[Research advances on the function of skin touch receptor Merkel cells]

The reconstruction of tactile function during the repair of skin damage caused by factors including burns is inseparable from the functional regeneration of tactile receptor Merkel cells. Merkel cells mainly exist in the basal layer of the epidermis and are closely connected with nerves to form Merkel cell-nerve complexes, which play an important role in biological organisms. A large number of studies have shown that Merkel cells conduct precise transmission of mechanical force stimuli through the mechanically gated ion channels PIEZO2, and perform the function of tactile receptors. In this paper, we discussed the characteristics of Merkel cells and analyzed the different subgroups that may possibly exist in this type of cells and their functions, at the same time, we investigated the animal model research of touch-related diseases and the clinical diseases related to touch, revealing the importance of Merkel cell function research.

Influence of miR-34a on preeclampsia through the Notch signaling pathway

OBJECTIVE

The aim of this study was to investigate the influence of micro-ribonucleic acid-34a (miR-34a) on preeclampsia through the Notch signaling pathway.

PATIENTS AND METHODS

The expressions of miR-34a, Notch-1, Notch-2, and Notch-3 in the placenta of 39 preeclampsia patients and 42 normal patients were detected by immunohistochemistry and Reverse Transcription-Polymerase Chain Reaction (RT-PCR). The correlations between miR-34a expression with the expressions of Notch-1, Notch-2 and Notch-3 were analyzed, respectively. Besides, placental trophoblasts were isolated from preeclampsia patients and cultured in vitro. The expressions of miR-34a, Notch-1, Notch-2 and Notch-3 in placental trophoblasts were analyzed. Furthermore, the influences of miR-34a on the protein expressions of Notch-1, Notch-2, Notch-3, and hairy and enhancer of split-1 (Hes-1) in the Notch signaling pathway were analyzed by Luciferase reporter gene assay and Western blotting. The role of Notch in trophoblast invasion was investigated through the Notch inhibitors. In addition, its influence on the expression of urokinase-type plasminogen activator (uPA) was studied by miR-34a overexpression.

RESULTS

The expressions of miR-34a and Notch-1 were correlated with preeclampsia in the placentas of preeclampsia patients and normal patients to a certain degree. The expression of miR-34a in preeclamptic placenta was significantly higher than that of the normal placenta (p<0.05). However, Notch-1 expression was markedly lower in preeclamptic placenta (p<0.05). No significant differences were found in the expressions of Notch-2 and Notch-3 between the two types of placentas (p>0.05). MiR-34a had a remarkable negative correlation with Notch-1 expression in the Notch family (p<0.001, r=-0.5775). RT-PCR results revealed that the mRNA expression of miR-34a in placental trophoblasts of patients with preeclampsia was notably higher than that of normal people (p<0.01). However, Western blotting demonstrated that the protein expressions of Notch-1, Notch-2 and Notch-3 exhibited the opposite results. Additionally, the protein expression of Notch-1, Notch-2, Notch-3 and Hes-1 in trophoblasts transfected with pre-miR-34a was significantly decreased. The treatment with Notch inhibitors markedly reduced the trophoblast invasion. Furthermore, miR-34a overexpression or intracellular domain of Notch (ICN) overexpression regulated uPA expression.

CONCLUSIONS

MiR-34a regulates uPA system through the Notch signal transduction, thereby regulating the invasion of placental trophoblasts in patients with preeclampsia.

Higher dermal exposure of cashiers to BPA and its association with DNA oxidative damage

Bisphenol A (BPA) is a widely used chemical in the production of many polycarbonate plastics, epoxy resin linings for food and beverage containers and thermal papers. Oral intakes from the contaminated diets were considered as the predominant source of BPA exposure for humans. However, due to the high levels of BPA on thermal receipts and their wide applications in our daily life, the amount of BPA be transferred to the skin after holding thermal paper should not be underestimated, particularly for cashiers. To investigate the contribution of BPA exposure levels via the dermal contact route and the relationship between BPA exposure level and oxidative DNA damage, six male volunteers were recruited and required to simulate the cashiers' work and handle the thermal receipts during the study period. Triclosan (TCS, an antimicrobial compound used widely in personal health and skin care products) was applied as a reference compound. Their urinary BPA, TCS and 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations were determined by high performance liquid chromatography/ tandem spectrometer (LC/MS/MS). The results showed that after handling the thermal receipts, the urinary BPA concentrations of volunteers increased 3 times of those before the experimental period. But TCS levels in urine kept stable. There existed a correlation between BPA exposure and 8-OHdG (R²=0.237, p<0.001), but not between TCS and 8-OHdG concentrations (R²=0.026, p<0.777), indicating that more BPA exposure could lead to higher oxidative DNA damage. That the increases in 8-OHdG levels in urine being almost consistent with those of BPA suggested that handling thermal receipts resulted in the increasing BPA intakes and BPA exposure was correlated with DNA oxidative damage. After 48h of the end of handling thermal receipts, the urinary BPA levels did not descend to the levels before experiment, suggesting that the excretion of BPA via dermal contact was over 48h. BPA exposure through dermal contact route contributed 51.9% to 84% to urinary BPA levels with the GM ratio of 70.9% for cashiers, indicating that it might be seriously underestimated for cashiers according to the previous studies. More attentions should be paid on the exposure of BPA via dermal penetration for cashiers.

