The inhibitory effect of DIF-3 on polyinosinic-polycytidylic acid-induced innate immunity activation in human cerebral microvascular endothelial cells

For the treatment and prevention of autoinflammatory diseases, it is essential to develop the drug, regulating the innate immune system. Although differentiation-inducing factor (DIF) derivatives, extracted from the cellular slime mold, Dictyostelium discoideum, exhibit immunomodulatory effects, their effects on the regulation of innate immunity in brain are unknown. In this study, we used the human cerebral microvascular endothelial cell line, hCMEC/D3, to investigate the effects of DIF derivatives on the generation of C-X-C motif chemokine (CXCL) 10 and interferon (IFN)-β induced by polyinosinic-polycytidylic acid (poly IC). DIF-3 (1-10 μM), but not DIF-1 and DIF-2, dose-dependently inhibited the biosynthesis of not only CXCL10 but also CXCL16 and C-C motif chemokine 2 induced by poly IC. DIF-3 also strongly decreased IFN-β mRNA expression and protein release from the cells induced by poly IC through the prohibition of p65, a subtype of NF-ĸB, not interferon regulatory transcription factor 3 phosphorylation. In the docking simulation study, we confirmed that DIF-3 had a high affinity to p65. These results suggest that DIF-3 regulates the innate immune system by inhibiting TLR3/IFN-β signaling axis through the NF-ĸB phosphorylation inhibition.

Correction to: Warfarin calcifies human aortic valve interstitial cells at high-phosphate conditions via pregnane X receptor

In the original publication of the article, part of Fig. 1 was published incorrectly.

Menaquinone-4 Accelerates Calcification of Human Aortic Valve Interstitial Cells in High-Phosphate Medium through PXR

Recently, we confirmed that in human aortic valve interstitial cells (HAVICs) isolated from patients with aortic valve stenosis (AVS), calcification is induced in high inorganic phosphate (high-Pi) medium by warfarin (WFN). Because WFN is known as a vitamin K antagonist, reducing the formation of blood clots by vitamin K cycle, we hypothesized that vitamin K regulates WFN-induced HAVIC calcification. Here, we sought to determine whether WFN-induced HAVIC calcification in high-Pi medium is inhibited by menaquinone-4 (MK-4), the most common form of vitamin K₂ in animals. HAVICs obtained from patients with AVS were cultured in α-modified Eagle's medium containing 10% FBS, and when the cells reached 80%-90% confluency, they were further cultured in the presence or absence of MK-4 and WFN for 7 days in high-Pi medium (3.2 mM Pi). Intriguingly, in high-Pi medium, MK-4 dose-dependently accelerated WFN-induced HAVIC calcification and also accelerated the calcification when used alone (at 10 nM). Furthermore, MK-4 enhanced alkaline phosphatase (ALP) activity in HAVICs, and 7 days of MK-4 treatment markedly upregulated the gene expression of the calcification marker bone morphogenetic protein 2 (BMP2). Notably, MK-4-induced calcification was potently suppressed by two pregnane X receptor (PXR) inhibitors, ketoconazole and coumestrol; conversely, PXR activity was weakly increased, but in a statistically significant and dose-dependent manner, by MK-4. Lastly, in physiologic-Pi medium, MK-4 increased BMP2 gene expression and accelerated excess BMP2 (30 ng/ml)-induced HAVIC calcification. These results suggest that MK-4, namely vitamin K₂, accelerates calcification of HAVICs from patients with AVS like WFN via PXR-BMP2-ALP pathway. SIGNIFICANCE STATEMENT: For aortic valve stenosis (AVS) induced by irreversible valve calcification, the most effective treatment is surgical aortic or transcatheter aortic valve replacement, but ∼20% of patients are deemed unsuitable because of its invasiveness. For effective drug treatment strategies for AVS, the mechanisms underlying aortic valve calcification must be elucidated. Here, we show that menaquinone-4 accelerates warfarin-induced calcification of AVS-patient human aortic valve interstitial cells in high inorganic phosphate medium; this effect is mediated by pregnane X receptor-bone morphogenetic protein 2-alkaline phosphatase signaling, which could be targeted for novel drug development.

Warfarin calcifies human aortic valve interstitial cells at high-phosphate conditions via pregnane X receptor

Warfarin, a vitamin K antagonist, is the most common anticoagulant used to prevent thromboembolisms associated with atrial fibrillation or following valvular surgery. Although several studies have revealed that long-term warfarin use accelerates aortic valve calcification and the development of aortic stenosis (AS), the detailed mechanism for this phenomenon remains unclear. Therefore, our aim was twofold: to establish the conditions for warfarin-induced calcification of human aortic valve interstitial cells (HAVICs) using high-inorganic phosphate (Pi) conditions and to investigate the underlying mechanism. We prepared and cultured HAVICs from aortic valves affected by calcific aortic valve stenosis (AS group) and aortic valves affected by aortic regurgitation but without any signs of calcification (non-AS group). Under Pi concentrations of 3.2 mM, warfarin significantly increased the calcification and alkaline phosphatase (ALP) activity of AS but not non-AS group HAVICs. Furthermore, gene expression of bone morphogenetic protein 2 (BMP2), a calcigenic marker, was significantly increased following 7 days of warfarin treatment. Warfarin-induced calcification of AS group HAVICs at 3.2 mM Pi was significantly inhibited by dorsomorphin, a Smad inhibitor, and the pregnane X receptor (PXR) inhibitors, ketoconazole and coumestrol, but was unaffected by SN-50, an NF-κB inhibitor. Warfarin was also able to increase BMP2 gene expression at a physiological Pi concentration (1.0 mM). Furthermore, excess BMP2 (30 ng/mL) facilitated warfarin-induced ALP upregulation and HAVIC calcification, an effect which was significantly reduced in the presence of coumestrol. Together, our results suggest that warfarin accelerates calcification of HAVICs from AS patients via the PXR-BMP2-ALP pathway.

Neurotrophic Factor Secretion and Neural Differentiation Potential of Multilineage-differentiating Stress-enduring (Muse) Cells Derived from Mouse Adipose Tissue

Multilineage-differentiating stress-enduring (Muse) cells are endogenous pluripotent stem cells that can be isolated based on stage-specific embryonic antigen-3 (SSEA-3), a pluripotent stem cell-surface marker. However, their capacities for survival, neurotrophic factor secretion, and neuronal and glial differentiation are unclear in rodents. Here we analyzed mouse adipose tissue-derived Muse cells in vitro. We collected mesenchymal stem cells (MSCs) from C57BL/6 J mouse adipose tissue and separated SSEA-3⁺, namely Muse cells, and SSEA-3^-, non-Muse cells, to assess self-renewability; pluripotency marker expression (Nanog, Oct3/4, Sox2, and SSEA-3); spontaneous differentiation into endodermal, mesodermal, and ectodermal lineages; and neural differentiation capabilities under cytokine induction. Neurally differentiated Muse and non-Muse cell functions were assessed by calcium imaging. Antioxidant ability was measured to assess survival under oxidative stress. Brain-derived neurotrophic factor (BDNF), vascular endothelial cell growth factor (VEGF), and hepatocyte growth factor (HGF) secretion were analyzed in enzyme-linked immunosorbent assays. SSEA-3⁺ Muse cells (6.3 ± 1.9% of mouse adipose-MSCs), but not non-Muse cells, exhibited self-renewability, spontaneous differentiation into the three germ layers, and differentiation into cells positive for Tuj-1 (27 ± 0.9%), O4 (17 ± 3.4%), or GFAP (23 ± 1.3%) under cytokine induction. Neurally differentiated Muse cells responded to KCl depolarization with greater increases in cytoplasmic Ca²⁺ levels than non-Muse cells. Cell survival under oxidative stress was significantly higher in Muse cells (50 ± 2.7%) versus non-Muse cells (22 ± 2.8%). Muse cells secreted significantly more BDNF, VEGF, and HGF (273 ± 12, 1479 ± 7.5, and 6591 ± 1216 pg/mL, respectively) than non-Muse cells (133 ± 4.0, 1165 ± 20, and 2383 ± 540 pg/mL, respectively). Mouse Muse cells were isolated and characterized for the first time. Muse cells showed greater pluripotency-like characteristics, survival, neurotrophic factor secretion, and neuronal and glial-differentiation capacities than non-Muse cells, indicating that they may have better neural-regeneration potential.

