Inhibition of UV-induced DNA repair at different steps by quinacrine and anthralin

Inhibition of DNA repair can result in accumulation of unrepaired and partially repaired lesions in DNA. Such lesions are important, not only for their primary disruption of information fidelity, but because they may serve as inducers for repair pathways which may be error prone. Inhibition of UV repair by quinacrine and anthralin (50μM each) was detected in ³H thymidine-labeled mouse L1210 cells by sedimentation of nucleoids on neutral sucrose gradients. Quinacrine delayed strand-nicking (and presumably lesion removal) following uv irradiation and anthralin exerted its strongest effects on some other repair step(s) subsequent to strand-incision with accumulation of strand disruptions. Since anthralin is a potent tumor promoter, it will be interesting to examine other promoters to see if they also cause accumulation of repair ‘intermediates’ which could act as inducers of error prone repair.     

Influences of hypothyroidism on lipid composition and inositol lipid-linked receptors responsiveness and protein kinase C (PKC) activity in the cerebral cortex of lewis rats

The influence of hypothyroidism (HO) induced by treatment with propylthiouracil on lipid composition, receptor responsiveness of MI-muscarinic receptors (M₁AChRs) and metabotropic glutamate receptors (mGluRs) as well as on protein kinase C (PKC) activity was investigated in the cerebral cortex of Lewis rats. HO did not influence the lipid composition. There was a significant 2-fold increase of efficacy and 6-fold decrease of potency of carbachol-induced inositol phosphate (IP) accumulation in HO, with respect to control rats. The efficacy of trans-(1S,3R)-1-amino-1,3-cyclopentanedicarboxylic acid (ACPD)-induced IP accumulation was also higher in HO (by 50%), without differences in EC50 values. The activities of soluble calcium-dependent and calcium-independent PKC were higher in HO than in control rats (both roughly 30%); membrane-associated PKCs were not modified. The data indicate that HO induces an increased responsiveness of M₁AChRs and mGluRs and a rise in the soluble PKC activity that could be available and ready for translocation. Department of Metabolism and Pathological Biochemistry.     

重组人表皮生长因子联合光子嫩肤M22对痤疮凹陷性瘢痕患者皮肤屏障功能的影响

摘要 目的：探讨与分析重组人表皮生长因子联合光子嫩肤M22对痤疮凹陷性瘢痕患者皮肤屏障功能的影响。方法：2020年9月到2022年2月选择在本院诊治的痤疮凹陷性瘢痕患者120例作为研究对象,根据1:1简单分配原则把患者分为联合组与对照组各60例。对照组给予重组人表皮生长因子治疗,联合组在对照组治疗的基础上给予光子嫩肤M22治疗,两组都治疗观察4周。结果：治疗后联合组的总有效率为88.3 %,高于对照组的66.7 %（P<0.05）。联合组的红斑消退时间等临床症状较对照组少（P<0.05）。两组治疗后皮肤油脂比例低于治疗前,皮肤含量水高于治疗前,治疗后联合组的皮肤油脂比例、含水量与对照组对比有差异（P<0.05）。两组治疗后的瘢痕基底深度较治疗前低,联合组较对照组低（P<0.05）。治疗后,两组主观、客观美学评分较治疗前高,联合组较对照组高（P<0.05）。结论：重组人表皮生长因子联合光子嫩肤M22在痤疮凹陷性瘢痕患者的能改善皮肤屏障功能,能降低瘢痕基底深度与皮肤油脂比例,提高皮肤含水量,能促进改善临床症状,提高皮肤的美学评分,从而提高总体治疗效果。     

Drug targeted virtual screening and molecular dynamics of LipU protein of Mycobacterium tuberculosis and Mycobacterium leprae

