Quantifying division of aortal smooth muscle cells in culture stimulated by 1,25(OH)2D3

Inhibitory effect of 1α,25dihydroxycholecalciferol (1,25D₃ = calcitriol) in different cell type is well recognized but its promoting effect on vascular smooth muscle cells (SMCs) is poor established. Therefore, the aim of this study was to determine stimulatory effect of calcitriol on aortal SMCs proliferation in culture. We used the cell division analysis procedure based on the quantitative sequential halving of the stably incorporating fluorescent dye carboxyfluorescein diacetate succinimidyl ester (CFSE). This technique allowed the visualization of cycles of SMCs division by flow cytometry. Rat aortal SMCs were labeled with CFSE and cultured for up to 10 days with defined concentration of calcitriol in medium. Proliferative activity as the percentage of SMCs in different phases of the cell cycle using propidium iodide was determined. Apoptosis was assessed using Annexin-V/CFDA method. The results suggest that low concentrations of an active form of vitamin D—1α,25dihydroxycholecalciferol applied in supraphysiological concentration of 10 nmol/l is a mitogenic factor for aortal SMCs. None of the applied concentrations of calcitriol caused apoptosis. The findings well support our morphological (LM) and ultrastructural (TEM and SEM) observations.     

Caffeine decreases vitamin D receptor protein expression and 1,25(OH)2D3 stimulated alkaline phosphatase activity in human osteoblast cells

Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300 mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D₃ (1,25(OH)₂D₃) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)₂D₃, VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)₂D₃ mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10 mM) on 1,25(OH)₂D₃ induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)₂D₃ induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)₂D₃ induced VDR expression and at concentrations of 1 and 10 mM, VDR expression was decreased by about 50–70%, respectively. In addition, the 1,25(OH)₂D₃ induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)₂D₃ stimulated VDR protein expression and 1,25(OH)₂D₃ mediated actions in human osteoblast cells.     

Clusterin over-expression modulates proapoptotic and antiproliferative effects of 1,25(OH)2D3 in prostate cancer cells in vitro

Prostate cancer is the most commonly diagnosed cancer in the majority of western countries. Due to their antiproliferative and proapoptotic activity, vitamin D analogues have been introduced recently as an experimental therapy for prostate cancer. Clusterin (CLU) is a glycoprotein that has two known isoforms generated in human cells. A nuclear form of CLU protein (nCLU) is pro-apoptotic, and a secretory form (sCLU) is pro-survival. In this study, we analyzed whether proapoptotic and antiproliferative effects of 1,25(OH)₂D₃ on LNCaP prostate cancer cells are modulated by expression of sCLU. Using colony forming assay, we studied the effect of treatment with different doses of 1,25(OH)₂D₃ (10⁻⁶, 10⁻⁷, 10⁻¹⁰ M) on proliferation of LNCaP cells that were stable transfected and over-express sCLU (LNT-1) as compared to empty vector-transfected cells (LN/C). We also measured apoptosis using TUNEL assay. sCLU over-expression protected against both antiproliferative (30%) and proapoptotic (15%) effects of 1,25(OH)₂D₃, although this effect was statistically not significant. In conclusion, our findings demonstrate that expression of sCLU modulates growth regulatory effects of 1,25(OH)₂D₃ in prostate cancer indicating that CLU interferes with vitamin D signalling pathways.     

PTH(7-84) inhibits PTH(1-34)-induced 1,25-(OH)2D3 production in murine renal tubules

To elucidate whether PTH(7-84), a degradation product of PTH(1-84), which inhibits PTH(1-84)-induced bone resorption, also exerts an antagonistic effect on the kidney, we studied the effect of PTH(7-84) on PTH(1-34)-induced production of 1,25-(OH)₂D₃ in primary cultured murine renal tubules.Neonatal mouse renal tubules cultured in serum-free MEM for 7 days were treated with PTH(1-34) and/or PTH(7-84). Three hours after addition of 25-OHD₃ (10⁻⁶ M), 1,25-(OH)₂D₃ was determined. PTH(1-34) stimulated the conversion of 25-OHD₃ to 1,25-(OH)₂D₃, and PTH(7-84) dose-dependently inhibited this process. Real-time PCR revealed that PTH(1-34) increased the expression level of 1α-hydroxylase mRNA, whereas PTH(7-84) did not affect the expression level 1α or 24-hydroxylase mRNA.These in vitro data suggest that PTH(7-84) elicits an antagonistic effect in renal tubules through receptors different from the type I PTH/PTHrP receptor. This may at least partly account for the decreased serum level of 1,25-(OH)₂D in patients with severe primary hyperparathyroidism with renal failure.     

