Identification of a D-amino acid decapeptide HIV-1 entry inhibitor

Entry of human immunodeficiency virus type 1 (HIV-1) virion into host cells involves three major steps, each being a potential target for the development of entry inhibitors: gp120 binding to CD4, gp120-CD4 complex interacting with a coreceptor, and gp41 refolding to form a six-helix bundle. Using a D-amino acid decapeptide combinatorial library, we identified peptide dC13 as having potent HIV-1 fusion inhibitory activity, and effectively inhibiting infection by several laboratory-adapted and primary HIV-1 strains. While dC13 did not block binding of gp120 to CD4, nor disrupt the gp41 six-helix bundle formation, it effectively blocked the binding of an anti-CXCR4 monoclonal antibody and chemokine SDF-1alpha to CXCR4-expressing cells. However, because R5-using primary viruses were also neutralized, the antiviral activity of dC13 implies additional mode(s) of action. These results suggest that dC13 is a useful HIV-1 coreceptor antagonist for CXCR4 and, due to its biostability and simplicity, may be of value for developing a new class of HIV-1 entry inhibitors.     

中国全新世人群颞下颌关节尺寸的时代变化

本文通过对中国北方地区新石器时代(54例)、青铜铁器时代(189例) 和近代(92例) 成年男性颞下颌关节的多项测量项目的对比、分析, 对中国全新世人群颞下颌关节测量性状的变异问题进行了研究。结果显示近7000年来颞下颌关节的不同部位在全新世不同阶段有不同的变化特点。髁突、冠突在全新世厚度变薄, 髁突的变薄主要在新石器-青铜铁器时代, 冠突的变薄主要在青铜铁器-近代。髁突面积在全新世也在缩小, 在新石器-青铜铁器时代缩小的幅度更大。髁突顶缘弧度的变平、下颌窝的变浅主要发生在新石器-青铜铁器时代。髁突面积/下颌窝面积, 其变化主要发生在青铜铁器时代。这些变化可能与生活环境、食物结构改变、下颌骨与头骨不同的演化速率等有关。     

内蒙古清水河县姑姑庵汉代墓地人骨研究

本文对内蒙古清水河县姑姑庵墓地出土的13例汉代的颅骨(男性6例, 女性7例)进行了体质人类学的研究, 该组颅骨在种族特征上可归入现代亚洲蒙古人种中的东亚人种范围。在若干古代和现代对比组中,姑姑庵汉代居民的体质特征与将军沟组、近代华北组最为接近,很可能是来自中原地区的移民或是当地早期中原移民的后裔。     

Paradoxical effects of a stress signal on pro- and anti-apoptotic machinery in HTLV-1 tax expressing cells

Adult T-cell leukemia (ATL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) are associated with Human T-cell lymphotropic virus type 1 (HTLV-1) infection. The viral transactivator, Tax is able to mediate the cell cycle progression by targeting key regulators of the cell cycle such as p21/waf1, p16/ink4a, p53, cyclins D1-3/cdk complexes, and the mitotic spindle checkpoint MAD apparatus, thereby deregulating cellular DNA damage and checkpoint control. Genome expression profiling of infected cells exemplified by the development of DNA microarrays represents a major advance in genome-wide functional analysis. Utilizing cDNA microarray analysis, we have observed an apparent opposing and paradoxical regulatory network of host cell gene expression upon the introduction of DNA damage stress signal. We find the apparent induction of cell cycle inhibitors, and pro- as well as anti-apoptotic gene expression is directly linked to whether cells are at either G1, S, or G2/M phases of the cell cycle. Specifically, a G1/S block is induced by p21/waf1 and p16/ink4a, while pro-apoptotic expression at S, and G2/M is associated with caspase activation, and anti-apoptotic gene expression is associated with up regulation of Bcl-2 family member, namely bfl-1 gene. Therefore, the microarray results indicating expression of both pro- and anti-apoptotic genes could easily be explained by the particular stage of the cell cycle. Mechanism and the functional outcome of induction for both pathways are discussed.     

