Signaling and subcellular localization of the TNF receptor Edar

Tabby and downless mutant mice have identical phenotypes characterized by deficient development of several ectodermally derived organs such as teeth, hair, and sweat glands. Edar, encoded by the mouse downless gene and defective in human dominant and recessive forms of autosomal hypohidrotic ectodermal dysplasia (EDA) syndrome, is a new member of the tumor necrosis factor (TNF) receptor superfamily. The ligand of Edar is ectodysplasin, a TNF-like molecule mutated in the X-linked form of EDA and in the spontaneous mouse mutant Tabby. We have analyzed the response of Edar signaling in transfected cells and show that it activates nuclear factor-kappaB (NF-kappaB) in a dose-dependent manner. When Edar was expressed at low levels, the NF-kappaB response was enhanced by coexpression of ectodysplasin. The activation of NF-kappaB was greatly reduced in cells expressing mutant forms of Edar associated with the downless phenotype. Overexpression of Edar did not activate SAPK/JNK nor p38 kinase. Even though Edar harbors a death domain its overexpression did not induce apoptosis in any of the four cell lines analyzed, nor was there any difference in apoptosis in developing teeth of wild-type and Tabby mice. Additionally, we show that the subcellular localization of dominant negative alleles of downless is dramatically different from that of recessive or wild-type alleles. This together with differences in NF-kappaB responses suggests an explanation for the different mode of inheritance of the different downless alleles.     

EZH2在衰老细胞中表达下调引起Netrin-1表达增加进而促进交感神经轴突生长

交感神经在一些疾病动物模型和老年小鼠模型组织中呈现发芽生长和密度增加的趋势。这提示,交感神经与衰老密切相关。本研究采用免疫组织化学检测老年小鼠肝、肺、脾组织和人结肠腺瘤组织衰老模型中交感神经标记蛋白酪氨酸羟化酶（TH）的表达情况。结果证实,衰老组织中的交感神经密度显著增加。然而,目前对衰老组织的这种生物学改变机制尚不明确。本研究以人成纤维细胞系2BS为实验材料,经转录组测序发现,分泌性轴突导向因子导蛋白-1在衰老细胞中上调表达。ELISA和实时定量PCR结果显示,在博来霉素、离子射线、癌蛋白RasV12过表达所诱导的早衰及复制性衰老的2BS细胞中,导蛋白-1的蛋白质和mRNA表达量均比年轻对照组高。DNA损伤反应（DNA damage response,DDR）是调控衰老细胞分泌蛋白质表达的重要途径。为明确导蛋白-1在衰老细胞的上调表达是否与DDR相关,使用小分子化合物抑制DDR的重要效应分子ATM（ataxia telangiectasia mutated）和CHK2（checkpoint kinase 2）在博来霉素诱导的衰老2BS细胞中的活性。ELISA和实时定量PCR结果显示,与博来霉素诱导衰老组相比,阻断衰老细胞中的DDR活性未引起导蛋白-1表达水平的改变。提示导蛋白-1在衰老细胞中的表达不依赖于DDR途径。Western印迹检测发现组蛋白甲基转移酶EZH2在衰老细胞中的蛋白质表达明显少于年轻细胞;实时定量PCR结果表明使用小分子化合物抑制EZH2在年轻细胞中的活性引起导蛋白-1表达增加;CHIP实验检测发现,EZH2对年轻细胞的导蛋白-1启动子区DNA片段富集显著而在衰老细胞未见富集。以上结果提示EZH2在衰老细胞中的下调表达是导蛋白-1表达增加的重要原因。大鼠DRG与衰老细胞共培养结果证实,衰老细胞对交感神经具有导向作用,并且该现象依赖于导蛋白-1的分泌。根据以上结果得出结论,导蛋白-1在衰老细胞中的上调表达不依赖于DDR途径而与EZH2的下调表达相关,衰老细胞通过分泌导蛋白-1促进交感神经轴突定向生长。本研究为深入探讨衰老相关疾病的发生机制以及防治提供了新线索,具有一定的科学意义和潜在的转化应用价值。     