不明原因复发性流产再次妊娠患者血清1,25(OH)2D3、sTim-3与Th17/Treg免疫失衡和妊娠结局的关系

摘要 目的：探讨不明原因复发性流产（URSA）再次妊娠患者血清1,25-二羟维生素D3[1,25（OH)）₂D₃]、可溶性T细胞免疫球蛋白黏蛋白分子3（sTim-3）与辅助性T细胞17（Th17）/调节性T细胞（Treg）免疫失衡和妊娠结局的关系。方法：选择于湖南省妇幼保健院2020年1月~2022年1月就诊的62例URSA再次妊娠患者作为研究组,另选择同期进行孕检的正常早孕妇女30例作为对照组。比较两组孕早期血清1,25(OH) ₂D₃、sTim-3及外周血Th17细胞、Treg细胞水平、Th17/Treg比值。Pearson法分析URSA再次妊娠患者血清1,25(OH) ₂D₃、sTim-3与外周血Th17细胞、Treg细胞水平、Th17/Treg比值平的相关性。根据URSA再次妊娠患者妊娠结局的不同分为妊娠成功分娩组和妊娠再次流产组,比较两组孕早期血清1,25(OH) ₂D₃、sTim-3与外周血Th17细胞、Treg细胞水平、Th17/Treg比值。受试者工作特征（ROC）曲线分析血清1,25(OH) ₂D₃、sTim-3与外周血Th17细胞、Treg细胞水平、Th17/Treg比值对妊娠结局的预测价值。结果：研究组血清sTim-3、外周血Th17细胞水平、Th17/Treg比值高于对照组,血清1,25(OH) ₂D₃、外周血Treg细胞水平低于对照组（P<0.05）。Pearson相关分析显示,URSA再次妊娠患者血清1,25(OH) ₂D₃与血清sTim-3、外周血Th17细胞水平、Th17/Treg比值呈负相关,与Treg细胞水平呈正相关（P<0.05）;血清sTim-3与外周血Treg细胞水平呈负相关,与Th17细胞水平、Th17/Treg比值呈正相关（P<0.05）。妊娠再次流产组血清sTim-3、外周血Th17细胞水平、Th17/Treg比值高于妊娠成功分娩组,血清1,25(OH) ₂D₃、外周血Treg细胞水平低于妊娠成功分娩组（P<0.05）。ROC曲线分析显示,血清1,25(OH) ₂D₃、sTim-3及外周血Th17细胞、Treg细胞水平及Th17/Treg比值均可预测URSA再次妊娠患者妊娠再次流产的发生风险,且上述指标联合检测的预测效能更高。结论：血清1,25(OH) ₂D₃水平异常降低、sTim-3水平异常升高可导致Th17/Treg免疫失衡,导致URSA再次妊娠患者再次发生流产。上述指标联合检测对URSA再次妊娠患者妊娠再次流产的预测效能更高。     