两种光呼吸抑制剂对草莓若干生理指标及产量品质的影响

以"丰香"草莓为试材,在花期喷施不同浓度的光呼吸抑制剂NaHSO₃和异烟肼。结果表明,喷施一定浓度的NaHSO₃(100 mg/L)和异烟肼(0.5 mg/ml),可增加草莓植株叶面积、叶绿素总量和光合速率;同时可提高坐果率,增加单果重和产量,果实总糖、可溶性固形物含量也显著提高。     

Novel complexes of guanylate cyclase with heat shock protein 90 and nitric oxide synthase

Soluble guanylate cyclase (sGC) is an important downstream intracellular target of nitric oxide (NO) that is produced by endothelial NO synthase (eNOS) and inducible NO synthase (iNOS). In this study, we demonstrate that sGC exists in a complex with eNOS and heat shock protein 90 (HSP90) in aortic endothelial cells. In addition, we show that in aortic smooth muscle cells, sGC forms a complex with HSP90. Formation of the sGC/eNOS/HSP90 complex is increased in response to eNOS-activating agonists in a manner that depends on HSP90 activity. In vitro binding assays with glutathione S-transferase fusion proteins that contain the alpha- or beta-subunit of sGC show that the sGC beta-subunit interacts directly with HSP90 and indirectly with eNOS. Confocal immunofluorescent studies confirm the subcellular colocalization of sGC and HSP90 in both endothelial and smooth muscle cells. Complex formation of sGC with HSP90 facilitates responses to NO donors in cultured cells (cGMP accumulation) as well as in anesthetized rats (hypotension). These complexes likely function to stabilize sGC as well as to provide directed intracellular transfer of NO from NOS to sGC, thus preventing inactivation of NO by superoxide anion and formation of peroxynitrite, which is a toxic molecule that has been implicated in the pathology of several vascular diseases.     

GC-GAP,a Rho family GTPase-activating protein that interacts with signaling adapters Gab1 and Gab2

Gab1 and Gab2 are scaffolding proteins acting downstream of cell surface receptors and interact with a variety of cytoplasmic signaling proteins such as Grb2, Shp-2, phosphatidylinositol 3-kinase, Shc, and Crk. To identify new binding partners for GAB proteins and better understand their functions, we performed a yeast two-hybrid screening with hGab2-(120-587) as bait. This work led to identification of a novel GTPase-activating protein (GAP) for Rho family GTPases. The GAP domain shows high similarity to the recently cloned CdGAP and displays activity toward RhoA, Rac1, and Cdc42 in vitro. The protein was named GC-GAP for its ability to interact with GAB proteins and its activity toward Rac and Cdc42. GC-GAP is predominantly expressed in the brain with low levels detected in other tissues. Antibodies directed against GC-GAP recognized a protein of approximately 200 kDa. Expression of GC-GAP in 293T cells led to a reduction in active Rac1 and Cdc42 levels but not RhoA. Suppression of GC-GAP expression by siRNA inhibited proliferation of C6 astroglioma cells. In addition, GC-GAP contains several classic proline-rich motifs, and it interacts with the first SH3 domain of Crk and full-length Nck in vitro. We propose that Gab1 and Gab2 in cooperation with other adapter molecules might regulate the cellular localization of GC-GAP under specific stimuli, acting to regulate precisely Rac and Cdc42 activities. Given that GC-GAP is specifically expressed in the nervous system and that it is localized to the dendritic processes of cultured neurons, GC-GAP may play a role in dendritic morphogenesis and also possibly in neural/glial cell proliferation.     

Regulation of ubiquitin and 26S proteasome mediated by phenolic compounds during oxidative stress

Little attention has been devoted to studying the roles of natural antioxidants in the ubiquitin-proteasome pathway during oxidative stress. We demonstrated that a time course revealed that the reassociation of the 19S regulators with the 20S proteasomes occurred automatically and rapidly to reconstitute the 26S proteasomes, with up to 80% completion, within 5 min after H₂O₂ treatment. Ubiquitin, methyl gallate and tannic acid are able to prevent H₂O₂ from inhibiting the 26S activity. We further show that the level of the ubiquitin, S5a and 20S core subunits decreased within 30 min and increased after 24 h of H₂O₂ treatment in Hep-2 cells. Phenolic compounds not only inhibited the 26S activity but also decreased the USP47 levels, which reduce the DNA damage repair rate during oxidative stress; in addition, the presence of DNA fragments, procaspase-3 and a decreased poly (ADP-ribose) polymerase also appeared as a result of the above conditions. Ubiquitin could serve as a protective substrate in H₂O₂ and phenolic compound-treated Hep-2 cells. Methyl gallate and tannic acid, as prooxidants, can attenuate the apoptotic response resulting from long-term oxidative stress. Collectively, these data demonstrate an important role for phenolic compounds in regulating the 26S proteasome and ubiquitin during oxidative stress.