Objective To investigate the mechanism and protective effect of Humanin (HN) on rotenone (Rot)-induced toxic damage for dopamine neurons. Methods The Rot-poisened PC12 cell model was constructed, and the control group, the Rot poisening group, the HN pretreated Rot poisening group, and the HN treatment group were set up. ELISA was used to detect the content of HN inside and outside of Rot-infected cells, CCK-8 assay was used to detect cell viability, and ATP detection kit was used to detect the intracellular ATP content. Dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay was used to detect the level of reactive oxygen species (ROS) in cells. Western blotting was performed to detect the expression level of mitochondrial autophagy regulatory proteins Pink1, Parkin, p62, LC3, mitochondrial biogenesis regulatory protein PGC1α, division/fusion regulatory proteins OPA1, MFN2, DRP1, p-DRP1 and antioxidant stress regulatory proteins Keap1 and Nrf2. HBAD-mcherry-EGFP-LC3 adenovirus transfected cells was used to observed the number of autophagosomes and autophagolysosomes. Results The results showed that the intracellular concentration of HN in PC12 in the Rot poisening group was significantly higher than that in the control group (P < 0.05);Compared with the control group, the Rot poisening group had significantly decreased activity of PC12 cells, decreased ATP content and increased production of ROS. After the poisen of Rot in PC12 cells, the expression of Pink1 and p-Parkin, the ratio of LC3Ⅱ/LC3Ⅰ and the expression of p-DRP1 in mitochondrial fusion protein was increased, while the expression of p62, the expression of mitochondrial biogenesis protein PGC1α, mitochondrial fusion proteins MFN2 and OPA1, and antioxidant stress proteins Keap1 and Nrf2 were decreased (all P < 0.05). The number of autophagosomes and autophagolysosomes in PC12 cells in the Rot poisening group was higher than that in the control group (P < 0.05), and HN pretreatment (20 μmol/L) could significantly improve the changes mentioned above caused by Rot poisening (P < 0.05). Conclusion HN ameliorates Rot-induced toxic damage for dopamine neurons by inhibiting mitophagy and mitochondrial division and promoting mitochondrial biogenesis and fusion, and anti-oxidative stress.

Nitrogen mustard (NM) is a chemotherapeutic agent capable of alkylating nucleophilic proteins and DNA, causing severe cell damage. However, no reports have been on the dynamic changes in proteomics induced by NM. In this study, we established a model of acute exposure to NM for 1 h and a continuous cultured model for 24 h after NM removal (repair stage) using 16HBE cells. The nuclear protein spectrum and nuclear proteins crosslinked with DNA were analyzed, and the function of p97 during NM damage was examined. An hour of NM exposure resulted in severe changes in the nuclear protein spectrum and protein into the cell nucleus, which is mainly involved in nuclear acid-related issues. After 24 h, the return to normal process of the types and amounts of differentially expressed proteins was inhibited by si-p97. The main processes involved in si-p97 intervention were nucleocytoplasmic transport, processing in the endoplasmic reticulum, metabolic abnormalities, and DNA-response; however. An hour of exposure to NM increased DNA-protein crosslinking (DPC), total-H2AX, and p-H2AX. In contrast, si-p97 only further increased or maintained their levels at 24 h yet not at 1 h. The effect of the proteasome inhibitor, MG132, was similar to that of si-p97. The siRNA of DVC1, a partner of p97, also increased the DPC content. Both si-p97 and si-DVC1 increased the cytoplasmic levels of the proteasome (PSMD2). These results suggest acute NM exposure induces severe nuclear protein spectral changes, rapid protein influx into the nucleus, DPC formation, and DNA double-strand breaks. Furthermore, our data indicated that p97 is involved in normal protein spectrum maintenance and DPC removal after NM withdrawal, requiring the participation of DVC1 and the proteasome.

