tRNA-derived fragments tRFGlnCTG induced by arterial injury promote vascular smooth muscle cell proliferation.

tRNA-derived fragments (tRFs) and tRNA halves (tiRNAs) are originated from the specific cleavage of endogenous tRNAs or their precursors and regulate gene expression when the cells are in stressful circumstances. Here, we replicated the rat common carotid artery (CCA) intimal hyperplasia model and investigated the expression of tRFs/tiRNAs in the artery. The normal and the balloon-injured rat CCAs were subjected to small RNA sequencing, and then the differentially expressed tRFs/tiRNAs were identified and analyzed. The expression profiles of tRFs/tiRNAs in the healthy and injured CCAs were remarkably different. tRNAGlnCTG-derived fragments (tRFGlnCTG) were found to be overexpressed with a high abundance in the injured CCA. In in vitro experiments, the synthetic tRFGlnCTG mimetics elevated the proliferation and migration of rat vascular smooth muscle cells (VSMCs). Through bioinformatics analysis and an overexpression experiment, tRFGlnCTG was found to negatively regulate the expression of FAS cell surface death receptor (FAS). This study revealed that tRFGlnCTG is a crucial regulator in promoting VSMC proliferation. The investigation of the roles of tRFs/tiRNAs is of significance for understanding the mechanism, diagnosis, and treatment of intimal hyperplasia.

A novel tri-band T-junction impedance-transforming power divider with independent power division ratios.

In this paper, a novel L network (LN) is presented, which is composed of a frequency-selected section (FSS) and a middle stub (MS). Based on the proposed LN, a tri-band T-junction power divider (TTPD) with impedance transformation and independent power division ratios is designed. Moreover, the closed-form design theory of the TTPD is derived based on the transmission line theory and circuit theory. Finally, a microstrip prototype of the TTPD is simulated, fabricated, and measured. The design is for three arbitrarily chosen frequencies, 1 GHz, 1.6 GHz, and 2.35 GHz with the independent power division ratios of 0.5, 0.7, and 0.9. The measured results show that the fabricated prototype is consistent with the simulation, which demonstrates the effectiveness of this proposed design.

APP, APLP2 and LRP1 interact with PCSK9 but are not required for PCSK9-mediated degradation of the LDLR in vivo.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein that post-transcriptionally regulates the levels of hepatic low-density lipoprotein receptors (LDLRs). PCSK9 binds to the extracellular domain of the LDLR, and the PCSK9-LDLR complex is internalized through canonical clathrin-dependent endocytosis and then delivered to lysosomes for degradation. The mechanism by which PCSK9 blocks recycling of the LDLR has not been fully defined. Previous reports showed that amyloid precursor-like protein 2 (APLP2) interacts with PCSK9, but its role in PCSK9-mediated LDLR degradation remains controversial. Here we found that amyloid precursor protein (APP), APLP2 and LDL receptor-related protein 1 (LRP1) interact with PCSK9. To test whether any of these proteins are required for PCSK9-mediated LDLR degradation, we examined the effects of disrupting these proteins in mice. Infusion of PCSK9 into App-/-, Aplp2-/-, Aplp2-depleted App-/-, or liver-specific Lrp1-/- mice resulted in similar reductions in the levels of hepatic LDLR as seen in wild-type (WT) mice. Infusion of PCSK9 into WT mice also had no effect on the levels of hepatic APP, APLP2 or LRP1. Thus, APP, APLP2 and LRP1 are not required for PCSK9-mediated LDLR degradation and are not regulated by PCSK9 in vivo.

ERCC2/XPD Lys751Gln alter DNA repair efficiency of platinum-induced DNA damage through P53 pathway.

Platinum-based treatment causes Pt-DNA adducts which lead to cell death. The platinum-induced DNA damage is recognized and repaired by the nucleotide excision repair (NER) system of which ERCC2/XPD is a critical enzyme. Single nucleotide polymorphisms in ERCC2/XPD have been found to be associated with platinum resistance. The aim of the present study was to investigate whether ERCC2/XPD Lys751Gln (rs13181) polymorphism is causally related to DNA repair capacity of platinum-induced DNA damage. First, cDNA clones expressing different genotypes of the polymorphism was transfected to an ERCC2/XPD defective CHO cell line (UV5). Second, all cells were treated with cisplatin. Cellular survival rate were investigated by MTT growth inhibition assay, DNA damage levels were investigated by comet assay and RAD51 staining. The distribution of cell cycle and the change of apoptosis rates were detected by a flow cytometric method (FCM). Finally, P53mRNA and phospho-P53 protein levels were further investigated in order to explore a possible explanation. As expected, there was a significantly increased in viability of UV5ERCC2 (AA) as compared to UV5ERCC2 (CC) after cisplatin treatment. The DNA damage level of UV5ERCC2 (AA) was significant decreased compared to UV5ERCC2 (CC) at 24 h of treatment. Mutation of ERCC2rs13181 AA to CC causes a prolonged S phase in cell cycle. UV5ERCC2 (AA) alleviated the apoptosis compared to UV5ERCC2 (CC), meanwhile P53mRNA levels in UVERCC2 (AA) was also lower when compared UV5ERCC2 (CC). It co-incides with a prolonged high expression of phospho-P53, which is relevant for cell cycle regulation, apoptosis, and the DNA damage response (DDR). We concluded that ERCC2/XPD rs13181 polymorphism is possibly related to the DNA repair capacity of platinum-induced DNA damage. This functional study provides some clues to clarify the relationship between cisplatin resistance and ERCC2/XPDrs13181 polymorphism.

The ERCC2/XPD Lys751Gln polymorphism affects DNA repair of benzo[a]pyrene induced damage, tested in an in vitro model.

