Differential effects of osteogenic protein-1 (BMP-7) on gene expression of BMP and GDF family members during differentiation of the mouse MC615 chondrocyte cells

Knockout of miR-21-5p alleviates cartilage matrix degradation by targeting Gdf5 in temporomandibular joint osteoarthritis

AIMS

The study aimed to determine whether the microRNA miR21-5p (MiR21) mediates temporomandibular joint osteoarthritis (TMJ-OA) by targeting growth differentiation factor 5 (Gdf5).

METHODS

TMJ-OA was induced in MiR21 knockout (KO) mice and wild-type (WT) mice by a unilateral anterior crossbite (UAC) procedure. Mouse tissues exhibited histopathological changes, as assessed by: Safranin O, toluidine blue, and immunohistochemistry staining; western blotting (WB); and quantitative real-time polymerase chain reaction (RT-qPCR). Mouse condylar chondrocytes were transfected with a series of MiR21 mimic, MiR21 inhibitor, Gdf5 siRNA (si-GDF5), and flag-GDF5 constructs. The effects of MiR-21 and Gdf5 on the expression of OA related molecules were evaluated by immunofluorescence, alcian blue staining, WB, and RT-qPCR.

RESULTS

UAC altered the histological structure and extracellular matrix content of cartilage in the temporomandibular joint (TMJ), and KO of MiR21 alleviated this effect (p < 0.05). Upregulation of MiR21 influenced the expression of TMJ-OA related molecules in mandibular condylar chondrocytes via targeting Gdf5 (p < 0.05). Gdf5 overexpression significantly decreased matrix metalloproteinase 13 (MMP13) expression (p < 0.05) and reversed the effects of MiR21 (p < 0.05).

CONCLUSION

MiR21, which acts as a critical regulator of Gdf5 in chondrocytes, regulates TMJ-OA related molecules and is involved in cartilage matrix degradation, contributing to the progression of TMJ-OA. Cite this article: Bone Joint Res 2020;9(10):689-700.

The Role of miRNAs in Cartilage Homeostasis

Osteoarthritis (OA) is an age-related disease with poorly understood pathogenesis. Recent studies have demonstrated that miRNA might play a key role in OA initiation and development. We reviewed recent publications and elucidated the connection between miRNA and OA cartilage anabolic and catabolic signals, including four signaling pathways: TGF-β/Smads and BMPs signaling, associated with cartilage anabolism; and MAPK and NF-KB signaling, associated with cartilage catabolism. We also explored the relationships with MMP, ADAMTS and NOS (NitricOxide Synthases) families, as well as with the catabolic cytokines IL-1 and TNF-α. The potential role of miRNAs in biological processes such as cartilage degeneration, chondrocyte proliferation, and differentiation is discussed. Collective evidence indicates that miRNAs play a critical role in cartilage degeneration. These findings will aid in understanding the molecular network that governs articular cartilage homeostasis and in to elucidate the role of miRNA in the pathogenesis of OA.

MicroRNA-21 controls the development of osteoarthritis by targeting GDF-5 in chondrocytes

Osteoarthritis is a common cause of functional deterioration in older adults and is an immense burden on the aging population. Altered chondrogenesis is the most important pathophysiological process involved in the development of osteoarthritis. However, the molecular mechanism underlying the regulation of chondrogenesis in patients with osteoarthritis requires further elucidation, particularly with respect to the role of microRNAs. MiR-21 expression in cartilage specimens was examined in 10 patients with knee osteoarthritis and 10 traumatic amputees. The effect of miR-21 on chondrogenesis was also investigated in a chondrocyte cell line. The effect of miR-21 on the expression of growth differentiation factor 5 (GDF-5) was further assessed by luciferase reporter assay and western blot. We found that endogenous miR-21 is upregulated in osteoarthritis patients, and overexpression of miR-21 could attenuate the process of chondrogenesis. Furthermore, we identified GDF-5 as the direct target of miR-21 during the regulation of chondrogenesis. Our data suggest that miR-21 has an important role in the pathogenesis of osteoarthritis and is a potential therapeutic target.