CD40L reverse signaling suppresses prevertebral sympathetic axon growth and tissue innervation

CD40‐activated CD40L reverse signaling is a major physiological regulator of the growth of neural processes in the developing nervous system. Previous work on superior cervical ganglion (SCG) neurons of the paravertebral sympathetic chain has shown that CD40L reverse signaling enhances NGF‐promoted axon growth and tissue innervation. Here we show that CD40L reverse signaling has the opposite function in prevertebral ganglion (PVG) sympathetic neurons. During a circumscribed perinatal window of development, PVG neurons cultured from Cd40^–/– mice had substantially larger, more exuberant axon arbors in the presence of NGF than PVG neurons cultured from wild‐type mice. Tissues that receive their sympathetic innervation from PVG neurons were markedly hyperinnervated in Cd40^–/– mice compared with wild‐type mice. The exuberant axonal growth phenotype of cultured CD40‐deficient perinatal PVG neurons was pared back to wild‐type levels by activating CD40L reverse signaling with a CD40‐Fc chimeric protein, but not by activating CD40 forward signaling with CD40L. The co‐expression of CD40 and CD40L in PVG neurons suggests that these proteins engage in an autocrine signaling loop in these neurons. Our work shows that CD40L reverse signaling is a physiological regulator of NGF‐promoted sympathetic axon growth and tissue innervation with opposite effects in paravertebral and prevertebral neurons.     

Modulation of the enkephalinergic phenotype of rat sympathetic neurons by hormonal and transynaptic mechanisms

Most sympathetic neurons contain one or more neuropeptides in addition to catecholamines. Although the regulation of catecholamines has been studied extensively, comparatively little is known about the regulation of neuropeptides. Since glucocorticoids and preganglionic innervation regulate catecholaminergic properties in chromaffin cells, we examined the effects of these factors on a co-localized neuropeptide, leucine enkephalin (L-Enk), in adult rat sympathetic neurons in vivo. Lowered serum glucocorticoid levels as a consequence of bilateral adrenalectomy resulted in a reduction of ganglionic L-Enk content that was reversed by exposure of adrenalectomized animals to the synthetic glucocorticoid, dexamethasone. Surgical denervation of the SCG eliminated L-Enk-IR preganglionic fibers and caused a dramatic increase in the number of L-Enk-IR neurons. Inhibition of the enkephalinergic component of the preganglionic innervation by chronic exposure to the opiate receptor antagonist naloxone increases the number of L-Enk-IR cell bodies and total ganglionic L-Enk content. None of the experimental manipulations noticeably altered the number or distribution of NPY-IR neurons, suggesting that the effects of glucocorticoids and the innervation on ganglionic L-Enk levels were specific and not simply an alteration of the biosynthetic state of the cells. These results demonstrate that circulating glucocorticoids and the preganglionic innervation regulate L-Enk levels in sympathetic neurons. Since both glucocorticoid levels and preganglionic activity are known to be altered by stressful stimuli, acute regulation of sympathetic L-Enk levels may constitute an important component of the autonomic response to stress. © 1993 John Wiley & Sons, Inc.     

Structure-Function Relationship of Tumor Necrosis Factor (TNF) and Its Receptor Interaction Based on 3D Structural Analysis of a Fully Active TNFR1-Selective TNF Mutant

