Project description:Longitudinal bone growth depends upon the execution of an intricate series of cellular activities by epiphyseal growth plate chondrocytes. In order to better understand these coordinated events, microarray analysis was used to compare gene expression in chondrocytes isolated from the proliferative and hypertrophic zones of the avian growth plate. In this experiment we compared pooled samples of proliferative and hypertrophic chondrocytes isolated from the chick growth plate. The expression of 745 genes was found to differ 3-fold or greater at the 0.05 level of probability. Experiment Overall Design: We examined 8 samples using arrays: 4 from proliferative and 4 from hypertrophic chondrocytes.
Project description:Longitudinal bone growth depends upon the execution of an intricate series of cellular activities by epiphyseal growth plate chondrocytes. In order to better understand these coordinated events, microarray analysis was used to compare gene expression in chondrocytes isolated from the proliferative and hypertrophic zones of the avian growth plate. In this experiment we compared pooled samples of proliferative and hypertrophic chondrocytes isolated from the chick growth plate. The expression of 745 genes was found to differ 3-fold or greater at the 0.05 level of probability.
Project description:A comprehensive analysis of Sox9 binding profiles in developing chondrocytes identified marked enrichment of an AP-1-like motif (Ohba et al. 2015). Here, we have explored the functional interplay between Sox9 and AP-1 in mammalian chondrocyte development. Among AP-1 family members, Jun and Fosl2 were highly expressed within prehypertrophic and early hypertrophic chondrocytes. Chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq) showed a striking overlap in Jun- and Sox9-bound regions throughout the chondrocyte genome, a reflection of direct binding of each factor to target motifs in shared enhancers, and physical interactions of AP-1 with Sox9. In vitro expression analysis indicates that direct co-binding of Sox9 and AP-1 at target motifs enhanced target gene expression, while protein-protein interactions suppressed AP-1- and Sox9-driven transcription. Analysis of prehypertrophic chondrocyte removal of Sox9 demonstrated Sox9 was essential for hypertrophic chondrocyte development, while in vitro and ex vivo analyses showed AP-1 promotes chondrocyte hypertrophy. Sox9 and Jun co-bound and co-activated a Col10a1 enhancer in Sox9 and AP-1 motif-dependent manners consistent with their combined action promoting hypertrophic gene expression. Together, the data support a model where AP-1-family members promote Sox9-action in the transition of chondrocytes to a terminal hypertrophic program. Intersection of ChIP-seq data from Sox9 and AP-1 factor Jun, RNA-seq data from developing rib chondrocytes and Col10a1mCherry positive hypertrophic chondrocytes in neonatal mice to uncover regulation of Sox9 by AP-1 factors during chondrocyte hypertrophy.
Project description:We set out to generate transcriptional maps of chondrocyte UPR gene networks in vivo using two mouse models (Schmid and Cog) of Schmid chondrodysplasia, in order to define the consequences of UPR activation for the adaptation, differentiation, and survival of chondrocytes experiencing ER stress during hypertrophy, thus providing insights into ER stress signaling and its impact on cartilage pathophysiology. Our data demonstrate that both models displayed similar unfolded protein responses (UPRs), involving activation of ER stress sensors Ire1 and Atf6 and upregulation of their downstream targets, including molecular chaperones, foldases, and ER-associated degradation machinery. Also upregulated were the emerging UPR regulators Wfs1 and Syvn1, recently identified UPR components including Armet and Creld2, and genes not previously implicated in ER stress such as Steap1 and Fgf21. Moreover, we transcriptionally profiled the expression of wildtype growth plate zone gene signatures in the mutant hypertrophic zones, in order to define the differentiation status of ER-stressed chondrocytes in the mutant hypertrophic zones. Hypertrophic zone gene upregulation and proliferative zone gene downregulation were both inhibited in Schmid hypertrophic zones, resulting in the persistence of a proliferative chondrocyte-like expression profile in ER-stressed Schmid chondrocytes. For the mutant hypertrophic zone gene expression profiling, the hypertrophic zone from one tibia from each of three two week old Schmid, wildtype (Schmid background), Cog, and wildtype (Cog background) mice was microdissected. In all cases, total RNA was extracted and amplified through two rounds of linear amplification, labelled with Cy3, and interrogated by microarray analysis using the Agilent 44K, mouse whole genome platform.