To investigate the role of the liver kinase (LK) B1 protein, an activator of AMP-activated protein kinase (AMPK), in AMPK signaling suppression when exposed to vesicant, a kind of chemical warfare agent. Cultured human bronchial epithelial cells were inflicted with sulfur mustard (SM) analog, 2-chloroethyl ethyl sulfide (CEES) of 0.2-1.0 mM concentration, and cell proliferation, apoptosis, autophagy, and cellular ATP level were analyzed up to 24 h after the exposure. Focusing on LKB1, heat shock protein (HSP) 90, and cell division cycle (CDC) 37 proteins, the protein expression, phosphorylation, and interaction were examined with western blot, immunofluorescence staining, and/or immunoprecipitation. AMPK signaling was found to be inhibited 24 h after being exposed to either sub-cytotoxic (0.5 mM) or cytotoxic (1.0 mM) concentration of CEES based on MTS assay. Consistently, the degradation of the LKB1 protein and its less interaction with the HSP90/CDC37 complex was confirmed. It was found that 1.0, not 0.5 mM CEES also decreased the CDC37 protein, proteasome activity, and cellular ATP content that modulates HSP90 protein conformation. Inhibiting proteasome activity could alternatively activate autophagy. Finally, either 0.5 or 1.0 mM CEES activated HSP70 and autophagy, and the application of an HSP70 inhibitor blocked autophagy and autophagic degradation of the LKB1 protein. In conclusion, we reported here that AMPK signaling inactivation by CEES was a result of LKB1 protein loss via less protein complex formation and enhanced degradation.

Abstract Nitrogen mustard (NM) can alkylate nucleophilic proteins and DNA, causing severe cell damage. However, there are no reports on NM-induced proteomics dynamic changes. In this study, nuclear and cytoplasmic proteins of 16HBE cell were separated and the components and amounts were detected and analyzed. The amount of DNA protein cross-linking (DPC) and the function of p97 were also explored. One-hour-NM-exposure caused a tremendous number of proteins entered into the nucleus and DPC formation. As repair progressed, proteins exited. Although the protein influx at 1 h was delayed by si-p97 intervention, it continued to 24 h after NM withdrawal. In the early damage, the affected pathways mainly included spliceosome, ribosome biogenesis in eukaryotes, and mRNA surveillance, which switched to protein processing in endoplasmic reticulum and energy production in presumed repair stage. Si-p97 aggravated ferroptosis, cysteine and methionine metabolism at beginning of the damage, followed by downward ranking the transcription related pathways at 24 h. NM caused DPC and H2AX increases at 1 h. Si-p97 suppressed them at 1 h and extended the increase time to 24 h. MG132 effected similar to si-p97. Si-p97 and si-DVC1 increased the cytoplasmic level of proteasome (PSMD2). Si-DVC1 also increased the DPC content. These results suggest that NM caused a severe and rapid protein influx and crosslink in the nucleus in the early stage of injury, followed by the formation of secondary double-strand breaks. P97 was involved in the clearance of proteins in nucleus and DPC for repair, which required the participation of DVC1 and proteasome.

Using sulfur mustard analog 2-chloroethyl ethyl sulfide (CEES), we established an in vitro model by poisoning cultured immortalized human bronchial epithelial cells. Nile Red staining revealed lipids accumulated 24 h after a toxic dose of CEES (0.9 mM). Lipidomics analysis showed most of the increased lipids were triglycerides (TGs), and the increase in TGs was further confirmed using a Triglyceride-Glo (TM) Assay kit. Protein and mRNA levels of DGAT1, an important TG biogenesis enzyme, were increased following 0.4 mM CEES exposure. Under higher dose CEES (0.9 mM) exposure, protein and mRNA levels of PPAR gamma coactivator-1alpha (PGC-1alpha), a well-known transcription factor that regulates fatty acid oxidation, were decreased. Finally, application with DGAT1 inhibitor A 922500 or PGC1alpha agonist ZLN005 was able to block the CEES-induced TGs increase. Overall, our dissection of CEES-induced TGs accumulation provides new insight into energy metabolism dysfunction upon vesicant exposure.