Tumor necrosis factor (TNF) is an important cytokine that suppresses carcinogenesis and excludes infectious pathogens to maintain homeostasis. TNF activates its two receptors [TNF receptor (TNFR) 1 and TNFR2], but the contribution of each receptor to various host defense functions and immunologic surveillance is not yet clear. Here, we used phage display techniques to generate receptor-selective TNF mutants that activate only one TNFR. These TNF mutants will be useful in the functional analysis of TNFR.Six amino acids in the receptor binding interface (near TNF residues 30, 80, and 140) were randomly mutated by polymerase chain reaction. Two phage libraries comprising over 5 million TNF mutants were constructed. By selecting the mutants without affinity for TNFR1 or TNFR2, we successfully isolated 4 TNFR2-selective candidates and 16 TNFR1-selective candidates, respectively. The TNFR1-selective candidates were highly mutated near residue 30, whereas TNFR2-selective candidates were highly mutated near residue 140, although both had conserved sequences near residues 140 and 30, respectively. This finding suggested that the phage display technique was suitable for identifying important regions for the TNF interaction with TNFR1 and TNFR2. Purified clone R1-6, a TNFR1-selective candidate, remained fully bioactive and had full affinity for TNFR1 without activating TNFR2, indicating the usefulness of the R1-6 TNF mutant in analyzing TNFR1 receptor function.To further elucidate the receptor selectivity of R1-6, we examined the structure of R1-6 by X-ray crystallography. The results suggested that R31A and R32G mutations strongly influenced electrostatic interaction with TNFR2, and that L29K mutation contributed to the binding of R1-6 to TNFR1. This phage display technique can be used to efficiently construct functional mutants for analysis of the TNF structure-function relationship, which might facilitate in silico drug design based on receptor selectivity.     

Raji细胞培养中HSV持续感染模型的建立及免疫因素(TNF IFNs)对它的影响

本文观察HSV持续感染Raji细胞培养物150天。发现整个感染过程似呵分为两个阶段:急性期(前30天)和稳定期(30天以后)。在急性期上清液中HSV滴度达10~(6.2)TCID_(50)/ml.病毒抗原阳性细胞达21％,死细胞达42％;在稳定期病毒和细胞处于相对平衡状态,上清液中IISV滴度在10~(3.5-4.2)TCID_(50)/ml,病毒抗原阳性细胞约占5—10％,感染细胞与对照细胞在生长特性上无明显差异。用rIFNs、rlL-2和TNF处理稳定期的细胞培养物,发现TNF和rlFNa能明显抑制HSV的复制,rIENy作用较弱,去除上述因子5天后又恢复到处理前水平。rlL-2无明显作用。用HSV抗体处理上述细胞培养物上清液中病毒和病毒抗原阳性细胞都消失,且在去除抗体后连续观察50天仍未出现。本实验为体外研究HSV持续感染提供了一个有用的模型。     

Apc+/Min colonic epithelial cells express TNF receptors and ICAM-1 when they are co-cultured with large intestine intra-epithelial lymphocytes

Adenomatous polyposis coli (APC) functions are involved in the heterotypic interactions occurring between intestinal epithelial cells (IECs) and intra-epithelial lymphocytes (IELs). These interactions may be of interest in cancer prevention, since recent data provide evidence for lymphocyte mediated immunosurveillance of epithelial cancers. The present study attempts to determine if APC inactivation induces changes in the cross-talk between IEC and large intestine IEL (LI-IEL) through intercellular adhesion molecule (ICAM-1)/leukocyte function-associated (LFA-1) interactions. Mouse Apc+/+ and Apc+/Min colonocytes were co-cultivated with LI-IEL. When co-cultured with LI-IEL Apc+/Min IEC but not Apc+/+ IEC expressed high levels of ICAM-1. The presence of ICAM-1 was linked to TNFalpha production in both co-cultures and TNFR expression only in co-cultivated Apc+/Min IEC. Finally, butyrate enhanced the expression of ICAM-1 in Apc+/Min IEC co-cultured with LI-IEL, and the secretion of TNFalpha by both types of co-cultures. These events could participate in determining the Apc+/Min IEC immunogenicity under different in vivo conditions.     

Glutamate Transmission in the Rostral Ventrolateral Medullary Sympathetic Premotor Pathway

1. The aim of these studies was to test the hypothesis that glutamate is the principal excitatory neurotransmitter in the sympathetic premotor pathway from the rostral ventrolateral medulla (RVLM) to the sympathetic preganglionic neurons (SPNs) in the thoracic spinal cord.2. Iontophoretic and pressure ejection of glutamate receptor agonists and antagonists was made onto antidromically identified splanchnic and adrenal SPNs before and during electrical stimulation of the RVLM in urethane/chloralose-anesthetized, artificially ventilated rats.3. SPNs were excited by both NMDA and non-NMDA glutamate receptor agonists. Blockade of glutamate receptors in the IML interrupted the ability of electrical activation of sympathetic premotor neurons in the RVLM to excite SPNs. Within the IML, antergradely labeled terminals of RVLM neurons were found to contain glutamate immunoreactivity and to make asymmetric synapses on local dendrites.4. These data support a significant role for glutamate neurotransmission in mediating the tonic and phasic excitation of SPNs by the sympathetic premotor pathway from the RVLM. It seems likely that stimulation of the RVLM produces glutamate release from both C1 and non-PNMT-containing axon terminals in the IML.     

