Temporal gene expression across osteoblastogenesis.

Purpose: Osteoblast cells mature from a mesenchymal stem cell pool to become cells capable of forming bone matrix and mineralizing this matrix. The goal of this study was to characterize temporal changes in the transcriptome across osteoblast maturation, starting with committed mesenchymal stem cell/ early pre-osteoblast stage through to mature osteoblasts capable of matrix mineralization. Methods: Enriched populations of pre-osteoblast like cells were obtained from neonatal calvaria from C57BL/6J mice expressing CFP under the control of the Col3.6 promoter. These cells were placed into culture for 4 days, removed from culture and subjected FACS sorting based on the presence/absence of CFP expression. Cells expressing CFP were returned to culture, subjected to an osteoblast differentiation cocktail and RNA was collected at 2, 4, 6, 8, 10, 12, 14, 16 and 18 days post differentiation. Methods II: mRNA profiles for each time point were generated by next generation RNA sequencing, using an Illumina HiSeq 2000. Three technical replicates per samples were sequenced. The alignments for abundance estimation of transcripts was conducted using Bowtie version 0.12.9, using the NCBIm37 reference genome. Expression level per gene was calculated using RSEM version 1.2.0 with the parameters of --fragment-length-mean 280 and --fragment-length-sd 50, and the expression level for each sample was normalized relative to the per sample upper quartile. Overall design: Gene expression in calvarial osteoblasts from neonatal C57BL/6J-Col3.6 CFP mice at 9 time points post differentiation

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Kemp JP, Morris JA, Medina-Gomez C, Forgetta V, Warrington NM, Youlten SE, Zheng J, Gregson CL, Grundberg E, Trajanoska K, Logan JG, Pollard AS, Sparkes PC, Ghirardello EJ, Allen R, Leitch VD, Butterfield NC, Komla-Ebri D, Adoum AT, Curry KF, White JK, Kussy F, Greenlaw KM, Xu C, Harvey NC, Cooper C, Adams DJ, Greenwood CMT, Maurano MT, Kaptoge S, Rivadeneira F, Tobias JH, Croucher PI, Ackert-Bicknell CL, Bassett JHD, Williams GR, Richards JB, Evans DM