title: Monocyte Proteomics Reveals Involvement of Phosphorylated HSP27 in the Pathogenesis of Osteoporosis.
abstract: Peripheral monocytes, precursors of osteoclasts, have emerged as important candidates for identifying proteins relevant to osteoporosis, a condition characterized by low Bone Mineral Density (BMD) and increased susceptibility for fractures. We employed 4-plex iTRAQ (isobaric tags for relative and absolute quantification) coupled with LC-MS/MS (liquid chromatography coupled with tandem mass spectrometry) to identify differentially expressed monocyte proteins from premenopausal and postmenopausal women with low versus high BMD. Of 1801 proteins identified, 45 were differentially abundant in low versus high BMD, with heat shock protein 27 (HSP27) distinctly upregulated in low BMD condition in both premenopausal and postmenopausal categories. Validation in individual samples (n = 80) using intracellular ELISA confirmed that total HSP27 (tHSP27) as well as phosphorylated HSP27 (pHSP27) was elevated in low BMD condition in both categories (P < 0.05). Further, using transwell assays, pHSP27, when placed in the upper chamber, could increase monocyte migration (P < 0.0001) and this was additive in combination with RANKL (receptor activator of NFkB ligand) placed in the lower chamber (P = 0.05). Effect of pHSP27 in monocyte migration towards bone milieu can result in increased osteoclast formation and thus contribute to pathogenesis of osteoporosis. Overall, this study reveals for the first time a novel link between monocyte HSP27 and BMD.
authors.affiliation: National Institute for Research in Reproductive Health (ICMR), J. M. Street, Parel, Mumbai 400012, India.
authors.forename: Bhavna
authors.initials: B
authors.lastname: Daswani
authors.affiliation: Institute of Bioinformatics, International Tech Park, Bangalore 560066, India.
authors.forename: Manoj Kumar
authors.initials: MK
authors.lastname: Gupta
authors.affiliation: National Institute for Research in Reproductive Health (ICMR), J. M. Street, Parel, Mumbai 400012, India.
authors.forename: Shubhangi
authors.initials: S
authors.lastname: Gavali
authors.affiliation: National Institute for Research in Reproductive Health (ICMR), J. M. Street, Parel, Mumbai 400012, India.
authors.forename: Meena
authors.initials: M
authors.lastname: Desai
authors.affiliation: Institute of Bioinformatics, International Tech Park, Bangalore 560066, India.
authors.forename: Gajanan J
authors.initials: GJ
authors.lastname: Sathe
authors.affiliation: National Institute for Research in Reproductive Health (ICMR), J. M. Street, Parel, Mumbai 400012, India.
authors.forename: Anushree
authors.initials: A
authors.lastname: Patil
authors.affiliation: National Institute for Research in Reproductive Health (ICMR), J. M. Street, Parel, Mumbai 400012, India.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Parte
authors.affiliation: Institute of Bioinformatics, International Tech Park, Bangalore 560066, India ; Mazumdar Shaw Centre for Translational Research, Narayana Health, Bangalore 560099, India.
authors.forename: Ravi
authors.initials: R
authors.lastname: Sirdeshmukh
authors.affiliation: National Institute for Research in Reproductive Health (ICMR), J. M. Street, Parel, Mumbai 400012, India.
authors.forename: M Ikram
authors.initials: MI
authors.lastname: Khatkhatay
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D015519:Bone Density / Q000235:genetics*; D016022:Case-Control Studies; D002465:Cell Movement; D005260:Female; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins; D006801:Humans; D008875:Middle Aged; D018832:Molecular Chaperones; D009000:Monocytes / Q000378:metabolism* / Q000502:physiology; D010024:Osteoporosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D017698:Postmenopause / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D053245:RANK Ligand / Q000378:metabolism
chemical_list: D015415:Biomarkers; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D053245:RANK Ligand