The DNase domain-containing protein TATDN1 is a conserved nuclease in both prokaryotes and eukaryotes. It was previously implicated to play a role in apoptotic DNA fragmentation in yeast and C. elegans. However, its biological function in higher organisms, such as vertebrates, is unknown. Here, we report that zebrafish TATDN1 (zTATDN1) possesses a novel endonuclease activity, which first makes a nick at the DNA duplex and subsequently converts the nick into a DNA double-strand break in vitro. This biochemical property allows zTATDN1 to catalyze decatenation of catenated kinetoplast DNA to produce separated linear DNA in vitro. We further determine that zTATDN1 is predominantly expressed in eye cells during embryonic development. Knockdown of TATDN1 in zebrafish embryos results in an abnormal cell cycle progression, formation of polyploidy and aberrant chromatin structures. Consequently, the TATDN1-deficient morphants have disordered eye cell layers and significantly smaller eyes compared with the WT control. Altogether, our current studies suggest that zTATDN1 plays an important role in chromosome segregation and eye development in zebrafish.
TATDN1; nuclease; decatenation; cell cycle; zebrafish; eye
It has been suggested that paclitaxel and gemcitabine modulate the immune system. This paper reports the safety and efficacy of paclitaxel plus gemcitabine followed by interleukin-2 (IL-2)and granulocyte macrophage colony-stimulating factor (GM-CSF), the PGIG chemobiotherapy, for patients with metastatic melanoma. All patients received 175 mg/m2 paclitaxel on day 1 and 800 mg/m2 gemcitabine on day two. IL-2 and GM-CSF were administered from day 4 to day 8 at a dosage of 2 MIU/m2 and 100 μg, respectively. The PGIG chemobiotherapy was repeated every 21 d. Serum cytokine levels at baseline and at the end of the second cycle were measured via flow cytometry. Twenty-seven patients with metastatic melanoma accepted PGIG chemobiotherapy from August 2009 to March 2011. There were five patients that exhibited a partial response, 14 patients that exhibited a stable response and eight that displayed progressive disease. Therefore, the response rate was 18.5%, and the disease control rate was 70.4%. The median time to progression and median survival were 4 mo and 8 mo, respectively. The one-year and two-year survival rates were 25.9% and 18.5%, respectively. Frequent side effects included chills, fever, arthralgia, rash and pruritus. Among the 13 patients who experienced a rash and pruritus and the 14 patients who did not suffer from this side effect, the response rates and disease control rates were 30.8% vs 7.1% and 77% vs 64.2%, respectively. No relationship between serum IL-6 levels, clinical response, and either skin side effect was observed. The PGIG chemobiotherapy is safe and effective for the treatment of patients with advanced melanoma, but randomized trials are necessary to validate this effect.
chemobiotherapy; metastatic melanoma; paclitaxel; pruritus; rash; gemcitabine; pilot study
Signaling via the Akt serine/threonine protein kinase plays critical roles in the self-renewal of embryonic stem cells and their malignant counterpart, embryonal carcinoma cells (ECCs). Here we show that in ECCs, Akt phosphorylated the master pluripotency factor Oct4 at threonine 235, and that the levels of phosphorylated Oct4 in ECCs correlated with resistance to apoptosis and tumorigenic potential. Phosphorylation of Oct4 increased its stability, and facilitated its nuclear localization and its interaction with Sox2, which promoted the transcription of the core stemness genes POU5F1 and NANOG. Furthermore, in ECCs, unphosphorylated Oct4 bound to the AKT1 promoter and repressed its transcription. Phosphorylation of Oct4 by Akt resulted in dissociation of Oct4 from the AKT1 promoter, which activated AKT1 transcription and promoted cell survival. Therefore, a site-specific, post-translational modification of the Oct4 protein orchestrates the regulation of its stability, subcellular localization and transcriptional activities, which collectively promotes the survival and tumorigenicity of ECCs.
