Estradiol‑enhanced osteogenesis of rat bone marrow stromal cells is associated with the JNK pathway

USF2 reduces BMP3 expression via transcriptional activation of miR-34a, thus promoting osteogenic differentiation of BMSCs

INTRODUCTION

Osteoporosis is the most susceptible disease for people over 60. The main cause of osteoporosis is the decreased osteogenic differentiation of mesenchymal stem cells (MSCs). Here we showed that upstream stimulatory factor 2 (USF2)/microRNA-34a (miR-34a)/bone morphogenetic protein 3 (BMP3) axis regulated osteogenic differentiation of BMSCs.

MATERIALS AND METHODS

USF2 and miR-34a expression were examined using qPCR. Protein levels of BMP3 and osteogenic markers expression were evaluated using both western blot and qPCR. Activity of ALP was determined by ALP assay kit. Mineralization capacity of hBMSCs was assessed using ARS. Besides, CHIP assay was employed to verify whether USF2 could bind to miR-34a promoter. Finally, RIP assay and dual-luciferase reporter assay were employed to verify whether miR-34a directly bound to BMP3.

RESULTS

Our results suggested that miR-34a was upregulated during osteogenic differentiation of BMSCs, and miR-34a overexpression could enhance osteogenic differentiation of BMSCs. USF2 could positively regulate miR-34a expression by interacting with its promoter. USF2 overexpression enhanced osteogenic differentiation of BMSCs, while miR-34a inhibition reversed the effect. Besides, BMP3 was the target of miR-34a. MiR-34a overexpression enhanced osteogenic differentiation of BMSCs, which was abolished by BMP3 overexpression.

CONCLUSION

Taken together, USF2 enhanced osteogenic differentiation of BMSCs via downregulating BMP3 by interacting with miR-34a promoter.

Timing and dosage of and adherence to hormone replacement therapy and fracture risk in women with menopausal syndrome in Taiwan: A nested case-control study

OBJECTIVE

To investigate the association between hormone replacement therapy (HRT) and the risk of bone fracture in menopausal women in Taiwan.

STUDY DESIGN

The longitudinal, population-based, nested case-control study in Taiwan involved 5269 women aged > 45 years with fractures and 21,076 matched randomly selected controls without fractures. A conditional logistic regression model of analysis was employed.

MAIN OUTCOME MEASURES

The association between the risk of bone fracture and various HRT-related parameters, including the timing, dosage, and adherence, was investigated.

RESULTS

Women with menopausal syndrome were protected from fractures when they received hormone drugs at high cumulative defined daily doses (DDDs) (Cumulative DDDs≥360) (odds ratio [OR]: 0.90, 95 % confidence interval [CI]: 0.82-0.99) and when their adherence was high (over 0.5) (OR: 0.70, 95 % CI: 0.60-0.82). The risk of fracture also decreased with high cumulative DDDs and high adherence combined (OR: 0.71, 95 % CI: 058-0.86). Subgroup analyses suggested that estrogen-containing regimens showed a protective effect against fractures at high cumulative DDDs or when adherence was high. Similar results were also observed with progestogen-containing regimens. Past exposure to an estrogen-containing regimen showed a protective effect against fractures when adherence was high. Past exposure to a progestogen-containing regimen showed a protective effect against fractures at high cumulative DDDs and when adherence was high.

CONCLUSIONS

The results indicate that past exposure to estrogen-containing or progestogen-containing regimens exerts protective effects against bone fracture. These effects increased with higher cumulative DDDs and with adherence in a dose-dependent manner.

JUN promotes chicken female differentiation by inhibiting Smad2

The sex determination and control of poultry is a key problem in production and scientific research despite few studies on regulatory factors, especially transcription factors in sex determination. In the early stage of this study, high-throughput sequencing was used to screen the differentially expressed gene JUN in male and female embryonic stem cells (ESCs) and primordial germ cells (PGCs). The qRT-PCR discovered that the JUN gene significantly increased from embryonic days (E) 2.5 later in chicken embryo development, and the female gonad expression was much higher than that of the male after E14.5. Lentivirus shRNA-JUN, shRNA-Smad2 interference, and OE-JUN overexpression vectors were successfully constructed. After interfering with JUN in vivo, male characteristics appeared in ZW embryonic gonads at E18.5. Meanwhile, the male-specific genes DMRT1 and Sox9 were upregulated, the female-specific genes FOXL2, ESR1, and CYP19A1 were downregulated, and the estradiol in the gonads was significantly decreased. The situation was reversed after the overexpression of JUN, ZZ chicken embryo developed into female sexual characteristics. The double luciferase report has found that the Smad2 promoter activity was significantly upregulated after interference with JUN, and significantly increased after the deletion of the JUN binding site. After the injection of the Smad2-shRNA vector into the blood vessel in vivo, it was discovered that DMRT1 and Sox9 of ZW embryos at E18.5 were downregulated, FOXL2 and CYP19A1 were significantly upregulated, and the gonads show femininity. In conclusion, this study proves that JUN is a key regulator in the process of chicken female sex differentiation, which can inhibit the transcription of Smad2 and promote the synthesis of estradiol, and participate in the process of chicken sex differentiation. This study lays a foundation for the analysis of the molecular mechanism of chicken sex determination and the development of poultry sex control technology.

