Polo-like kinase 4 (Plk4) is a key regulator of centriole duplication, an event critical for the maintenance of genomic integrity. Here we showed that Plk4 relocalizes from the inner Cep192 ring to the outer Cep152 ring as newly recruited Cep152 assembles around the Cep192-encircled daughter centriole. Crystal structure analyses revealed that Cep192 - and Cep152-derived peptides bind the cryptic polo box (CPB) of Plk4 in opposite orientations and in a mutually exclusive manner. The Cep152-peptide bound to the CPB markedly better than the Cep192-peptide and effectively snatched the CPB away from a preformed CPB–Cep192-peptide complex. A cancer-associated Cep152 mutation impairing the Plk4 interaction induced defects in procentriole assembly and chromosome segregation. Thus, Plk4 is intricately regulated in time and space through ordered interactions with two distinct scaffolds, Cep192 and Cep152, and a failure in this process may lead to human cancer.

Recent studies have demonstrated the generation of midbrain-like organoids (MOs) from human pluripotent stem cells. However, the low efficiency of MO generation and the relatively immature and heterogeneous structures of the MOs hinder the translation of these organoids from the bench to the clinic. Here we describe the robust generation of MOs with homogeneous distribution of midbrain dopaminergic (mDA) neurons. Our MOs contain not only mDA neurons but also other neuronal subtypes as well as functional glial cells, including astrocytes and oligodendrocytes. Furthermore, our MOs exhibit mDA neuron-specific cell death upon treatment with 1-methyl-4-phenyl-1,-2,3,6-tetrahydropyridine, indicating that MOs could be a proper human model system for studying the in vivo pathology of Parkinson's disease (PD). Our optimized conditions for producing homogeneous and mature MOs might provide an advanced patientspecific platform for in vitro disease modeling as well as for drug screening for PD.

Mycotoxins which mainly consist of Aflatoxin (AF), Zearalenone (ZEN) and Deoxynivalenol (DON) are commonly found in many food commodities. Although each component has been shown to cause liver toxicity and oxidative stress in several species, there is no evidence regarding the effect of naturally contained multiple mycotoxins on tissue toxicity and oxidative stress in vivo. In the present study, mycotoxins-contaminated maize (AF 597 µg/kg, ZEN 729 µg/kg, DON 3.1 mg/kg maize) was incorporated into the diet at three different doses (0, 5 and 20%) to feed the mice, and blood and tissue samples were collected to examine the oxidative stress related indexes. The results showed that the indexes of liver, kidney and spleen were all increased and the liver and kidney morphologies changed in the mycotoxin-treated mice. Also, the treatment resulted in the elevated glutathione peroxidase (GPx) activity and malondialdehyde (MDA) level in the serum and liver, indicating the presence of the oxidative stress. Moreover, the decrease of catalase (CAT) activity in the serum, liver and kidney as well as superoxide dismutase (SOD) activity in the liver and kidney tissue further confirmed the occurrence of oxidative stress. In conclusion, our data indicate that the naturally contained mycotoxins are toxic in vivo and able to induce the oxidant stress in the mouse.

SummaryEvaluation of apoptosis and expression level of apoptosis-related genes is useful for examining the variation in embryo quality according to environmental change. The objective of this study was to investigate DNA fragmentation and apoptosis-related gene expression patterns in frozen-thawed bovine blastocysts.In vitroproduced day 7 blastocysts were frozen by two different vitrification methods (conventional 0.25 ml straw or MVC straw). After thawing, DNA fragmentation of surviving embryos was examined by TUNEL assay, and the expression patterns of their apoptotic genes (survivin, Fas, Hsp 70 and caspase-3) were evaluated using real-time quantitative reverse transcriptase polymerase chain reaction.In vitrosurvival rates of frozen-thawed embryos were higher following the MVC vitrification method (88.2% re-expanded at 24 h, 77.1% hatching at 48 h) than the conventional (C) vitrification method (77.0% re-expanded at 24 h, 66.7% hatching at 48 h). However, both vitrified methods resulted in a significantly higher apoptotic index (C vitrification method 11.9%, MVC vitrification method 11.0%) than in non-frozen embryos (3.0%). Expression levels of survivin, Fas, caspase-3, and Hsp 70 were also increased in the frozen-thawed embryos compared with non-frozen embryos. These results indicate that the cryopreservation procedure might cause damage that results in an increase in DNA fragmentation and apoptosis-related gene transcription, reducing developmental capacity of frozen-thawed embryos.

Signal transducers and activators of transcription-3 (Stat3) plays a central role in interleukin-6 (IL-6)-mediated cell proliferation by inhibiting apoptosis in a variety of cell types. MicroRNA-21 (miRNA-21), a ubiquitous miRNA, acts as an anti-apoptotic factor that seems to be indirectly but strictly linked to Stat3. In order to determine whether the IL-6 induced Stat3 anti-apoptosis pathway is linked with miRNA-21, we first determined the effects of recombinant mouse IL-6 on Stat3 expression, mouse embryo viability, and the mRNA levels of apoptosis related genes and miRNA-21 during mouse embryo development in vitro. Addition of 10 or 100 ng/ml of recombinant IL-6 to the culture medium did not affect the developmental ability of 2-cell stage embryos into blastocysts. However, total cell number was significantly increased and apoptosis was reduced in blastocyst stage embryos cultured in the presence of 100 ng/ml of recombinant IL-6. Furthermore, addition of recombinant IL-6 to the culture medium significantly increased the copy numbers of anti-apoptotic miRNA-21, up-regulated Bcl2l1, and down-regulated casp3. Similarly, the injection of mature miRNA-21 into cells up-regulated Bcl2l1 and down-regulated casp3. These results suggest that the induction of the Stat3 anti-apoptotic pathway by IL-6 is linked to miRNA-21 expression, which possibly results in the regulation of cell apoptosis in early mouse embryo development.