title: Impact of dietary aromatic amino acids on osteoclastic activity.
abstract: We had shown that aromatic amino acid (phenylalanine, tyrosine, and tryptophan) supplementation prevented bone loss in an aging C57BL/6 mice model. In vivo results from the markers of bone breakdown suggested an inhibition of osteoclastic activity or differentiation. To assess osteoclastic differentiation, we examined the effects of aromatic amino acids on early /structural markers as vitronectin receptor, calcitonin receptor, and carbonic anhydrase II as well as, late/functional differentiation markers; cathepsin K and matrix metalloproteinase 9 (MMP-9). Our data demonstrate that the aromatic amino acids down-regulated early and late osteoclastic differentiation markers as measured by real time PCR. Our data also suggest a link between the vitronectin receptor and the secreted cathepsin K that both showed consistent effects to the aromatic amino acid treatment. However, the non-attachment related proteins, calcitonin receptor, and carbonic anhydrase II, demonstrated less consistent effects in response to treatment. Our data are consistent with aromatic amino acids down-regulating osteoclastic differentiation by suppressing remodeling gene expression thus contributing initially to the net increase in bone mass seen in vivo.
authors.affiliation: Institute for Regenerative and Reparative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA, 30912, USA.
authors.forename: Mona El
authors.initials: ME
authors.lastname: Refaey
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhong
authors.forename: Ke-Hong
authors.initials: KH
authors.lastname: Ding
authors.forename: Xing-Ming
authors.initials: XM
authors.lastname: Shi
authors.forename: Jianrui
authors.initials: J
authors.lastname: Xu
authors.forename: Wendy B
authors.initials: WB
authors.lastname: Bollag
authors.forename: William D
authors.initials: WD
authors.lastname: Hill
authors.forename: Norman
authors.initials: N
authors.lastname: Chutkan
authors.forename: Richard
authors.initials: R
authors.lastname: Robbins
authors.forename: Hugh
authors.initials: H
authors.lastname: Nadeau
authors.forename: Maribeth
authors.initials: M
authors.lastname: Johnson
authors.forename: Mark W
authors.initials: MW
authors.lastname: Hamrick
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Isales
mesh_terms: D024322:Amino Acids, Aromatic / Q000494:pharmacology*; D000818:Animals; D001862:Bone Resorption / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004032:Diet; D019587:Dietary Supplements; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000187:drug effects*; D010649:Phenylalanine / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D014364:Tryptophan / Q000494:pharmacology*; D014443:Tyrosine / Q000494:pharmacology*
chemical_list: D024322:Amino Acids, Aromatic; D014443:Tyrosine; D010649:Phenylalanine; D014364:Tryptophan