Distribution of αvβT3, αvβTB5 Integrins and the Integrin Associated Protein — IAP (CD47) in Human Glomerular Diseases

The av integrins present on the membrane of numerous cells, mediate attachment to matrix proteins, cell proliferation, migration and survival. We studied the expression of av integrins and CD47 (a 03 chain integrin associated protein) in various forms of glomerulonephritis (GN) characterized by mesangial proliferation and/or increased mesangial matrix. In normal glomeruli, epithelial cells expressed αvβT3, αvβT5 and CD47; endothelial cells expressed α5βT1 and CD47; mesangial cells expressed αvβT5, CD47, and to a less extent αvβT3. In acute post infectious GN (APIGN), membranoproliferative GN (MPGN) and diabetic nephropathy (DN), we observed that the βT3 chain, normally expressed by mesangial cells, was not detectable in the mesangium while its expression by epithelial cells was not modified. Parallel to the disappearance of αvβT3, the CD47 expression was decreased on the mesangial cells in MPGN, APIGN and DN. The expression of αvβT5 was clearly increased on podocytes and on proliferating mesangial cells in APIGN. By contrast, the mesangial expression of αvβT5 normal or decreased in DN. The α5 chain of integrin, absent on normal mesangial cell, was expressed on proliferating mesangial cells in MPGN and APIGN.

Thus, we observed modifications of avp3 and avp5 expression during human GN. The modulations of αvβT3 and αvβT5 expression differed according to the different glomerular cell types and were not parallel in glomerular cells: avp3 was decreased (and αvβT5 unchanged) on proliferating mesangial cells and αvβT5 was increased (and αvβT3 unchanged) in podocytes. This may reflect the existence of two distinct regulatory pathways.     

Remodeling and spacing factor 1 (RSF1) deposits centromere proteins at DNA double-strand breaks to promote non-homologous end-joining

The cellular response to ionizing radiation (IR)-induced DNA double-strand breaks (DSBs) in native chromatin requires a tight coordination between the activities of DNA repair machineries and factors that modulate chromatin structure. SMARCA5 is an ATPase of the SNF2 family of chromatin remodeling factors that has recently been implicated in the DSB response. It forms distinct chromatin remodeling complexes with several non-canonical subunits, including the remodeling and spacing factor 1 (RSF1) protein. Despite the fact that RSF1 is often overexpressed in tumors and linked to tumorigenesis and genome instability, its role in the DSB response remains largely unclear. Here we show that RSF1 accumulates at DSB sites and protects human cells against IR-induced DSBs by promoting repair of these lesions through homologous recombination (HR) and non-homologous end-joining (NHEJ). Although SMARCA5 regulates the RNF168-dependent ubiquitin response that targets BRCA1 to DSBs, we found RSF1 to be dispensable for this process. Conversely, we found that RSF1 facilitates the assembly of centromere proteins CENP-S and CENP-X at sites of DNA damage, while SMARCA5 was not required for these events. Mechanistically, we uncovered that CENP-S and CENP-X, upon their incorporation by RSF1, promote assembly of the NHEJ factor XRCC4 at damaged chromatin. In contrast, CENP-S and CENP-X were dispensable for HR, suggesting that RSF1 regulates HR independently of these centromere proteins. Our findings reveal distinct functions of RSF1 in the 2 major pathways of DSB repair and explain how RSF1, through the loading of centromere proteins and XRCC4 at DSBs, promotes repair by non-homologous end-joining.     

DNA damage causes TP53-dependent coupling of self-renewal and senescence pathways in embryonal carcinoma cells

Comment on: Wu R, et al. Clin Cancer Res 2011; 17:7359–72     

MEK2 regulates ribonucleotide reductase activity through functional interaction with ribonucleotide reductase small subunit p53R2