A critical observation in sporadic cancers is that not all individuals are equally prone to developing cancer following exposure to a given environmental carcinogen. Epidemiological studies have suggested that the difference in the timing of cancer onset in response to exogenous DNA damage is likely attributable to genetic variations, such as those associated with base excision repair genes. To test this long-standing hypothesis and elucidate how a genetic variation in the base excision repair gene flap endonuclease 1 (FEN1) results in susceptibility to environment insults and causes cancer, we established a mutant mouse model carrying a point mutation (E160D) in Fen1. We demonstrate that the E160D mutation impairs the ability of FEN1 to process DNA intermediate structures in long-patch base excision repair using nuclear extracts or reconstituted purified base excision repair proteins. E160D cells were more sensitive to the base damaging agents methylnitrosourea and hydrogen peroxide, leading to DNA strand breaks, chromosomal breakage, and chromosome instabilities in response these DNA insults. We further show that E160D mice are significantly more susceptible to exposure to methylnitrosourea and develop lung adenocarcinoma. Thus, our current study demonstrates that a subtle genetic variation (E160D) in base excision repair genes (FEN1) may cause a functional deficiency in repairing base damage, such that individuals carrying the mutation or similar mutations are predisposed to chemical-induced cancer development.
FEN1; Long-patch base excision repair; methylnitrosourea; tetraploidy; aneuploidy; cancer
One genus and species are synonymized in the tribe Empoascini of the subfamily Typhlocybinae. Bhatasca Dworakowska, 1995is a junior synonym of Alebrasca Hayashi & Okada, 1994, Bhatasca rectangulata Qin & Zhang, 2011is a junior synonym of Alebrasca actinidiae Hayashi & Okada, 1994. Furthermore, Bhatasca expansa is (necessarily) transferred to the genus Alebrasca.
Homoptera; Auchenorryncha; taxonomy; leafhopper; synonym; China
In this study we established a bipedal animal model of steroid-associated hip joint collapse in emus for testing potential treatment protocols to be developed for prevention of steroid-associated joint collapse in preclinical settings. Five adult male emus were treated with a steroid-associated osteonecrosis (SAON) induction protocol using combination of pulsed lipopolysaccharide (LPS) and methylprednisolone (MPS). Additional three emus were used as normal control. Post-induction, emu gait was observed, magnetic resonance imaging (MRI) was performed, and blood was collected for routine examination, including testing blood coagulation and lipid metabolism. Emus were sacrificed at week 24 post-induction, bilateral femora were collected for micro-computed tomography (micro-CT) and histological analysis. Asymmetric limping gait and abnormal MRI signals were found in steroid-treated emus. SAON was found in all emus with a joint collapse incidence of 70%. The percentage of neutrophils (Neut %) and parameters on lipid metabolism significantly increased after induction. Micro-CT revealed structure deterioration of subchondral trabecular bone. Histomorphometry showed larger fat cell fraction and size, thinning of subchondral plate and cartilage layer, smaller osteoblast perimeter percentage and less blood vessels distributed at collapsed region in SAON group as compared with the normal controls. Scanning electron microscope (SEM) showed poor mineral matrix and more osteo-lacunae outline in the collapsed region in SAON group. The combination of pulsed LPS and MPS developed in the current study was safe and effective to induce SAON and deterioration of subchondral bone in bipedal emus with subsequent femoral head collapse, a typical clinical feature observed in patients under pulsed steroid treatment. In conclusion, bipedal emus could be used as an effective preclinical experimental model to evaluate potential treatment protocols to be developed for prevention of ON-induced hip joint collapse in patients.
Obesity exhibits a wide variety of electrocardiogram (ECG) abnormalities in adults, which often lead to cardiovascular events. However, there is currently no evidence of an association between obesity and ECG variables in children and adolescents. The present study aimed to explore the associations between obesity and ECG intervals and axes in children and adolescents. A cross-sectional observational study of 5,556 students aged 5–18 years was performed. Anthropometric data, blood pressure and standard 12-lead ECGs were collected for each participant. ECG variables were measured manually based on the temporal alignment of simultaneous 12 leads using a CV200 ECG Work Station. Overweight and obese groups demonstrated significantly longer PR intervals, wider QRS durations and leftward shifts of frontal P-wave, QRS and T-wave axes, while the obese group also demonstrated significantly higher heart rates, compared with normal weight groups within normotensive or hypertensive subjects (P<0.05). Abdominal obesity was also associated with longer PR intervals, wider QRS duration and a leftward shift of frontal ECG axes compared with normal waist circumference (WC) within normotensive or hypertensive subjects (P<0.05). Gender was a possible factor affecting the ECG variables. Furthermore, the ECG variables, including PR interval, QRS duration and frontal P-wave, QRS and T-wave axes, were significantly linearly correlated with body mass index, WC and waist-to-height ratio adjusted for age, gender, ethnicity and blood pressure. However, there was no significant association between obesity and the corrected QT interval (P>0.05). The results of the current study indicate that in children and adolescents, general and abdominal obesity is associated with longer PR intervals, wider QRS duration and a leftward shift of frontal P-wave, QRS and T-wave axes, independent of age, gender, ethnicity and blood pressure.
