Report on a case of liver-originating malignant melanoma of unknown primary.

Malignant melanoma (MM) frequently occurs in the skin or mucosa, whereas malignant melanoma of unknown primary (MUP) is diagnosed in patients with lymph nodes or visceral organs as the site of origin, where it is challenging to detect the primary lesion by comprehensive examination. MUP is possibly related to the spontaneous regression of the primary lesion. In addition, primary hepatic melanoma (PHM) usually refers to the primary MM occurring in the liver, with no typical primary lesions and no manifestations of tumor metastasis. A 61-year-old male patient with liver as the site of origin was diagnosed with MM by Melan-A, HMB-45, and S-100 immunohistochemistry staining of liver biopsy tissue. Based on a comprehensive examination, no basis was found for melanoma in sites such as the skin, mucosa, five sense organs, brain, digestive tract, respiratory tract, or genitalia, and the patient was subsequently diagnosed with MUP. MMs require a comprehensive inspection, beginning with the liver, to search for the primary lesion; if the primary lesion is not found, the possibility of PHM or MUP should be considered.

TBX18 knockdown sensitizes esophageal squamous cell carcinoma to radiotherapy by blocking the CHN1/RhoA axis.

OBJECTIVE: Radioresistance is a challenge in the effective treatment of esophageal squamous cell carcinoma (ESCC). Herein, this research ascertained whether TBX18 reduced the radiosensitivity of ESCC. METHODS: Bioinformatics analysis was utilized to retrieve differentially expressed genes. Then, the expression of corresponding candidate genes was tested using qRT-PCR in ESCC clinical specimens, and TBX18 was selected for subsequent experiments. The binding between TBX18 and CHN1 was evaluated by dual-luciferase reporter and ChIP assays, and the relationship between CHN1 and RhoA was identified by GST pull-down. Ectopic expression or knockdown experiments and radiation treatment were performed in cells and the nude mouse xenograft model to clarify the impacts of TBX18, CHN1, and RhoA on radiosensitivity in ESCC. RESULTS: Bioinformatics analysis and qRT-PCR retrieved upregulated TBX18 in ESCC for the follow-up study. Additionally, TBX18 was positively correlated with CHN1 in ESCC clinical specimens. Mechanistically, TBX18 bound to the CHN1 promoter region to transcriptionally activate CHN1, thus elevating RhoA activity. Moreover, TBX18 knockdown reduced ESCC cell proliferation and migration while augmenting their apoptosis after radiation, which was negated by further overexpressing CHN1 or RhoA. CHN1 or RhoA knockdown diminished ESCC cell proliferation and migration, as well as enhanced cell apoptosis, subsequent to radiation. Likewise, TBX18 overexpression increased ESCC cell autophagy after radiation, which was partially reversed by knockdown of RhoA. The results of in vivo xenograft experiments in nude mice were concurrent with the in vitro results. CONCLUSION: TBX18 knockdown lowered CHN1 transcription and thus reduced RhoA activity, which sensitized ESCC cells to radiotherapy.

Four thermostatic steps: A novel CRISPR-Cas12-based system for the rapid at-home detection of respiratory pathogens.