miR-122 Exerts Inhibitory Effects on Osteoblast Proliferation/Differentiation in Osteoporosis by Activating the PCP4-Mediated JNK Pathway

Osteoporosis is characterized by the reduction of bone mineral density and deterioration of bone quality which leads to high risk of fractures. Some microRNAs (miRNAs) have been confirmed as potential modulators of osteoblast differentiation to maintain bone mass maintenance. We aimed to clarify whether miR-122 could regulate osteoblast differentiation in ovariectomized rats with osteoporosis. miR-122 was upregulated and Purkinje cell protein 4 (PCP4) was downregulated in ovariectomized rats. PCP4 was identified as a target of miR-122 by dual-luciferase reporter gene assay. We transfected isolated osteoblasts from ovariectomized rats with miR-122 mimic or inhibitor or PCP4 overexpression vectors. Proliferation and differentiation of osteoblasts were repressed by the overexpression of miR-122 but enhanced by overexpression of PCP4. miR-122 could induce the activation of the c-Jun NH2-terminal kinase (JNK) signaling pathway, while PCP4 blocked this pathway. Rescue experiments further demonstrated that the inhibiting effects of miR-122 on osteoblast differentiation could be compensated by activation of the PCP4 or inhibition of JNK signaling pathway. Collectively, our data imply that miR-122 inhibits osteoblast proliferation and differentiation in rats with osteoporosis, highlighting a novel therapeutic target for osteoporotic patients.

Effects of testosterone and 17β-estradiol on osteogenic and adipogenic differentiation capacity of human bone-derived mesenchymal stromal cells of postmenopausal women

Progressive bone loss is a predominant symptom of aging and osteoporosis. Therefore, the effects of sex steroids (i.e. testosterone and 17β-estradiol) on the differentiation capacity of human bone-derived mesenchymal stromal cells (hMSCs), as progenitors of osteoblasts and adipocytes, are of particular interest. The objectives of the present study were, thus, to elucidate whether bone-derived hMSCs of postmenopausal women produce aromatase (CYP19A1) and, whether they modulate their differentiation behaviour in response to testosterone and 17β-estradiol (E2), in relation to their steroid receptor expression. Supplementation of testosterone resulted in a considerable formation of E2 under osteogenic and adipogenic culture conditions, whereas E2 synthesis remained minimal in the cells cultured in basal medium. Concomitant with high aromatase expression and 17β-estradiol formation of the cells cultured in osteogenic medium supplemented with testosterone, a distinct promotion of late-stage osteogenesis was found, as shown by significant matrix mineralization and a notable increase in osteogenic markers. These effects were abrogated by the aromatase inhibitor anastrozole. Under adipogenic conditions, testosterone reduced the occurrence of lipid droplets and led to a decrease in PPARγ and AR expression, independent of anastrozole. Regardless of the culture conditions, ERα was detectable whilst ERβ was not. In conclusion, aromatase activity is limited to differentiated hMSCs and the resulting 17β-estradiol enhances late osteogenic differentiation stages via ERα. Adipogenic differentiation, on the other hand, is reduced by both sex steroids: testosterone via AR and 17β-estradiol.

Dihydrotestosterone and 17-Estradiol Enhancement of in vitro Osteogenic Differentiation of Castrated Male Rat Bone Marrow Mesenchymal Stem Cells (rBMMSCs)

Background: In vitro impact of dihydrotestosterone (DHT) and 17-estradiol (E2) in osteogenic differentiation of castrated rat bone marrow mesenchymal stem cells (rBMMSC) still need to be clarified. Materials and Methods: The viability, proliferation and density of cultured rBMMSC isolated from sham operated (Sham) and castrated (Cast) male rats were evaluated. rBMMSC were cultured with osteogenic differentiating medium (ODM) in the presence of DHT (5,10 nM) and E2 (10,100 nM). Osteogenesis was evaluated by alizarin red staining and measurement of calcium deposition and bone alkaline phosphatase (B-ALP) activity. Results: Population doubling (PD) of rBMMSC isolated from Cast rats was significantly lower (P<0.05) compared to that isolated from Sham rats. rBMMSC from Cast rats showed low scattered calcified nodule after culturing in ODM and did not cause a significant increase in calcium deposition and B-ALP activity compared to rBMMSCs from Sham rats. Exposure of rBMMSC isolated from Cast rats to DHT (5 nM) or E2 (10 nM) in ODM showed medium scattered calcified nodules with significantly higher (P<0.05) calcium deposition and B-ALP activity. Moreover, exposure of rBMMSC to DHT (10 nM) or E2 (100 nM) showed high scattered calcified nodules with higher (P<0.01) calcium deposition and B-ALP activity Conclusion: These results indicated that the presence of testes might participate in controlling the in vitro proliferation and osteogenic differentiation capacity of rBMMSCs. DHT and E2 can enhance the osteogenic capacity of rBMMSCs in a dose-dependent manner. Based on these observations, optimum usage of DHT and E2 can overcome the limitations of MSCs and advance the therapeutic bone regeneration potential in the future.