The significance and occurrence of TNF receptor polymorphisms in the Saudi population

Background and objective: On the basis that the inflammatory effects of TNF (tumour necrosis factor) are predominantly mediated through interaction with the TNF receptor-1 (TNFRSF1A), the current study was designed to establish the prevalence of the mutations, R92Q and P46L TNFRSF1A polymorphisms both in the general healthy Saudi population, and in Saudi patients carrying inflammatory diseases such as atherosclerosis or rheumatoid arthritis. We felt it important to report the frequency of the mutations, R92Q and P46L TNFRSF1A polymorphisms in healthy Saudi individuals, and those with inflammatory conditions, as well as to describe the pattern of immunological factors in individuals expressing R92Q or P46L TNFRSF1A. Patients and methods: We collected in PAX gene blood RNA tubes (for RT-PCR and sequencing) 500 blood samples from normal healthy individuals from the West and Center of Saudi Arabia, as well as 100 from patients with atherosclerosis, and 100 patients diagnosed with rheumatoid arthritis. All were screened for the levels of soluble TNF, C-reactive protein (CRP), interleukin6 (IL-6) and sTNFR1. In addition, they were screened for R92Q and P46L TNFRSF1A by RT-PCR. Moreover, phenotype and expression of peripheral blood mononuclear cells (PBMCs) was performed by flow cytometry (FACS). Results: Across 500 normal individuals, 8 (1.6%) expressed both R92Q and P46L mutations. By contrast, of the 100 patients in our study with atherosclerosis, 34% expressed both the R92Q and P46L mutations, whilst 42% of patients with rheumatoid arthritis expressed both mutations R92Q and P46L. No significant differences were observed between cell markers of normal individuals (CD3, 4, 8, 16, 56, 19, 25, ICAM-1, VLA-4 & l-selectin) and patients with atherosclerosis. There were significantly high values of cell markers in patients with rheumatoid arthritis compared with normal individuals both in terms of percentage and absolute counts (p < 0.05). Soluble IL-6 and sTNFR1 showed significant decreases in atherosclerosis and rheumatoid arthritis when compared with controls (p < 0.05). In addition, CRP and sTNF showed significant increases in the atherosclerosis and rheumatoid arthritis groups when compared to controls (p < 0.05). Conclusion: Our findings reasonably anticipate the presence of TRAPS disease (low penetrance mutations) amongst the Saudi population although further studies are needed to confirm these results.     

依泽替米贝对胆囊结石患者血清TNF及IL-1水平影响

目的：探究依泽替米贝对胆囊结石患者血清TNF及IL-1 水平变化的影响。方法：选取2014 年8 月至2015 年2 月我院收治 的胆囊结石患者70 例,采用随机数字表随机分为两组,其中对照组35 例,给予溶石疗法等临床常规治疗;实验组35 例,在与对 照组相同的临床常规溶石治疗基础上加用依泽替米贝进行治疗。治疗结束后,比较两组患者胆囊结石数量、重量的差异以及血清 TNF及IL-1 水平变化。结果：①经治疗后实验组患者胆囊内结石平均数量（6.1± 2.5）,明显少于对照组（9.2± 2.7）,且差异有统计 学意义（t=2.269,P=0.037<0.05）;②经治疗后实验组患者胆囊内结石平均重量（0.17± 3.31）g 明显少于对照组（0.48± 3.04）g,且差 异有统计学意义（t=2.237,P=0.026<0.05）;③经治疗后实验组患者血清TNF水平为（15.93± 4.78）ng/mg,明显低于对照组（22.13± 5.17）ng/mg,且差异有统计学意义（t=2.501,P=0.036<0.05）;④经治疗后实验组患者血清IL-1 水平（63.41± 8.12）ng/mg 明显低于 对照组（89.60± 7.08）ng/mg,且差异有统计学意义（t=2.439,P=0.029<0.05）;⑤治疗后,实验组患者的治疗有效率明显高于对照组, 且差异具有统计学意义（t=2.321,P=0.034<0.05）。结论：依泽替米贝能有效减少结石数量和体积,缓解胆囊结石患者症状,有较好 的临床疗效,对临床治疗具有指导意义,值得临床应用和推广。     