早产儿急性呼吸窘迫综合征血清1,25-(OH)2D3、PGRN、SIRT1、CTRP3水平与炎症反应和预后的关系研究

摘要 目的：探讨不同病情严重程度早产儿急性呼吸窘迫综合征（ARDS）血清1,25-二羟维生素D₃（1,25-(OH) ₂D₃）、颗粒体蛋白前体（PGRN）、沉默信息调节因子2相关酶1（SIRT1）、C1q/肿瘤坏死因子相关蛋白3（CTRP3）的变化，分析其与炎症反应和预后的关系。方法：选择2018年10月至2019年12月安徽省妇幼保健院收治的ARDS早产儿100例作为ARDS组，另选取同期在我院出生的健康新生儿60例作为对照组。根据《"新生儿急性呼吸窘迫综合征"蒙特勒标准（2017年版）》的病情判定标准将ARDS早产儿分为轻度组（n=40）、中度组（n=32）、重度组（n=28），比较不同病情严重程度ARDS早产儿血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3、炎症反应指标肿瘤坏死子因子-α（TNF-α）、白细胞介素-6（IL-6）、白细胞介素-1β（IL-1β）水平变化，采用Pearson法分析ARDS早产儿血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3与炎症反应指标的相关性。另根据ARDS组患儿预后情况分为预后良好组（n=65）和预后不良组（n=35），采用单因素和多因素Logistic回归分析影响ARDS早产儿预后不良的危险因素。结果：ARDS组血清1,25-(OH) ₂D₃、SIRT1、CTRP3、PGRN水平明显低于对照组（P<0.05），ARDS组血清TNF-α、IL-6、IL-1β水平明显高于对照组（P<0.05）。不同病情严重程度ARDS早产儿血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3、炎症反应指标比较差异有统计学意义（P<0.05）。ARDS早产儿血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3水平与TNF-α、IL-6、IL-1β水平呈负相关（P<0.05）。多因素Logistic回归分析结果显示，低出生体重、肺表面活性物质（PS）使用次数≥3次、出现低白蛋白血症是影响ARDS早产儿预后不良的危险因素（P<0.05），血清1,25-(OH)2D3（较高）、PGRN（较高）、SIRT1（较高）、CTRP3（较高）是ARDS早产儿预后不良的保护因素（P<0.05）。结论：血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3可能参与ARDS早产儿的炎症反应过程，与ARDS早产儿的病情进展及预后密切相关，检测血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3有助于评估ARDS早产儿的预后。     

Phosphate uptake in chick kidney cells: effects of 1,25(OH)2D3 and 24,25(OH)2D3

Phosphate homeostasis is controlled in part by absorption from the intestine, and reabsorption in the kidney. While the effect of Vitamin D metabolites on enterocytes is well documented, in the current study we assess selected responses in primary cultures of kidney cells. Time course studies revealed a rapid stimulation of phosphate uptake in cells treated with 1,25(OH)(2)D(3), relative to controls. Dose-response studies indicated a biphasic curve with optimal stimulation at 300 pM 1,25(OH)(2)D(3) and inhibition at 600 pM seco-steroid. Antibody 099--against the 1,25D(3)-MARRS receptor - abolished stimulation by the steroid hormone. Moreover, phosphate uptake was mediated by the protein kinase C pathway. The metabolite 24,25(OH)(2)D(3), which was found to inhibit the rapid stimulation of phosphate uptake in intestinal cells, had a parallel effect in cultured kidney cells. Finally, the 24,25(OH)(2)D(3) binding protein, catalase, was assessed for longer term down regulation. In both intestinal epithelial cells and kidney cells incubated with 24,25(OH)(2)D(3) for 5-24h, both the specific activity of the enzyme and protein levels were decreased relative to controls, while 1,25(OH)(2)D(3) increased both parameters over the same time periods. We conclude that the Vitamin D metabolites have similar effects in both kidney and intestine, and that 24,25(OH)(2)D(3) may have effects at the level of gene expression.     

Beta-1 integrins mediate substrate dependent effects of 1α,25(OH)2D3 on osteoblasts

Surface micron-scale and submicron scale features increase osteoblast differentiation and enhance responses of osteoblasts to 1,25-dihydroxyvitamin D₃ [1α,25(OH)₂D₃]. β₁ integrin expression is increased in osteoblasts grown on Ti substrates with rough microarchitecture, and it is regulated by 1α,25(OH)₂D₃ in a surface-dependent manner. To determine if β₁ has a role in mediating osteoblast response, we silenced β₁ expression in MG63 human osteoblast-like cells using small interfering RNA (siRNA). In addition, MG63 cells were treated with two different monoclonal antibodies to human β₁ to block ligand binding. β₁-silenced MG63 cells grown on a tissue culture plastic had reduced alkaline phosphatase activity and levels of osteocalcin, transforming growth factor β₁, prostaglandin E₂, and osteoprotegerin in comparison with control cells. Moreover, β₁-silencing inhibited the effects of surface roughness on these parameters and partially inhibited effects of 1α,25(OH)₂D₃. Anti β₁ antibodies decreased alkaline phosphatase but increase osteocalcin; effects of 1α,25(OH)₂D₃ on cell number and alkaline phosphatase were reduced and effects on osteocalcin were increased. These findings indicate that β₁ plays a major and complex role in osteoblastic differentiation modulated by either surface microarchitecture or 1α,25(OH)₂D₃. The results also show that β₁ mediates, in part, the synergistic effects of surface roughness and 1α,25(OH)₂D₃.     

