Transcription factor XBP-1 is expressed during osteoblast differentiation and is transcriptionally regulated by parathyroid hormone (PTH).
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.
Zambelli
A
A
Wellcome Trust Centre for Cell-Matrix Research, 2.205 Stopford Building, School of Biological Sciences, University of Manchester, UK. andres.zambelli@ar.advantaseeds.com
Mongiardini
E
E
Villegas
S N
SN
Carri
N G
NG
Boot-Handford
R P
RP
Wallis
G A
GA
D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000187:drug effects*; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects*; D005994:Glycerophosphates / Q000494:pharmacology; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D010281:Parathyroid Hormone / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D000071701:Regulatory Factor X Transcription Factors; D015534:Trans-Activators; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1
D004268:DNA-Binding Proteins; D005994:Glycerophosphates; D009687:Nuclear Proteins; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D015534:Trans-Activators; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D001205:Ascorbic Acid; C031463:beta-glycerophosphoric acid