The outbreak of coronavirus disease 2019 (COVID-19) in 2019 has severely damaged the world's economy and public health and made people pay more attention to respiratory infectious diseases. However, traditional quantitative real-time polymerase chain reaction (qRT-PCR) nucleic acid detection kits require RNA extraction, reverse transcription, and amplification, as well as the support of large-scale equipment to enrich and purify nucleic acids and precise temperature control. Therefore, novel, fast, convenient, sensitive and specific detection methods are urgently being developed and moving to proof of concept test. In this study, we developed a new nucleic acid detection system, referred to as 4 Thermostatic steps (4TS), which innovatively allows all the detection processes to be completed in a constant temperature device, which performs extraction, amplification, cutting of targets, and detection within 40 min. The assay can specifically and sensitively detect five respiratory pathogens, namely SARS-CoV-2, Mycoplasma felis (MF), Chlamydia felis (CF), Feline calicivirus (FCV), and Feline herpes virus (FHV). In addition, a cost-effective and practical small-scale reaction device was designed and developed to maintain stable reaction conditions. The results of the detection of the five viruses show that the sensitivity of the system is greater than 94%, and specificity is 100%. The 4TS system does not require complex equipment, which makes it convenient and fast to operate, and allows immediate testing for suspected infectious agents at home or in small clinics. Therefore, the assay system has diagnostic value and significant potential for further reducing the cost of early screening of infectious diseases and expanding its application. KEY POINTS: • The 4TS system enables the accurate and specific detection of nucleic acid of pathogens at 37 °C in four simple steps, and the whole process only takes 40 min. •A simple alkali solution can be used to extract nucleic acid. • A small portable device simple to operate is developed for home diagnosis and detection of respiratory pathogens.

A CT-Based Deep Learning Radiomics Nomogram to Predict Histological Grades of Head and Neck Squamous Cell Carcinoma.

RATIONALE AND OBJECTIVES: Accurate pretreatment assessment of histological differentiation grade of head and neck squamous cell carcinoma (HNSCC) is crucial for prognosis evaluation. This study aimed to construct and validate a contrast-enhanced computed tomography (CECT)-based deep learning radiomics nomogram (DLRN) to predict histological differentiation grades of HNSCC. MATERIALS AND METHODS: A total of 204 patients with HNSCC who underwent CECT scans were enrolled in this study. The participants recruited from two hospitals were split into a training set (n=124, 74 well/moderately differentiated and 50 poorly differentiated) of patients from one hospital and an external test set of patients from the other hospital (n=80, 49 well/moderately differentiated and 31 poorly differentiated). CECT-based manually-extracted radiomics (MER) features and deep learning (DL) features were extracted and selected. The selected MER features and DL features were then combined to construct a DLRN via multivariate logistic regression. The predictive performance of the DLRN was assessed using ROCs and decision curve analysis (DCA). RESULTS: Three MER features and seven DL features were finally selected. The DLRN incorporating the selected MER and DL features showed good predictive value for the histological differentiation grades of HNSCC (well/moderately differentiated vs. poorly differentiated) in both the training (AUC, 0.878) and test (AUC, 0.822) sets. DCA demonstrated that the DLRN was clinically useful for predicting histological differentiation grades of HNSCC. CONCLUSION: A CECT-based DLRN was constructed to predict histological differentiation grades of HNSCC. The DLRN showed good predictive efficacy and might be useful for prognostic evaluation of patients with HNSCC.

How many authors does it take to publish a high profile or classic paper?

Although the process of publishing a scientific paper has gotten simpler, it is increasingly difficult to publish a paper in high profile journals. We have analyzed the publishing data in the cell biology field and found several alarming trends developing over the last two decades. There is an emerging divide between scientist-run journals and professional-run high profile journals. How did this happen? What should we do? The core issue is whether the current standard for high profile journals hurts rather than helps the scientific discovery process. In this regard, we suggest that the editors and scientists should direct their focus on the potential impact and rigor of the work instead of the "perfection" or "completeness" of the study.

Total, bioavailable and free 25-hydroxyvitamin D are associated with the prognosis of patients with non-small cell lung cancer.