Matrix Gla protein negatively regulates calcification of human aortic valve interstitial cells isolated from calcified aortic valves

Calcified aortic valve stenosis (CAS) is a common heart valve disease in elderly people, and is mostly accompanied by ectopic valve calcification. We recently demonstrated that tumor necrosis factor-α (TNF-α) induces calcification of human aortic valve interstitial cells (HAVICs) obtained from CAS patients. In this study, we investigated the role of matrix Gla protein (MGP), a known calcification inhibitor that antagonizes bone morphogenetic protein 2 (BMP2) in TNF-α-induced calcification of HAVICs. HAVICs isolated from aortic valves were cultured, and calcification was significantly induced with 30 ng/mL TNF-α. Gene expression of the calcigenic marker, BMP2, was significantly increased in response to TNF-α, while the gene and protein expression of MGP was strongly decreased. To confirm the role of MGP, MGP-knockdown HAVICs and HAVICs overexpressing MGP were generated. In HAVICs, in which MGP expression was inhibited by small interfering RNA, calcification and BMP2 gene expression were induced following long-term culture for 32 days in the absence of TNF-α. In contrast, HAVICs overexpressing MGP had significantly decreased TNF-α-induced calcification. These results suggest that MGP acts as a negative regulator of HAVIC calcification, and as such, may be helpful in the development of new therapies for ectopic calcification of the aortic valve.

Ketamine suppresses the proliferation of rat C6 glioma cells

The present study investigated the effects of N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine, on the growth of gliomas. To analyze the effects of ketamine treatment, rat C6 glioma cells arising from astrocytes, and RNB cells representing non-malignant astrocytes, were examined. In ketamine-treated C6 cells, the gene expression changes associated with cell proliferation following ketamine treatment were evaluated using a cDNA microarray. A cell proliferation assay was performed to analyze the dose-dependent proliferation of C6 glioma and RNB cells following culture (72 h) with ketamine treatment (0-100 µM). Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays were performed following cell incubation with/without ketamine, to confirm if the ketamine-induced cell death of C6 glioma and RNB cells were due to apoptosis. In addition, cell proliferation and TUNEL assays were performed following cell incubations with a selective NMDAR antagonist, D-2-amino-5-phosphonovaleric acid (D-AP5). Analysis of the cDNA microarray indicated that the growth of C6 glioma cells were suppressed by the effects of ketamine. Furthermore, results of the proliferation assay confirmed that ketamine treatment inhibited C6 cell proliferation, most notably at a dose of 30 µM (n=7, 66.4%; P<0.001). The TUNEL assay results revealed that ketamine induced an apoptotic effect on C6 glioma cells, with a significant effect on the rate of death observed at all tested concentrations (3, 10, 30 and 100 µM). Results of the aforementioned proliferation and TUNEL assay experiments were reproduced when ketamine was replaced with a selective NMDAR antagonist, D-AP5. However, the NMDARantagonist-induced effects were not observed in RNB cell cultures. Although it would be premature to apply the results from the present study to human cases, these results indicated that ketamine is an anesthetic candidate providing potential benefit for glioma resection.

Hyaluronic acid induces the release of growth factors from platelet-rich plasma

Background/Objective

Platelet-rich plasma (PRP) and hyaluronic acid (HA) injection are both therapeutic options for osteoarthritis and chronic tendinopathy. Although several comparative studies on the two have been published, the effects of mixing PRP and HA are not fully understood. The purpose of this study is to investigate the influence of HA on platelets in PRP by measuring releasing growth factors.

Methods

PRP was produced from nine healthy adult volunteers (mean age, 32.8 ± 2.9 years; range, 29–37) with a commercial separation system. HA of weight-average molecular weight of 50–120 kDa was used. PRP group (PRP 1 mL + phosphate buffered saline 0.2 mL) and PRP + HA group (PRP 1 mL + HA 0.2 mL) were incubated at 37°C for 2 hours. The amounts of transforming growth factor β1 (TGF-β1) and platelet-derived growth factor (PDGF-AA) released from the PRP and PRP + HA samples were measured on Day 0, Day 3, and Day 5. In addition, the same growth factors on Day 5 were measured for PRP + high HA group (PRP 1 mL + HA 0.6 mL) with five donors. After collecting all of the samples on Day 5, the remaining gels were observed with Giemsa stain. Statistical analyses were performed using paired t tests to compare the PRP and HA groups at each time point, and a one-way analysis of variance (one-way ANOVA) with Tukey post hoc tests was used to compare the PRP, PRP + HA, and PRP + high HA groups.

Results

The TGF-β1 concentrations in the PRP and PRP + HA were 24.3 ± 7.2 μg/mL and 22.4 ± 1.8 μg/mL (p = 0.689) on Day 0, 17.2 ± 13.9 μg/mL and 25.4 ± 7.1 μg/mL (p = 0.331) on Day 3, and 12.7 ± 10.5 μg/mL and 33.7 ± 8.3 μg/mL (p = 0.034) on Day 5. The TGF-β1 concentrations on Day 5 were 24.1 ± 5.2 μg/mL (PRP group), 28.3 ± 2.4 μg/mL (PRP + HA), and 31.9 ± 4.8 μg/mL (PRP + high HA; one-way ANOVA: p = 0.003; post hoc PRP vs. PRP + HA: p = 0.016). The PDGF-AA concentrations in the PRP and PRP + HA groups were 2.30 ± 1.21 μg/mL and 2.32 ± 0.79 μg/mL (p = 0.931) on Day 0, 2.03 ± 0.53 μg/mL and 2.13 ± 0.73 μg/mL (p = 0.500) on Day 3, and 1.51 ± 0.40 μg/mL and 2.00 ± 0.52 μg/mL (p = 0.003) on Day 5. The PDGF-AA concentrations were 1.48 ± 0.46 μg/mL (PRP group), 1.94 ± 0.57 μg/mL (PRP + HA), and 2.69 ± 0.70 μg/mL (PRP + high HA; one-way ANOVA: p = 0.0002; PRP vs. PRP + high HA: p = 0.002; PRP + HA vs. PRP + high HA: p = 0.011) on Day 5. The PRP showed larger coagulated masses than the PRP + HA. The high concentration HA group had the smallest coagulated mass of all of the group.

Conclusion

The levels of growth factors released by PRP on Day 5 were increased by the addition of HA. A mixture of PRP and HA may be a more effective therapy than PRP or HA alone for osteoarthritis and tendinopathy.

