Bone mesenchymal stem cells (BMSCs) have multiple potentials to differentiate into osteoblasts and adipocytes, and methods to enhance their osteogenic differentiation are gaining increasing attention. MicroRNAs are critical regulation factors during the process of the osteogenic induction in BMSCs, and mir-205 has been substantiated to be involved in the osteogenic process, but the underlying mechanisms remain unclear. The purpose of this article is to investigate the role of mir-205 in the osteogenic differentiation of BMSCs. We found that mir-205 expression was down-regulated in a time-dependent manner during BMSC osteo-induction. Inhibition of mir-205 enhanced osteogenic abilities by up-regulating bone sialoprotein (BSP) and osteopontin (OPN) protein levels and increasing alkaline phosphatase (ALP) activity and osteocalcin secretion. Furthermore, we found that mir-205 could regulate protein expression of special AT-rich sequence-binding protein 2 (SATB2) and runt-related transcription factor 2 (Runx2), and over-expression of SATB2 activated Runx2 and reversed the negative effects of mir-205 on osteoblastic differentiation. Furthermore, we examined the extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38 MAPK) pathways during osteogenic induction and our data indicates that mir-205 might exert negative functions on the osteogenic differentiation in BMSCs at least partly via altering phosphorylation of ERK and p38 MAPK. These results shed new light on the molecular mechanisms of microRNAs in governing differentiation of BMSCs.

Parkinson's disease (PD) is the second most prevalent progressive neurodegenerative disease. Although several hypotheses have been proposed to explain the pathogenesis of PD, apoptotic cell death and oxidative stress are the most prevalent mechanisms. Tetramethylpyrazine (TMP) is a biological component that has been extracted from Ligusticum wallichii Franchat (ChuanXiong), which exhibits anti-apoptotic and antioxidant roles. In the current study, we aimed to investigate the possible protective effect of TMP against dopaminergic neuron injury in a rat model of Parkinson's disease induced by MPTP and to elucidate probable molecular mechanisms. The results showed that TMP could notably prevent MPTP-induced dopaminergic neurons damage, reflected by improvement of motor deficits, enhancement of TH expression and the content of dopamine and its metabolite, DOPAC. We observed MPTP-induced activation of mitochondrial apoptotic death pathway, evidenced by up-regulation of Bax, down-regulation of Bcl-2, release of cytochrome c and cleavage of caspase 3, which was significantly inhibited by TMP. Moreover, TMP could prevent MPTP-increased TBARS level and MPTP-decreased GSH level, indicating the antioxidant role of TMP in PD model. And the antioxidant role of TMP attributes to the prevention of MPTP-induced reduction of Nrf2 and GCLc expression. In conclusion, in MPTP-induced PD model, TMP prevents the down-regulation of Nrf2 and GCLc, maintaining redox balance and inhibiting apoptosis, leading to the attenuation of dopaminergic neuron damage. The effectiveness of TMP in treating PD potentially leads to interesting therapeutic perspectives.

The traditional Chinese medicine bufalin, extracted from toad’s skin, has been demonstrated to exert anticancer activities in various kinds of human cancers. The mechanisms of action lie in its capacity to induce apoptosis, or termed type I programmed cell death (PCD). However, type II PCD, or autophagy, participates in cancer proliferation, progression, and relapse, as well. Recent studies on autophagy seem to be controversial because of the dual roles of autophagy in cancer survival and death. In good agreement with previous studies, we found that 100 nM bufalin induced extensive HepG2 cell apoptosis. However, we also noticed bufalin triggered autophagy and enhanced Beclin-1 expression, LC3-I to LC3-II conversion, as well as decreased p62 expression and mTOR signaling activation in HepG2 cells. Blockage of autophagy by selective inhibitor 3-MA decreased apoptotic ratio in bufalin-treated HepG2 cells, suggesting a proapoptotic role of bufalin-induced autophagy. Furthermore, we investigated the underlying mechanisms of bufalin-induced autophagy. Bufalin treatment dose-dependently promoted AMPK phosphorylation while AMPK inhibition by compound C significantly attenuated bufalin-induced autophagy. Taken together, we report for the first time that bufalin induces HepG2 cells PCD, especially for autophagy, and the mechanism of action is, at least in part, AMPK-mTOR dependent.

Genistein, a major phytoestrogen of soy, is considered a potential drug for the prevention and treatment of post-menopausal osteoporosis. Mounting evidence suggested a positive correlation between genistein consumption and bone health both in vivo and in vitro. Earlier studies have revealed that genistein acted as a natural estrogen analogue which activated estrogen receptor and exerted anti-osteoporotic effect. However, it remains unclear whether PTH, the most crucial hormone that regulates mineral homeostasis, participates in the process of genistein-mediated bone protection. In the present study, we compared the therapeutic effects between genistein and nilestriol and investigated whether PTH and its specific receptor PTHR1 altered in response to genistein-containing diet in the animal model of ovariectomy. Our results showed that genistein administration significantly improved femoral mechanical properties and alleviates femoral turnover. Genistein at all doses (4.5 mg/kg, 9.0 mg/kg and 18.0 mg/kg per day, respectively) exerted improved bending strength and b-ALP limiting effects than nilestriol in the present study. However, genistein administration did not exert superior effects on bone protection than nilestriol. We also observed circulating PTH restoration in ovariectomized rats receiving genistein at the dose of 18 mg/kg per day. Meanwhile, PTHR1 abnormalities were attenuated in the presence of genistein as confirmed by RT-PCR, Western blot and immunohistochemistry. These findings strongly support the idea that besides serving as an estrogen, genistein could interact with PTH/PTHR1, causing a superior mineral restoring effect than nilestriol on certain circumstance. In conclusion, our study reported for the first time that the anti-osteoporotic effect of genistein is partly PTH/PTHR1-dependent. Genistein might be a potential option in the prevention and treatment of post-menopausal osteoporosis with good tolerance, more clinical benefits and few undesirable side effects.

Tryptanthrin, a kind of indole quinazoline alkaloid, has been shown to exhibit anti-microbial, anti-inflammation and anti-tumor effects both in vivo and in vitro. However, its biological activity on human chronic myeloid leukemia cell line K562 is not fully understood. In the present study, we investigated the proliferation-attenuating and apoptosis-inducing effects of tryptanthrin on leukemia K562 cells in vitro and explored the underlying mechanisms. The results showed that tryptanthrin could significantly inhibit K562 cells proliferation in a time- and dose-dependent manner as evidenced by MTT assay and flow cytometry analysis. We also observed pyknosis, chromatin margination and the formation of apoptotic bodies in the presence of tryptanthrin under the electron microscope. Nuclei fragmentation and condensation by Hoechst 33258 staining were detected as well. The amount of apoptotic cells significantly increased whereas the mitochondrial membrane potential decreased dramatically after tryptanthrin exposure. K562 cells in the tryptanthrin treated group exhibited an increase in cytosol cyt-c, Bax and activated caspase-3 expression while a decrease in Bcl-2, mito cyt-c and pro-caspase-3 contents. However, the changes of pro-caspase-3 and activated caspase-3 could be abolished by a pan-caspase inhibitor ZVAD-FMK. These results suggest that tryptanthrin has proliferation-attenuating and apoptosis-inducing effects on K562 cells. The underlying mechanism is probably attributed to the reduction in mitochondria membrane potential, the release of mito cyt-c and pro-caspase-3 activation.