Transcription factor XBP-1 is expressed during osteoblast differentiation and is transcriptionally regulated by parathyroid hormone (PTH)

Authors

  • A. Zambelli,

    Corresponding author
    1. Wellcome Trust Centre for Cell-Matrix Research, 2.205 Stopford Building, School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
    2. Instituto Multidisciplinario de Biología Celular (IMBICE), CC403 (1900) La Plata, Argentina
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  • E. Mongiardini,

    1. Instituto Multidisciplinario de Biología Celular (IMBICE), CC403 (1900) La Plata, Argentina
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  • S.N. Villegas,

    1. Instituto Multidisciplinario de Biología Celular (IMBICE), CC403 (1900) La Plata, Argentina
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  • N.G. Carri,

    1. Instituto Multidisciplinario de Biología Celular (IMBICE), CC403 (1900) La Plata, Argentina
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  • R.P. Boot-Handford,

    1. Wellcome Trust Centre for Cell-Matrix Research, 2.205 Stopford Building, School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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  • G.A. Wallis

    1. Wellcome Trust Centre for Cell-Matrix Research, 2.205 Stopford Building, School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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Corresponding author. Present address: Advanta Semillas, Ruta 226 Km 60.5, CC30 (7620) Balcarce, Argentina. Tel.: +54 2266 430001; fax: +54 2266 430002. andres.zambelli@ar.advantaseeds.com

Abstract

X-box-binding protein 1 (XBP-1) is a basic-region leucine zipper protein in the cyclic AMP response element binding protein/activating transcription factor (CREB/ATF) family of transcription factors involved in different cell-differentiation processes. We have investigated the expression of XBP-1 in differentiating MC3T3-E1 osteoblastic cells. Cultures were treated with ascorbic acid (AA) and β-glycerophosphate (BGP) to induce differentiation. Under these conditions, the basal transcription of xbp-1 increases at day 2 following induction, peaks at day 5 and decreases thereafter. This result showed that xbp-1 gene is differentially expressed during MC3T3-E1 cell differentiation. Detection of XBP-1 by immunofluorescence at days 0 (control culture without AA and BGP), 8 and 21 showed that the protein has a major cytoplasmic perinuclear location. In addition, xbp-1 is transcriptionally upregulated by parathyroid hormone within 2.5 h of treatment and decreases thereafter.

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