Decreased DNA methylation in the promoter region of the WNT5A and GDNF genes may promote the osteogenicity of mesenchymal stem cells from patients with ossified spinal ligaments

Mesenchymal stem cells (MSCs) isolated from spinal ligaments with ectopic ossification have a propensity toward the osteogenic lineage. To explore epigenetic control of the osteogenic features of MSCs, we treated MSCs obtained from the spinal ligaments of ossification of yellow ligament (OYL) patients and non-OYL patients with the DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5AdC). We compared the non-OYL groups (untreated and treated with 5AdC) with the OYL groups (untreated and treated with 5AdC) by genome-wide microarray analysis. Next, we used methylated DNA immunoprecipitation combined with quantitative real-time PCR to assess gene methylation. Ninety-eight genes showed expression significantly increased by 5AdC treatment in MSCs from non-OYL patients but not from OYL patients. In contrast, only two genes, GDNF and WNT5A, showed significantly higher expression in OYL MSCs compared with non-OYL MSCs without 5AdC treatment. Both genes were hypermethylated in non-OYL MSCs but not in OYL MSCs. Small interfering RNA targeted to each gene decreased expression of the target gene and also several osteogenic genes. Both small interfering RNAs also suppressed the activity of alkaline phosphatase, a typical marker of osteogenesis. These results suggest that the osteogenic features of MSCs from OYL patients are promoted by unmethylated WNT5A and GDNF genes.

Identification of a novel COL2A1 mutation (c.1744G>A) in a Japanese family: a case report

Introduction

Mutations in the gene encoding the type II collagen gene (COL2A1) have been found to affect the entire skeletal system. Recently, inheritable skeletal dysplasia caused by novel COL2A1 mutations has been linked to an inherited disease of the hip joint that neither involves the entire skeletal system nor is characterized by the presence of concomitant disorders, such as spinal or ocular abnormalities.

Case presentation

A 27-year-old Japanese woman previously diagnosed with avasucular necrosis (AVN) of the femoral head on the basis of radiological findings was referred to the study site for surgical management of a painful hip joint. She had no history of disease but suffered from bilateral hip joint lesions. Analysis of her pedigree revealed that bilateral hip joint lesions affected more than three generations of her family. Based on these findings, haplotype analysis of her and her family members was performed by examining select candidate genes from the critical interval for epiphyseal dysplasia of the femoral head on 12q13 and sequencing the promoter and exonic regions of COL2A1.

Conclusion

A novel COL2A1 mutation (c.1744G>A) was identified within one Japanese family.

A genome-wide association study identifies susceptibility loci for ossification of the posterior longitudinal ligament of the spine

Ossification of the posterior longitudinal ligament of the spine (OPLL) is a common spinal disorder among the elderly that causes myelopathy and radiculopathy. To identify genetic factors for OPLL, we performed a genome-wide association study (GWAS) in ∼8,000 individuals followed by a replication study using an additional ∼7,000 individuals. We identified six susceptibility loci for OPLL: 20p12.3 (rs2423294: P = 1.10 × 10(-13)), 8q23.1 (rs374810: P = 1.88 × 10(-13)), 12p11.22 (rs1979679: P = 4.34 × 10(-12)), 12p12.2 (rs11045000: P = 2.95 × 10(-11)), 8q23.3 (rs13279799: P = 1.28 × 10(-10)) and 6p21.1 (rs927485: P = 9.40 × 10(-9)). Analyses of gene expression in and around the loci suggested that several genes are involved in OPLL etiology through membranous and/or endochondral ossification processes. Our results bring new insight to the etiology of OPLL.

8-Methyltryptanthrin-induced differentiation of P19CL6 embryonal carcinoma cells into spontaneously beating cardiomyocyte-like cells

Enhancement of cardiac differentiation is critical to stem cell transplantation therapy for severe ischemic heart disease. The aim of this study was to investigate whether several derivatives of tryptanthrin (1), extracted from the medicinal plant Polygonum tinctorium, induce the differentiation of P19CL6 mouse embryonal carcinoma cells into beating cardiomyocyte-like cells. P19CL6 cells were cultured in α-MEM supplemented with 10% FBS including a test compound or vehicle. Drug-induced differentiation was assessed by measuring the number of beating and nonbeating aggregates and the area of beating aggregates, and the expression of genes involved in cardiac differentiation was evaluated by real-time PCR. A 1 μM concentration of 8-methyltryptanthrin (2) induced the differentiation of P19CL6 cells into cardiomyocyte-like cells to a significantly greater degree than 1% dimethyl sulfoxide (DMSO), a conventional differentiation inducer of P19CL6 cells. Furthermore, 2 strongly increased both the number and the area of spontaneously beating aggregates in comparison with DMSO. Two distinct genes of the calcium channel family, Cav1.2 and Cav3.1, underlying cardiac automaticity were significantly expressed in the presence of 2. Gap junction genes GJA1 and GJA5 contributing to the synchronized contraction of the myocardium were also induced significantly by 2. These results suggest that 2 successfully differentiated P19CL6 cells into spontaneously beating cardiomyocyte-like cells by activating the gene expression of pacemaker channels and gap junctions.

Generation of Antitumor Active Neutral Medium-Sized α-Glycan in Apple Vinegar Fermentation

The physiologically active substances in apple vinegar have not yet been chemically characterized. We studied the biological functions of apple vinegar produced from crushed apples, and found that the constituent neutral medium-sized alpha-glycan (NMalphaG) acts as an antitumor agent against experimental mouse tumors. NMalphaG is a homoglycan composed of glucose having a molecular weight of about 10,000 and a branched structure bearing alpha (1-4,6) linkages. In this study, we clarified the origin of NMalphaG in apple vinegar by examination of its content in alcohol and acetic acid fermentation products sequentially. We found that NMalphaG appeared in acetic acid fermentation, but not in alcohol fermentation. Furthermore we investigated NMalphaG origin using acetic acid fermentation from alcohol fortifiied apple without alcohol fermentation and from raw material with varying amounts of pomace. The results indicate that NMalphaG originated in the apple fruit body and that its production requires both fermentation processes.

Immunohistochemical localization of mesenchymal stem cells in ossified human spinal ligaments

Mesenchymal stem cells (MSCs) have been isolated from various tissues and used for elucidating the pathogenesis of numerous diseases. In our previous in vitro study, we showed the existence of MSCs in human spinal ligaments and hypothesized that these MSCs contributed to the pathogenesis of ossification of spinal ligaments. The purpose of this study was to use immunohistochemical techniques to analyze the localization of MSCs in ossified human spinal ligaments in situ. Ossified (OLF) or non-ossified ligamentum flavum (non-OLF) samples from the thoracic vertebra were obtained from patients who had undergone posterior spinal surgery. Serial sections were prepared from paraffin-embedded samples, and double immunofluorescence staining was performed using antibodies against markers for MSCs (CD73, CD90 and CD105), endothelial cells (CD31), pericytes (α-smooth muscle actin), and chondrocytes (S100). Immunolocalization of MSCs was observed in the perivascular area and collagenous matrix in spinal ligaments. Markers for MSCs and pericytes were co-expressed in the perivascular area. Compared with non-OLF, OLF had a large amount of neovascularization in the fragmented ligament matrix, and a high accumulation of MSCs around blood vessels. The prevalence of MSCs in OLF within collagenous matrix was significantly higher than that in non-OLF. Chondrocytes near the ossification front in OLF also presented expression of MSC markers. MSCs may contribute to the ectopic ossification process of OLF through endochondral ossification.