PURPOSE: To analyze the prognostic value of total, bioavailable and free 25-hydroxyvitamin D [25(OH)D] as well as vitamin D-binding protein (VDBP) in patients with non-small cell lung cancer (NSCLC). METHODS: We prospectively collected and analyzed data for 395 patients diagnosed with NSCLC between January 2016 and December 2018 in two university-affiliated hospitals. Total and free 25(OH)D and VDBP were measured directly, and bioavailable 25(OH)D was calculated using a validated formula. Their prognostic values were evaluated by Cox proportional hazards model, and hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. RESULTS: Patients with NSCLC had significantly lower levels of total, bioavailable, and free 25(OH)D and higher VDBP levels in comparison to healthy controls (all p < 0.001). In multivariate analyses, higher levels of total, bioavailable, and free 25(OH)D were independently associated better overall survival (OS) and progression-free survival (PFS). For OS, the adjusted HRs were 0.58 (95% CI, 0.40-0.87; p for trend = 0.008), 0.45 (95% CI, 0.30-0.67; p for trend < 0.001) and 0.49 (95% CI, 0.33-0.73; p for trend < 0.001) for the highest versus the lowest tertile of total, bioavailable and free 25(OH)D, respectively. The corresponding adjusted HRs for PFS were 0.61 (95% CI, 0.43-0.86; p for trend = 0.006), 0.56 (95% CI, 0.40-0.80; p for trend = 0.001) and 0.60 (95% CI, 0.42-0.85; p for trend = 0.004), respectively. However, VDBP was not associated with either OS or PFS. CONCLUSION: The current study suggested that total, bioavailable and free 25(OH)D may be reliable prognosis indicators in NSCLC patients, though the optimal 25(OH)D form for NSCLC prognosis remains to be assessed in future studies.

A novel deep learning-based method for detection of weeds in vegetables.

BACKGROUND: Precision weed control in vegetable fields can substantially reduce the required weed control inputs. Rapid and accurate weed detection in vegetable fields is a challenging task due to the presence of a wide variety of weed species at various growth stages and densities. This paper presents a novel deep-learning-based method for weed detection that recognizes vegetable crops and classifies all other green objects as weeds. RESULTS: The optimal confidence threshold values for YOLO-v3, CenterNet, and Faster R-CNN were 0.4, 0.6, and 0.4/0.5, respectively. These deep-learning models had average precision (AP) above 97% in the testing dataset. YOLO-v3 was the most accurate model for detection of vegetables and yielded the highest F 1 score of 0.971, along with high precision and recall values of 0.971 and 0.970, respectively. The inference time of YOLO-v3 was similar to CenterNet, but significantly shorter than that of Faster R-CNN. Overall, YOLO-v3 showed the highest accuracy and computational efficiency among the deep-learning architectures evaluated in this study. CONCLUSION: These results demonstrate that deep-learning-based methods can reliably detect weeds in vegetable crops. The proposed method avoids dealing with various weed species, and thus greatly reduces the overall complexity of weed detection in vegetable fields. Findings have implications for advancing site-specific robotic weed control in vegetable crops.

PCNA Ubiquitylation: Instructive or Permissive to DNA Damage Tolerance Pathways?

DNA lesions escaping from repair often block the DNA replicative polymerases required for DNA replication and are handled during the S/G2 phases by the DNA damage tolerance (DDT) mechanisms, which include the error-prone translesion synthesis (TLS) and the error-free template switching (TS) pathways. Where the mono-ubiquitylation of PCNA K164 is critical for TLS, the poly-ubiquitylation of the same residue is obligatory for TS. However, it is not known how cells divide the labor between TLS and TS. Due to the fact that the type of DNA lesion significantly influences the TLS and TS choice, we propose that, instead of altering the ratio between the mono- and poly-Ub forms of PCNA, the competition between TLS and TS would automatically determine the selection between the two pathways. Future studies, especially the single integrated lesion "i-Damage" system, would elucidate detailed mechanisms governing the choices of specific DDT pathways.

Effects and mechanisms of ziqi ruangan decoction on hepatic fibrosis.

To investigate effect and mechanism of Ziqi Ruangan Decoction (ZQRGD) on hepatic fibrosis in rats. Rats were randomly assigned to blank group, model group, colchicine group, ZQRGD high-dose group, ZQRGD middle-dose group, and ZQRGD low-dose group. All groups except group A were intraperitoneally injected with 40% CCl4/olive oil for 8 weeks; group C was then given intragastric colchicine administration. Groups D, E, and F were intragastrically dosed with ZQRGD. Compared with the colchicine group, the superoxide dismutase (SOD) activity of each dose group of ZQRGD significantly increased. TNF-α and IL-6 concentration significantly decreased in each drug intervention group, while these significantly decreased in the high-dose and medium-dose ZQRGD groups. The expression of α-SMA and collagen I significantly decreased in the drug treatment group compared with the model group, as did the expression of PI3K, AKT, and mTOR. Ziqi Ruangan Decoction had a favorable anti-liver fibrosis effect and the mechanism is related to anti-oxidative stress, anti-inflammation, the inhibition of the PI3K/Akt/mTOR signaling pathway, and the inhibition of hepatic stellate cell activation.