MOTS-c is a 16-amino acid mitochondrial-derived peptide reported to be involved in regulating energy metabolism. However, few studies have reported the role of MOTS-c on neuron degeneration. In this study, it was aimed to explore the action of MOTS-c in rotenone-induced dopaminergic neurotoxicity. In an in vitro study, it was observed that rotenone could influence the expression and localization of MOTS-c significantly in PC12 cells, with more MOTS-c translocating into the nucleus from mitochondria. Further study showed that the translocation of MOTS-c from the mitochondria into the nucleus could directly interact with Nrf2 to regulate HO-1 and NQO1 expression in PC12 cells exposed to rotenone, which had been suggested to be involved in the antioxidant defense system. In vivo and in vitro experiments demonstrated that exogenous MOTS-c pretreatment could protect PC12 cells and rats from mitochondrial dysfunction and oxidative stress induced by rotenone. Moreover, MOTS-c pretreatment significantly decreased the loss of TH, PSD95, and SYP protein expression in the striatum of rats exposed to rotenone. In addition, MOTS-c pretreatment could clearly alleviate the downregulated expression of Nrf2, HO-1, and NQO1, as well as the upregulated Keap1 protein expression in the striatum of rotenone-treated rats. Taken together, these findings suggested that MOTS-c could directly interact with Nrf2 to activate the Nrf2/HO-1/NQO1 signal pathway to defend the antioxidant system to prevent dopaminergic neurons from rotenone-induced oxidative stress and neurotoxicity in vitro and in vivo.

TDCPP is a flame retardant which has nervous and reproductive toxicity. Although there is a close association between nervous and reproductive system, the exact toxic mechanism of TDCPP in these systems is still seldom, especially in a genome scale. In this study, we explored the transcriptomic landscape of TDCPP in PC12 and GC2 cells using RNAseq method. A total of 465 co-differential expressed genes were found. These genes were mainly enriched in extra-cellular matrix, cell adhesion, cell cycle arrest, oxidoreductase activity GO terms, and PI3K/AKT, focal adhesion, ECM-receptor interaction KEGG pathways. Hub genes (ANXA1, COL27A1, GAS6, GNB4 and THBS1) were extracted using STRING and confirmed by qPCR experiment. Vimentin, HSPA5 and Caspase3 were proved to be responsible to TDCPP in GC2 and PC12 cells. Knockdown assay in PC12 cells showed that these hub genes could also affect the protein expression of vimentin, HSPA5 and Caspase3. In summary, TDCPP might exert its toxic effect through disturbing focal adhesion, ECM-receptor interaction and PI3K/Akt pathways. One of the mechanisms could be influence on the cytoskeleton (vimentin), ER stress (HSPA5) and apoptosis (Caspase3). The sequence data in this study might be a useful resource for future TDCPP related researches.

AbstractNitrogen mustard (NM) causes severe skin injury with an obvious inflammatory response, which is lack of effective and targeted therapies. Vitamin D3 (VD3) has excellent anti‐inflammatory properties and is considered as a potential candidate for the treatment of NM‐induced dermal toxicity; however, the underlying mechanisms are currently unclear. Cyclooxygenase‐2 (COX2; a widely used marker of skin inflammation) plays a key role in NM‐induced cutaneous inflammation. Herein, we initially confirmed that NM markedly promoted COX2 expression in vitro and in vivo. NM also increased NOD‐like receptor family pyrin domain containing 3 (NLRP3) expression, caspase‐1 activity, and interleukin‐1β (IL‐1β) release. Notably, treatment with a caspase‐1 inhibitor (zYVAD‐fmk), NLRP3 inhibitor (MCC950), and NLRP3 or caspase‐1 siRNA attenuated NM‐induced NLRP3 inflammasome activation, with subsequent suppression of COX2 expression and IL‐1β release in keratinocytes. Meanwhile, NM increased mitochondrial reactive oxygen species (mtROS) and decreased manganese superoxide dismutase 2 (SOD2) and sirtuin 3 (SIRT3) activities. Mito‐TEMPO (a mtROS scavenger) ameliorated NM‐caused NLRP3 inflammasome activation in keratinocytes. Moreover, VD3 improved SIRT3 and SOD2 activities, decreased mtROS contents, inactivated the NLRP3 inflammasome, and attenuated cutaneous inflammation induced by NM in vitro and in vivo. The beneficial activity of VD3 against NM‐triggered cutaneous inflammation was enhanced by the inhibitors of IL‐1, mtROS, NLRP3, caspase‐1, and NLRP3 or caspase‐1 siRNAs, which was abolished in SIRT3 inhibitor or SIRT3 siRNA‐treated keratinocytes and skins from SIRT3−/− mice. In conclusion, VD3 ameliorated NM‐induced cutaneous inflammation by inactivating the NLRP3 inflammasome, which was partially mediated through the SIRT3–SOD2–mtROS signaling pathway.