obesity; abdominal obesity; electrocardiography; intervals; axes; children; adolescents
We provide a new and definitive spectral assignment for the absorption, emission, high-resolution fluorescence excitation, linear dichroism, and/or magnetic circular dichroism spectra of 32 chlorophyllides in various environments. This encompases all data used to justify previous assignments and provides a simple interpretation of unexplained complex decoherence phenomena associated with Qx → Qy relaxation. Whilst most chlorophylls conform to the Gouterman model and display two independent transitions Qx (S2) and Qy (S1), strong vibronic coupling inseparably mixes these states in chlorophyll-a. This spreads x-polarized absorption intensity over the entire
Q-band system to influence all exciton-transport, relaxation and coherence properties of chlorophyll-based photosystems. The fraction of the total absorption intensity attributed to Qx ranges between 7% and 33%, depending on chlorophyllide and coordination, and is between 10% and 25% for chlorophyll-a. CAM-B3LYP density-functional-theory calculations of the band origins, relative intensities, vibrational Huang-Rhys factors, and vibronic coupling strengths fully support this new assignment.
Intrathoracic impedance monitoring has emerged as a promising new technique for the detection of impending heart failure (HF). Although false positive episodes have been reported in case reports and clinical trials, the efficacy and false positive rate in real-world practice remain unclear.
The aim of this study is to investigate the utility and reliability of the OptiVol alert feature in clinical practice.
We continuously recruited patients who underwent implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy with defibrillator (CRT-D) implantation with feature of intrathoracic impedance monitoring system in our center from Sep. 2010 to Oct. 2012. Regular in-office follow-up were required of all patients and the following information was collected at each visit: medical history, device interrogation, N-terminal pro-brain natriuretic peptide (NT-proBNP) measurement and an echocardiogram. Worsening HF was defined as hospitalization or the presentation of signs or symptoms of HF.
Forty three patients (male: 76.7%, mean age: 57 ± 15 years, left ventricular ejection fraction (LVEF): 33% ± 14%) were included in this observational study. Fifty four alert events and 14 adjudicated worsening HF were detected within 288 ±163 days follow-up. Eleven (20.4%) alert episodes were associated with acute cardiac decompensation in 9 patients with a positive predictive value of 78.6%. Forty three audible alerts showed no connection to worsening HF. The unexplained alerts rate was 79.6% and 1.27 per person-year. Thirty seven alarm alerts were detected in patients with EF < 45%, among which 9 accompanied with HF, 17 alerts detected in patients with LVEF ≥ 45% and 2 associated with HF. There was no significant difference between the two groups (9/37 vs. 2/17; P = 0.47).
Patients with normal or nearly normal left ventricular systolic function also exhibited considerable alert events. The OptiVol fluid index predicted worsening cardiac events with a high unexplained detection rate, and any alert must therefore be analyzed with great caution. Efforts to improve the specificity of this monitoring system represent a significant aspect of future studies.
Heart failure; Intrathoracic impedance measurement; OptiVol fluid index; Left ventricular ejection fraction
We propose that cell cycle-dependent timing of FEN1 nuclease activity is essential for cell cycle progression and the maintenance of genome stability. After DNA replication is complete at the exit point of the S-phase, removal of excess FEN1 may be crucial. Here, we report a mechanism that controls the programmed degradation of FEN1 via a sequential cascade of post-translational modifications. We found that FEN1 phosphorylation stimulated its SUMOylation, which, in turn, stimulated its ubiquitination and ultimately led to its degradation via the proteasome pathway. Mutations or inhibitors that blocked the modification at any step in this pathway suppressed FEN1 degradation. Critically, the presence of SUMOylation- or ubiquitination- defective, non-degradable FEN1 mutant protein caused accumulation of Cyclin B, delays in the G1 and G2/M phases and polyploidy. These findings may represent a newly identified regulatory mechanism used by cells to ensure precise cell cycle progression and to prevent transformation.