Domain Contributions to Signaling Specificity Differences Between Ras-Guanine Nucleotide Releasing Factor (Ras-GRF) 1 and Ras-GRF2

Ras-GRF1 (GRF1) and Ras-GRF2 (GRF2) constitute a family of similar calcium sensors that regulate synaptic plasticity. They are both guanine exchange factors that contain a very similar set of functional domains, including N-terminal pleckstrin homology, coiled-coil, and calmodulin-binding IQ domains and C-terminal Dbl homology Rac-activating domains, Ras-exchange motifs, and CDC25 Ras-activating domains. Nevertheless, they regulate different forms of synaptic plasticity. Although both GRF proteins transduce calcium signals emanating from NMDA-type glutamate receptors in the CA1 region of the hippocampus, GRF1 promotes LTD, whereas GRF2 promotes θ-burst stimulation-induced LTP (TBS-LTP). GRF1 can also mediate high frequency stimulation-induced LTP (HFS-LTP) in mice over 2-months of age, which involves calcium-permeable AMPA-type glutamate receptors. To add to our understanding of how proteins with similar domains can have different functions, WT and various chimeras between GRF1 and GRF2 proteins were tested for their abilities to reconstitute defective LTP and/or LTD in the CA1 hippocampus of Grf1/Grf2 double knock-out mice. These studies revealed a critical role for the GRF2 CDC25 domain in the induction of TBS-LTP by GRF proteins. In contrast, the N-terminal pleckstrin homology and/or coiled-coil domains of GRF1 are key to the induction of HFS-LTP by GRF proteins. Finally, the IQ motif of GRF1 determines whether a GRF protein can induce LTD. Overall, these findings show that for the three forms of synaptic plasticity that are regulated by GRF proteins in the CA1 hippocampus, specificity is encoded in only one or two domains, and a different set of domains for each form of synaptic plasticity.     

交感神经系统内递质共存及其相互作用

在外周交感神经系统内,神经递质或神经肽类物质主要存在于大、小囊泡内;递质共存的现象在交感神经内不断得以发现．去甲肾上腺素和乙酰胆碱、神经肽Y、脑啡肽、P物质、血管活性肠肽、生长抑素、神经降压素、降钙素基因相关肽等物质共存的证实,扩大了交感神经递质的调节范围,递质之间网络式的相互调节作用有着重要的生理意义。     

Innervation of the arteriovenous anastomoses in the dog tongue

Summary Profiles of nerve plexuses in the arteriovenous anastomoses of the dog tongue were investigated by both transmission and scanning electron microscopy. Three-dimensional morphology of the vascular nerves was examined after removal of the connective tissue components by the HCl-hydrolysis method. Tight bending and a rich nerve supply were the most characteristic features of the anastomosing channels. The tunica media consisted of an outer circular layer of typical smooth-muscle cells and an inner region containing longitudinal plicae of ramified smoothmuscle cells. The tunica adventitia was exclusively occupied by nerve bundles; fibroblasts were poorly developed. Numerous nerve bundles of variable size were coiled around the anastomosing channels, and occasional bundles ran crosswise over the U-shaped bent vessels.     