Respiratory system injury is the main cause of mortality for nitrogen mustard (NM)-induced damage. Previous studies indicate that reactive oxygen species (ROS) participates in NM-mediated respiratory injuries, but the detailed mechanism is not quite clear. Human bronchial epithelial cell lines 16HBE and BEAS-2B were treated with HN2, a type of NM. In detail, it was shown that HN2 treatment induced impaired cell viability, excessive mitochondrial ROS production and enhanced cellular apoptosis in bronchial epithelial cells. Moreover, impaired Sirt3/SOD2 axis was observed upon HN2 treatment, with decreased Sirt3 and increased acetylated SOD2 expression levels. Sirt3 overexpression partially ameliorated HN2-induced cell injury. Meanwhile, vitamin D3 treatment partially attenuated HN2-induced apoptosis and improved the mitochondrial functions upon HN2 intervention. In addition, HN2 exposure decreased VDR expression, thus inhibiting the Nrf2 phosphorylation and Sirt3 activation. Inhibition of Nrf2 or Sirt3 could decrease the protective effects of vitamin D3 and enhance mitochondrial ROS production via modulating mitochondrial redox balance. In conclusion, impaired VDR/Nrf2/Sirt3 axis contributed to NM-induced apoptosis, while vitamin D3 supplementation provides protective effects via the activation of VDR and the improvement of mitochondrial functions. This study provides novel mechanism and strategy for NM exposure-induced pulmonary injuries.

Mitochondria harbor small circular genomes (mtDNA) that encode 13 oxidative phosphorylation (OXPHOS) proteins, and types of damage to mtDNA may contribute to neuronal damage. Recent studies suggested that regulation of mtDNA repair proteins may be a potential strategy for treating neuronal damage. The mtDNA repair system contains its own repair enzymes and is independent from the nuclear DNA repair system. Endo/exonuclease G-like(EXOG) is a mitochondria-specific 5-exo/endonuclease required for repairing endogenous single-strand breaks (SSBs) in mtDNA. However, whether EXOG plays a key role in neuronal damage induced by rotenone remains unknown. Thus, in this study, we aimed to investigate the effect of EXOG on mtDNA repair and mitochondrial functional maintenance in rotenone-induced neurotoxicity. Our results indicated that rotenone influenced the expression and location of EXOG in PC12 cells. Meanwhile, after rotenone exposure, the expression was reduced for proteins responsible for mtDNA repair, including DNA polymerase γ (POLG), high-temperature requirement protease A2 (HtrA2), and the heat-shock factor 1-single-stranded DNA-binding protein 1 (HSF1-SSBP1) complex. Further analysis demonstrated that EXOG knockdown led to reduced mtDNA copy number and mtDNA transcript level and increased mtDNA deletion, which further aggravated the mtDNA damage and mitochondrial dysfunction under rotenone stress. In turn, EXOG overexpression protected PC12 cells from mtDNA damage and mitochondrial dysfunction induced by rotenone. As a result, EXOG knockdown reduced cell viability and tyrosine hydroxylase expression, while EXOG overexpression alleviated rotenone's effect on cell viability and tyrosine hydroxylase expression in PC12 cells. Further, we observed that EXOG influenced mtDNA repair by regulating protein expression of the HSF1-SSBP1 complex and POLG. Furthermore, our study showed that PGC-1α upregulation with ZLN005 led to increased protein levels of EXOG, POLG, HSF1, and SSBP1, all of which contribute to mtDNA homeostasis. Therefore, PGC-1α may be involved in mtDNA repair through interacting with multiple mtDNA repair proteins, especially with the help of EXOG. In summary, EXOG regulation by PGC-1α plays an essential role in rotenone-induced neurotoxicity in PC12 cells. EXOG represents a protective effect strategy in PC12 cells exposed to rotenone.

