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Gene expression analyses of subchondral bone in early experimental osteoarthritis by microarray.

ABSTRACT: Osteoarthritis (OA) is a degenerative joint disease that affects both cartilage and bone. A better understanding of the early molecular changes in subchondral bone may help elucidate the pathogenesis of OA. We used microarray technology to investigate the time course of molecular changes in the subchondral bone in the early stages of experimental osteoarthritis in a rat model. We identified 2,234 differentially expressed (DE) genes at 1 week, 1,944 at 2 weeks and 1,517 at 4 weeks post-surgery. Further analyses of the dysregulated genes indicated that the events underlying subchondral bone remodeling occurred sequentially and in a time-dependent manner at the gene expression level. Some of the identified dysregulated genes that were identified have suspected roles in bone development or remodeling; these genes include Alp, Igf1, Tgf ?1, Postn, Mmp3, Tnfsf11, Acp5, Bmp5, Aspn and Ihh. The differences in the expression of these genes were confirmed by real-time PCR, and the results indicated that our microarray data accurately reflected gene expression patterns characteristic of early OA. To validate the results of our microarray analysis at the protein level, immunohistochemistry staining was used to investigate the expression of Mmp3 and Aspn protein in tissue sections. These analyses indicate that Mmp3 protein expression completely matched the results of both the microarray and real-time PCR analyses; however, Aspn protein expression was not observed to differ at any time. In summary, our study demonstrated a simple method of separation of subchondral bone sample from the knee joint of rat, which can effectively avoid bone RNA degradation. These findings also revealed the gene expression profiles of subchondral bone in the rat OA model at multiple time points post-surgery and identified important DE genes with known or suspected roles in bone development or remodeling. These genes may be novel diagnostic markers or therapeutic targets for OA.

SUBMITTER: Zhang R

PROVIDER: S-EPMC3288107 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Gene expression analyses of subchondral bone in early experimental osteoarthritis by microarray.

Zhang RongKai R Fang Hang H Chen YuXian Y Shen Jun J Lu HuaDing H Zeng Chun C Ren JianHua J Zeng Hua H Li Zhifu Z Chen ShaoMing S Cai DaoZhang D Zhao Qing Q

PloS one 20120227 2

Osteoarthritis (OA) is a degenerative joint disease that affects both cartilage and bone. A better understanding of the early molecular changes in subchondral bone may help elucidate the pathogenesis of OA. We used microarray technology to investigate the time course of molecular changes in the subchondral bone in the early stages of experimental osteoarthritis in a rat model. We identified 2,234 differentially expressed (DE) genes at 1 week, 1,944 at 2 weeks and 1,517 at 4 weeks post-surgery. F ...[more]

PMID: 22384228

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Project description:Osteoarthritis (OA) is a complex degenerative joint disease, which is not only a cartilage but also a bone disease. A better understanding of the early molecular mechanism changes of subchondral bone in vivo may contribute to elucidating the pathogenesis of OA. We used microarray technology to investigate the time-course molecular changes of subchondral bone just beneath damaged cartilage in early stage of experimental osteoarthritis, and found 2,234 differentially expressed (DE) genes at 1 week, 1,944 at 2 weeks and 1,517 at 4 weeks postsurgery.Further analysis of dysregulated genes indicated that subchondral bone remodeling occurred sequentially and in a time-dependent manner at the gene expression level. Some known dysregulated genes suspected roles in influencing bone development or bone remodeling, such as Alp, Igf1, Tgf M-NM-21, Postn, Mmp3, Tnfsf11, Acp5, Bmp5, Aspn and Ihh, were confirmed by real-time PCR, and results indicated that our microarray data could accurately reflect gene expression patterns of early OA. Subsequently, to validate the results of our microarray analysis at protein level, immunohistochemistry staining was introduced to investigate the translational level of genes Mmp3 and Aspn in tissue sections, and results showed that the level of Mmp3 protein expression was totally matched the results of microarray and real-time PCR analysis. Nevertheless, the expression of Aspn protein was not observed differentially expressed at any time point. Ninety 10-week-old male Sprague-Dawley rats, weighing 300-325g, were used in the study. Animals were equally divided into two groups: experimental group (E-Group) and sham-operated group (S-Group). The E-Group rats underwent open surgery, involved in both medial meniscectomy and medial collateral ligament (MCL) transaction with micro-scissors. The S-Group rats were carried out with a sham operation, via a similar incision, without operations of the medial meniscus and the medial collateral ligament.Animals were killed at 1, 2, and 4 weeks postsurgery, and 15 animals were put into use per-timepoint in each treatment group. 5 animals were used for histological analysis and immunohistochemistry, and others were used for microarray study and Real-time polymerase chain reaction (PCR) analysis equally at each timepoint.

Project description:OBJECTIVE: To analyze genome-wide changes in chondrocyte gene expression in a surgically induced model of early osteoarthritis (OA) in rats, to assess the similarity of this model to human OA, and to identify genes and mechanisms leading to OA pathogenesis. METHODS: OA was surgically induced in 5 rats by anterior cruciate ligament transection and partial medial meniscectomy. Sham surgery was performed in 5 additional animals, which were used as controls. Both groups underwent 4 weeks of forced mobilization, 3 times per week. RNA was extracted directly from articular chondrocytes in the OA (operated), contralateral, and sham-operated knees. Affymetrix GeneChip expression arrays were used to assess genome-wide changes in gene expression. Expression patterns of selected dysregulated genes, including Col2a1, Mmp13, Adamts5, Ctsc, Ptges, and Cxcr4, were validated by real-time polymerase chain reaction, immunofluorescence, or immunohistochemistry 2, 4, and 8 weeks after surgery. RESULTS: After normalization, comparison of OA and sham-operated samples showed 1,619 differentially expressed probe sets with changes in their levels of expression >/=1.5-fold, 722 with changes >/=2-fold, 135 with changes >/=4-fold, and 20 with changes of 8-fold. Dysregulated genes known to be involved in human OA included Mmp13, Adamts5, and Ptgs2, among others. Several dysregulated genes (e.g., Reln, Phex, and Ltbp2) had been identified in our earlier microarray study of hypertrophic chondrocyte differentiation. Other genes involved in cytokine and chemokine signaling, including Cxcr4 and Ccl2, were identified. Changes in gene expression were also observed in the contralateral knee, validating the sham operation as the appropriate control. CONCLUSION: Our results demonstrate that the animal model mimics gene expression changes seen in human OA, supporting the relevance of newly identified genes and pathways to early human OA. We propose new avenues for OA pathogenesis research and potential targets for novel OA treatments, including cathepsins and cytokine, chemokine, and growth factor signaling pathways, in addition to factors controlling the progression of chondrocyte differentiation. Keywords: disease state analysis

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Gene expression analyses of subchondral bone in early experimental osteoarthritis by microarray.

Publications

Gene expression analyses of subchondral bone in early experimental osteoarthritis by microarray.

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