endocrinology, Gansu Provincial People's Hospital, Lanzhou 730000, China.
Zheng
Fang
F
Qiu
Ming-cai
MC
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D053244:Osteoprotegerin / Q000235:genetics*; D053245:RANK Ligand / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger; D005576:Colforsin; D003994:Bucladesine; D015232:Dinoprostone