Nitrogen mustard (NM) causes severe vesicating skin injury, which lacks effective targeted therapies. The major limitation is that the specific mechanism of NM-induced skin injury is not well understood. Recently, autophagy has been found to play important roles in physical and chemical exposure-caused cutaneous injuries. However, whether autophagy contributes to NM-induced dermal toxicity is unclear. Herein, we initially confirmed that NM dose-dependently caused cell death and induced autophagy in keratinocytes. Suppression of autophagy by 3-methyladenine, chloroquine, and bafilomycin A1 or ATG5 siRNA attenuated NM-induced keratinocyte cell death. Furthermore, NM increased transient receptor potential vanilloid 1 (TRPV1) expression, intracellular Ca 2+ content, and the activities of Ca 2+ /calmodulin-dependent kinase kinase β (CaMKKβ), AMP-activated protein kinase (AMPK), unc-51-like kinase 1 (ULK1), and mammalian target of rapamycin (mTOR). NM-induced autophagy in keratinocytes was abolished by treatment with inhibitors of TRPV1 (capsazepine), CaMKKβ (STO-609), AMPK (compound C), and ULK1 (SBI-0206965) as well as TRPV1 , CaMKKβ , and AMPK siRNA transfection. In addition, an mTOR inhibitor (rapamycin) had no significant effect on NM-stimulated autophagy or cell death of keratinocytes. Finally, the results of the in vivo experiment in NM-treated skin tissues were consistent with the findings of the in vitro experiment. In conclusion, NM-caused dermal toxicity by overactivating autophagy partially through the activation of TRPV1-Ca 2+ -CaMKKβ-AMPK-ULK1 signaling pathway. These results suggest that blocking TRPV1-dependent autophagy could be a potential treatment strategy for NM-caused cutaneous injury.

Sulfur mustard (a type of vesicant) can directly damage lung bronchial epithelium via aerosol inhalation, and prevalent cell death is an early event that obstructs the respiratory tract. JNK/c-Jun is a stress response pathway, but its role in cell death of the injured cells is not clear. Here, we report that JNK/c-Jun was activated in immortalized human bronchial epithelial (HBE) cells exposed to a lethal dose (20 μM) of nitrogen mustard (NM, a sulfur mustard analog). c-Jun silencing using small-interfering RNA (siRNA) rendered the cells resistant to NM-mediated cell death by blocking poly(ADP-ribose) polymerase 1 (PARP1) cleavage and DNA fragmentation. In addition, the transduction of upstream extrinsic (Fasl-Fas-caspase-8) and intrinsic (loss of Bcl-2 and mitochondrial membrane potential, ΔΨm) apoptosis pathways, as well as phosphorylated (p)-H2AX (Ser139), an epigenetic marker contributing to DNA fragmentation and PARP1 activity, was partially suppressed. To mimic the detachment of cells by NM, HBE cells were trypsinized and seeded on culture plates that were pre-coated with poly-HEMA to prevent cell adhesion. The JNK/c-Jun pathway was found to be activated in the detached cells. In conclusion, our results indicate that JNK/c-Jun pathway activation is necessary for NM-caused HBE cell death and further suggest that c-Jun silencing may be a potential approach to protect HBE cells from vesicant damage.

Pesticides are widely used in the world for agriculture and industry. A lot of pesticide residues are observed in our air, soil, and water, which has been regarded as serious environmental contaminations. More and more researches begin to pay attention to the potential toxic effects of pesticides on human health. Till now, it has been confirmed that pesticides exposures are associated with carcinogenicity, neurotoxicity, pulmonotoxicity, reproductive toxicity, developmental toxicity, and metabolic toxicity. Pesticides exposure might play an important role in the pathogenesis of neurodegenerative diseases, such as Parkinson disease and Alzheimer disease. In this review, we focused on the relationship between the main commonly used pesticides and dopaminergic neurodegeneration. The main mechanism of neurotoxicity induced by pesticides exposure were also discussed. Additionally, it is known that the main histological hallmark of dopamine neurodegeneration is the presence of α-synuclein aggregates called Lewy bodies. Therefore, we also discussed the linkages between pesticide exposure and synuclein protein aggregation, which would be helpful to understand the etiology of neurodegeneration.