CLPTM1L induces estrogen receptor ß signaling-mediated radioresistance in non-small cell lung cancer cells.

INTRODUCTION: Radioresistance is a major challenge in lung cancer radiotherapy, and new radiosensitizers are urgently needed. Estrogen receptor ß (ERß) is involved in the progression of non-small cell lung cancer (NSCLC), however, the role of ERß in the response to radiotherapy in lung cancer remains elusive. In the present study, we investigated the mechanism underlying ERß-mediated transcriptional activation and radioresistance of NSCLC cells. METHODS: Quantitative real-time PCR, western blot and immunohistochemistry were used to detect the expression of CLPTM1L, ERß and other target genes. The mechanism of CLPTM1L in modulation of radiosensitivity was investigated by chromatin immunoprecipitation assay, luciferase reporter gene assay, immunofluorescence staining, confocal microscopy, coimmunoprecipitation and GST pull-down assays. The functional role of CLPTM1L was detected by function assays in vitro and in vivo. RESULTS: CLPTM1L expression was negatively correlated with the radiosensitivity of NSCLC cell lines, and irradiation upregulated CLPTM1L in radioresistant (A549) but not in radiosensitive (H460) NSCLC cells. Meanwhile, IR induced the translocation of CLPTM1L from the cytoplasm into the nucleus in NSCLC cells. Moreover, CLPTM1L induced radioresistance in NSCLC cells. iTRAQ-based analysis and cDNA microarray identified irradiation-related genes commonly targeted by CLPTM1L and ERß, and CLPTM1L upregulated ERß-induced genes CDC25A, c-Jun, and BCL2. Mechanistically, CLPTM1L coactivated ERß by directly interacting with ERß through the LXXLL NR (nuclear receptor)-binding motif. Functionally, ERß silencing was sufficient to block CLPTM1L-enhanced radioresistance of NSCLC cells in vitro. CLPTM1L shRNA treatment in combination with irradiation significantly inhibited cancer cell growth in NSCLC xenograft tumors in vivo. CONCLUSIONS: The present results indicate that CLPTM1L acts as a critical coactivator of ERß to promote the transcription of its target genes and induce radioresistance of NSCLC cells, suggesting a new target for radiosensitization in NSCLC therapy. Video Abstract.

DNA Dosimeter Measurement of Relative Biological Effectiveness for 160 kVp and 6 MV X Rays.

In this work, we developed a DNA dosimeter, consisting of 4-kb DNA strands attached to magnetic streptavidin beads and labeled with fluorescein, to detect double-strand breaks (DSBs). The purpose here was to evaluate whether the DNA dosimeter readings reflect the relative biological effects of 160 kVp and 6 MV X rays. AVarian 600 C/D linac (6 MV) and a Faxitron cabinet X-ray system (160 kVp), both calibrated using traceable methods, were used to deliver high- and low-energy photons, respectively, to DNA dosimeters and multiple cell lines (mNs-5, HT-22 and Daoy). The responses were fit versus dose, and were used to quantify the dose of low-energy photons that produced the same response as that of the high-energy photons, at doses of 3, 6 and 9 Gy. The equivalent doses were utilized to calculate the relative biological effectiveness (RBEDSB and RBEcell survival). Additionally, a neutral comet assay was performed to measure the amount of intracellular DNA DSB, and ultimately the RBEcomet assay. The results of this work showed 160-kVp photon RBE values and 95% confidence intervals of 1.12 ± 0.04 (mNS-5), 1.16 ± 0.06 (HT-22), 1.25 ± 0.09 (Daoy) and 1.21 ± 0.24 (DNA dosimeter) at 9 Gy and 1.32 ± 0.16 (comet assay) at 3 Gy. Within the current error, the DNA dosimeter measured RBEDSB values in agreement with the RBEcell survival and assay from the cell survival and comet assay RBEcomet measurements. These results suggest that the DNA dosimeter can measure the changes in the radiobiological effects from different energy photons.