Post injury changes in the properties of mesenchymal stem cells derived from human anterior cruciate ligaments

PURPOSE

The anterior cruciate ligament (ACL) rarely heals spontaneously after rupture. Mesenchymal stem cells (MSCs) contribute to healing in various tissues, therefore, they may also have a key role in healing after ACL rupture. The purpose of this study was to investigate the properties of MSCs in ruptured ACLs.

METHODS

Human ACL samples were harvested from patients undergoing primary ACL reconstruction, and samples were classified by the number of days post rupture (phase I<21 days; phase II 21–56 days; phase III 57–139 days phase IV≥140 days). We evaluated the characteristics of MSCs, such as colony-forming capacity, differentiation potential and cell-surface markers.

RESULTS

There was a tendency for high colony-forming capacity during phases I and II, which tended to decrease in phase III. Chondrogenic, adipogenic and osteogenic differentiation potential was maintained until phase II but decreased in phase III. Most surface-epitope expression was consistent from phase I to III: positive for CD44, CD73, CD90 and CD105; negative for CD11b, CD19, CD34, CD45 and human leukocyte antigen-D-related (HLA-DR). The presence of these surface markers proved the existence of MSCs in ruptured ACL tissue.

CONCLUSIONS

Our results suggest that colony-forming and differentiation potential decrease over time. It is important to consider changes in properties of MSCs and use ACL tissue in the acute phase of rupture when biological manipulation is required.

[Bone and calcium update; diagnosis and therapy of bone metabolism disease update. Molecular mechanism in cardiac valve calcification]

When cardiac valve stenosis is accompanied by calcification, symptoms and prognosis become much worse and may cause sudden cardiac death. The prevalence of this disease has increased with the rapidly aging in Japanese society. It has recently been revealed that several genes which relate to physiological ossification and calcification play important roles in this process. To find a suitable target for medical treatment, the molecular mechanism for calcification of cardiac valves should be elucidated in detail. In this review, we summarize the current knowledge on the pathology and molecular mechanism for ectopic calcification of the cardiac valve.

Genetic differences in the osteogenic differentiation potency according to the classification of ossification of the posterior longitudinal ligament of the cervical spine

STUDY DESIGN

We categorized the four types of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine into two groups. We biochemically investigated the genetic differences in the osteogenic differentiation potency between the two groups.

OBJECTIVE

To investigate the genetic differences in the osteogenic differentiation potency according to the OPLL classification.

SUMMARY OF BACKGROUND DATA

Clinical studies on OPLL have revealed that the risk of progression of the ossification area is greatest for continuous and mixed type OPLL. However, until now, these four types of OPLL have been studied as a single condition.

METHODS

We categorized the four types of OPLL into the OPLL continuous (continuous or mixed type) and OPLL segmental groups (segmental or circumscribed type). Paraspinal ligaments were aseptically obtained from OPLL patients during surgery. The fibroblast-like cells that migrated from the explants were used for experiments. The cells were placed in a 60-mm culture dishes for total ribonucleic acid preparation and 12 well microplates for alkaline phosphatase (ALP) activity staining. After cultures reached confluence, the cells were cultured in osteogenic medium. The messenger ribonucleic acid expression of bone morphogenetic protein-2 (BMP-2), osterix, tumor necrosis factor-α-stimulated gene-6, and ALP was analyzed by quantitative real time-polymerase chain reaction. Osteogenic differentiation of fibroblast-like cells was determined by histochemically detecting ALP production.

RESULTS

After osteogenic induction, BMP-2 expression increased in the OPLL continuous and segmental groups. Osterix expression increased in the OPLL continuous group only. Tumor necrosis factor-α-stimulated gene-6 expression was suppressed in the OPLL continuous and segmental groups. ALP expression as well as ALP activity staining was higher in the OPLL continuous group than in the OPLL segmental group. CONCLUSION.: The study revealed genetic differences in the osteogenic differentiation potency between the OPLL continuous and segmental groups. We propose to distinguish OPLL continuous group from segmental group in biochemical studies on OPLL.

P2Y1 transient overexpression induced mineralization in spinal ligament cells derived from patients with ossification of the posterior longitudinal ligament of the cervical spine

Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic bone formation in the spinal ligaments. We previously reported that P2 purinoceptor Y1 (P2Y1) expression is elevated in the spinal ligament cells of OPLL patients, but the role of P2Y1 in the spinal ligament calcification process is unknown. To verify the hypothesis that P2Y1 expression causes ossification of the spinal ligaments, we forced expression of P2Y1 in spinal ligament cells obtained from OPLL and non-OPLL patients using a cytomegaloviral vector. The expression of mRNA and protein was investigated by quantitative real-time polymerase chain reaction and immunofluorescence staining, respectively. After transfection, bone morphogenetic protein-2 (BMP-2) and Sox9 mRNA expression was significantly increased in spinal ligament cells derived from OPLL patients (4.36- and 6.44-fold, respectively) compared with cells from non-OPLL patients (0.57- and 3.64-fold, respectively) 2 days after P2Y1 transient transfection. Furthermore, a statistically significant correlation was observed between BMP-2 and P2Y1 mRNA expression levels in cells obtained from OPLL patients but not from non-OPLL patients. Immunofluorescence analysis showed that BMP-2 and P2Y1 expression was increased in OPLL patients only, while Sox9 expression was increased in OPLL and non-OPLL patients. MRS2279, a selective P2Y1 antagonist, blocked the upregulation of Sox9 and BMP-2 after forced expression of P2Y1. Furthermore, 4 days after transient transfection of P2Y1, mineralization was observed only in spinal ligament cells from OPLL patients. These results suggest that P2Y1 expression plays an important role in ectopic bone formation in the spinal ligaments of OPLL patients.

Tumor necrosis factor-α accelerates the calcification of human aortic valve interstitial cells obtained from patients with calcific aortic valve stenosis via the BMP2-Dlx5 pathway

Calcific aortic valve stenosis (CAS) is the most frequent heart valve disease in the elderly, accompanied by valve calcification. Tumor necrosis factor-α (TNF-α), a pleiotropic cytokine secreted mainly from macrophages, has been detected in human calcified valves. However, the role of TNF-α in valve calcification remains unclear. To clarify whether TNF-α accelerates the calcification of aortic valves, we investigated the effect of TNF-α on human aortic valve interstitial cells (HAVICs) obtained from patients with CAS (CAS group) and with aortic regurgitation or aortic dissection having a noncalcified aortic valve (control group). HAVICs (2 × 10(4)) were cultured in a 12-well dish in Dulbecco's modified Eagle's medium with 10% fetal bovine serum. The medium containing TNF-α (30 ng/ml) was replenished every 3 days after the cells reached confluence. TNF-α significantly accelerated the calcification and alkaline phosphatase (ALP) activity of HAVICs from CAS but not the control group after 12 days of culture. Furthermore, gene expression of calcigenic markers, ALP, bone morphogenetic protein 2 (BMP2), and distal-less homeobox 5 (Dlx5) were significantly increased after 6 days of TNF-α treatment in the CAS group but not the control group. Dorsomorphin, an inhibitor of mothers against decapentaplegic homologs (Smads) 1/5/8 phosphorylation, significantly inhibited the enhancement of TNF-α-induced calcification, ALP activity, Smad phosphorylation, and Dlx5 gene expression of HAVICs from the CAS group. These results suggest that HAVICs from the CAS group have greater sensitivity to TNF-α, which accelerates the calcification of aortic valves via the BMP2-Dlx5 pathway.