Background: Medical defense against chemical, biological, radiological, and nuclear (CBRN) threats should be established through systematic education in college and career development training to counter the response successfully. Methods: Taking the course of Medical Countermeasures against CBRN Weapons is compulsorily for all military medical students in the Chinese People’s Liberation Army (PLA). In the present study, a modularized course for field training of Chemical Defense Medicine is provided, which is an important part of the Integrated Military Medicine Exercise (IMME) conducted annually in PLA military medical university. Discussion: The established modules are functionally designed as passing through a contaminated area with protective posture, operating chemical defense equipment, battlefield rescue after a chemical attack, and early treatment of chemically contaminated casualties. This modularized training is task-oriented, function-based, and integrate with a functional drill, which provides an example in the training of CBRN defense medicine.

Sulfur mustard (SM) is a chemical alkylating agent that causes severe vesicating skin injuries. However, the exact mechanisms have not been thoroughly elucidated, limiting the development and optimization of effective therapeutic interventions against SM. MicroRNAs (miRNAs) are small non-coding RNAs with similar to 22 nucleotide lengths, serving as important posttranscriptional gene regulators in cellular activities. Recently, miRNAs, especially miR-210, have been identified to be involved in skin wound healing. Thus, the present study aimed to determine the roles of miR-210 in SM-induced skin injuries in SKH-1 hairless mice. It was confirmed that SM significantly increased expression of miR-210 in skin from 3 days to 14 days post-exposure. miR-210 expressing cells were allocated to the epidermis by in situ hybridization. HIF1 alpha, a key regulator of miR-210, was also increased in line with miR-210 expression. Injections of antago-miR-210 around the wound bed could efficiently lower miR-210 expression levels and promote wound healing. Moreover, antago-miR-210 application promoted keratinocytes migration to the vicinity of wounds. In conclusion, topical SM contamination in the skin could notably upregulate miR-210 expression, while downregulation of miR-210 could accelerate cutaneous wound healing, partially via promoting keratinocyte migration. Present results provide a therapeutic rationale of miR-210 on SM-caused skin injuries.

SM (Sulfur mustard) is an oily, hydrophobic, and lipophilic chemical agent that damages cells with intricate patterns. CEES (2-chloroethyl ethyl sulfide soluble) is a standard SM analog commonly employed in the toxicity mechanism study. To obtain ideal results in vitro, researchers should disperse CEES well in the medium, avoiding the presence of undissolved droplets. However, such a purpose is not easy to reach under the conventional solution preparation, and the information about droplet formation and function is little available. Here, we showed that phospholipid and triglyceride, two essential components of serum lipids, could prevent CEES from dissolving in water after vortex, which kept partial CEES as small droplets. By detecting CEES level, we proved that residual droplets slowed CEES hydrolysis and conversion. Under the microscope, CEES droplets were observed to degrade and diffuse with time to induce the necrosis and mitochondrial membrane potential decline from nearby cells. In conclusion, the damage pattern of CEES droplets is quite different from that of dissolved CEES, and a low level of phospholipid and triglyceride is beneficial for preventing droplets formation in preparing CEES solution.

N-methyl-2,2-di(chloroethyl)amine (HN2) is a kind of bifunctional alkyltating agent, which can react with nucleophilic groups in DNA and/or protein to form HN2-bridged crosslinking of target molecules, such as DNA-protein crosslinkings (DPC). O6-methylguanine-DNA methyltransferase (MGMT) is a DNA damage repair enzyme which solely repairs alkyl adduct on DNA directly. However, MGMT was detected to act as a protein cross-linked with DNA via alkylation in presence of HN2, and unexpectedly turned into a DNA damage enhancer in the form of MGMT-DNA cross-link (mDPC). Present study aimed to explore the possible ways to lessen the incorporation of MGMT into DPC as well as to save it for DNA repair. To find out the influencing factors of mDPC formation and cleavage, human bronchial epithelial cell line 16HBE was exposed to HN2 and the factors related with MGMT expression and degradation were investigated. When c-Myc, a negative transcriptional factor of MGMT was inhibited by 10058-F4, MGMT expression and mDPC formation were increased, and more γ-H2AX was also detected. Sustained treatment with O6BG, a specific exogenous substrate and depleter of MGMT, could reduce the level of MGMT and mDPC formation. In contrast, a transient 1h pre-treatment of O6GB before HN2 exposure would cause a high MGMT and mDPC level. MGMT was increasingly ubiquitinated after HN2 exposure in a time-dependent manner. At the same time, MGMT was also SUMOylated with a downward time-dependent manner compared to its ubiquitination. Inhibitors of E1, E2 or E3 ligases of ubiqutination all led to the accumulation of mDPC and total-DPC (tDPC) with the difference as that mDPC was sensitive to E1 inhibitor while tDPC more sensitive to E2 and E3 inhibitor. Our results demonstrated the control of mDPC level could be realized through transcription inhibitory effect of c-Myc, O6GB application, and the acceleration of mDPC ubiquitination and subsequent degradation.