The p53R2 protein, a newly identified member of the ribonucleotide reductase family that provides nucleotides for DNA damage repair, is directly regulated by p53. We show that p53R2 is also regulated by a MEK2 (ERK kinase 2/MAP kinase kinase 2)-dependent pathway. Increased MEK1/2 phosphorylation by serum stimulation coincided with an increase in the RNR activity in U2OS and H1299 cells. The inhibition of MEK2 activity, either by treatment with a MEK inhibitor or by transfection with MEK2 siRNA, dramatically decreased the serum-stimulated RNR activity. Moreover, p53R2 siRNA, but not R2 siRNA, significantly inhibits serum-stimulated RNR activity, indicating that p53R2 is specifically regulated by a MEK2-dependent pathway. Co-immunoprecipitation analyses revealed that the MEK2 segment comprising amino acids 65–171 is critical for p53R2–MEK2 interaction, and the binding domain of MEK2 is required for MEK2-mediated increased RNR activity. Phosphorylation of MEK1/2 was greatly augmented by ionizing radiation, and RNR activity was concurrently increased. Ionizing radiation-induced RNR activity was markedly attenuated by transfection of MEK2 or p53R2 siRNA, but not R2 siRNA. These data show that MEK2 is an endogenous regulator of p53R2 and suggest that MEK2 may associate with p53R2 and upregulate its activity.     

Serotonin and the search for the anatomical substrate of aggression

Abstract

All species of animals display aggression in order to obtain resources such as territories, mates, or food. Appropriate displays of aggression rely on the correct identification of a potential competitor, an evaluation of the environmental signals, and the physiological state of the animal. With a hard-wired circuitry involving fixed numbers of neurons, neuromodulators like serotonin offer adaptive flexibility in behavioral responses without changing the “hard-wiring”. In a recent report, we combined intersectional genetics, quantitative behavioral assays and morphological analyses to identify single serotonergic neurons that modulate the escalation of aggression. We found anatomical target areas within the brain where these neurons appear to form synaptic contacts with 5HT1A receptor-expressing neurons, and then confirmed the likelihood of those connections on a functional level. In this Extra View article, we offer an extended discussion of these recent findings and elaborate on how they can link a cellular and functional mapping of an aggression-regulating circuit at a single-cell resolution level.     

The roles of G proteins in the activation of TRPC4 and TRPC5 transient receptor potential channels

TRPC4 and TRPC5 channels are important regulators of electrical excitability in both gastrointestinal myocytes and neurons. Much is known regarding the assembly and function of these channels including TRPC1 as a homotetramer or a heteromultimer and the roles that their interacting proteins play in controlling these events. Further, they are one of the best-studied targets of G protein-coupled receptors and growth factors in general and Gαq protein coupled receptor or epidermal growth factor in particular. However, our understanding of the roles of Gαi/o proteins on TRPC4/5 channels is still rudimentary. We discuss potential roles for Gαi/o proteins in channel activation in addition to their known role in cellular signaling.     

Wnt5a抑制Wnt3a促黑素细胞黑素生成的作用探究

目的：研究WntSa对Wnt3a处理过的melan—a细胞分泌黑色素的影响。方法：体外培养黑色素细胞（melan-a细胞）,分别进行GFP、Wnt3a、Wnt3a＋WntSa处理,比较细胞的突起,酪氨酸酶的活性以及黑素合成相关基因（TYR、TRP2、MITF）表达情况。结果：Wnt3a促进黑色素细胞突起的生长和TYR、TRP2、MITF的表达,而Wnt5a逆转了Wnt3a对黑色素细胞的作用。结论：Wnt5a抑制Wnt3a促黑素细胞黑素生成的作用,表明在melan．a黑素细胞中Wnt5a可有效抑制wnt经典通路。     

Association study of 37 genes related to serotonin and dopamine neurotransmission and neurotrophic factors in cocaine dependence

Cocaine dependence is a neuropsychiatric disorder in which both environmental and genetic factors are involved. Several processes, that include reward and neuroadaptations, mediate the transition from use to dependence. In this regard, dopamine and serotonin neurotransmission systems are clearly involved in reward and other cocaine‐related effects, whereas neurotrophic factors may be responsible for neuroadaptations associated with cocaine dependence. We examined the contribution to cocaine dependence of 37 genes related to the dopaminergic and serotoninergic systems, neurotrophic factors and their receptors through a case–control association study with 319 single nucleotide polymorphisms selected according to genetic coverage criteria in 432 cocaine‐dependent patients and 482 sex‐matched unrelated controls. Single marker analyses provided evidence for association of the serotonin receptor HTR2A with cocaine dependence [rs6561333; nominal P‐value adjusted for age = 1.9e?04, odds ratio = 1.72 (1.29–2.30)]. When patients were subdivided according to the presence or absence of psychotic symptoms, we confirmed the association between cocaine dependence and HTR2A in both subgroups of patients. Our data show additional evidence for the involvement of the serotoninergic system in the genetic susceptibility to cocaine dependence.     