To achieve an easily established, safe, and reproducible animal model for the study of heterotopic bone formation around vessels, a small animal series using New Zealand White rabbits was performed. Three different dosages of recombinant human bone morphogenic protein (rhBMP-2) carried by fibrin matrix were tested. A guided tissue regeneration (GTR) membrane sheet was formed into a tube and allowed to harden; it served both to maintain the space around the vessel bundle and to separate the fibrin matrix with rhBMP-2 from skeletal muscle. Wrapped around the femoral vessel bundle and fixed in place, the tube was filled with the fibrin matrix containing rhBMP-2. The surgical site was closed in layers, and the postoperative healing was uneventful. All animals resumed their full preoperative daily activities 3–4 days after the operation. No adverse events such as wound dehiscence or infection occurred, and all animals could be sacrified at the scheduled date. Micro–computed tomography and histological investigations showed heterotopic bone formation around the vessel bundle in the medium- and high-dosage rhBMP-2 groups. An easy, safe, and reproducible animal model that allows the study of heterotopic bone formation around vessels was successfully established.
biomaterials; growth factor; tissue engineering
Cycloclasticus sp. strain PY97M was isolated from a phenanthrene-degrading consortium, enriched from Yellow Sea sediment of China. Here, we present the draft genome sequence of strain PY97M, which contains 2,359,509 bp with a G+C content of 41.92% and contains 2, 264 protein-coding genes and 40 tRNAs.
The mitochondrial transcription factor A (TFAM) is required for mitochondrial DNA (mtDNA) replication and transcription. Disruption of TFAM results in heart failure and premature aging in mice. But very little is known about the role of TFAM in cancer development. Here, we report the identification of frequent frameshift mutations in the coding mononucleotide repeat of TFAM in sporadic colorectal cancer (CRC) cell lines and in primary tumors with microsatellite instability (MSI), but not in microsatellite stable (MSS) CRC cell lines and tumors. The presence of the TFAM truncating mutation, in CRC cells with MSI, reduced the TFAM protein level in vivo and in vitro and correlated with mtDNA depletion. Furthermore, forced overexpression of wild-type TFAM in RKO cells carrying a TFAM truncating mutation suppressed cell proliferation and inhibited RKO cell-induced xenograft tumor growth. Moreover, these cells showed more susceptibility to cisplatin-induced apoptosis due to an increase of cytochrome b (Cyt b) expression and its release from mitochondria. An interaction assay between TFAM and the heavy-strand promoter (HSP) of mitochondria revealed that mutant TFAM exhibited reduced binding to HSP, leading to reduction in Cyt b transcription. Collectively, these data provide evidence that a high incidence of TFAM truncating mutations leads to mitochondrial copy number reduction and mitochondrial instability, distinguishing most CRC with MSI from MSS CRC. These mutations may play an important role in tumorigenesis and cisplatin-induced apoptotic resistance of most microsatellite-unstable CRCs.
Patient-derived tumor xenograft models have been established and increasingly used for preclinical studies of targeted therapies in recent years. However, patient-derived non-small cell lung cancer (NSCLC) xenograft mouse models are relatively few in number and are limited in their degree of genetic characterization and validation. In this study, we aimed to establish a variety of patient-derived NSCLC models and characterize these for common genetic aberrations to provide more informative models for preclinical drug efficacy testing.
NSCLC tissues from thirty-one patients were collected and implanted into immunodeficient mice. Established xenograft models were characterized for common genetic aberrations, including detection of gene mutations within EGFR and KRAS, and genetic amplification of FGFR1 and cMET. Finally, gefitinib anti-tumor efficacy was tested in these patient-derived NSCLC xenograft models.
Ten passable patient-derived NSCLC xenograft models were established by implantation of NSCLC specimens of thirty-one patients into immunodeficient mice. Genetic aberrations were detected in six of the models, including one model with an EGFR activating mutation (Exon19 Del), one model with KRAS mutation, one model with both KRAS mutation and cMET gene amplification, and three models with FGFR1 amplification. Anti-tumor efficacy studies using gefitinib demonstrated that the EGFR activating mutation model had superior sensitivity and that the KRAS mutation models were resistant to gefitinib. The range of gefitinib responses in the patient-derived NSCLC xenograft models were consistent with the results reported from clinical trials. Furthermore, we observed that patient-derived NSCLC models with FGFR1 gene amplification were insensitive to gefitinib treatment.
