Melatonin promotes proliferation and differentiation of neural stem cells subjected to hypoxia in vitro.

Melatonin, an endogenously produced neurohormone secreted by the pineal gland, has a variety of physiological functions and neuroprotective effects. It can modulate the functions of neural stem cells (NSCs) including proliferation and differentiation in embryonic brain tissue but its effect and mechanism on the stem cells in hypoxia remains to be explored. Here, we show that melatonin stimulates proliferation of NSCs during hypoxia. Additionally, it also promoted the differentiation of NSCs into neurons. However, it did not appear to exert an obvious effect on the differentiation of astrocytes. The present results have further shown that the promotional effect of NSCs proliferation by melatonin involved the MT1 receptor and increased phosphorylation of ERK1/2. The effect of melatonin on differentiation of NSCs is linked to altered expression of differentiation-related genes. In the light of these findings, it is suggested that melatonin may be beneficial as a supplement for treatment of neonatal hypoxic-ischemic brain injury for promoting the proliferation and differentiation of NSCs.

miR-181d regulates human dendritic cell maturation through NF-κB pathway.

OBJECTIVES: MicroRNAs (miRNAs) are considered as the cellular regulators which post-transcriptionally modulate gene expression in diverse biological processes including cell development and immunity. In this study, we investigated functions of miR-181d in dendritic cells (DCs) maturation, and the underlying mechanisms were also explored. MATERIALS AND METHODS: Here we did the miRNA screening in human DCs in response to lipopolysaccharides (LPS) by quantitative real-time PCR (qRT-PCR). The expressions of DCs maturation markers were measured after miRNA mimics transfections. The pharmacological inhibitors of signalling pathways were applied to examine miR-181d effect on DCs maturation by Western blot. Luciferase assay and mixed lymphocyte reaction (MLR) were also performed to reveal the target gene of miR-181d and test the viability of T cells treated with miR-181d transfected DCs. RESULTS: Overexpression of miR-181d per se is sufficient to promote DCs maturation, and up-regulate CD80 and CD83 expressions without LPS. Besides, we showed that miR-181d activated NF-κB pathway and also promoted the expression of pro-inflammatory cytokine IL12 and TNF-α. Inhibition of NF-κB pathway suppressed DCs maturation. Luciferase reporter assay and target gene knockdown assay indicated that miR-181d targets regulator cylindromatosis (CYLD), a primary negative regulator of NF-κB pathway. MLR assay showed that miR-181d-transfected DCs could promote T-cell proliferation than iDCs in vitro. CONCLUSION: Our study demonstrates that miR-181d is required for DCs maturation through the activation of NF-κB pathway by targeting CYLD.

High levels of testosterone inhibit ovarian follicle development by repressing the FSH signaling pathway.

The effect of high concentrations of testosterone on ovarian follicle development was investigated. Primary follicles and granulosa cells were cultured in vitro in media supplemented with a testosterone concentration gradient. The combined effects of testosterone and follicle-stimulating hormone (FSH) on follicular growth and granulosa cell gonadotropin receptor mRNA expression were also investigated. Follicle growth in the presence of high testosterone concentrations was promoted at early stages (days 1-7), but inhibited at later stage (days 7-14) of in vitro culture. Interestingly, testosterone-induced follicle development arrest was rescued by treatment with high concentrations of FSH (400 mIU/mL). In addition, in cultured granulosa cells, high testosterone concentrations induced cell proliferation, and increased the mRNA expression level of FSH receptor (FSHR), and luteinized hormone/choriogonadotropin receptor. It was concluded that high concentrations of testosterone inhibited follicle development, most likely through regulation of the FSH signaling pathway, although independently from FSHR downregulation. These findings are an important step in further understanding the pathogenesis of polycystic ovary syndrome.

Roles of activated astrocyte in neural stem cell proliferation and differentiation.

Recent studies demonstrated that the molecules secreted from astrocytes play important roles in the cell fate determination of neural stem cells (NSCs). However, the exact molecules involved and its possible mechanisms in the process remain largely unknown. In this study, astrocyte-conditioned medium (ACM) obtained from astrocytes unstimulated or stimulated by lipopolysaccharide was prepared to treat NSCs. The results showed that both the proliferation and differentiation of NSCs treated with stimulated ACMs were significantly increased compared with those treated with unstimulated ACM. Interleukin-6 (IL-6) antibody neutralization of the ACMs decreased NSC proliferation and astrogliogenesis, while NSC neurogenesis was increased. In contrast, recombinant IL-6 cytokine increased NSC proliferation and astrogliogenesis, but decreased neurogenesis. Furthermore, the expression of phosphorylated signal transducer and activator of transcription 3 (p-stat3) protein as well as serial of basic helix-loop-helix transcription factors (bHLH) mRNA in NSCs exposed to stimulated ACMs significantly increased, respectively. The expression levels of p-stat3 protein and bHLH mRNA of NSCs were significantly altered after adding anti-IL-6 antibody or recombinant IL-6, respectively. The data suggest that IL-6 secreted from activated astrocytes participates in ACM-induced proliferation and differentiation of NSCs via the phosphorylation of stat3 signals and the expression of bHLH transcription factors.