Contribution of bone morphogenetic protein-2 to aortic valve calcification in aged rat

Although aging is well established as an important risk factor for aortic stenosis, the mechanism of age-related aortic valve calcification is yet unknown. Here, we investigated this mechanism in tissue and cellular levels using middle-aged rats. Aortic valve specimens were obtained by dissecting from 9-week-old (young) and 30-week-old (aged) male Wistar rats. In the aged rats, the main risk factors for aortic stenosis in plasma were still in the normal range; however, their number of calcified specimens was significantly increased in comparison with the young rats. Aortic valve interstitial cells (AVICs) obtained from explants of aortic valve specimens were cultured for 14 days after reaching confluence. Spontaneous calcification, the expressions of calcigenic genes, that is, BMP-2, alkaline phosphatase (ALP), and osterix (osteogenic transcription factor) and ALP enzyme activity in AVICs from aged rats were enhanced in comparison with those from young rats. However, neither typical calcification inducing reagents (dexamethasone, β-glycerophosphate, and high concentration of phosphate) nor tumor necrosis factor-α (an inflammatory cytokine) accelerated the spontaneous calcification of AVICs from aged rats. These results suggest that aortic valve calcification progresses with age partly through an activation of the BMP-2 pathway.

A functional RNAi screen for Runx2-regulated genes associated with ectopic bone formation in human spinal ligaments

Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic ossification in the spinal ligaments, which enlarges with time and compresses the spinal cord, resulting in serious neurological symptoms. We previously reported that Runx2 expression was enhanced in spinal ligament cells from OPLL patients (OPLL cells). To clarify genes regulated by Runx2, Runx2 expression was first enhanced by culturing primary OPLL cells in osteogenic medium (OS induction) and then inhibited by siRNAs targeted to Runx2. DNA microarray demonstrated that in addition to chondrogenic factors such as connective tissue growth factor and cartilage oligomeric matrix protein, angiopoietin-1 was also significantly increased by OS induction and decreased by siRNAs for Runx2 in OPLL cells, suggesting that these genes are regulated by Runx2. However, these changes were not observed in non-OPLL control cells (from cervical spondylotic myelopathy patients). Furthermore, Runx2 was not decreased by siRNAs for angiopoietin-1. OS induction and RNAi inhibition of angiopoietin-1 expression was also observed in osteoblasts. Both siRNAs for Runx2 and angiopoietin-1 completely inhibited aggrecan-1 expression. These results suggest that angiopoietin-1 is downstream of Runx2 in both OPLL primary cells and osteoblasts. Angiopoietin-1 may play an important role in ectopic ossification.

Possible role of extracellular nucleotides in ectopic ossification of human spinal ligaments

To reveal the involvement of extracellular nucleotides in the ossification process in ossification of the posterior longitudinal ligament of the spine (OPLL), the mRNA expression profiles of P2 purinoceptors, mechanical stress-induced ATP release, and ATP-stimulated expression of osteogenic genes were analyzed in ligament cells derived from the spinal ligament of OPLL patients (OPLL cells) and non-OPLL cells derived from the spinal ligaments of cervical spondylotic myelopathy patients as a control. The extracellular ATP concentrations of OPLL cells in static culture were significantly higher than those of non-OPLL cells, and this difference was diminished in the presence of ARL67156, an ecto-nuclease inhibitor. Cyclic stretch markedly increased the extracellular ATP concentrations of both cell types to almost the same level. P2Y1 purinoceptor subtypes were intensively expressed in OPLL cells, but only weakly expressed in non-OPLL cells. Not only ATP addition but also cyclic stretch raised the mRNA levels of alkaline phosphatase and osteopontin in OPLL cells, which were blocked by MRS2179, a selective P2Y1 antagonist. These increases in the expression of osteogenic genes were not observed in non-OPLL cells. These results suggest an important role of P2Y1 and extracellular ATP in the progression of OPLL stimulated by mechanical stress.

Inhibitory effects of glucocorticoids on urocortin-mediated increases in interleukin-6 gene expression in rat aortic smooth muscle cells

Urocortin (Ucn) 1, Ucn2, and Ucn3 have potent effects on appetite and the cardiovascular system. Endogenous Ucns in combination with CRF receptor type 2beta may have a physiological role in the cardiovascular system. We previously demonstrated that both Ucn1 and Ucn2 increased IL-6 output levels in A7r5 aortic smooth muscle cells. In the present study, we extended observations on stress or hormone-induced changes in IL-6 gene expression in the cardiovascular system, and determined the effects of glucocorticoids on Ucn-mediated increases in IL-6 mRNA levels, protein levels, and gene transcription activity in A7r5 cells. Ucn1, Ucn2, and Ucn3 all increased IL-6 mRNA levels via CRF receptor type 2. Dexamethasone blocked the ability of Ucn1 to increase IL-6 mRNA and protein levels, while it failed to attenuate the Ucns-mediated changes in cyclic AMP (cAMP)-response element binding protein or extracellular signal-related kinases phosphorylation. Dexamethasone also suppressed Ucn1- or cAMP-stimulated IL-6 gene transcription via a glucocorticoid receptor. Together, these findings demonstrate that glucocorticoids suppress IL-6 gene transcription via Ucn-induced cAMP-dependent pathways in A7r5 cells.

Cardiac mitochondrial cGMP stimulates cytochrome c release

Although the existence of cardiac mitochondrial cGMP has been reported previously [Kimura and Murad (1974) J. Biol. Chem. 249, 6910-6916], the physiological and pathophysiological properties of cGMP in cardiac mitochondria have remained unknown. The aim of the present study was to clarify whether cardiac mitochondrial cGMP regulates the apoptosis of cardiomyocytes. In the presence of GTP, the NO donors SNAP (S-nitroso-N-acetyl-DL-penicillamine; 1 mmol/l) and SNP (sodium nitroprusside; 1 mmol/l) each markedly increased the cGMP level in a highly purified mitochondrial protein fraction prepared from left ventricular myocytes of male Wistar rats, and these increases were inhibited by 1 micromol/l ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), an inhibitor of NO-sensitive guanylate cyclase. In purified mitochondria, both SNAP (1 mmol/l) and the membrane-permeant cGMP analogue 8-Br-cGMP (8-bromo-cGMP; 1 mmol/l), but not cGMP (1 mmol/l), increased cytochrome c release from succinate-energized mitochondria without inducing mitochondrial swelling and depolarization of the mitochondrial membrane as factors of activation of MPT (mitochondrial permeability transition). The cytochrome c release mediated by SNAP was inhibited in the presence of 1 micromol/l ODQ. On the other hand, 1 mmol/l SNAP induced apoptosis in primary cultured adult rat cardiomyocytes in a time-dependent manner, and this induction was significantly inhibited in the presence of ODQ. Furthermore, apoptosis induced in primary cultured cardiomyocytes by hypoxia/re-oxygenation was also inhibited by ODQ. These results suggest that the acceleration of cGMP production in cardiac mitochondria stimulates cytochrome c release from mitochondria in an MPT-independent manner, resulting in apoptosis.