Nucleotide excision repair (NER) is an important defense mechanism of the body to exogenous carcinogens and mutagens, such as benzo[a]pyrene (B[a]P). Genetic polymorphisms in ERCC2/XPD, a critical element in NER, are thought to be associated with individual's cancer susceptibility. Although ERCC2/XPD Lys751Gln (rs13181) is the most studied polymorphism, the impact of this polymorphism on DNA repair capacity to carcinogen remains unclear. In the present study, cDNA clones carrying different genotypes of ERCC2/XPD (Lys751Gln) were introduced into an ERCC2/XPD deficient cell line (UV5) in a well-controlled biological system. After B[a]P treatment, cell growth inhibition rates and DNA damage levels in all cells were detected respectively. As expected, we found that the DNA repair capacity in UV5 cells was restored to levels similar to wildtype parent AA8 cells upon introduction of the cDNA clone of ERCC2/XPD (Lys751). Interestingly, after B[a]P treatment, transfected cells expressing variant ERCC2/XPD (751Gln) showed an enhanced cellular sensitivity and a diminished DNA repair capacity. The wildtype genotype AA (Lys) was found to be associated with a higher DNA repair capacity as compared to its polymorphic genotype CC (Gln). These data indicate that ERCC2/XPD Lys751Gln polymorphism affects DNA repair capacity after exposure to environmental carcinogens such as B[a]P in this well-controlled in vitro system and could act as a biomarker to increase the predictive value to develop cancer.

[Study on the effect of deficient ERCC2/XPD gene on the repair of DNA damage induced by UVC in CHO cell line].

OBJECTIVE: To explore the function of ERCC2/XPD in the repair of DNA damage induced by UVC. METHODS: Chinese hamster ovary (CHO) cell line including AA8 (wild-type) and UV5 (mutant type, ERCC2/XPD defective), was selected as a cell control model. The cell inhibition rate of AA8 and UV5 after UVC treatment was estimated by MTT assay, and DNA repair capacity to difference irradiation intensity of UVC in cells after 1 h, 3 h, 6 h, 24 h incubation were measured by the Comet Assay and Rad51 immunofluorescence test. RESULTS: As compared to AA8, UV5 was more sensitive to UVC, and whose cell viability decreased. Comet assay and Rad51 immunofluorescence test results show, DNA damage level of UV5 was more serious than AA8. In addition, the DNA damage repair capacity reduced obviously compared with AA8. CONCLUSION: DNA damage repair capacity of UV5 cells reduced due to ERCC2/XPD defective, indicating us that ERCC2/XPD play a critical role in the repair process of DNA damage induced by UVC.

[Study on association between ERCC2/XPD single nucleotide polymorphisms and DNA adducts damage induced by B[a]P in vitro].

OBJECTIVE: To evaluate the association between DNA damage repair capacity induced by environment carcinogen benzo[a] pyrene (B [a] P) and ERCC2/XPD single nucleotide polymorphisms(SNP). METHODS: 8 ml peripheral bloods of 282 healthy ethnic Han people from Liao-ning province were collected, isolated lymphocytes and extracted DNA. The genotypes of ERCC2/XPD Lys751 Gln (rs13181), Asp312Asn (rs1799793), Arg156Arg (rs238406) were detected by Taqman real time PCR; BPDE-DNA adduct in vitro induced by B[a]P and S9 mixture in lymphocyte were detected by high performance liquid chromatography (HPLC). RESULTS: The BPDE-DNA adduct levels of ERCC2/XPD Arg156Arg AA genotype were significantly higher than CC genotype. Compared with < or = 30 years, people at age of 50 - 70 years and > or = 70 years have higher BPDE-DNA adduct level (P < 0.05). Multiple covariates analysis showed SNP of ERCC2/XPD Arg156Arg (rs238406) and age have been related to BPDE-DNA adduct levels closely among all covariates (P < 0.05). CONCLUSION: ERCC2/XPD Arg156Arg rs238406 polymorphisms may be associated with DNA repair capacity in excising BPDE-DNA adduct and A allele may increase the risks of cancer susceptibility.

Prenatal and lactational lead exposure enhanced oxidative stress and altered apoptosis status in offspring rats' hippocampus.

Oxidative stress and apoptosis facilitation in the developing central nervous system (CNS) have been inferred as two mechanisms related to lead's neurotoxicity, and excessive reactive oxygen species (ROS) can promote oxidative stress and apoptosis facilitation. Few studies systematically investigated the potential relationship among oxidative stress, ROS generation, and apoptosis facilitation after lead exposure in earlier life as a whole. To better understand the adverse effect on the developing central nervous system (CNS) after lead exposure during pregnancy and lactation, the indexes of oxidative stress, apoptosis status, and Bax and Bcl-2 expression of offspring rats' hippocampus were determined. Pregnant rats were randomly divided into four groups and given free access to drinking water which contained 0 %, 0.05 %, 0.1 %, and 0.2 % Pb(AC)(2) respectively from gestation day 0 to postnatal day 21 (PND21). Results showed that ROS and malondialdehyde level of either PND7 or PND21 pups' hippocampus were significantly raised; reduced glutathione level and superoxide dismutase activity were obviously decreased following the increase of blood and brain lead level. Similar to apoptotic indexes, Bax/Bcl-2 ratio increased after 0.1 % and 0.2 % Pb(AC)(2) exposure, especially for the pups on PND7. Comparing with cortex, the hippocampus seemed much more sensitive to damage induced by lead. We concluded that the disruption of pro-oxidant and antioxidant balance and apoptosis facilitation could be associated with the mechanisms of neurotoxicity after lead exposure in earlier life.