1,25(OH)2-vitamin D3 actions on cell proliferation, size, gene expression, and receptor localization, in the HL-1 cardiac myocyte

The steroid hormone 1,25(OH)₂-vitamin D₃ [1,25D] has been shown to affect the growth and proliferation of primary cultures of ventricular myocytes isolated from neonatal rat hearts. The research presented here shows that the vitamin D receptor [VDR] is present in murine cardiac myocytes (HL-1 cells), and that 1,25D affects the growth, proliferation and morphology of these cells. In addition we show that 1,25D effects expression of ANP, myotrophin, and c-myc. Furthermore, 1,25D effects expression and localization of the VDR within the cell. Murine HL-1 cardiac myocytes were grown and treated with 1,25D in culture, and growth and morphology were assessed with microscopic analysis. Cells were counted and protein levels were evaluated through Western blot analysis. Subcellular localization of the VDR was determined using immunofluorescence and confocal microscopy. 1,25D was found to decrease proliferation and alter cellular morphology of the HL-1 cells. Treatment with 1,25D increased expression of myotrophin while decreasing expression of atrial natriuretic peptide [ANP] and c-myc. 1,25D treatment also increased expression and nuclear localization of the VDR in these cardiac myocytes. Thus 1,25D is an important hormone involved in modulating and maintaining heart cell structure and function.     

Autoradiographic studies with 3H 1,25 (OH)2 vitamin D3 and 3H 25 (OH) vitamin D3 in rat parathyroid glands

Summary After injection of radiolabeled 1,25 (OH)₂ vitamin D₃, nuclear concentration of radioactivity is observed in parenchymal cells of the parathyroid gland in pregnant, adult male, and 10-day male neonatal rats. In competition studies with unlabeled 1,25 (OH)₂ vitamin D₃, but not with 25 (OH) vitamin D₃, nuclear uptake is prevented. Experiments with ³H 25 (OH) vitamin D₃, in contrast to ³H 1,25 (OH)₂ vitamin D₃, do not show nuclear concentration in cells of the parathyroid. The results of the autoradiographic studies suggest the presence of receptors for a direct effect of 1,25 (OH)₂ vitamin D₃ on the parathyroid gland for modulation of parathyroid hormone secretion.     

Vanadium and 1, 25 (OH)2 vitamin D3 combination in inhibitions of 1,2, dimethylhydrazine-induced rat colon carcinogenesis

The current investigation demonstrates the antitumor effects of combined supplementations of vanadium (V) (4.27 µmol/L drinking water ad libitum) and1α, 25-dihydroxy vitamin D₃ (Vitamin D₃) (0.3 μg/100 μL propylene glycol per os twice a week) on 1, 2 dimethylhydrazine (DMH) (20 mg/kg body weight) induced rat colon carcinogenesis. There was a significant reduction in incidence (70%), multiplicity (P < 0.0001) and volume (P < 0.01) of colon tumors. HPLC-fluorescence assay detected the combinatorial actions of V and Vitamin D₃ against DMH-induced colonic O⁶-methylguanine DNA adducts formation (at four sequential time points; ANOVA, F = 13.56, P < 0.01). Simultaneous inhibition of DNA single strand breaks (P < 0.001) indicates the potency of the combination regimen in limiting the initiation event of colon carcinogenesis. Immunohistochemical analysis revealed that the effect of V and vitamin D₃ occurred through suppression of cell proliferation (BrdU-LI: P < 0.001) along with an induction of apoptosis (TUNEL-LI: P < 0.01). The immunoexpression of tumor suppressor p53 and downregulation of antiapoptotic protein BCl-2 in subsequent immunofluorescence assay further provide strong evidence for the combinatorial inhibitory actions of vanadium and vitamin D₃ against DMH-induced rat colon carcinogenesis.     