Assessment of the Effects of L- and N-Type Ca2+ Channel Blocking Drugs Using Canine Blood-Perfused Papillary Muscle Preparations

It is important to accurately and conveniently assess the effects of L- and N-type Ca(2+) channel blocking drugs, which are commonly used for treatment of hypertension, but no method is available to simultaneously assess the effects of them in the same preparation. We have therefore designed an ex vivo method to measure the changes in contractile response of anterior papillary muscle of right ventricle and myocardial interstitial norepinephrine (NE) level using canine blood-perfused papillary muscle preparations. Papillary muscle-developed tension (PMDT) induced by an electronic stimulator was measured with force transducer. Myocardial interstitial NE effluent was collected by microdialysis fiber, which was implanted at the base of the papillary muscle, and measured with high performance liquid chromatography. Cilnidipine, a typical L- and N-type Ca(2+) channel blocker, was used to prove the efficiency of this method. First, to assess the effects of drugs on L-type Ca(2+) channel, the changes in basal PMDT were measured. Cilnidipine and nicardipine, a selective L-type Ca(2+) channel blocker, but not omega-conotoxin GVIA (omega-CTX), a selective N-type Ca(2+) channel blocking peptide, decreased basal PMDT dose-dependently. Second, to assess the effects of drugs on N-type Ca(2+) channel, the changes in PMDT and myocardial interstitial NE level by intracardiac sympathetic ganglion stimulation were measured. Cilnidipine and omega-CTX, but not nicardipine, dose-dependently reduced sympathomimetic increases in PMDT and myocardial interstitial NE level. These results indicate that our method is efficient to assess the effects of various L- and N-type Ca(2+) channel blocking drugs in the same papillary muscle preparation.

Tumour necrosis factor alpha-stimulated gene-6 inhibits osteoblastic differentiation of human mesenchymal stem cells induced by osteogenic differentiation medium and BMP-2

To better understand the molecular pathogenesis of OPLL (ossification of the posterior longitudinal ligament) of the spine, an ectopic bone formation disease, we performed cDNA microarray analysis on cultured ligament cells from OPLL patients. We found that TSG-6 (tumour necrosis factor alpha-stimulated gene-6) is down-regulated during osteoblastic differentiation. Adenovirus vector-mediated overexpression of TSG-6 inhibited osteoblastic differentiation of human mesenchymal stem cells induced by BMP (bone morphogenetic protein)-2 or OS (osteogenic differentiation medium). TSG-6 suppressed phosphorylation and nuclear accumulation of Smad 1/5 induced by BMP-2, probably by inhibiting binding of the ligand to the receptor, since interaction between TSG-6 and BMP-2 was observed in vitro. TSG-6 has two functional domains, a Link domain (a hyaluronan binding domain) and a CUB domain implicated in protein interaction. The inhibitory effect on osteoblastic differentiation was completely lost with exogenously added Link domain-truncated TSG-6, while partial inhibition was retained by the CUB domain-truncated protein. In addition, the inhibitory action of TSG-6 and the in vitro interaction of TSG-6 with BMP-2 were abolished by the addition of hyaluronan. Thus, TSG-6, identified as a down-regulated gene during osteoblastic differentiation, suppresses osteoblastic differentiation induced by both BMP-2 and OS and is a plausible target for therapeutic intervention in OPLL.

Nifedipine enhances cGMP production through the activation of soluble guanylyl cyclase in rat ventricular papillary muscle

It is known that nifedipine, an L-type calcium channel blocker, increases cGMP production, which partially contributes to the relaxation of vascular smooth muscle. The aim of our investigation was to clarify whether or not nifedipine regulates cGMP production, which has a physiological role in cardiac muscle. To measure contractile responses and tissue cGMP levels, left ventricular papillary muscles prepared from male Wistar rats (350-400 g) were mounted in the isolated organ chamber under isometric conditions and electrically paced by means of platinum punctate electrodes (1 Hz, 1 ms duration). In papillary muscle preparation, the negative inotropic effect induced by nifedipine (30 to 300 nM) was significantly inhibited in the presence of ODQ(1H-[1,2,4]oxidazolo[4,3-a]quinoxaline1-one; 10 microM), a soluble guanylyl cyclase inhibitor. Furthermore, nifedipine (100 nM) strongly increased the tissue cGMP level, which was significantly decreased in the presence of ODQ. On the other hand,N(G)-monomethyl-(L)-arginine (100 microM), a nitric oxide synthase inhibitor, did not inhibit either the negative inotropic effect or cGMP production induced by nifedipine. These results indicate that in rat left ventricular papillary muscle, nifedipine augments its negative inotropic effect at least partly through direct activation of cardiac soluble guanylyl cyclase but not nitric oxide synthase.

Current Topics in Pharmacological Research on Bone Metabolism: Molecular Basis of Ectopic Bone Formation Induced by Mechanical Stress

Ectopic bone formation (EBF) is frequently found in various tissues and affects the prognosis of diseases accompanied by EBF. Although the mechanism of EBF remains unclear, several local factors that influence the progression of EBF have been proposed. We have been focusing on the role of mechanical stress as a local factor in EBF in spinal ligament tissues, that is, ossification of the posterior longitudinal ligament (OPLL), which causes serious neurological deficiencies. Transcriptome analyses revealed that the expressions of several marker genes related to bone remodeling were enhanced after exposure of ligament cells derived from OPLL patients (OPLL cells) to cyclic stretching as a type of mechanical stress. However, no significant alterations in gene expressions were detected after cyclic stretching of ligament cells derived from non-OPLL patients. OPLL cells exposed to cyclic stretching released several autocrine/paracrine factors that are known to mediate bone remodeling. These results suggest that OPLL cells have been transformed into cells that are highly sensitive to mechanical stress, which may induce the progression of OPLL. These observations provide information regarding the role of mechanical stress in the process of EBF.

Changes in pH Increase Perfusion Pressure of Coronary Arteries in the Rat

Stricture of coronary arteries is closely related to ischemic heart disease. The purpose of this study was to examine whether changes in pH caused contraction of rat coronary arteries, as determined using Langendorff perfused hearts. Changing the pH of the perfusate increased perfusion pressure as an indication of the contractile state of coronary arteries. Alkaline pH-induced increase of perfusion pressure in Wistar Kyoto rats (WKY) was almost identical to that of spontaneously hypertensive rats (SHR), whereas acidic pH-induced increase in SHR was much greater than that in WKY. Acidic pH-induced increase in perfusion pressure was inhibited by verapamil, cromakalim, and adenosine. Feeding WKY with N(G)-nitro-L-arginine resulted in hypertension followed by enhanced acidic pH-induced increase in perfusion pressure. These results suggest that acidic-pH induced contraction of rat coronary arteries is caused by Ca(2+) influx through voltage-dependent Ca(2+) channels and the contraction is enhanced by hypertension.

Gene expression and functional activity of sodium/calcium exchanger enhanced in vascular smooth muscle cells of spontaneously hypertensive rats

Effects of hypertension on the function of the Na+/Ca2+ exchanger (NCX) were investigated by analyzing vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats. Angiotensin II-induced 45Ca2+ efflux from VSMCs mediated by NCX was enhanced by up to 3-fold in SHR compared with WKY, whereas ionomycin-induced Ca efflux mediated by NCX was not different between SHR and WKY. The decline rate from the peak value of intracellular 45Ca2+ concentration ([Ca2+]i) mobilized by angiotensin II was decelerated by removal of extracellular sodium (Na+o) in SHR but not in WKY. Gene expressions of NCX subtype 1 and angiotensin II receptor type1A assessed by quantitative RT-PCR were increased by 1.3- and 1.5-fold, respectively in SHR compared with WKY. NCX protein was also increased 1.6-fold in SHR compared with WKY. MEK inhibitor, PD98059, partly blocked the Nao-dependent acceleration of the [Ca2+]i recovery rate and tyrosine kinase inhibitor, genistein, diminished it in SHR. Genistein decreased angiotensin II-induced Nao- dependent 45Ca2+ efflux. However, angiotensin II did not enhance the tyrosine phosphorylation of NCX. These results suggest that acceleration of Ca2+ efflux from VSMCs of SHR was at least partly due to the enhancement of functional activity of NCX via increased gene expression and tyrosine phosphorylation in connection with hypertension.

