title: An 8-O-4' norlignan exerts oestrogen-like actions in osteoblastic cells via rapid nongenomic ER signaling pathway.
abstract: BACKGROUND
  Sambucus williamsii Hance (SWH), which belongs to the Caprifoliaceae family distributed in various regions of China, Korea and Japan, has been used as a folk medicine for treatment of bone and joint diseases in China for thousands of years. In previous studies, SWH was shown to possess anti-osteoporosis, healing fracture, anti-inflammatory and analgesic activities. Our previous studies showed that SWH extract effectively suppressed ovariectomy-induced increase in bone turnover and improved bone mineral density and bone biomechanical strength in rats as well as in mice. An 8-O-4' norlignan, (7R,8S)-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-1,3-propanediol (PPD) was previously isolated and identified as the bioactive ingredient in SWH. The present study aimed to characterize the bone protective effects as well as its mechanism of actions in osteoblasts.
  
  
  METHODS
  Bone protective actions of PPD on different cells were determined by proliferation assay, alkaline phosphatase (ALP) activity assay, calcium deposition as well as real-time reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, estrogen receptor (ER) antagonist ICI182,780 and mitogen-activated protein kinase kinase (MEK) inhibitor U0126 blocking assays, competitive ER radioligand binding assay, ERE-dependent luciferase reporter assay and immunoblotting were used to determine if PPD activated ER and if the effects of PPD on osteoblastic functions were ER dependent.
  
  
  RESULTS
  PPD exerted anabolic effects in osteoblasts and its effects were abolished by co-incubation with ICI182,780 or U0126. PPD induced mRNA expressions of Runx2, ALP, osteocalcin, and increased the ratio of osteoprotegerin/receptor activator of nuclear factor κB (OPG/RANKL). PPD failed to bind to either ERα or ERβ and did not activate ERE-luciferase activity via ER. PPD induced the phosphorylation of extracellular regulated kinases (ERK) and its effect was completely abolished by U0126. It also induced the phosphorylation of ERα at serine 118.
  
  
  CONCLUSIONS
  These data show that PPD is a bioactive compound in SWH that exerts oestrogen-like actions in osteoblast-like cells via ligand-independent, estrogen response element (ERE)-independent and mitogen-activated protein (MAP) Kinase-mediated rapid nongenomic ER signaling pathway.
authors.affiliation: State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen Research Institute of The Hong Kong Polytechnic University, Shenzhen 518057, PR China; Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
authors.forename: Hui-Hui
authors.initials: HH
authors.lastname: Xiao
authors.affiliation: Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
authors.forename: Quan-Gui
authors.initials: QG
authors.lastname: Gao
authors.affiliation: Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
authors.forename: Ming-Xian
authors.initials: MX
authors.lastname: Ho
authors.affiliation: Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China; Center for Systems Biomedical Sciences, University of Shanghai for Science and Technology, Shanghai 200093, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
authors.forename: Ka-Chun
authors.initials: KC
authors.lastname: Wong
authors.affiliation: Institute of Traditional Chinese Medicine & Natural Products, College of Pharmacy, Jinan University, Guangzhou 510632, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Dai
authors.affiliation: Institute of Traditional Chinese Medicine & Natural Products, College of Pharmacy, Jinan University, Guangzhou 510632, PR China. Electronic address: tyaoxs@jnu.edu.cn.
authors.forename: Xin-Sheng
authors.initials: XS
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen Research Institute of The Hong Kong Polytechnic University, Shenzhen 518057, PR China; Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China. Electronic address: bcmswong@polyu.edu.hk.
authors.forename: Man-Sau
authors.initials: MS
authors.lastname: Wong
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D047628:Estrogen Receptor alpha / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000378:metabolism; D017705:Lignans / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects*; D010766:Phosphorylation / Q000187:drug effects; D048789:Phytoestrogens / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D027923:Sambucus / Q000737:chemistry*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C000605654:(7R,8S)-1-(4-hydroxy-3-methoxyphenyl)-2-(4-(3-hydroxypropyl)-2-methoxyphenoxy)-1,3-propanediol; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D017705:Lignans; D048789:Phytoestrogens
keywords: 8-O-4′ lignan; MAP kinase signaling pathway; Osteoblast; Phytoestrogen; Sambucus willamsii Hance