25(OH)D3 and 1,25(OH)2D3 serum concentration and breast tissue expression of 1alpha-hydroxylase, 24-hydroxylase and Vitamin D receptor in women with and without breast cancer

1,25(OH)2D3 is an antiproliferative agent that may inhibit proliferation of breast cancer (BC) cells in vitro and BC development in animals. Epidemiological studies have shown a high incidence of BC in people less exposed to solar rays. To unravel the role of Vitamin D3 in BC patients, we have investigated serum levels of 25(OH)D3 and its active form 1,25(OH)2D3 as well as tissue expression of 1alpha-hydroxylase, 24-hydroxylase, and Vitamin D-receptor (VDR), determined by semiquantitative RT-PCR, in 88 Brazilian BC patients and 35 women without cancer (submitted to mammoplasties or resection of benign lesions). Median age of women with and without cancer was 51 and 46 years, respectively, and the majority of BC patients were classified as clinical stage II (67%). Although no differences in 25(OH)D3 serum concentration were found, 1,25(OH)2D3 (40+/-21 pg/ml) levels in BC patients were lower than in women without cancer (53+/-23). Our results indicate that 24-hydroxylase, VDR and 1alpha-hydroxylase mRNA tissue expression is similar in both groups and no correlation between 24-hydroxylase, 1alpha-hydroxylase, and VDR expression in breast tumors was found. A low 1,25(OH)2D3 serum concentration seems to be associated to breast cancer, however, the mechanism involved in this regulation is still unclear.     

Effect of 1,25(OH)(2)D(3) on rat peritoneal mesothelial cells treated with high glucose plus lipopolysaccharide

1,25(OH)₂D₃, the active metabolite of vitamin D₃, its activity is not limited to mineral and skeletal homeostasis. In recent years, there has been increasing evidence pointing to the role of its activity in the regulation of cell proliferation, cell differentiation and immunomodulation. Here we report lipopolysaccharide (LPS), a glycolipid that is produced and secreted by gram-negative bacteria during peritonitis, plus high glucose (HG) can significantly inhibit mesothelial cell viability while induce more apoptosis in rat peritoneal mesothelial cells (RPMC). Pretreatment with 1,25(OH)₂D₃ can reverse the above effect in a concentration dependent manner. HG plus LPS can down-regulate the levels of both mRNA and protein of VDR, and up-regulate the expression of TGF-β1 and TNF-α in RPMC, which can also be effectively reversed by pretreatment with 1,25(OH)₂D₃. The above results suggest that HG plus LPS may induce changes in RPMC’s viability and apoptosis, leading to peritoneal injury. 1,25(OH)₂D₃ can reverse the inhibition of cell viability, the increase of apoptotic rate and induction of fibrosis related cytokine TGF-β1 and TNF-α by HG plus LPS in RPMC, thus protect peritoneal membrane.     

A novel interaction between thyroid hormones and 1,25(OH)(2)D(3) in osteoclast formation

Thyroid hormones enhance osteoclast formation and their excess is an important cause of secondary osteoporosis. 3,5,3' -Triiodo-L-thyronine (T3) induced the mRNA expression of receptor activator of nuclear factor-kappa B ligand (RANKL), which is a key molecule in osteoclast formation, in primary osteoblastic cells (POB). This effect was amplified in the copresence of 1 alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)). Although T3 alone did not induce octeoclasts in coculture of bone marrow cells with POB, T3 enhanced 1,25(OH)(2)D(3)-induced osteoclast formation. Thyroxine (T4) also enhanced 1,25(OH)(2)D(3)-induced osteoclast formation. These data suggested that T4 was locally metabolized to T3 for its action, since T4 is a prohormone with little hormonal activity. The mRNA expression of type-2 iodothyronine deiodinase (D2), which is responsible for maintaining local T3 concentration, was induced by 1,25(OH)(2)D(3) dose- and time-dependently. Our data would facilitate our understanding of the mechanism of osteoclast formation by thyroid hormones and suggest a novel interaction between thyroid hormones and 1,25(OH)(2)D(3).     