Ten patient-derived NSCLC xenograft models were established containing a variety of genetic aberrations including EGFR activating mutation, KRAS mutation, and FGFR1 and cMET amplification. Gefitinib anti-tumor efficacy in these patient-derived NSCLC xenografts containing EGFR and KRAS mutation was consistent with the reported results from previous clinical trials. Thus, data from our panel of patient-derived NSCLC xenograft models confirms the utility of these models in furthering our understanding of this disease and aiding the development of personalized therapies for NSCLC patients.
NSCLC; Patient-derived NSCLC xenograft; EGFR/KRAS mutations; FGFR1 amplification
telomere; G-quadruplex; DNA2; telomere replication; genome instability; tumor suppression; helicase; nuclease
Human empathy is not merely a resonance with others’ physical condition, but is modulated by social factors. Using functional magnetic resonance imaging, the present study demonstrated an increased brain empathic response to others in pain when they received no rather than a large reward, with increments of the ACC, aMCC, insula and postcentral gyrus in the pain matrix and temporoparietal junction. Thus, pain target’s financial situation modulated brain empathic responses in the pain matrix based on an understanding of the situation pain target faces.
empathy; pain; monetary reward; aMCC; insula
Marinobacter nanhaiticus strain D15-8WT was isolated from a phenanthrene-degrading consortium, enriched from sediment of the South China Sea. Here, we present the draft genome of strain D15-8WT, which contains 5,358,309 bp with a G+C content of 58.53% and contains 4,829 protein-coding genes and 47 tRNA genes.
Pten (phosphatase and tensin homolog deleted on chromosome 10), a kind of tumor suppressor gene, plays important roles in female reproductive system. But its expression and roles in the formation of polycystic ovaries are yet to be known. In this study, we constructed a rat model of PCOS using norethindrone and HCG injections and found the expressions of pten mRNA and PTEN protein increased significantly in the polycystic ovary tissue by immunohistochemistry, RT-PCR, and western blot. Furthermore, the results showed that in vivo ovaries could be effectively transfected by lentiviral vectors through the ovarian microinjection method and indicated that pten shRNA may inhibit the formation of polycystic ovaries by pten down-regulation. Our study provides new information regarding the role of PTEN in female reproductive disorders, such as polycystic ovary syndrome.
Polycystic ovary; pten; RNA interference; Follicular development
Dopamine D2 receptor is involved in reward-mediating mesocorticolimbic pathways. It plays an important role in major depressive disorder (MDD). Three gene polymorphisms Taq1A, C957T and -141C ins/del, were identified in the DRD2 gene among the Western population. These variants in the DRD2 gene might be associated with the susceptibility of MDD patients through affecting the bioeffects of endogenous dopamine neurotransmission. However, little is known about their occurrence in Chinese population and their association with the susceptibility of patients with major depressive disorder. In this study, a total of 338 unrelated adult Chinese Han population, including 224 healthy volunteers and 114 patients with major depressive disorder, were recruited. DRD2 polymorphisms (Taq1A and -141C ins/del) were detected using restriction fragment length polymorphism (RFLP) analysis and the C957T were detected by sequencing directly. As a result, three polymorphisms were identified in Chinese Han population and all were common SNP. However, we could detect no evidence of genetic association between 3 markers in DRD2 and major depressive disorder in the Chinese Han population. To conclude, this result suggests that Taq1A, C957T and -141C ins/del of DRD2 gene may not be associated with major depressive disorder, also may be the sample sizes too small to allow a meaningful test.
Dopamine D2 receptor; polymorphism; major depressive disorder
Somitogenesis is a fundamental characteristic feature of development in various animal embryos. Molecular evidence has proved that the Notch and Wnt pathways play important roles in regulating the process of somitogenesis and there is crosstalk between these two pathways. However, it is difficult to investigate the detailed mechanism of these two pathways and their interactions in somitogenesis through biological experiments. In recent years some mathematical models have been proposed for the purpose of studying the dynamics of the Notch and Wnt pathways in somitogenesis. Unfortunately, only a few of these models have explored the interactions between them.