Methylated PTGER4 is better than CA125, CEA, Cyfra211 and NSE as a therapeutic response assessment marker in stage IV lung cancer.

Real-time assessment of therapeutic response in patients with advanced lung cancer presents a major challenge throughout the treatment process. Currently, computed tomography imaging is often used; however, it is radiation-based and hysteretic and is not suitable for repeated use as a real-time assessment. Blood biomarkers represent a novel solution for assessing therapeutic response in patients with advanced lung cancer. In the present study, the efficacy of a methylation marker [methylated prostaglandin E receptor 4 (mPTGER4)] and four protein markers [carcinoma antigen 125 (CA125), carcinoembryonic antigen (CEA), cytokeratin 19-fragments (cyfra21-1) and neuron-specific enolase (NSE)] were simultaneously evaluated to determine their potential in facilitating therapeutic response monitoring as well as their prognostic values in patients with stage IV lung cancer. The results indicated that, following treatment, the blood levels of methylated PTGER4 and NSE had significantly decreased, and mPRGER4, CA125, CEA and NSE exhibited a significant decrease in percentage level. Since mPTGER4 exhibited a higher rate of positive detection prior to therapy, and a greater response of sensitivity to therapy compared to the protein markers, it may represent an improved marker for the monitoring of therapeutic response. The efficacy of the markers in predicting the overall survival (OS) rate of patients with stage IV lung cancer was also assessed. Results from the follow-up of patients (up to 891 days) revealed that the blood levels of mPTGER4, CA125 and NSE before treatment were able to predict overall survival (OS) rate. Additionally, the percentage change in expression levels of CA125, CEA and NSE was also able to predict the OS rate. In conclusion, the present results indicate that mPTGER4 represents an improved biomarker for monitoring therapeutic efficacy compared with CA125, CEA, Cyfra21-1 and NSE. In predicting the long-term survival of patients with stage IV lung cancer; however, the pre-treatment levels of mPTGER4, CA125 and NSE and the percentage changes of CA125, CEA and NSE may be used as the markers.

Compressive myelopathy and compression fracture of aggressive vertebral hemangioma after parturition: A case report and review of literature.

RATIONALE: Compressive myelopathy and compression fracture of aggressive vertebral hemangioma after parturition is a rare condition. Vertebral body compression fracture and high serum progesterone lead to extraosseous hemangioma enlargment cause narrowing the spinal canal which contribute to compressive myelopathy relate to pregnancy. PATIENT CONCERNS: We report a case of compressive myelopathy and compression fracture of aggressive vertebral hemangioma after parturition in a 35-year-old woman. The patient complained unable to walk and experienced intense pain in the back. DIAGNOSIS: Based on the clinical features and imaging studies, the patient underwent a T4-T6 laminectomy. Histopathology consistent with vertebral hemangioma. INTERVENTIONS: The patient underwent laminectomy for decompression. After subperiosteal dissection of the paraspinal muscles and exposure of the laminae, there was no involvement of the lamina by the tumor. The epidural tumor was removed through the spaces lateral to the thecal sac. Vertebroplasty was performed through T5 pedicles bilaterally and 7 ml of polymethylmethacrylate (PMMA) cement was injected. T4-T6 pedicle screw fixation was performed for segmental fixation and fusion. OUTCOMES: Six months after resection of the tumor the patient remained asymptomatic. She reported no low back pain and had returned to her normal daily activities, with no radiographic evidence of recurrence on MRI. Physical examination revealed that superficial and deep sensation was restored to normal levels in the lower extremities. LESSONS: The occurrence of compressive myelopathy of pregnancy related vertebral hemangiomas is quite unusual. It can lead to serious neurologic deficits if not treated immediately. So, prompt diagnosis is important in planning optimal therapy and preventing morbidity for patients.