Exposure of children to BPA through dust and the association of urinary BPA and triclosan with oxidative stress in Guangzhou, China

Both bisphenol A (BPA) and triclosan (TCS) are phenolic compounds widely used in a variety of household applications. These compounds could be released into the environment, enter the human body and cause a series of potential health hazards. Children are sensitive and susceptible to these contaminants. To investigate the potential oxidative DNA damage from exposure to BPA and TCS, ninety six urine samples of children (aged 3-6) and 57 dust samples were collected from a kindergarten in Guangzhou, China. The concentrations of urinary BPA, TCS and 8-hydroxy-2'-deoxyguanosine (8-OHdG, a biomarker of oxidative DNA damage) in urine were determined using a liquid chromatography tandem mass spectrometer. The geometric mean concentrations of urinary BPA, TCS and 8-OHdG were 1.08 μg L^-1, 1.34 μg L^-1 and 1.90 μg L^-1, respectively. The results showed that both BPA and TCS exposures were associated with oxidative damage. Significant dose-effects existed between the urinary BPA, TCS levels and the 8-OHdG concentrations. Multiple linear regression analysis showed that one percent increase in BPA and in TCS could generate 0.15% and 0.081% increase in 8-OHdG in urine for children in Guangzhou. We also determined the concentrations of BPA in dust using high performance liquid chromatography. The mean concentration of BPA was 2.86 μg g^-1 in indoor dust and 3.23 μg g^-1 in outdoor dust. The dust contributes approximately 9.23% to the urinary BPA exposure for the children. In conclusion, BPA and TCS exposure correlates with oxidative DNA damage.

The effect of aerobic exercise and Macrothele raven venom on tumor-bearing mice

Liver cancer is one of the most common cancers in the world. Macrothele raven venom, a complicated mixture of neurotoxic peptides, proteins and low molecular weight material, has antitumor properties, but its mechanism of action is unknown. Moderate exercise has been shown to shrink tumors and cause a remarkable reduction in the tumor growth rate. In this study, we examined the antitumor effect of Macrothele raven venom in combination with exercise on tumor-bearing mice. Our results demonstrate that aerobic exercise in combination with venom administered at different doses was much more effective in a mouse H22 hepatoma model compared to separate administration of the 2 treatments. The underlying mechanism of this effect may be related to the expression of various tumor suppressor factors.

Molecular and enzymatic profiles of mammalian DNA methyltransferases: structures and targets for drugs

DNA methylation is an epigenetic event involved in a variety array of processes that may be the foundation of genetic phenomena and diseases. DNA methyltransferase is a key enzyme for cytosine methylation in DNA, and can be divided into two functional families (Dnmt1 and Dnmt3) in mammals. All mammalian DNA methyltransferases are encoded by their own single gene, and consisted of catalytic and regulatory regions (except Dnmt2). Via interactions between functional domains in the regulatory or catalytic regions and other adaptors or cofactors, DNA methyltransferases can be localized at selective areas (specific DNA/nucleotide sequence) and linked to specific chromosome status (euchromatin/heterochromatin, various histone modification status). With assistance from UHRF1 and Dnmt3L or other factors in Dnmt1 and Dnmt3a/Dnmt3b, mammalian DNA methyltransferases can be recruited, and then specifically bind to hemimethylated and unmethylated double-stranded DNA sequence to maintain and de novo setup patterns for DNA methylation. Complicated enzymatic steps catalyzed by DNA methyltransferases include methyl group transferred from cofactor Ado-Met to C5 position of the flipped-out cytosine in targeted DNA duplex. In the light of the fact that different DNA methyltransferases are divergent in both structures and functions, and use unique reprogrammed or distorted routines in development of diseases, design of new drugs targeting specific mammalian DNA methyltransferases or their adaptors in the control of key steps in either maintenance or de novo DNA methylation processes will contribute to individually treating diseases related to DNA methyltransferases.