In this study, we have proposed three mathematical models for the Notch signalling pathway alone, the Wnt signalling pathway alone, and the interactions between them. These models can simulate the dynamics of the Notch and Wnt pathways in somitogenesis, and are capable of reproducing the observations derived from wet experiments. They were used to investigate the molecular mechanisms of the Notch and Wnt pathways and their crosstalk in somitogenesis through the model simulations.
Three mathematical models are proposed for the Notch and Wnt pathways and their interaction during somitogenesis. The simulations demonstrate that the extracellular Notch and Wnt signals are essential for the oscillating expressions of both Notch and Wnt target genes. Moreover, the internal negative feedback loops and the three levels of crosstalk between these pathways play important but distinct roles in maintaining the system oscillation. In addition, the results of the parameter sensitivity analysis of the models indicate that the Notch pathway is more sensitive to perturbation in somitogenesis.
Notch signaling is reliant on γ-secretase–mediated processing, although the subcellular location where it cleaves Notch to initiate signaling remains unresolved. Findings here support a model in which Notch signaling in mammalian systems is initiated from either the plasma membrane or lysosome, but not the early endosome.
Notch signaling is reliant on γ-secretase–mediated processing, although the subcellular location where γ-secretase cleaves Notch to initiate signaling remains unresolved. Accumulating evidence demonstrates that Notch signaling is modulated by endocytosis and endosomal transport. In this study, we investigated the relationship between Notch transport itinerary and signaling capacity. In doing so, we discovered a highly conserved dileucine sorting signal encoded within the cytoplasmic tail that directs Notch to the limiting membrane of the lysosome for signaling. Mutating the dileucine motif led to receptor accumulation in cation-dependent mannose-phosphate receptor–positive tubular early endosomes and a reduction in Notch signaling capacity. Moreover, truncated receptor forms that mimic activated Notch were readily cleaved by γ-secretase within the endosome; however, the cleavage product was proteasome-sensitive and failed to contribute to robust signaling. Collectively these results indicate that Notch signaling from the lysosome limiting membrane is conserved and that receptor targeting to this compartment is an active process. Moreover, the data support a model in which Notch signaling in mammalian systems is initiated from either the plasma membrane or lysosome, but not the early endosome.
This study aimed to compare epithelial cells derived from human embryonic stem cells (hESCs) to human ameloblast-lineage cells (ALCs), as a way to determine their potential use as a cell source for ameloblast regeneration. Induced by various concentrations of bone morphogenetic protein 4 (BMP4), retinoic acid (RA) and lithium chloride (LiCl) for 7 days, hESCs adopted cobble-stone epithelial phenotype (hESC-derived epithelial cells (ES-ECs)) and expressed cytokeratin 14. Compared with ALCs and oral epithelial cells (OE), ES-ECs expressed amelogenesis-associated genes similar to ALCs. ES-ECs were compared with human fetal skin epithelium, human fetal oral buccal mucosal epithelial cells and human ALCs for their expression pattern of cytokeratins as well. ALCs had relatively high expression levels of cytokeratin 76, which was also found to be upregulated in ES-ECs. Based on the present study, with the similarity of gene expression with ALCs, ES-ECs are a promising potential cell source for regeneration, which are not available in erupted human teeth for regeneration of enamel.
ameloblast; cytokeratin; dental epithelial cells; human embryonic stem cells; odontogenesis
Flap endonuclease 1 (FEN1), a member of the Rad2 nuclease family, possesses 5’ flap endonuclease (FEN), 5’ exonuclease (EXO), and gap-endonuclease (GEN) activities. The multiple, structure-specific nuclease activities of FEN1 allow it to process different intermediate DNA structures during DNA replication and repair. We previously identified a group of FEN1 mutations and single nucleotide polymorphisms that impair FEN1’s EXO and GEN activities in human cancer patients. We also established a mouse model carrying the E160D FEN1 mutation, which mimics the mutations seen in humans. FEN1 mutant mice developed spontaneous lung cancer at high frequency at their late life stages. An important unanswered question is whether individuals carrying such FEN1 mutation are more susceptible to tobacco smoke and have an earlier onset of lung cancer. Here, we report our study on E160D mutant mice exposed to benzo[α]pyrene (B[α]P), a major DNA damaging compound found in tobacco smoke. We demonstrate that FEN1 employs its GEN activity to cleave DNA bubble substrates with BP-induced lesions, but the E160D FEN1 mutation abolishes such activity. As a consequence, Mouse cells carrying the E160D mutation display defects in the repair of B[α]P adducts and accumulate DNA double-stranded breaks and chromosomal aberrations upon treatments with B[α]P. Furthermore, more E160D mice than WT mice have an early onset of B[α]P-induced lung adenocarcinoma. All together, our current study suggests that individuals carrying the GEN-deficient FEN1 mutations have high risk to develop lung cancer upon exposure to B[α]P-containing agents such as tobacco smoke.