The lipolytic protein LipU was conserved in mycobacterium sp. including M. tuberculosis (MTB LipU) and M. leprae (MLP LipU). The MTB LipU was identified in extracellular fraction and was reported to be essential for the survival of mycobacterium. Therefore to address the problem of drug resistance in pathogen, LipU was selected as a drug target and the viability of finding out some FDA approved drugs as LipU inhibitors in both the cases was explored. Three-dimensional (3D) model structures of MTB LipU and MLP LipU were generated and stabilized through molecular dynamics (MD). FDA approved drugs were screened against these proteins. The result showed that the top-scoring compounds for MTB LipU were Diosmin, Acarbose and Ouabain with the Glide XP score of ?12.8, ?11.9 and ?11.7 kcal/mol, respectively, whereas for MLP LipU protein, Digoxin (?9.2 kcal/mol), Indinavir (?8.2 kcal/mol) and Travoprost (?8.2 kcal/mol) showed highest affinity. These drugs remained bound in the active site pocket of MTB LipU and MLP LipU structure and interaction grew stronger after dynamics. RMSD, RMSF and Rg were found to be persistent throughout the simulation period. Hydrogen bonds along with large number of hydrophobic interactions stabilized the complex structures. Binding free energies obtained through Prime/MM-GBSA were found in the significant range from ?63.85 kcal/mol to ?34.57 kcal/mol for MTB LipU and ?71.33 kcal/mol to ?23.91 kcal/mol for MLP LipU. The report suggested high probability of these drugs to demolish the LipU activity and could be probable drug candidates to combat TB and leprosy disease.     

Matrix proteins of enveloped viruses: a case study of Influenza A virus M1 protein

Influenza A virus, a member of the Orthomyxoviridae family of enveloped viruses, is one of the human and animal top killers, and its structure and components are therefore extensively studied during the last decades. The most abundant component, M1 matrix protein, forms a matrix layer (scaffold) under the viral lipid envelope, and the functional roles as well as structural peculiarities of the M1 protein are still under heavy debate. Despite multiple attempts of crystallization, no high resolution structure is available for the full length M1 of Influenza A virus. The likely reason for the difficulties lies in the intrinsic disorder of the M1 C-terminal part preventing diffraction quality crystals to be grown. Alternative structural methods including synchrotron small-angle X-ray scattering (SAXS), atomic force microscopy, cryo-electron microscopy/tomography are therefore widely applied to understand the structure of M1, its self-association and interactions with the lipid membrane and the viral nucleocapsid. These methods reveal striking similarities in the behavior of M1 and matrix proteins of other enveloped RNA viruses, with the differences accompanied by the specific features of the viral lifecycles, thus suggesting common interaction principles and, possibly, common evolutional ancestors. The structural information on the Influenza A virus M1 protein obtained to the date strongly suggests that the intrinsic disorder in the C-terminal domain has important functional implications.     

Overexpression of oncostatin M receptor regulates local immune response in glioblastoma

Glioblastoma (GBM) is the most lethal cancer in central nervous system. It is urgently needed to look for novel therapeutics for GBM. Oncostatin M receptor (OSMR) is a cytokine receptor gene of IL-6 family and has been reported to be involved in regulating GBM tumorigenesis. However, the role of OSMR regulating the disrupted immune response in GBM need to be further investigated. Three gene expression profiles, Chinese Glioma Genome Atlas (CGGA), The Cancer Genome Atlas (TCGA), and Gene Expression Omnibus (GEO) data set (GSE16011), were enrolled in our study and used for OSMR expression and survival analysis. The expression of OSMR was further verified with immunohistochemistry and western blot analysis in glioma tissues. Microenvironment cell populations-counter (MCP-counter) was applied for analyzing the relationship between OSMR expression and nontumor cells. The functions of OSMR in GBM was investigated by Gene Ontology, Gene set enrichment analysis (GSEA), gene set variation analysis and so on. The analysis of cytokine receptor activity-related genes in glioma identifies OSMR as a gene with an independent predictive factor for progressive malignancy in GBM. Furthermore, OSMR expression is a prognostic marker in the response prediction to radiotherapy and chemotherapy. OSMR contributes to the regulation of local immune response and extracellular matrix process in GBM. Our findings define an important role of OSMR in the regulation of local immune response in GBM, which may suggest OSMR as a possible biomarker in developing new therapeutic immune strategies in GBM.     

