A new metal ion chelator attenuates human tau accumulation-induced neurodegeneration and memory deficits in mice.

Neuronal neurofibrillary tangles containing Tau hyperphosphorylation proteins are a typical pathological marker of Alzheimer's disease (AD). The level of tangles in neurons correlates positively with severe dementia. However, how Tau induces cognitive dysfunction is still unknown, which leads to a lack of effective treatments for AD. Metal ions deposition occurs with tangles in AD brain autopsy. Reduced metal ion can improve the pathology of AD. To explore whether abnormally phosphorylated Tau causes metal ion deposition, we overexpressed human full-length Tau (hTau) in the hippocampal CA3 area of mice and primary cultured hippocampal neurons (CPHN) and found that Tau accumulation induced iron deposition and activated calcineurin (CaN), which dephosphorylates glycogen synthase kinase 3 beta (GSK3ß), mediating Tau hyperphosphorylation. Simultaneous activation of CaN dephosphorylates cyclic-AMP response binding protein (CREB), leading to synaptic deficits and memory impairment, as shown in our previous study; this seems to be a vicious cycle exacerbating tauopathy. In the current study, we developed a new metal ion chelator that displayed a significant inhibitory effect on Tau phosphorylation and memory impairment by chelating iron ions in vivo and in vitro. These findings provide new insight into the mechanism of memory impairment induced by Tau accumulation and develop a novel potential treatment for tauopathy in AD.

Advances in the molecular mechanisms of NLRP3 inflammasome activators and inactivators.

NLRP3 inflammasome is an intracellular protein complex that initiates cellular injury via assembly of NLRP3, ASC and caspase-1 in response to microbial infection and sterile stressors. The importance of NLRP3 inflammasome in immunity and human diseases has been well documented. Up to now, targeted inhibition of the assembly of NLRP3 inflammasome complex and of its activation was thought to be therapeutic strategy for associated diseases. Recent studies show that a host of molecules such as NIMA-related kinase 7 (Nek7) and DEAD-box helicase 3 X-linked (DDX3X) and a large number of biological mediators including cytokines, microRNAs, nitric oxide, carbon monoxide, nuclear factor erythroid-2 related factor 2 (Nrf2) and cellular autophagy participate in the activation and inactivation of NLRP3 inflammasome. This review summarizes current understanding of the molecular basis of NLRP3 inflammasome activation and inactivation. This knowledge may lead to development of new therapies directed at NLRP3 inflammasome related diseases.

Effect of bone marrow stem cell mobilisation on the expression levels of cellular growth factors in a rat model of acute tubular necrosis.

The aim of the present study was to observe the mobilisation effects of stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) on bone marrow stem cells (BMSCs) in rats with renal ischaemia-reperfusion injury. In addition, the effects of the BMSCs on the expression levels of hepatocyte growth factor (HGF) and epidermal growth factor (EGF) were investigated, with the aim to further the understanding of the protective mechanisms of SCF and G-CSF in renal ischaemia-reperfusion injury. The model and treatment groups were established using a model of unilateral renal ischaemia-reperfusion injury, in which the treatment group and the treatment control group were subcutaneously injected once a day with 200 µg/kg SCF and 50 µg/kg G-CSF, 24 h after the modelling, for five consecutive days. The CD34+ cell count was measured in the peripheral blood using flow cytometry. The mRNA expression levels of HGF and EGF were determined using polymerase chain reaction analysis, while the protein expression levels of HGF and EGF were detected using immunohistochemistry. The CD34+ cell count in the peripheral blood of the treatment and treatment control groups was significantly higher compared with that in the model group (P<0.05). However, CD34 expression levels in the cells from the renal tissues of the model and treatment groups were significantly higher compared with that of the control and treatment control groups (P<0.05), with the greatest increase observed in the treatment group. The mRNA and protein expression levels of HGF and EGF in the treatment group were significantly higher compared with the model group (P<0.05). Therefore, the results indicated that a combination of SCF and G-CSF can promote the repair of acute tubular necrosis. This combination, which can mobilise sufficient numbers of BMSCs to migrate back to the injured site, is a key factor in promoting the repair of renal tubular injury. Upregulation of HGF and EGF was also shown to promote the repair of renal tubular injury.

Erythropoietin protects lipopolysaccharide-induced renal mesangial cells from autophagy.

The aim of this study was to investigate the effects of erythropoietin (EPO) on the impairment of autophagy induced by lipopolysaccharide (LPS) in primary cultured rat glomerular mesangial cells (GMCs). Rat GMCs were isolated and cultured in normal glucose, high-glucose, LPS or LPS + EPO medium. At 24 and 72 h of culture, the cells were examined for expression levels of the autophagy markers LC3 and p62/sequestosome-1 (SQSTM1) using western blot analysis. At 24 h, no significant difference in the expression of LC3 and p62/SQSTM1 was observed among the groups; however, the cells exposed to high-glucose medium for 72 h showed downregulated LC3 expression and upregulated p62/SQSTM1 expression. The cells exposed to LPS (10 ng/ml) for 72 h showed upregulated LC3 expression and upregulated p62/SQSTM1 expression. These changes were reversed in the LPS + EPO group at 72 h. In conclusion, EPO can inhibit LPS-induced autophagy in rat GMCs.

Effects of progesterone on hippocampal ultrastructure and expression of inflammatory mediators in neonatal rats with hypoxic-ischemic brain injury.