Molecular study of a Hoxa2 gain-of-function in chondrogenesis: a model of idiopathic proportionate short stature

In a previous study using transgenic mice ectopically expressing Hoxa2 during chondrogenesis, we associated the animal phenotype to human idiopathic proportionate short stature. Our analysis showed that this overall size reduction was correlated with a negative influence of Hoxa2 at the first step of endochondral ossification. However, the molecular pathways leading to such phenotype are still unknown. Using protein immunodetection and histological techniques comparing transgenic mice to controls, we show here that the persistent expression of Hoxa2 in chondrogenic territories provokes a general down-regulation of the main factors controlling the differentiation cascade, such as Bapx1, Bmp7, Bmpr1a, Ihh, Msx1, Pax9, Sox6, Sox9 and Wnt5a. These data confirm the impairment of chondrogenic differentiation by Hoxa2 overexpression. They also show a selective effect of Hoxa2 on endochondral ossification processes since Gdf5 and Gdf10, and Bmp4 or PthrP were up-regulated and unmodified, respectively. Since Hoxa2 deregulation in mice induces a proportionate short stature phenotype mimicking human idiopathic conditions, our results give an insight into understanding proportionate short stature pathogenesis by highlighting molecular factors whose combined deregulation may be involved in such a disease.

Effects of cartilage-derived morphogenetic protein-3 on the expression of chondrogenic and osteoblastic markers in the pluripotent mesenchymal C3H10T1/2 cell line

CDMP-3/GDF-7/BMP-12 treatment of pluripotent mesenchymal C3H10T1/2 cells resulted in a dose- and time-dependent change in cell morphology and in the expression of alkaline phosphatase, mRNA expression of osteocalcin, and bone sialoprotein, as well as mineralized bone nodule formation. CDMP-3 also stimulated Alcian Blue staining indicative of extracellular matrix formation without affecting aggrecan expression. CDMP-3 downregulated mRNA expression of BMP-4 and BMP-8A. CDMP-3 stimulated mRNA expression of ALK-1, ALK-2(ActR-IA), ALK-3(BMPR-IA), and ALK-4 without affecting that of ALK-6(BMPR-IB), ALK-7, and BMPR-II. These findings suggest that, under the experimental conditions studied, CDMP-3 induces the pluripotent mesenchymal C3H10T1/2 cells to express both chondrocytic and osteoblastic markers. The results further reveal potential complex interplay between the different bone morphogenetic proteins and their receptors in these processes.

Therapeutic effects of adenovirus-mediated growth and differentiation factor-5 in a mice disc degeneration model induced by annulus needle puncture

BACKGROUND CONTEXT

The therapeutic strategies that have thus far been used for the treatment of intervertebral disc degeneration (IDD) have focused on relieving the symptoms, although reversal of the degeneration remains an important challenge for the effective treatment of IDD. Growth and differentiation factor-5 (GDF5), of which deficiency leads to early disc degeneration changes, has the potential to increase proliferation of disc cells and expression of extracellular matrix proteins.

PURPOSE

The purpose of the study was to develop a lumbar disc degeneration model in mice and determine the effect of adenoviral GDF5 gene therapy.

STUDY DESIGN

The study design was to compare the degeneration changes of discs punctured by different-size needles to develop a mice lumbar disc degeneration model and to evaluate the effects of in vivo gene therapy for the mice disc degeneration model by an adenoviral vector carrying GDF5 gene.

METHODS

A lumbar disc degeneration model was developed by needle punctures to the discs in Balb/c mice. Afterward, a gene therapy treatment to disc degeneration was evaluated. Two of the mice lumbar discs were randomly chosen to be punctured by a 30-gauge needle and then injected with adenovirus that had been engineered to express either the luciferase gene (Ad-Luc) or the GDF5 gene (Ad-GDF5). Animals were analyzed by bioluminescent imaging, radiographic, and magnetic resonance imaging (MRI) scanning, then sacrificed at 1, 2, 4, or 8 weeks after operation, and subjected to histological and biochemical assays.