广东汉族人TNF多态性

采用PCR－RFLP技术对103例广东汉族人TNF多态性进行了检测,结果是：TNFβ^*1纯合子表型频率为0．2524,TNFβ^*2纯合子表型频率为0．2913,TNFβ^*1／TNFβ^*2杂合子表型频率为0．4563,TNFβ^*1基因频率0．4806,TNFβ^*1基因频率0．5194。本结果与其他人群的结果进行了比较。     

c-IAP1 and UbcH5 promote K11-linked polyubiquitination of RIP1 in TNF signalling

Ubiquitin ligases are critical components of the ubiquitination process that determine substrate specificity and, in collaboration with E2 ubiquitin-conjugating enzymes, regulate the nature of polyubiquitin chains assembled on their substrates. Cellular inhibitor of apoptosis (c-IAP1 and c-IAP2) proteins are recruited to TNFR1-associated signalling complexes where they regulate receptor-stimulated NF-κB activation through their RING domain ubiquitin ligase activity. Using a directed yeast two-hybrid screen, we found several novel and previously identified E2 partners of IAP RING domains. Among these, the UbcH5 family of E2 enzymes are critical regulators of the stability of c-IAP1 protein following destabilizing stimuli such as TWEAK or CD40 signalling or IAP antagonists. We demonstrate that c-IAP1 and UbcH5 family promote K11-linked polyubiquitination of receptor-interacting protein 1 (RIP1) in vitro and in vivo. We further show that TNFα-stimulated NF-κB activation involves endogenous K11-linked ubiquitination of RIP1 within the TNFR1 signalling complex that is c-IAP1 and UbcH5 dependent. Lastly, NF-κB essential modifier efficiently binds K11-linked ubiquitin chains, suggesting that this ubiquitin linkage may have a signalling role in the activation of proliferative cellular pathways.     

Tissue distribution and clearance of soluble murine TNF receptors in mice

In this study, clearance of sTNFR was investigated. The data show that bilateral nephrectomy results in an increase of the levels of both sTNFR after which a new steady state situation develops, suggesting that other organs, apart from the kidneys, are involved in clearing of sTNFR. Bilateral nephrectomy also leads to an increase in circulating TNF. This TNF was detected by ELISA and appeared to be not biologically active. To investigate whether the endotoxin induced increase in sTNFR is dependent of renal function, endotoxin was injected in nephrectomized mice. The data show that nephrectomy followed by endotoxin injection resulted in a further increase of the levels of both sTNFR. However, the endotoxin induced increase in nephrectomized mice was similar to the situation in normal mice after LPS indicating that the endtoxin induced increase is kidney independent in these mice. To investigate the relative participation of various organs in sTNFR clearance, ¹²⁵I labelled sTNFR-P75 was injected. The data reveal that the majority of the sTNFR is removed from the circulation by the kidneys although indications for involvement of the liver and the lungs were also obtained. Calculation of the parametric clearance revealed that nephrectomy resulted in a 50% reduction of sTNFR-P75 clearance. Furthermore, the data presented strongly suggest that sTNFR release seems to be a continuous process, which is in balance with clearance of the sTNFR by the kidney, although other organs such as the liver and the lungs are involved.     

Differences of the electrical and nicotinic receptor stimulation-evoked liberation of norepinephrine from chicken sympathetic neurons in culture: Possible involvement of different pools of the transmitter

We studied the release of [³H]norepinephrine from chicken sympathetic neurons in culture evoked by nicotinic and electrical stimulation with an intention to establish functional identity or nonidentity of the two stimuli in investigations of neurotransmitter release. Nicotinic stimulation evoked extracellular calcium dependent release of [³H]norepinephrine and the rise of intracellular calcium concentration. The release was completely blocked by nicotinic antagonists hexamethonium (100 mol/l) and mecamylamine (10 mol/l), and decreased by tetrodotoxin (0.3 mol/l) and -conotoxin (0.1 mol/l) to 17% and 27%, resp. The intracellular calcium response was decreased by nicotinic antagonists and tetrodotoxin, but not changed by -conotoxin. The electrical stimulation-evoked release was blocked by both tetrodotoxin and -conotoxin, and decreased by previous electrical, but not nicotinic, stimulation. The differential sensitivity to -conotoxin and tetrodotoxin, and the inability of nicotinic stimulation to decrease the liberation by following electrical stimulation may suggest the mobilization of different pools of the transmitter.