Progesterone (PROG) has been shown to exhibit a protective function against hypoxic-ischemic brain damage. The aim of the present study was to study the effects of PROG in a neonatal rat model of hypoxic-ischemic brain injury. A total of 30 Wistar rats, aged 7 days, were randomly divided into three groups: Sham, model and PROG. The rats in the model and PROG groups underwent a left common carotid artery ligation and were placed in a sealed container at 37°C with 8% O2 and 92% N2 gas mixtures for 2.5 h to establish animal models of hypoxic-ischemic encephalopathy. The rats in the PROG group were intraperitoneally treated with 8 mg/kg PROG solution 30 min prior to the induction of hypoxia-ischemia. All animals were sacrificed after 24 h and neuronal changes were observed with electron microscopy to investigate the hypoxic-ischemic brain damage. The protein and mRNA expression levels of tumor necrosis factor-α (TNF-α) and nuclear factor-κB (NF-κB) in the hippocampus were detected by immunohistochemistry and quantitative polymerase chain reaction, respectively. The results revealed that the neuronal structures in the sham group were normal. The neuronal structures in the model group exhibited cavitation changes, but these were reduced following PROG administration. The protein and mRNA expression levels of TNF-α and NF-κB in the hippocampal neurons were increased in the model group, and pretreatment with 8 mg/kg PROG was shown to reduce the expression levels of these inflammatory mediators. Therefore, PROG was shown to exert an important protective function in hypoxic-ischemic brain injury by inhibiting the cascade of inflammatory injury induced by TNF-α and NF-κB.

Calycosin suppresses breast cancer cell growth via ERß-dependent regulation of IGF-1R, p38 MAPK and PI3K/Akt pathways.

We previously reported that calycosin, a natural phytoestrogen structurally similar to estrogen, successfully triggered apoptosis of estrogen receptor (ER)-positive breast cancer cell line, MCF-7. To better understand the antitumor activities of calycosin against breast cancer, besides MCF-7 cells, another ER-positive cell line T-47D was analyzed here, with ER-negative cell lines (MDA-231, MDA-435) as control. Notably, calycosin led to inhibited cell proliferation and apoptosis only in ER-positive cells, particularly in MCF-7 cells, whereas no such effect was observed in ER-negative cells. Then we investigated whether regulation of ERß, a subtype of ER, contributed to calycosin-induced apoptosis in breast cancer cells. The results showed that incubation of calycosin resulted in enhanced expression ERß in MCF-7 and T-47D cells, rather than MDA-231 and MDA-435 cells. Moreover, with the upregulation of ERß, successive changes in downstream signaling pathways were found, including inactivation of insulin-like growth factor 1 receptor (IGF-1R), then stimulation of p38 MAPK and suppression of the serine/threonine kinase (Akt), and finally poly(ADP-ribose) polymerase 1 (PARP-1) cleavage. However, the other two members of the mitogen-activated protein kinase (MAPK) family, extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK), were not consequently regulated by downregulated IGF-1R, indicating ERK 1/2 and JNK pathways were not necessary to allow proliferation inhibition by calycosin. Taken together, our results indicate that calycosin tends to inhibit growth and induce apoptosis in ER-positive breast cancer cells, which is mediated by ERß-induced inhibition of IGF-1R, along with the selective regulation of MAPK and phosphatidylinositol 3-kinase (PI3K)/Akt pathways.

Progesterone treatment before experimental hypoxia-ischemia enhances the expression of glucose transporter proteins GLUT1 and GLUT3 in neonatal rats.

Progesterone is an efficient candidate for treating stroke and traumatic brain damage. The current study was designed to investigate the effects of progesterone on glucose transporter proteins (GLUT1 and GLUT3) during hypoxic-ischemic injury in a neonatal rat model. We demonstrated strong staining for GLUT1 in the walls of blood vessels and GLUT3 immunoreactivity in hippocampal neurons after hypoxiaischemia. Hypoxia-ischemia elevated GLUT1 and GLUT3 at both the mRNA and protein levels in the hippocampus, and pre-treatment with progesterone (8 mg/kg) further enhanced their accumulation until 24 h after hypoxic-ischemic injury. These results showed that progesterone treatment induced the accumulation of both GLUT1 and GLUT3 transporters, and an energy-compensation mechanism may be involved in the neuroprotective effect of progesterone during hypoxic-ischemic injury after cerebral ischemic attacks.

Calycosin promotes proliferation of estrogen receptor-positive cells via estrogen receptors and ERK1/2 activation in vitro and in vivo.

Calycosin is a main active component of the herb Radix Astragali, and is considered as a phytoestrogen. Its effects in vivo may be either estrogenic or antiestrogenic, mainly depending upon the estrogen levels. This study was a continuation of our investigations of calycosin's promotion of the proliferation of estrogen receptor (ER)-positive cells via ERs and ERK1/2 activation in vitro and in vivo. ER-positive MCF-7 (human breast cancer) cells were treated with different concentrations of calycosin. Proliferation of the cells treated with calycosin was assayed by CCK8. Apoptosis in the treated cells was measured by flow cytometry. The protein expression of ERK1/2 in treated cells was determined by Western blot. In addition, the in vivo expression of ERα in the uterine tissues of ovariectomized (OVX) mice was assessed by immunohistochemistry. Compared with the control, low concentrations of calycosin (2-8 µM) stimulated the proliferation of MCF-7 cells and decreased the percentage of early apoptosis. The level of p-ERK1/2 was also downregulated at these low concentrations. Furthermore, we found that an ERK1/2 inhibitor significantly blocked the effect of calycosin in MCF-7 cells. In the in vivo studies, calycosin stimulated a dramatic increase in uterine weight and downregulated the level of ERα protein in OVX mice. This study demonstrated that at relatively low concentrations calycosin had stimulatory effects on the proliferation of MCF-7 cells, and we conclude that this is due to its estrogenic effect.