The effect of bisphenol A (BPA) on the reproductive system is highly debated but has been associated with meiotic abnormalities. However, evidence is lacking with regard to the mechanisms involved. In order to explore the underlying mechanisms of BPA-induced meiotic abnormalities in adult male rats, we exposed 9-week-old male Wistar rats to BPA by gavage at 0, 2, 20 or 200 μg/kg body weight (bw)/day for 60 consecutive days. 17β-Estradiol (E2) was administered at 10 μg/kg bw/day as the estrogenic positive control. Treatments with 200 μg/kg bw/day of BPA and E2 significantly decreased sperm counts and inhibited spermiation, characterized by an increase in stage VII and decrease in stage VIII in the seminiferous epithelium. This was concomitant with a disruption in the progression of meiosis I and the persistence of meiotic DNA strand breaks in pachytene spermatocytes,and the ataxia–telangiectasia-mutated and checkpoint kinase 2 signal pathway was also activated; Eventually, germ cell apoptosis was triggered as evaluated by terminal dUTP nick-end labeling assay and western blot for caspase 3. Using the estrogen receptor (ER) antagonist ICI 182780, we determined that ER signaling mediated BPA-induced meiotic disruption and reproductive impairment. Our results suggest that ER signaling-mediated meiotic disruption may be a major contributor to the molecular events leading to BPA-related male reproductive disorders. These rodent data support the growing association between BPA exposure and the rapid increase in the incidence of male reproductive disorders.

The cellular energy metabolism shift, characterized by the inhibition of oxidative phosphorylation (OXPHOS) and enhancement of glycolysis, is involved in nickel-induced neurotoxicity. MicroRNA-210 (miR-210) is regulated by hypoxia-inducible transcription factor-1α (HIF-1α) under hypoxic conditions and controls mitochondrial energy metabolism by repressing the iron–sulfur cluster assembly protein (ISCU1/2). ISCU1/2 facilitates the assembly of iron–sulfur clusters (ISCs), the prosthetic groups that are critical for mitochondrial oxidation-reduction reactions. This study aimed to investigate whether miR-210 modulates alterations in energy metabolism after nickel exposure through suppressing ISCU1/2 and inactivating ISCs-containing metabolic enzymes. We determined that NiCl2 exposure leads to a significant accumulation of HIF-1α, rather than HIF-1β, in Neuro-2a cells. The miR-210 overexpression and ISCU1/2 downregulation was observed in a dose- and time-dependent manner. The gain-of-function and loss-of-dysfunction assays revealed that miR-210 mediated the ISCU1/2 suppression, energy metabolism alterations, and ISC-containing metabolic enzyme inactivation after nickel exposure. In addition, the impact of miR-210 on ISC-containing metabolic enzymes was independent from cellular iron regulation. Overall, these data suggest that repression of miR-210 on ISCU1/2 may contribute to HIF-1α-triggered alterations in energy metabolism after nickel exposure. A better understanding of how nickel impacts cellular energy metabolism may facilitate the elucidation of the mechanisms by which nickel affects the human health.

The diterpene triepoxide triptolide is a major active component of Tripterygium wilfordii Hook F, a popular Chinese herbal medicine with the potential to treat hematologic malignancies. In this study, we investigated the roles of triptolide in apoptosis and cell signaling events in human leukemia cell lines and primary human leukemia blasts. Triptolide selectively induced caspase-dependent cell death that was accompanied by the loss of mitochondrial membrane potential, cytochrome c release, and Bax translocation from the cytosol to the mitochondria. Furthermore, we found that triptolide dramatically induced ROCK1 cleavage/activation and MLC and MYPT phosphorylation. ROCK1 was cleaved and activated by caspase-3, rather than RhoA. Inhibiting MLC phosphorylation by ML-7 significantly attenuated triptolide-mediated apoptosis, caspase activation, and cytochrome c release. In addition, ROCK1 inhibition also abrogated MLC and MYPT phosphorylation. Our in vivo study showed that both ROCK1 activation and MLC phosphorylation were associated with the tumor growth inhibition caused by triptolide in mouse leukemia xenograft models. Collectively, these findings suggest that triptolide-mediated ROCK1 activation and MLC phosphorylation may be a novel therapeutic strategy for treating hematological malignancies.

The activation of Toll-like receptor 4 (TLR4) signaling has an important role in promoting lipid accumulation and pro-inflammatory effects in vascular smooth muscle cells (VSMCs), which facilitate atherosclerosis development and progression. Previous studies have demonstrated that excess lipid accumulation in VSMCs is due to an inhibition of the expression of ATP-binding cassette transporter A1 (ABCA1), an important molecular mediator of lipid efflux from VSMCs. However, the underlying molecular mechanisms of this process are unclear. The purpose of this study was to disclose the underlying molecular mechanisms of TLR4 signaling in regulating ABCA1 expression. Primary cultured VSMCs were stimulated with 50 μg/ml oxidized low-density lipoprotein (oxLDL). We determined that enhancing TLR4 signaling using oxLDL significantly downregulated ABCA1 expression and induced lipid accumulation in VSMCs. However, TLR4 knockout significantly rescued oxLDL-induced ABCA1 downregulation and lipid accumulation. In addition, IL-1R-associated kinase 1 (IRAK1) was involved in the effects of TLR4 signaling on ABCA1 expression and lipid accumulation. Silencing IRAK1 expression using a specific siRNA reversed TLR4-induced ABCA1 downregulation and lipid accumulation in vitro. These results were further confirmed by our in vivo experiments. We determined that enhancing TLR4 signaling by administering a 12-week-long high-fat diet (HFD) to mice significantly increased IRAK1 expression, which downregulated ABCA1 expression and induced lipid accumulation. In addition, TLR4 knockout in vivo reversed the effects of the HFD on IRAK1 and ABCA1 expression, as well as on lipid accumulation. In conclusion, IRAK1 is involved in TLR4-mediated downregulation of ABCA1 expression and lipid accumulation in VSMCs.

Increased expression of BAFF (B cell-activating factor belonging to the TNF family) and its receptors has been identified in numerous B-cell malignancies. A soluble human BAFF mutant (mBAFF), binding to BAFF receptors but failing to activate B-lymphocyte proliferation, may function as a competitive inhibitor of BAFF and may serve as a novel ligand for targeted therapy of BAFF receptor-positive malignancies. Pin2/TRF1-interacting protein X1 (PinX1), a nucleolar protein, potently inhibits telomerase activity and affects tumorigenicity. In this study, we generated novel recombinant proteins containing mBAFF, a polyarginine tract 9R and PinX1 (or its C/N terminal), to target lymphoma cells. The fusion proteins PinX1/C–G4S–9R–G4S–mBAFF and PinX1/C–9R–mBAFF specifically bind and internalize into BAFF receptor-positive cells, and subsequently induce growth inhibition and apoptosis. The selective cytotoxicity of the fusion proteins is a BAFF receptor-mediated process and depends on mBAFF, PinX1/C and 9R. Moreover, the fusion proteins specifically kill BAFF receptor-expressing Burkitt's lymphoma (BL) cells by inhibiting telomerase activity and the consequent shortening of telomeres. Therapeutic experiments using PinX1C–G4S–9R–G4S–mBAFF in severe combined immunodeficient (SCID) mice implanted with Raji cells showed significantly prolonged survival times, indicating the in vivo antitumor activity of the fusion protein. These results suggest the potential of PinX1/C–G4S–9R–G4S–mBAFF in targeted therapy of BL.