Proteomic analysis for Type I interferon antagonism of Japanese encephalitis virus NS5 protein

Japanese encephalitis virus (JEV) nonstructural protein 5 (NS5) exhibits a Type I interferon (IFN) antagonistic function. This study characterizes Type I IFN antagonism mechanism of NS5 protein, using proteomic approach. In human neuroblastoma cells, NS5 expression would suppress IFNβ‐induced responses, for example, expression of IFN‐stimulated genes PKR and OAS as well as STAT1 nuclear translocation and phosphorylation. Proteomic analysis showed JEV NS5 downregulating calreticulin, while upregulating cyclophilin A, HSP 60 and stress‐induced‐phosphoprotein 1. Gene silence of calreticulin raised intracellular Ca²⁺ levels while inhibiting nuclear translocalization of STAT1 and NFAT‐1 in response to IFNβ, thus, indicating calreticulin downregulation linked with Type I IFN antagonism of JEV NS5 via activation of Ca²⁺/calicineurin. Calcineurin inhibitor cyclosporin A attenuated NS5‐mediated inhibition of IFNβ‐induced responses, for example, IFN‐sensitive response element driven luciferase, STAT1‐dependent PKR mRNA expression, as well as phosphorylation and nuclear translocation of STAT1. Transfection with calcineurin (vs. control) siRNA enhanced nuclear translocalization of STAT1 and upregulated PKR expression in NS5‐expressing cells in response to IFNβ. Results prove Ca²⁺, calreticulin, and calcineurin involvement in STAT1‐mediated signaling as well as a key role of JEV NS5 in Type I IFN antagonism. This study offers insights into the molecular mechanism of Type I interferon antagonism by JEV NS5.     

5-羟色胺受体基因多态性位点与海洛因依赖的关联性研究

目的：5-HT（5-hydroxytryptamine,5-HT）参与了多种中枢神经活动的生理过程,其功能异常可以影响很多行为障碍,已有研究显示,5-HT水平与多种精神疾病密切相关。5-HT受体及其转运体基因在海洛因依赖发生发展中起到了重要的作用,是海洛因依赖的主要候选基因。探讨5羟色胺2A受体（Serotonin 2A receptor,HTR2A）基因启动子区-1438A/G（rs6311）、外显子区102T/C（rs6313）与5羟色胺1B受体（Serotonin 1B receptor,HTR1B）基因外显子区861G/C（rs6296）3个单核苷酸多态性和海洛因依赖的关联性分析。方法：严格按照诊断标准,选取无亲缘关系的海洛因依赖个体616例及健康个体600例提取基因组DNA,采用PCR-RFLP方法检测rs6311、rs6313和rs6296 3个SNPs位点的基因型频率,采用SPSS16.0软件分析各位点等位基因、基因型频率在病例-对照组间差异。结果：HTR2A基因rs6311和HTR1B基因rs6296位点的等位基因及基因型频率分布在2组间存在统计学差异（P〈0.05）,病例组rs6311位点的等位基因A频率显著高于对照组（X2=5.436,P=0.020,OR=1.208,CI=1.031~1.417）,rs6296位点的等位基因C频率显著高于对照组（X2=12.116,P=0.000,OR=1.329,CI=1.132~1.560）。连锁不平衡检验结果显示,HTR2A基因rs6311、rs6313位点处于不连锁状态,D＇〈0.5。结论：HTR2A基因rs6311和HTR1B基因rs6296多态性可能与海洛因成瘾有关,携带有rs6311 A等位基因与rs6296 C等位基因的人可能更容易对海洛因产生依赖。我们的研究为海洛因依赖易感人群筛选及药物靶向治疗提供了理论依据。