RESULTS

By the detection of T2-weighted MRI scanning and histological study, the degeneration was found in all of the discs punctured by different-size needles. But the development of the degeneration in the discs injured by the 30-gauge needle was more reliable and moderate compared with that in other groups. The detection of luciferase activity by bioluminescent imaging revealed that adenovirus survived and the introduced genes were expressed over 6 weeks after injection. There were no T2-weighted MRI signals in the mice injected with either Ad-Luc or Ad-GDF5 up to 4 weeks after operation. At 6 and 8 weeks, T2-weighted signals were detected in the Ad-GDF5 group but none in the Ad-Luc control group. The percent disc height index (%DHI) was significantly decreased (approximately 20%) by 1 week after injury in both groups, indicating the development of disc degeneration. At 2 weeks, the %DHI in the mice injected with Ad-GDF5 increased significantly compared with that of the mice injected with Ad-Luc; the increase was sustained for the rest of the experiment period. The disc histology treated with Ad-GDF5 was improved compared with that in the control group. Glycosaminoglycan (GAG) levels were significantly decreased in the Ad-Luc injection group since 2 weeks after injury, and the DNA content had diminished by 4 weeks after the operation. In contrast, in the discs injected with Ad-GDF5, there was no decrease in the GAG and DNA levels after injury throughout the 8-week treatment period.

CONCLUSIONS

Disc degeneration animal model can be developed by using needle puncture to the discs in mice. The adenovirus is an effective vehicle for gene delivery with rapid and prolonged expression of target protein and resulting improvement in markers of disc degeneration. Ad-GDF5 gene therapy could restore the functions of injured discs and has the potential to be an effective treatment.

Knockdown of the intraflagellar transport protein IFT46 stimulates selective gene expression in mouse chondrocytes and affects early development in zebrafish

Bone morphogenetic proteins (BMPs) act as multifunctional regulators in morphogenesis during development. In particular they play a determinant role in the formation of cartilage molds and their replacement by bone during endochondral ossification. In cell culture, BMP-2 favors chondrogenic expression and promotes hypertrophic maturation of chondrocytes. In mouse chondrocytes we have identified a BMP-2-sensitive gene encoding a protein of 301 amino acids. This protein, named mIFT46, is the mouse ortholog of recently identified Caenorhabditis elegans and Chlamydomonas reinhardtii intraflagellar transport (IFT) proteins. After generation of a polyclonal antibody against mIFT46, we showed for the first time that the endogenous protein is located in the primary cilium of chondrocytes. We also found that mIFT46 is preferentially expressed in early hypertrophic chondrocytes located in the growth plate. Additionally, mIFT46 knockdown by small interfering RNA oligonucleotides in cultured chondrocytes specifically stimulated the expression of several genes related to skeletogenesis. Furthermore, Northern blotting analysis indicated that mIFT46 is also expressed before chondrogenesis in embryonic mouse development, suggesting that the role of mIFT46 might not be restricted to cartilage. To explore the role of IFT46 during early development, we injected antisense morpholino oligonucleotides in Danio rerio embryos to reduce zebrafish IFT46 protein (zIFT46) synthesis. Dramatic defects in embryonic development such as a dorsalization and a tail duplication were observed. Thus our results taken together indicate that the ciliary protein IFT46 has a specific function in chondrocytes and is also essential for normal development of vertebrates.

Osteogenesis versus chondrogenesis by BMP-2 and BMP-7 in adipose stem cells

Bone morphogenetic proteins (BMPs) initiate, promote, and maintain chondrogenesis and osteogenesis. We hypothesize that BMP-2 induces an osteogenic, and BMP-7 a chondrogenic phenotype in adipose tissue-derived mesenchymal stem cells (AT-MSCs). We compared the effects of a short 15min BMP-2 or BMP-7 (10ng/ml) treatment on osteogenic and chondrogenic differentiation of AT-MSCs. Gene expression was studied 4 and 14 days after BMP-treatment. At day 4 BMP-2, but not BMP-7, stimulated runx-2 and osteopontin gene expression, and at day 14 BMP-7 down-regulated expression of these genes. At day 4 BMP-2 and BMP-7 stimulated biglycan gene expression, which was down-regulated by BMP-7 at day 14. BMP-7 stimulated aggrecan gene expression at day 14. Our data indicate that BMP-2 treatment for 15min induces osteogenic differentiation, whereas BMP-7 stimulates a chondrogenic phenotype of AT-MSCs. Therefore, AT-MSCs triggered for only 15min with BMP-2 or BMP-7 provide a feasible tool for bone and cartilage tissue engineering.