Nitrogen mustard (NM), a bifunctional alkylating agent (BAA), contains two alkyl arms and can act as a cross-linking bridge between DNA and protein to form a DNA-protein cross-link (DPC). O6-methylguanine–DNA methyltransferase (MGMT), a DNA repair enzyme for alkyl adducts removal, is found to enhance cell sensitivity to BAAs and to promote damage, possibly due to its stable covalent cross-linking with DNA mediated by BAAs. To investigate MGMT-DNA cross-link (mDPC) formation and its possible dual roles in NM exposure, human bronchial epithelial cell line 16HBE was subjected to different concentrations of HN2, a kind of NM, and we found mDPC was induced by HN2 in a concentration-dependent manner, but the mRNA and total protein of MGMT were suppressed. As early as 1h after HN2 treatment, high mDPC was achieved and the level maintained for up to 24h. Quick total DPC (tDPC) and γ-H2AX accumulation were observed. To evaluate the effect of newly predicted protease DVC1 on DPC cleavage, we applied siRNA of MGMT and DVC1, MG132 (proteasome inhibitor), and NMS-873 (p97 inhibitor) and found that proteolysis plays a role. DVC1 was proven to be more important in the cleavage of mDPC than tDPC in a p97-dependent manner. HN2 exposure induced DVC1 upregulation, which was at least partially contributed to MGMT cleavage by proteolysis because HN2-induced mDPC level and DNA damage was closely related with DVC1 expression. Homologous recombination (HR) was also activated. Our findings demonstrated that MGMT might turn into a DNA damage promoter by forming DPC when exposed to HN2. Proteolysis, especially DVC1, plays a crucial role in mDPC repair.

Mammalian AMP-activated protein kinase (AMPK) acts as an important sensor of cellular energy homeostasis related with AMP/ADP to ATP ratio. The overall architecture of AMPK has been determined in either homotrimer or monomer form by electron microscopy (EM) and X-ray crystallography successively. Accordingly proposed models have consistently revealed a key role of the α subunit linker in sensing adenosine nucleoside binding on the γ subunit and mediating allosteric regulation of kinase domain (KD) activity, whereas there are vital differences in orienting N-terminus of α subunit and locating carbohydrate-binding module (CBM) of β subunit. Given that Mg 2+ , an indispensable cofactor of AMPK was present in the EM sample preparation buffer however absent when forming crystals, here we carried out further reconstructions without Mg 2+ to expectably inspect if this ion may contribute to this difference. However, no essential alteration has been found in this study compared to our early work. Further analyses indicate that the intra-molecular movement of the KD and CBM are most likely due to the flexible linkage of the disordered linkers with the rest portion as well as a contribution from the plasticity in the inter-molecular assembly mode, which might ulteriorly reveal an architectural complication of AMPK.

BACKGROUND:MicroRNA-34a (miR-34a) is a potential prognostic factor for survival in patients with several types of cancer according to previous clinical researches. We conducted a systematic review and meta-analysis to summarize the significance of increased miR-34a expression in the prognosis of patients' overall survival. MATERIALS AND METHODS:The present systematic review and meta-analysis of 15 researches included 2,597 patients. Overexpression of miR-34a may predict good overall survival ([OS], HR =0.76, 95% confidence interval: 0.55-1.06, P=0.105), but the effect was not significant enough. Subgroup analysis results showed miR-34a was an ideal predictor for digestive system cancer (OS, HR =0.50, 95% confidence interval: 0.25-0.99, P=0.048). The predictive effects of elevated expression of miR-34a on the OS of untreated and treated patients were not of obvious differences. CONCLUSION:This systematic review and meta-analysis showed that miR-34a has a predictive effect on overall survival of patients with digestive system cancer.