Microhomology Selection for Microhomology Mediated End Joining in Saccharomyces cerevisiae.

Microhomology-mediated end joining (MMEJ) anneals short, imperfect microhomologies flanking DNA breaks, producing repair products with deletions in a Ku- and RAD52-independent fashion. Puzzlingly, MMEJ preferentially selects certain microhomologies over others, even when multiple microhomologies are available. To define rules and parameters for microhomology selection, we altered the length, the position, and the level of mismatches to the microhomologies flanking homothallic switching (HO) endonuclease-induced breaks and assessed their effect on MMEJ frequency and the types of repair product formation. We found that microhomology of eight to 20 base pairs carrying no more than 20% mismatches efficiently induced MMEJ. Deletion of MSH6 did not impact MMEJ frequency. MMEJ preferentially chose a microhomology pair that was more proximal from the break. Interestingly, MMEJ events preferentially retained the centromere proximal side of the HO break, while the sequences proximal to the telomere were frequently deleted. The asymmetry in the deletional profile among MMEJ products was reduced when HO was induced on the circular chromosome. The results provide insight into how cells search and select microhomologies for MMEJ in budding yeast.

Apn2 resolves blocked 3' ends and suppresses Top1-induced mutagenesis at genomic rNMP sites.

Ribonucleoside monophosphates (rNMPs) mis-incorporated during DNA replication are removed by RNase H2-dependent excision repair or by topoisomerase I (Top1)-catalyzed cleavage. The cleavage of rNMPs by Top1 produces 3' ends harboring terminal adducts, such as 2',3'-cyclic phosphate or Top1 cleavage complex (Top1cc), and leads to frequent mutagenesis and DNA damage checkpoint induction. We surveyed a range of candidate enzymes from Saccharomyces cerevisiae for potential roles in Top1-dependent genomic rNMP removal. Genetic and biochemical analyses reveal that Apn2 resolves phosphotyrosine-DNA conjugates, terminal 2',3'-cyclic phosphates, and their hydrolyzed products. APN2 also suppresses 2-base pair (bp) slippage mutagenesis in RNH201-deficient cells. Our results define additional activities of Apn2 in resolving a wide range of 3' end blocks and identify a role for Apn2 in maintaining genome integrity during rNMP repair.

Guidelines for DNA recombination and repair studies: Cellular assays of DNA repair pathways.

Understanding the plasticity of genomes has been greatly aided by assays for recombination, repair and mutagenesis. These assays have been developed in microbial systems that provide the advantages of genetic and molecular reporters that can readily be manipulated. Cellular assays comprise genetic, molecular, and cytological reporters. The assays are powerful tools but each comes with its particular advantages and limitations. Here the most commonly used assays are reviewed, discussed, and presented as the guidelines for future studies.

Prevention and Therapeutic Effects and Mechanisms of Tanshinone IIA Sodium Sulfonate on Acute Liver Injury Mice Model.

Tanshinone IIA sodium sulfonate (TSS) is a water-soluble derivative of tanshinone IIA, which is the main pharmacologically active component of Salvia miltiorrhiza. This study aimed to verify the preventive and therapeutic effects of TSS and its combined therapeutic effects with magnesium isoglycyrrhizinate (MI) in D-galactosamine- (D-Gal-) induced acute liver injury (ALI) in mice. The potential regulatory mechanisms of TSS on ALI were also examined. Our results may provide a basis for the development of novel therapeutics for ALI.

Hyper-Acetylation of Histone H3K56 Limits Break-Induced Replication by Inhibiting Extensive Repair Synthesis.