Bone Morphogenetic Proteins im Skelettsystem—

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor-beta superfamily. Their potential for organ and tissue regeneration and repair has been intensively investigated in recent years. Studies on fetal development have demonstrated the important role of these proteins for the development and differentiation of different organs. Miss-expression or mutation of BMPs may lead to severe abnormalities or even abortion. However, a regenerative potential has also been recognized for the adult organism. BMPs support fracture healing and may contribute to treatment of joint diseases. Thus, BMP-7 is one of the first BMPs approved for clinical application in non-unions of bone fractures resistant to conventional therapy. In degenerative and inflammatory joint diseases, experimental data suggest a decrease of BMP expression in cartilage tissue. Therefore, BMPs could be promising therapeutic candidates in these diseases, although more detailed analyses are necessary. In this review we will focus on bone morphogenetic proteins and discuss present and putative future clinical applications.

Cartilage-derived morphogenetic proteins induce osteogenic gene expression in the C2C12 mesenchymal cell line

Cartilage-derived morphogenetic protein-1, -2, and -3 (CDMP-1, -2, and -3) are members of the bone morphogenetic protein (BMP) family and have been shown to exhibit a variety of biological activities. In the present study, effects of these CDMPs on the temporal and spatial expression of genes in the pluripotent mesenchymal cell line C2C12 were examined. Cells cultured in the presence of CDMPs lost the characteristic elongated shape of myoblasts. At the molecular level, CDMP treatment did not change the mRNA expression of MyoD, aggrecan, Six1, and tendin. Scleraxis mRNA level was reduced by CDMP treatment. CDMP-1 and -3, but not CDMP-2, stimulated expression of osteogenic markers, such as alkaline phosphatase (AP), osteocalcin (OC), BSP, and type I collagen, in a dose- and time-dependent manner. With few exceptions, the three CDMPs changed, with different potencies, the expression profile of different members of the BMP family in a similar temporal pattern. Except at the late phase of treatment, CDMP treatment did not change the expression of ActR-IA, BMPR-IA, BMPR-IB, BMPR-II, and ALK-7 mRNAs. Based on the current data, the CDMPs appear to be able to stimulate the C2C12 cells to differentiate into the osteoblast pathway.

Effect of bone morphogenetic protein-2 (BMP-2) on matrix production, other BMPs, and BMP receptors in rat intervertebral disc cells

OBJECTIVE

An in vitro experiment study using rat disc cells was carried out to determine the effect of bone morphogenetic protein-2 (BMP-2) on extracellular matrix production, other BMPs, and BMP receptors (BMPRs).

METHODS

Cells from the anulus fibrosus and transition zone were harvested and cultured. When the cells reached 80% confluence, BMP-2 was added to reach a final concentration of 200 ng/mL. Three days later, the culture media were collected for the assay of sulfated glycosaminoglycans (sGAG) and collagen types I and II. The cells were harvested for RNA extraction to determine the genes expressed. All experiments were performed at least three times to ensure repeatability.

RESULTS

BMP-2 significantly increased aggrecan and collagen type II mRNA expression 8.30 and 4.61 times, respectively, and decreased versican mRNA expression 0.54 times as compared with control. Collagen type I production and mRNA level were not changed. BMP-2 significantly increased transforming growth factor-beta1 (TGFbeta1) and BMP-7 mRNA expression 2.32 and 2.45 times, respectively, compared with control. There was no significant change in BMP-6 mRNA expression. BMPR type IB and II mRNA expressions were increased and BMPR type 1A mRNA expression was decreased, but none of these differences was significant.

CONCLUSIONS

The results of this study show that in rat intervertebral disc cells, BMP-2 increases aggrecan and collagen type II mRNA expression and decreases versican gene expression. BMP-2 also up-regulates mRNA expression for BMP-7 and TGFbeta but has no significant effect on the BMPRs.