Characterization of the C584R variant in the mtDNA depletion syndrome gene FBXL4, reveals a novel role for FBXL4 as a regulator of mitochondrial fusion

Mutations in FBXL4 (F-Box and Leucine rich repeat protein 4), a nuclear-encoded mitochondrial protein with an unknown function, cause mitochondrial DNA depletion syndrome. We report two siblings, from consanguineous parents, harbouring a previously uncharacterized homozygous variant in FBXL4 (c.1750 T > C; p.Cys584Arg). Both patients presented with encephalomyopathy, lactic acidosis and cardiac hypertrophy, which are reported features of FBXL4 impairment. Remarkably, dichloroacetate (DCA) administration to the younger sibling improved metabolic acidosis and reversed cardiac hypertrophy. Characterization of FBXL4 patient fibroblasts revealed severe bioenergetic defects, mtDNA depletion, fragmentation of mitochondrial networks, and abnormalities in mtDNA nucleoids. These phenotypes, observed with other pathogenic FBXL4 variants, confirm the pathogenicity of the p.Cys584Arg variant. Although treating FBXL4 fibroblasts with DCA improved extracellular acidification, in line with reduced lactate levels in patients, DCA treatment did not improve any of the other mitochondrial functions. Nonetheless, we highlight DCA as a potentially effective drug for the management of elevated lactate and cardiomyopathy in patients with pathogenic FBXL4 variants. Finally, as the exact mechanism through which FBXL4 mutations lead to mtDNA depletion was unknown, we tested the hypothesis that FBXL4 promotes mitochondrial fusion. Using a photo-activatable GFP fusion assay, we found reduced mitochondrial fusion rates in cells harbouring a pathogenic FBXL4 variant. Meanwhile, overexpression of wildtype FBXL4, but not the p.Cys584Arg variant, promoted mitochondrial hyperfusion. Thus, we have uncovered a novel function for FBXL4 in promoting mitochondrial fusion, providing important mechanistic insights into the pathogenic mechanism underlying FBXL4 dysfunction.     

Pinealectomy or light exposure exacerbates biliary damage and liver fibrosis in cholestatic rats through decreased melatonin synthesis

Melatonin, a neuroendocrine hormone synthesized by the pineal gland and cholangiocytes, decreases biliary hyperplasia and liver fibrosis during cholestasis-induced biliary injury via melatonin-dependent autocrine signaling through increased biliary arylalkylamine N-acetyltransferase (AANAT) expression and melatonin secretion, downregulation of miR-200b and specific circadian clock genes. Melatonin synthesis is decreased by pinealectomy (PINX) or chronic exposure to light. We evaluated the effect of PINX or prolonged light exposure on melatonin-dependent modulation of biliary damage/ductular reaction/liver fibrosis. Studies were performed in male rats with/without BDL for 1 week with 12:12 h dark/light cycles, continuous light or after 1 week of PINX. The expression of AANAT and melatonin levels in serum and cholangiocyte supernatant were increased in BDL rats, while decreased in BDL rats following PINX or continuous light exposure. BDL-induced increase in serum chemistry, ductular reaction, liver fibrosis, inflammation, angiogenesis and ROS generation were significantly enhanced by PINX or light exposure. Concomitant with enhanced liver fibrosis, we observed increased biliary senescence and enhanced clock genes and miR-200b expression in total liver and cholangiocytes. In vitro, the expression of AANAT, clock genes and miR-200b was increased in PSC human cholangiocyte cell lines (hPSCL). The proliferation and activation of HHStecs (human hepatic stellate cell lines) were increased after stimulating with BDL cholangiocyte supernatant and further enhanced when stimulated with BDL rats following PINX or continuous light exposure cholangiocyte supernatant via intracellular ROS generation. Conclusion: Melatonin plays an important role in the protection of liver against cholestasis-induced damage and ductular reaction.