Vasodilative effects of urocortin II via protein kinase A and a mitogen-activated protein kinase in rat thoracic aorta

Four corticotropin-releasing factor (CRF)-related peptides have been found in mammals and are known as CRF, urocortin, urocortin II, and urocortin III (also known as stresscopin). The three urocortins have considerably higher affinities for CRF receptor type 2 (CRF R2) than CRF, and urocortin II and urocortin III are highly selective for CRF R2. In the present study, the authors examined the hypothesis that urocortin II or urocortin III, in addition to urocortin, produces vasodilation as a candidate for natural ligands of CRF R2beta in rat thoracic aorta. Involvement of protein kinases on urocortin-induced vasodilation was also explored. The vasodilative effects of urocortin II and urocortin III were more potent than that of CRF, but less potent than that of urocortin. Urocortin II-induced vasodilation was significantly attenuated by a CRF R2-selective antagonist, antisauvagine-30. Both SQ22536, an adenylate cyclase inhibitor, and Rp-8-Br-cAMPS, a protein kinase A (PKA) inhibitor, were found to attenuate the urocortin II-induced vasodilation. SB203580, a p38 mitogen-activated protein (MAP) kinase inhibitor, also inhibited the effects of urocortin and urocortin II on vasodilation. Thus, urocortins contribute to vasodilation via p38 MAP kinase as well as PKA pathways.

Role of Corticotropin-Releasing Factor Receptor Type 2β in Urocortin-Induced Vasodilation of Rat Aortas

Urocortin has a high affinity for the corticotropin-releasing factor receptor type 2beta (CRF-R2beta). This study was conducted to reveal the role of CRF-R2beta in blood vessels. CRF-R2beta expressions were detected both in smooth muscle and endothelium from Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) aortas, and there was no significant difference between them. Urocortin reduced phenylephrine-induced contraction of aorta with endothelium dose-dependently in both rats. However, deendothelialization significantly but not completely (about 50%) reduced the vasodilation. The reduction of vasodilatory action of urocortin by deendothelialization was age-dependent in SHR. An adenylyl cyclase inhibitor, SQ22536, significantly inhibited urocortin-induced relaxation in denuded WKY and SHR aortas, while in preparations with endothelium, neither SQ22536 nor L-NMMA reduced the relaxation. However, simultaneous addition of both drugs significantly reduced the relaxation. In contrast to young rats (7-week-old), in aged rats (19-week-old), L-NMMA successfully reduced urocortin-induced relaxation of aorta with endothelium. These results suggest that urocortin relaxes aorta at least partly via two signal pathways, that is, an increase in intracellular cAMP by binding to CRF-R2beta expressed in smooth muscle cells and NO production from endothelium evoked by binding to the receptors expressed in endothelium and that aging increases the role of the latter system.

[Role of PGI2 in ectopic bone formation of spinal ligaments]

Ossification of the posterior longitudinal ligament (OPLL) is characterized by ectopic bone formation in the spinal ligaments. It has been suggested some role of mechanical stress in the progression of OPLL. Differential display RT-PCR was carried out to identify the genes participating in OPLL. A cDNA fragment corresponding to PGI2 synthase was highly expressed in OPLL cells compared to non-OPLL cells. To examine the effect of mechanical stress on the PGI2 synthase expression, cells were subjected to cyclic stretch and PGI2 synthase expression was assessed by quantitative RT-PCR. Cyclic stretch induced a time-dependent increase in PGI2 synthase in OPLL cells but not in non-OPLL cells. The increase in PGI2 synthase was diminished by SQ22536, a potent adenylate cyclase inhibitor. Cyclic stretch also induced PGI2 production. Beraprost and dibutyryl cAMP increased the mRNA expression of alkaline phosphatase (ALP) as a marker for osteogenic differentiation in OPLL cells, whereas no change was observed in non-OPLL cells. Beraprost- and stretch-induced increases in ALP expressions were inhibited by SQ22536. These data suggest that PGI2 synthase activated by mechanical stress plays a key role in the progression of OPLL, at least in part through the osteogenic differentiation in spinal ligament cells via the PGI2/cAMP system.

Genomewide linkage and linkage disequilibrium analyses identify COL6A1, on chromosome 21, as the locus for ossification of the posterior longitudinal ligament of the spine

Ossification of the posterior longitudinal ligament (OPLL) of the spine is a subset of "bone-forming" diseases, characterized by ectopic ossification in the spinal ligaments. OPLL is a common disorder among elderly populations in eastern Asia and is the leading cause of spinal myelopathy in Japan. We performed a genomewide linkage study with 142 affected sib pairs, to identify genetic loci related to OPLL. In multipoint linkage analysis using GENEHUNTER-PLUS, evidence of linkage to OPLL was detected on chromosomes 1p, 6p, 11q, 14q, 16q, and 21q. The best evidence of linkage was detected near D21S1903 on chromosome 21q22.3 (maximum Zlr=3.97); therefore, the linkage region was extensively investigated for linkage disequilibrium with single-nucleotide polymorphisms (SNPs) covering 20 Mb. One hundred fifty positional candidate genes lie in the region, and 600 gene-based SNPs were genotyped. There were positive allelic associations with seven genes (P<.01) in 280 patients and 210 controls, and four of the seven genes were clustered within a region of 750 kb, approximately 1.2 Mb telomeric to D21S1903. Extensive linkage disequilibrium and association studies of the four genes indicated that SNPs in the collagen 6A1 gene (COL6A1) were strongly associated with OPLL (P=.000003 for the SNP in intron 32 [-29]). Haplotype analysis with three SNPs in COL6A1 gave a single-point P value of.0000007. Identification of the locus of susceptibility to OPLL by genomewide linkage and linkage disequilibrium studies permits us to investigate the pathogenesis of the disease, which may lead to the development of novel therapeutic tools.

Endothelium-dependent vasodilatory effect of vitisin C, a novel plant oligostilbene from Vitis plants (Vitaceae), in rabbit aorta

We investigated the pharmacological properties of vitisin C, a novel plant oligostilbene from Vitis plants. Vitisin C (1-10 microM) dose-dependently inhibited the contractile responses of endothelium-intact rabbit thoracic aorta induced by phenylephrine (1 microM). These inhibitory effects were abolished in the presence of N (G)-nitro-L-arginine methyl ester (L-NAME; 300 microM), a potent inhibitor of nitric oxide synthase, but not atropine (1 microM), a non-selective muscarinic cholinoceptor antagonist. In endothelium-denuded rabbit aorta, vitisin C was ineffective in attenuating phenylephrine-induced contraction. Moreover, vitisin C (10 microM) increased cGMP production in endothelium-intact, but not endothelium-denuded, aorta, and this increase was abolished in the presence of L-NAME (300 microM). To assess Ca(2+) movement across the endothelial cell membrane induced by vitisin C, we further investigated (45)Ca(2+) influx into cultured rabbit aortic endothelial cells in the presence of vitisin C (3 microM), carbachol (1 microM) or A23187 (10 nM). Vitisin C and carbachol significantly enhanced (45)Ca(2+) influx, which was inhibited by nifedipine (10 microM), a blocker of L-type Ca(2+) channels. In the presence of SK&F96365, a blocker of receptor-operated Ca(2+) channels, (45)Ca(2+) influx induced by carbachol was significantly inhibited, whereas that induced by vitisin C was not affected. On the other hand, A23187 enhanced (45)Ca(2+) influx in the presence and absence of nifedipine and SK&F96365. These results suggest that vitisin C evokes endothelium-dependent vasorelaxation through enhancing nitric oxide release, which is facilitated by Ca(2+) influx into endothelial cells via nifedipine-sensitive Ca(2+) channels.