Identification of an osteogenic protein-1 responsive element in the aggrecan promoter

Previous studies have demonstrated that osteogenic protein-1 (OP-1), a member of the bone morphogenetic protein (BMP) subfamily of the TGF-beta superfamily, stimulates aggrecan synthesis. To investigate transcriptional regulation of the aggrecan gene by OP-1, we constructed a clone containing a 1 kb region of the 5'-upstream sequence of the mouse aggrecan gene fused to the promoter-less luciferase reporter gene in pGL2-Basic vector. A series of promoter deletion constructs were also generated. Studies of the promoter activity of these DNA constructs in transient-transfected cells revealed that deletion of a 33 bp region rendered the promoter unresponsive to OP-1, BMP-6, and CDMP-1 without affecting BMP-2 and TGF-beta1 responsiveness. Thus, the expression of the mouse aggrecan gene in response to BMPs appears to be the result of a unique combination of different cis-acting elements.

Effects of osteogenic protein-1 (OP-1, BMP-7) on gene expression in cultured medial collateral ligament cells

Osteogenic protein-1 (OP-1, also called BMP-7), a member of the BMP family and the TGF-beta superfamily, induces formation of new bone and cartilage, but also regulates a wide array of processes. In the present study, the expression of several characteristic biochemical markers of ligaments, such as Six1, Scleraxis, aggrecan, and type I collagen in primary cultures of adult rat medial collateral ligament (MCL) cells was determined. The effects of OP-1 on cell proliferation and on gene expression were subsequently examined. OP-1 stimulated cell proliferation, alkaline phosphatase (AP) activity, and the steady-state mRNA levels of the transcription factor Runx2/Cbfa1 in a dose- and time-dependent manner. The mRNA levels of type I collagen only increased slightly, but the activity of the cloned collagen promoter increased by 2-fold in transiently transfected MCL cells. OP-1 also stimulated aggrecan mRNA expression. The mRNA levels of Six1 and Scleraxis were not detectably altered by OP-1. In control cultures, the steady-state mRNA levels of ActR-I, BMPR-IA, BMPR-IB, and BMPR-II increased as a function of time in culture. The mRNA levels of BMP-1 and -4 increased significantly after 12 days, but those of BMP-2 and -6 did not change. The GDF-1, -3, -5, -6, and -8 mRNA levels in the control cultures also increased as a function of time. OP-1 treatment stimulated mRNA expression of BMPR-IA and BMPR-II, but had little effect on ActR-I and BMPR-IB mRNA expression. OP-1 lowered the BMP-1, -2, and -6 mRNA levels without changing the BMP-4 mRNA level. OP-1 treatment also reduced the mRNA levels of GDFs detected. In summary, the present study demonstrated that OP-1 stimulated cell proliferation and mRNA expression of several biochemical markers in this ligament cell culture model and established the spatial and temporal appearance of several members of the TGF-beta superfamily.

Regulation of osteogenic proteins by chondrocytes

The purpose of this review is to summarize the current scientific knowledge of bone morphogenetic proteins (BMPs) in adult articular cartilage. We specifically focus on adult cartilage, since one of the major potential applications of the members of the BMP family may be a repair of adult tissue after trauma and/or disease. After reviewing cartilage physiology and BMPs, we analyze the data on the role of recombinant BMPs as anabolic agents in tissue formation and restoration in different in vitro and in vivo models following with the endogenous expression of BMPs and factors that regulate their expression. We also discuss recent transgenic modifications of BMP genes and subsequent effect on cartilage matrix synthesis. We found that the most studied BMPs in adult articular cartilage are BMP-7 and BMP-2 as well as transforming growth factor-beta (TGF-beta). There are a number of contradicting reports for some of these growth factors, since different models, animals, doses, time points, culture conditions and devices were used. However, regardless of the experimental conditions, only BMP-7 or osteogenic protein-1 (OP-1) exhibits the most convincing effects. It is the only BMP studied thus far in adult cartilage that demonstrates strong anabolic activity in vitro and in vivo with and without serum. OP-1 stimulates the synthesis of the majority of cartilage extracellular matrix proteins in adult articular chondrocytes derived from different species and of different age. OP-1 counteracts the degenerative effect of numerous catabolic mediators; it is also expressed in adult human, bovine, rabbit and goat articular cartilage. This review reveals the importance of the exploration of the BMPs in the cartilage field and highlights their significance for clinical applications in the treatment of cartilage-related diseases.