title: Osteoblast-Specific Overexpression of Human WNT16 Increases Both Cortical and Trabecular Bone Mass and Structure in Mice.
abstract: Previous genome-wide association studies have identified common variants in genes associated with bone mineral density (BMD) and risk of fracture. Recently, we identified single nucleotide polymorphisms (SNPs) in Wingless-type mouse mammary tumor virus integration site (WNT)16 that were associated with peak BMD in premenopausal women. To further identify the role of Wnt16 in bone mass regulation, we created transgenic (TG) mice overexpressing human WNT16 in osteoblasts. We compared bone phenotypes, serum biochemistry, gene expression, and dynamic bone histomorphometry between TG and wild-type (WT) mice. Compared with WT mice, WNT16-TG mice exhibited significantly higher whole-body areal BMD and bone mineral content (BMC) at 6 and 12 weeks of age in both male and female. Microcomputer tomography analysis of trabecular bone at distal femur revealed 3-fold (male) and 14-fold (female) higher bone volume/tissue volume (BV/TV), and significantly higher trabecular number and trabecular thickness but lower trabecular separation in TG mice compared with WT littermates in both sexes. The cortical bone at femur midshaft also displayed significantly greater bone area/total area and cortical thickness in the TG mice in both sexes. Serum biochemistry analysis showed that male TG mice had higher serum alkaline phosphatase, osteocalcin, osteoprotegerin (OPG), OPG to receptor activator of NF-kB ligand (tumor necrosis family ligand superfamily, number 11; RANKL) ratio as compared with WT mice. Also, lower carboxy-terminal collagen cross-link (CTX) to tartrate-resistant acid phosphatase 5, isoform b (TRAPc5b) ratio was observed in TG mice compared with WT littermates in both male and female. Histomorphometry data demonstrated that both male and female TG mice had significantly higher cortical and trabecular mineralizing surface/bone surface and bone formation rate compared with sex-matched WT mice. Gene expression analysis demonstrated higher expression of Alp, OC, Opg, and Opg to Rankl ratio in bone tissue in the TG mice compared with WT littermates. Our data indicate that WNT16 is critical for positive regulation of both cortical and trabecular bone mass and structure and that this molecule might be targeted for therapeutic interventions to treat osteoporosis.
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Imranul
authors.initials: I
authors.lastname: Alam
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Alkhouli
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Rita L
authors.initials: RL
authors.lastname: Gerard-O'Riley
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Weston B
authors.initials: WB
authors.lastname: Wright
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Dena
authors.initials: D
authors.lastname: Acton
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Amie K
authors.initials: AK
authors.lastname: Gray
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Bhavmik
authors.initials: B
authors.lastname: Patel
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Austin M
authors.initials: AM
authors.lastname: Reilly
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Kyung-Eun
authors.initials: KE
authors.lastname: Lim
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Robling
authors.affiliation: Departments of Medicine (I.A., M.A., R.L.G.O., W.B.W., D.A., A.K.G., B.P., A.M.R., M.J.E.), Medical and Molecular Genetics (M.J.E.), and Anatomy and Cell Biology (K.-E.L., A.G.R.), Indiana University School of Medicine, Indiana 46202.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Econs
mesh_terms: D000135:Acid Phosphatase / Q000235:genetics / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015519:Bone Density / Q000235:genetics*; D001842:Bone and Bones / Q000000981:diagnostic imaging; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000378:metabolism*; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D010012:Osteogenesis / Q000235:genetics*; D010024:Osteoporosis; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D000071681:Tartrate-Resistant Acid Phosphatase; D051153:Wnt Proteins / Q000235:genetics*; D060449:Wnt Signaling Pathway; D055114:X-Ray Microtomography
chemical_list: D024042:Collagen Type I; D007527:Isoenzymes; D053244:Osteoprotegerin; D010455:Peptides; D053245:RANK Ligand; D012333:RNA, Messenger; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; C417262:WNT16 protein, human; D051153:Wnt Proteins; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase