Common and distinct elements in cellular signaling via EGF and FGF receptors

Signaling pathways that are activated by epidermal growth factor (EGF) or fibroblast growth factor (FGF) receptors have been identified and compared (detailed Connections Maps are available at Science's Signal Transduction Knowledge Environment). Both receptors stimulate a similar complement of intracellular signaling pathways. However, whereas activated EGF receptors (EGFRs) function as the main platform for recruitment of signaling proteins, signaling through the FGF receptors (FGFRs) is mediated primarily by assembly of a multidocking protein complex. Moreover, FGFR signaling is subject to additional intracellular and extracellular control mechanisms that do not affect EGFR signaling. The differential circuitry of the intracellular networks that are activated by EGFR and FGFR may affect signal specificity and physiological responses.     

雄激素对去势大鼠脊髓缘核AR蛋白表达的影响

用免疫组化SP法检测了去势及去势后补充雄激素大鼠脊髓灰质缘核中雄激素受体（Androgen receptors,AR）蛋白的表达情况,以探讨雄激素对缘核的作用。结果表明,睾丸摘除组大鼠缘核内AR蛋白的表达和睾丸摘除并用睾酮替代组大鼠缘核内AR蛋白的表达接近。说明去睾丸大鼠阻断其内源性雄激素后,对缘核AR蛋白表达影响甚小,而补充外源性雄激素对此影响不大。     

Biosensors developments and potential applications in the agricultural diagnosis sector

There has been a phenomenal growth in the field of biosensor development in recent years with emerging applications in a wide range of disciplines, including medical analysis, food and the environment. The increase in the number of analytes requiring monitoring and others that require control, and the need for high sensitivity, speed, and accuracy of analytical measurements have stimulated considerable interest in developing sensors as diagnostics tools. A range of molecules with biorecognition powers are available naturally such as antibodies, enzymes, cell receptors and nucleic acids and are used as the sensing receptors in biosensors. The combined approaches of computer (molecular) modelling and combinatorial synthesis or molecularly imprinted polymers are undertaken today as a new method to produce synthetic receptors that can be used in sensor development. A wide range of transducers is also feasible to fulfil the rapid monitoring needs of the diagnostic market. Biosensors can also be incorporated into simple-to-use instruments as an on-line monitoring device or a one-shot sensor. This paper deals with recent developments in biosensors and their potential use in the agricultural diagnostic market.     

Distinct hepatic receptors for low density lipoprotein and apolipoprotein E in humans

Since the liver is a central organ for lipid and lipoprotein synthesis and catabolism, hepatic receptors for specific apolipoproteins on plasma lipoproteins would be expected to modulate lipid and lipoprotein metabolism. The role of hepatic receptors for low density lipoproteins and apolipoprotein E-containing lipoproteins was evaluated in patients with complementary disorders in lipoprotein metabolism: abetalipoproteinemia and homozygous familial hypercholesterolemia. In addition, hepatic membranes from a patient with familial hypercholesterolemia were studied and compared before and after portacaval shunt surgery. The results establish that the human liver has receptors for apolipoproteins B and E. Furthermore, in the human, hepatic receptors for low density lipoproteins and apolipoprotein E are genetically distinct and can undergo independent control.     

阿片受体类型和功能及其在猪脑中的个体发育特点

总结阿片受体类型的研究进展,介绍4种主要类型受体的功能。动物脑中阿片受体的数量以及它们与阿片配体亲和力的改变能够对脑功能的阿片控制或内分泌系统的中枢神经控制产生影响。为明确猪脑中阿片受体的变化,阐述了阿片受体在猪脑中的个体发育特点。     

Bimodal distribution of dopamine receptor densities in brains of schizophrenics

The dopamine hypothesis of schizophrenia was examined by measuring the density of dopamine receptors in the postmortem brains of 81 control subjects and 59 schizophrenics from four different countries. The densities of dopamine receptors in the tissues from the schizophrenic patients had a bimodal distribution in the caudate nucleus, putamen, and nucleus accumbens. One mode occurred 25 percent above the control density, and a second mode occurred at a density 2.3 times that of the control density for all three regions. Although almost all the patients had been medicated with neuroleptics, the two modes had the same dissociation constant for the labeled ligand used, suggesting that the neuroleptic doses were similar for the two populations of schizophrenics. The results thus provide direct evidence for two distinct categories of schizophrenia.     

