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Updated: Aug 17, 2026

Mechanism of Regulation of Adipocyte Numbers in Adult Organisms Through Differentiation and Apoptosis Homeostasis
Published on: June 3, 2016
Transcription factor XBP-1 is expressed during osteoblast differentiation and is transcriptionally regulated by
A Zambelli1, E Mongiardini, S N Villegas
1Wellcome Trust Centre for Cell-Matrix Research, 2.205 Stopford Building, School of Biological Sciences, University of Manchester, UK. 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 beta-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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