1α,25(OH)2D3 is an autocrine regulator of extracellular matrix turnover and growth factor release via ERp60 activated matrix vesicle metalloproteinases

Growth plate chondrocytes produce proteoglycan-rich type II collagen extracellular matrix (ECM). During cell maturation and hypertrophy, ECM is reorganized via a process regulated by 1α,25(OH)₂D₃ and involving matrix metalloproteinases (MMPs), including MMP-3 and MMP-2. 1α,25(OH)₂D₃ regulates MMP incorporation into matrix vesicles (MVs), where they are stored until released. Like plasma membranes (PM), MVs contain the 1α,25(OH)₂D₃-binding protein ERp60, phospholipase A₂ (PLA₂), and caveolin-1, but appear to lack nuclear Vitamin D receptors (VDRs). Chondrocytes produce 1α,25(OH)₂D₃ (10⁻⁸ M), which binds ERp60, activating PLA₂, and resulting lysophospholipids lead to MV membrane disorganization, releasing active MMPs. MV MMP-3 activates TGF-β1 stored in the ECM as large latent TGF-β1 complexes, consisting of latent TGF-β1 binding protein, latency associated peptide, and latent TGF-β1. Others have shown that MMP-2 specifically activates TGF-β2. TGF-β1 regulates 1α,25(OH)₂D₃-production, providing a mechanism for local control of growth factor activation. 1α,25(OH)₂D₃ activates PKCα in the PM via ERp60-signaling through PLA₂, lysophospholipid production, and PLCβ. It also regulates distribution of phospholipids and PKC isoforms between MVs and PMs, enriching the MVs in PKCζ. Direct activation of MMP-3 in MVs requires ERp60. However, when MVs are treated with 1α,25(OH)₂D₃, PKCζ activity is decreased and PKCα is unaffected, suggesting a more complex feedback mechanism, potentially involving MV lipid signaling.     

Sertoli cells in the testis and epithelium of the ductuli efferentes are targets for 3H 1,25 (OH)2 vitamin D3

Summary Evidence from results of autoradiographic studies in mice indicates that nuclei of Sertoli cells and of epithelial cells in the ductuli efferentes contain receptors for 1,25(OH)₂ vitamin D₃.     

Sn-S and Ru-Ru bonds cleavage reactions between [Ph3SnS(CH2)3SSnPh3] and Ru3(CO)12: X-ray crystal structures of [Ph3SnS(CH2)3SSnPh3] and trans-[Ru(CO)4(SnPh3)2]

The organotin complex [Ph₃SnS(CH₂)₃SSnPh₃] (1) was synthesized by PdCl₂ catalyzed reaction between Ph₃SnCl and disodium-1,3-propanedithiolate which in turn was prepared from 1,2-propanedithiol and sodium in refluxing THF. Reaction of 1 with Ru₃(CO)₁₂ in refluxing THF affords the mononuclear complex trans-[Ru(CO)₄(SnPh₃)₂] (2) and the dinuclear complex [Ru₂(CO)₆(μ-κ²-SCH₂CH₂CH₂S)] (3) in 20 and 11% yields, respectively, formed by cleavage of Sn-S bond of the ligand and Ru-Ru bonds of the cluster. Treatment of pymSSnPPh₃ (pymS = pyrimidine-2-thiolate) with Ru₃(CO)₁₂ at 55-60 °C also gives 2 in 38% yield. Both 1 and 2 have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction analysis.     

Bone morphogenetic protein-7 (OP1) and transforming growth factor-beta1 modulate 1,25(OH)2-vitamin D3-induced differentiation of human osteoblasts

Bone morphogenetic proteins (BMPs) and transforming growth factor-beta (TGFbeta) are potent regulators of osteoblast differentiation and proliferation, processes that are crucial in bone remodeling. BMPs and TGFbeta act in concert with other local factors and hormones, among them 1,25(OH)2-vitamin D3 and insulin. Here we show that BMP7 inhibits 1,25(OH)2-vitamin D3-induced differentiation of human osteoblasts, whereas TGFbeta1 stimulates it, as assessed by assays for alkaline phosphatase (ALP) induction, matrix mineralization, and morphology changes. BMP7 or TGFbeta1 alone affects the differentiation of human osteoblasts. Similar results were obtained in assays for ALP induction using conditionally immortalized human osteoblasts (hFOB) and primary osteoblasts obtained from trabecular bone of the femoral head after hip replacement surgery. BMP7 stimulation led to a decrease of 1,25(OH)2-vitamin D3-induced binding of nuclear proteins to a vitamin D response element, as shown by electrophoretic mobility shift assay. Our results suggest that 1,25(OH)2-vitamin D3 modulates in opposite ways the effects of BMP7 and TGFbeta1 on osteoblast differentiation.