Role of prostaglandin I2 in the gene expression induced by mechanical stress in spinal ligament cells derived from patients with ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic bone formation in the spinal ligaments, and mechanical stress has been suggested to play an important role in the progression of OPLL. To identify the genes that participate in OPLL, the differential display reverse transcription-polymerase chain reaction (RT-PCR) method was used. A 283-base pair cDNA fragment corresponding to prostaglandin I2 (PGI2) synthase was highly expressed in OPLL cells compared with non-OPLL cells. To examine the effect of mechanical stress on the expression of PGI2 synthase, cells were subjected to uniaxial cyclic stretch (0.5 Hz, 20% stretch), and PGI2 synthase mRNA expression was assessed by quantitative RT-PCR. Cyclic stretch induced an increase in PGI2 synthase in OPLL cells in a time-dependent manner, whereas no change was observed in non-OPLL cells. Cyclic stretch for 9 h also induced a 2.86x increase in PGI2 production. Beraprost (a stable PGI2 analog) and dibutyryl cAMP (a membrane-permeable cAMP analog) increased the mRNA expression of alkaline phosphatase (ALP) as a marker for osteogenic differentiation up to 240 and 200%, respectively, in OPLL cells, whereas no change was observed in non-OPLL cells. The increases in ALP mRNA induced by beraprost and cyclic stretch were both inhibited by SQ22536, a potent adenylate cyclase inhibitor. These data suggest that the increase in PGI2 synthase induced by mechanical stress plays a key role in the progression of OPLL, at least in part through the induction of osteogenic differentiation in spinal ligament cells via the PGI2/cAMP system.

Stimulated tyrosine phosphorylation of phosphatidylinositol 3-kinase causes acidic pH-induced contraction in spontaneously hypertensive rat aorta

Acidic pH induced a contraction (APIC) in isolated aortas from spontaneously hypertensive (SHR) and Wistar Kyoto rats, but failed to produce any response in age-matched Wistar rat aorta. This study was conducted to test the hypothesis that tyrosine phosphorylation of proteins is a molecular mechanism underlying the APIC. Tyrosine kinase inhibitors, genistein and tyrphostin 23 inhibited the APIC in a concentration-dependent manner. APIC was inhibited by phosphatidylinositol 3-kinase (PI3-kinase) inhibitors, LY-294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one hydrochloride] and wortmannin. Consistent with the results from tension measurement experiments, Western blot analysis showed that acidic pH induced an appreciable increment of tyrosine phosphorylation of 85-kDa protein (p85) in SHR aorta, which was completely inhibited by tyrphostin 23, whereas in Wistar rat aorta, the protein tyrosine phosphorylation was not observed. Further investigations using immunoprecipitation followed by Western blotting confirmed an increase in the tyrosine phosphorylation of p85. Analysis by SDS-polyacrylamide gel electrophoresis followed by silver staining of the gel revealed that amounts of multiple proteins with molecular sizes of 120, 130, 210, and 225 kDa were increased at acidic pH, which were immunoprecipitated with anti-phosphotyrosine antibody. Western blotting using a specific anti-PI3-kinase antibody identified the p85 as the regulatory subunit of PI3-kinase, whereas 120-, 130-, and 225-kDa proteins were identified by mass spectrometry as pro-alpha2 (I) collagen, collagen alpha1 (I) chain, and fibernectin I, respectively. As assayed by Western blotting using anti-myosin light chain (MLC) antibody, acidic pH induced a stimulation of MLC phosphorylation, and the stimulated MLC phosphorylation was abolished by tyrphostin 23 and LY-294002. These results suggest that acidic pH induces an increase in tyrosine phosphorylation of PI3-kinase, resulting in the MLC phosphorylation-dependent contraction of SHR aorta.

Antisense-inhibition of plasma membrane Ca2+ pump induces apoptosis in vascular smooth muscle cells

The effect of antisense oligodeoxynucleotides (ODNs) of plasma membrane Ca(2+)-pumping ATPase (PMCA) on rat aortic vascular smooth muscle cells (VSMCs) in primary culture was examined. More than 80% of the PMCA expressed in cultured VSMCs was the PMCA-1B subtype. Exposed to antisense ODNs against PMCA-1, not only the expression of the PMCA protein but also mRNA of PMCA-1B was diminished in a concentration-dependent manner. Extracellular Na(+)-independent (45)Ca(2+) efflux catalyzed via PMCA was inhibited with antisense ODNs. Both the resting and ionomycin- or ATP-stimulated levels of intracellular Ca(2+) were increased by antisense ODNs. Furthermore, prolonged treatment with antisense ODNs caused apoptosis in VSMCs. The occurrence of apoptosis was inhibited by FK506, a potent immunosuppressant. These results demonstrate that the PMCA was specifically inhibited by antisense ODNs and suggest that PMCA plays an important role in regulation of intracellular Ca(2+) concentrations, especially at the resting condition to prevent an occurrence of apoptosis that may be induced through the activation of calcineurin.

Possible roles of CTGF/Hcs24 in the initiation and development of ossification of the posterior longitudinal ligament

STUDY DESIGN

A biochemical and histochemical study investigating the role of CTGF/Hcs24 in the ossification of the posterior longitudinal ligament (OPLL) was conducted.

OBJECTIVE

To clarify the involvement of CTGF/Hcs24 in ectopic bone formation in OPLL through endochondral ossification using human tissue.

SUMMARY OF BACKGROUND DATA

Previous studies have shown that various cytokines are involved in the occurrence or development of ectopic bone formation in OPLL. Recently, the authors cloned an mRNA predominantly expressed in chondrocytes by differential display PCR and found that its gene, hcs24, is identical to that of connective tissue growth factor. It has been shown that CTGF/Hcs24 plays a major role in endochondral ossification.

METHODS

Ossified ligament tissues were taken from seven male OPLL patients during surgery. Immunohistochemical staining was performed using an antibody specific for CTGF/Hcs24. Spinal ligament cells were isolated from five OPLL patients as well as five non-OPLL patients. The cells were incubated with recombinant human CTGF/Hcs24 or TGFbeta. The expression of ALP was analyzed by RT-PCR. For the effects of TGFbeta, the expression of CTGF/Hcs24 mRNA was analyzed.

RESULTS

Immunohistochemical staining showed that chondrocytes in the transitional region from nonossified to ossified ligament were stained with an antibody against CTGF/Hcs24. It was found that CTGF/Hcs24 enhanced the expression ALP mRNA in OPLL cells, whereas the expression remained unchanged in non-OPLL cells. The expression of CTGF/Hcs24 mRNA in OPLL and non-OPLL cell lines was increased by TGFbeta, and there was no significant difference between the two groups. However, TGFbeta and CTGF/Hcs24 enhanced the expression of ALP mRNA only in OPLL cells.

CONCLUSIONS

According to the study results, CTGF/Hcs24 may not only be an important factor in the development of endochondral ossification in OPLL, but may also be responsible for initiating osteogenesis in spinal ligament cells.