Break-induced replication (BIR) has been implicated in restoring eroded telomeres and collapsed replication forks via single-ended invasion and extensive DNA synthesis on the recipient chromosome. Unlike other recombination subtypes, DNA synthesis in BIR likely relies heavily on mechanisms enabling efficient fork progression such as chromatin modification. Herein we report that deletion of HST3 and HST4, two redundant de-acetylases of histone H3 Lysine 56 (H3K56), inhibits BIR, sensitizes checkpoint deficient cells to deoxyribonucleotide triphosphate pool depletion, and elevates translocation-type gross chromosomal rearrangements (GCR). The basis for deficiency in BIR and gene conversion with long gap synthesis in hst3Δ hst4Δ cells can be traced to a defect in extensive DNA synthesis. Distinct from other cellular defects associated with deletion of HST3 and HST4 including thermo-sensitivity and elevated spontaneous mutagenesis, the BIR defect in hst3Δ hst4Δ cannot be offset by the deletion of RAD17 or MMS22, but rather by the loss of RTT109 or ASF1, or in combination with the H3K56R mutation, which also restores tolerance to replication stress in mrc1 mutants. Our studies suggest that acetylation of H3K56 limits extensive repair synthesis and interferes with efficient fork progression in BIR.

Levodopa/benserazide microsphere (LBM) prevents L-dopa induced dyskinesia by inactivation of the DR1/PKA/P-tau pathway in 6-OHDA-lesioned Parkinson's rats.

L-3, 4-dihydroxyphenylalanine (L-dopa) is the gold standard for symptomatic treatment of Parkinson's disease (PD), but long-term therapy is associated with the emergence of L-dopa-induced dyskinesia (LID). In the present study, L-dopa and benserazide were loaded by poly (lactic-co-glycolic acid) microspheres (LBM), which can release levodopa and benserazide in a sustained manner in order to continuous stimulate dopaminergic receptors. We investigated the role of striatal DR1/PKA/P-tau signal transduction in the molecular event underlying LID in the 6-OHDA-lesioned rat model of PD. We found that animals rendered dyskinetic by L-dopa treatment, administration of LBM prevented the severity of AIM score, as well as improvement in motor function. Moreover, we also showed L-dopa elicits profound alterations in the activity of three LID molecular markers, namely DR1/PKA/P-tau (ser396). These modifications are totally prevented by LBM treatment, a similar way to achieve continuous dopaminergic delivery (CDD). In conclusion, our experiments provided evidence that intermittent administration of L-dopa, but not continuous delivery, and DR1/PKA/p-tau (ser396) activation played a critical role in the molecular and behavioural induction of LID in 6-OHDA-lesioned rats. In addition, LBM treatment prevented the development of LID by inhibiting the expression of DR1/PKA/p-tau, as well as PPEB mRNA in dyskintic rats.

DNA end recognition by the Mre11 nuclease dimer: insights into resection and repair of damaged DNA.

The Mre11-Rad50-Nbs1 (MRN) complex plays important roles in sensing DNA damage, as well as in resecting and tethering DNA ends, and thus participates in double-strand break repair. An earlier structure of Mre11 bound to a short duplex DNA molecule suggested that each Mre11 in a dimer recognizes one DNA duplex to bridge two DNA ends at a short distance. Here, we provide an alternative DNA recognition model based on the structures of Methanococcus jannaschii Mre11 (MjMre11) bound to longer DNA molecules, which may more accurately reflect a broken chromosome. An extended stretch of B-form DNA asymmetrically runs across the whole dimer, with each end of this DNA molecule being recognized by an individual Mre11 monomer. DNA binding induces rigid-body rotation of the Mre11 dimer, which could facilitate melting of the DNA end and its juxtaposition to an active site of Mre11. The identified Mre11 interface binding DNA duplex ends is structurally conserved and shown to functionally contribute to efficient resection, non-homologous end joining, and tolerance to DNA-damaging agents when other resection enzymes are absent. Together, the structural, biochemical, and genetic findings presented here offer new insights into how Mre11 recognizes damaged DNA and facilitates DNA repair.