Zebrafish Dpr2 inhibits mesoderm induction by promoting degradation of nodal receptors

Nodal proteins, members of the transforming growth factor-beta (TGFbeta) superfamily, have been identified as key endogenous mesoderm inducers in vertebrates. Precise control of Nodal signaling is essential for normal development of embryos. Here, we report that zebrafish dapper2 (dpr2) is expressed in mesoderm precursors during early embryogenesis and is positively regulated by Nodal signals. In vivo functional studies in zebrafish suggest that Dpr2 suppresses mesoderm induction activities of Nodal signaling. Dpr2 is localized in late endosomes, binds to the TGFbeta receptors ALK5 and ALK4, and accelerates lysosomal degradation of these receptors.     

Diversity of G proteins in signal transduction

The heterotrimeric guanine nucleotide-binding proteins (G proteins) act as switches that regulate information processing circuits connecting cell surface receptors to a variety of effectors. The G proteins are present in all eukaryotic cells, and they control metabolic, humoral, neural, and developmental functions. More than a hundred different kinds of receptors and many different effectors have been described. The G proteins that coordinate receptor-effector activity are derived from a large gene family. At present, the family is known to contain at least sixteen different genes that encode the alpha subunit of the heterotrimer, four that encode beta subunits, and multiple genes encoding gamma subunits. Specific transient interactions between these components generate the pathways that modulate cellular responses to complex chemical signals.     

Receptors for dopamine and somatostatin: formation of hetero-oligomers with enhanced functional activity

Somatostatin and dopamine are two major neurotransmitter systems that share a number of structural and functional characteristics. Somatostatin receptors and dopamine receptors are colocalized in neuronal subgroups, and somatostatin is involved in modulating dopamine-mediated control of motor activity. However, the molecular basis for such interaction between the two systems is unclear. Here, we show that dopamine receptor D2R and somatostatin receptor SSTR5 interact physically through hetero-oligomerization to create a novel receptor with enhanced functional activity. Our results provide evidence that receptors from different G protein (heterotrimeric guanine nucleotide binding protein)-coupled receptor families interact through oligomerization. Such direct intramembrane association defines a new level of molecular crosstalk between related G protein-coupled receptor subfamilies.     

TGF-β受体mRNA在湖羊机体组织中的表达水平及其与排卵数的关系

 【目的】通过分析TGF-β受体(TGF-βRⅠ、TGF-βRⅡ)mRNA组织表达谱及其表达水平与湖羊排卵数的关系,研究TGF-β受体对湖羊排卵数的影响。【方法】挑选16头经产母羊,其中8只产多羔的为高产组,8只产单羔作为对照组,使用氯前列醇钠法进行同期发情,发情后48～60 h内屠宰,测定排卵数;分离取高产组母羊的下丘脑、垂体等组织样进行组织表达谱分析,用实时荧光定量PCR法检测湖羊卵巢TGF-βRⅠ和TGF-βRⅡ基因mRNA表达水平,分析TGF-β受体表达水平与湖羊排卵数的关系。【结果】TGF-βRⅠ在生殖器官相对表达量极显著高于肺和肌肉(P＜0.01),TGF-βRⅡ在生殖器官相对表达量极显著高于其它组织(P＜0.01),是卵巢高表达基因;高产组湖羊卵巢组织TGF-βRⅠ与TGF-βRⅡ基因mRNA表达量分别极显著(P＜0.01)与显著(P＝0.011)高于对照组;湖羊卵巢组织TGF-βRⅠ和TGF-βRⅡ基因mRNA表达量与排卵数呈正相关,相关系数分别为0.562 (P＞0.05)和0.711(P＜0.05)。【结论】TGF-β受体在卵巢组织中表达高,其中高产组TGF-βRⅠ和TGF-βRⅡ基因mRNA表达量极显著或显著高于对照组,而且与排卵数呈正相关。