Flap endonuclease 1 (FEN1); Benzo[α]pyrene (B[α]P); Lung cancer; Double-stranded breaks (DSBs); Near-tetraploid aneuploidy
Interferon-gamma (IFN-gamma) and interleukin-6 (IL-6) are multifunctional cytokines that regulate immune responses, cell proliferation, and tumour development and progression, which frequently have functionally opposing roles. The cellular responses to both cytokines are activated via the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. During the past 10 years, the crosstalk mechanism between the IFN-gamma and IL-6 pathways has been studied widely and several biological hypotheses have been proposed, but the kinetics and detailed crosstalk mechanism remain unclear.
Using established mathematical models and new experimental observations of the crosstalk between the IFN-gamma and IL-6 pathways, we constructed a new crosstalk model that considers three possible crosstalk levels: (1) the competition between STAT1 and STAT3 for common receptor docking sites; (2) the mutual negative regulation between SOCS1 and SOCS3; and (3) the negative regulatory effects of the formation of STAT1/3 heterodimers. A number of simulations were tested to explore the consequences of cross-regulation between the two pathways. The simulation results agreed well with the experimental data, thereby demonstrating the effectiveness and correctness of the model.
In this study, we developed a crosstalk model of the IFN-gamma and IL-6 pathways to theoretically investigate their cross-regulation mechanism. The simulation experiments showed the importance of the three crosstalk levels between the two pathways. In particular, the unbalanced competition between STAT1 and STAT3 for IFNR and gp130 led to preferential activation of IFN-gamma and IL-6, while at the same time the formation of STAT1/3 heterodimers enhanced preferential signal transduction by sequestering a fraction of the activated STATs. The model provided a good explanation of the experimental observations and provided insights that may inform further research to facilitate a better understanding of the cross-regulation mechanism between the two pathways.
The concept of one-protein–multiple-function, i.e. moonlighting proteins, is an ever-expanding paradigm. We obtained compelling evidence that an array of ‘cytoplasmic’ metabolic enzymes can enter the nuclei to carry out moonlighting transcription functions; this phenomenon is conserved from Drosophila to humans. Of particular interest are the classical glycolytic enzymes GAPDH (glyceraldehyde-3-phosphate dehydrogenase) and LDH (lactate dehydrogenase), which utilize NAD(H) as coenzymes and not only moonlight (in their nuclear forms) to regulate the transcription of S-phase-specific histone genes, but also act as metabolic/redox sensors that link histone gene switching to DNA replication and S-phase progression.
chromosome; enzyme; GAPDH; histone 2B; S-phase; ATM, ataxia telangiectasia mutated; ATR, ataxia telangiectasia mutated- and Rad3-related; awd, abnormal wing disc; CBP, CREB (cAMP-response-element-binding protein)-binding protein; CDK, cyclin-dependent kinase; dm, Drosophila melanogaster; DSB, double-strand break; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; H2B, histone 2B; HAT, histone acetyl transferase; HDAC, histone deacetylase; HU, hydroxyurea; LDH, lactate dehydrogenase; MMC, mammalian metabolic cycle; nm23, non-metastasis 23; NPAT, nuclear protein, ataxia-telangiectasia locus; OCA-S, Oct-1 co-activator in the S-phase; PIKK, phosphoinositide 3-kinase-related kinase; RNAi, RNA interference; SLBP, stem–loop-binding protein; Tip60, Tat (transactivator of transcription)-interactive protein 60 kDa; YMC, yeast metabolic cycle