Project description:We set out to generate transcriptional maps of chondrocyte UPR gene networks in vivo using two mouse models (Schmid and Cog) of Schmid chondrodysplasia, in order to define the consequences of UPR activation for the adaptation, differentiation, and survival of chondrocytes experiencing ER stress during hypertrophy, thus providing insights into ER stress signaling and its impact on cartilage pathophysiology. Our data demonstrate that both models displayed similar unfolded protein responses (UPRs), involving activation of ER stress sensors Ire1 and Atf6 and upregulation of their downstream targets, including molecular chaperones, foldases, and ER-associated degradation machinery. Also upregulated were the emerging UPR regulators Wfs1 and Syvn1, recently identified UPR components including Armet and Creld2, and genes not previously implicated in ER stress such as Steap1 and Fgf21. Moreover, we transcriptionally profiled the expression of wildtype growth plate zone gene signatures in the mutant hypertrophic zones, in order to define the differentiation status of ER-stressed chondrocytes in the mutant hypertrophic zones. Hypertrophic zone gene upregulation and proliferative zone gene downregulation were both inhibited in Schmid hypertrophic zones, resulting in the persistence of a proliferative chondrocyte-like expression profile in ER-stressed Schmid chondrocytes.
Project description:A comprehensive analysis of Sox9 binding profiles in developing chondrocytes identified marked enrichment of an AP-1-like motif (Ohba et al. 2015). Here, we have explored the functional interplay between Sox9 and AP-1 in mammalian chondrocyte development. Among AP-1 family members, Jun and Fosl2 were highly expressed within prehypertrophic and early hypertrophic chondrocytes. Chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq) showed a striking overlap in Jun- and Sox9-bound regions throughout the chondrocyte genome, a reflection of direct binding of each factor to target motifs in shared enhancers, and physical interactions of AP-1 with Sox9. In vitro expression analysis indicates that direct co-binding of Sox9 and AP-1 at target motifs enhanced target gene expression, while protein-protein interactions suppressed AP-1- and Sox9-driven transcription. Analysis of prehypertrophic chondrocyte removal of Sox9 demonstrated Sox9 was essential for hypertrophic chondrocyte development, while in vitro and ex vivo analyses showed AP-1 promotes chondrocyte hypertrophy. Sox9 and Jun co-bound and co-activated a Col10a1 enhancer in Sox9 and AP-1 motif-dependent manners consistent with their combined action promoting hypertrophic gene expression. Together, the data support a model where AP-1-family members promote Sox9-action in the transition of chondrocytes to a terminal hypertrophic program.
Project description:To survey altered gene expreesion in round, colmnar and hypertrophic chondrocytes of Tric-b-KO mice, total RNA preparations from round chondrocytes and colmnar/hypertrophic chondrocytes were subjected to gene microarray analysis. Results provide insight into the transcriptional profile of each Tric-b-KO chondrocyte and provide further insight into their functions.
Project description:LCM-RNA-Seq data obtained from chick HH36 chondrocytes and osteoblasts at different stages of differentiation -immature chondrocytes and mature (hypertrophic) chondrocytes- isolated from the head (ceratobranchial) and limb (humerus).
Project description:The developing vertebrate growth plates in long bones have three morphologically distinct layers of chondrocytes: Round Cell layer, Flat Cell layer, and Hypertrophic Cell layer. Round chondrocytes differentiate into flat chondrocytes, and then flat chondrocytes differentiate into hypertrophic chondrocytes. To investigate the genetic programs underlying the chondrocyte differentiation, we obtained total RNA from the microdissected cryosections from each layer and then performed microarray analysis.
Project description:Axial growth of long bones occurs through a coordinated process of growth plate chondrocyte proliferation and differentiation. This maturation of chondrocytes is reflected in a zonal change in gene expression and cell morphology from resting to proliferative, prehypertrophic, and hypertrophic chondrocytes of the growth plate followed by ossification. A major experimental limitation in understanding growth plate biology and pathophysiology is the lack of a robust technique to isolate cells from the different zones, particularly from small animals. Here, we report on a new strategy for separating distinct chondrocyte populations from mouse growth plates. By transcriptome profiling of microdissected zones of growth plates, we identified novel, zone-specific cell surface markers and used these for flow cytometry and immunomagnetic cell separation to quantify, enrich, and characterize chondrocytes populations with respect to their differentiation status. This approach provides a novel platform to study cartilage development and characterize mouse growth plate chondrocytes to reveal unique cellular phenotypes of the distinct subpopulations within the growth plate.