三磷酸肌醇在IL—2诱导的T细胞增殖分化中的信息传递作用

用不同浓度的IL-2刺激静息T淋巴细胞,其细胞内IP_3无明显改变,但ConA刺激则使IP_3增加45%。在IL-2依赖性T细胞,IL-2R表达率达83%,IL-2刺激时IP_3的变化依浓度不同而异,10u—50u/ml的IL-2使IP_3增高,以50u/ml最为显著,增加60%,但100u/ml IL-2及ConA不改变胞内IP_3的浓度。IL-2R封闭后的T淋巴细胞在IL-2刺激时IP_3的增加明显减弱。这些结果提示:IP_3作为细胞内的第二信使介导了IL-2诱导的T细胞的增殖反应,这种作用与IL-2的剂量及IL-2R表达有密切的关系。     

Longer term progesterone treatment induces changes of GABAA receptor levels in forebrain sites in the female hamster: quantitative autoradiography study

Summary Quantitative receptor autoradiography was applied to evaluate the effects of one and three injections of 1 mg progesterone (P) on ³H muscimol binding levels in the different forebrain areas of the female hamster. The overall effect of P resulted in substantial increases in ³H muscimol binding in brain areas containing gonadal steroid receptors: medial preoptic area and ventromedial hypothalamic nucleus as well as in bed nucleus stria terminalis and subiculum. Similarly, the caudate putamen, a region where gonadal steroid receptors are not abundant, also showed substantial increases of ³H muscimol binding receptor levels. Moreover, female hamsters treated with P for 3 days presented altered ³H muscimol binding levels in the amygdala and thalamic nucleus that were, in some cases, not produced by one dose of P. P treatment also decreased GABA_A binding in two areas of the thalamus. These results are consistent with the proposal that P may alter GABAergic inhibitory activity via changes in the levels of GABA_A receptors in certain forebrain areas in the female hamster, changes which may be linked to the mediation of anxiolytic effects and to the inhibition of aggressive behavior. These data also suggest that P treatment increases the binding of high affinity GABA receptors in some forebrain sites and may be responsible for maintenance of the anxiolytic effects.     

Distribution and pharmacological characterization of somatostatin receptor binding sites in the sheep brain

Somatostatin binding sites have been localized and quantified in the sheep brain using ¹²⁵I-Tyr₀-DTrp₈-somatostatin, by quantitative high resolution light microscopic autoradiography. Sections were analyzed by densitometry on radioautographic film, and subsequently on slides coated with photoemulsion. Specific somatostatin binding sites were concentrated in the medial habenula, superior colliculus, dorsal motor nucleus of the vagus nerve, inferior olive, spinal trigeminal nucleus, and cerebellum. In competition experiments, octreotide, a sst2/sst3/sst5 selective agonist only partially displaced ¹²⁵I-Tyr₀-DTrp₈-somatostatin in the three cerebellar layers while it was fully active as compared to somatostatin 14 and 28 in the deeper layers of the parietal cortex. Moderate to low somatostatin receptor densities were present in the mesencephalic periaqueductal gray, dorsal raphe, thalamic paraventricular nucleus, interpeduncular nucleus, pineal gland, dorsal tegmental, dorsolateral tegmental and parabrachial nuclei, nucleus of the solitary tract. The distribution of somatostatin binding sites generally correlates with the data obtained on slides dipped in photoemulsion which provided better resolution and more precise localization. In most of the labeled areas, ¹²⁵I-Tyr₀-DTrp₈-somatostatin receptor binding was distributed between both neuropil and perikarya. Perikarya bearing ¹²⁵I-Tyr₀-DTrp₈-somatostatin receptors were observed in areas which did not display detectable binding sites on film such as the preoptic-anterior hypothalamic complex and arcuate nucleus and in the locus coeruleus. In conclusion, the distribution of ¹²⁵I-Tyr₀-DTrp₈-somatostatin binding sites in sheep brain is very reminiscent of other mammals being closer to the human than to rodents.     

Absence of TREM2 polymorphisms in patients with Alzheimer's disease and Frontotemporal Lobar Degeneration

Triggering Receptor Expressed on Myeloid cells (TREM)2 deficiency originates a genetic syndrome characterized by bone cysts and presenile dementia, named Nasu-Hakola disease (NHD). Early onset dementia and marked involvement of frontal regions are features characterizing both NHD and other kinds of neurodegenerative disorders, such as Frontotemporal Lobar Degeneration (FTLD), and, in some cases, Alzheimer's disease (AD). Three Single Nucleotide Polymorphisms (SNPs) in TREM2 coding region were screened by allelic discrimination in a population of probable AD patients as well as FTLD patients as compared with age-matched controls. In addition, mutation scanning of the coding region of TREM2 gene was carried out in 7 patients with early onset AD (EOAD), 16 FTLD, and 20 controls. None of the SNPs analyzed was present, either in patients or controls. Moreover, mutation scanning of the five exons of TREM2 failed to detect the presence of novel polymorphisms. These data demonstrate that TREM2 coding region is highly conserved, implying a crucial role of this receptor. Further studies, including a functional analysis, are certainly required to clarify the role of TREM2 in neurodegenerative processes.     

gp130胞外区近膜端缺失的突变体介导IL-6信号的研究

目的研究ｇｐ１３０胞外区远膜端和近膜端在ＩＬ－６信号转导中的作用。方法用分子克隆手段构建全长的膜结合型ｇｐ１３０分子和胞外区第３０１～５８２位氨基酸残基缺失的突变体分子，并通过阻滞电泳方法比较突变体与野生型分子在传导信号方面的差异。结果通过酶切鉴定、序列分析和表达检测，证明野生型和突变体ｃＤＮＡ表达载体构建正确，并有效表达；阻滞电泳结果表明，在ＳＫＯ－００７细胞和Ｍｏｌｔ－４细胞中，突变体分子与野生型ｇｐ１３０都能介导ＩＬ－６信号。结论ｇｐ１３０分子胞外区远膜端在ＩＬ－６信号转导中发挥重要作用；而近膜端并非ＩＬ－６信号转导所必需。     

Expression of serotonin2A receptors in Purkinje cells of the developing rat cerebellum

Previous physiological and pharmacological studies have shown that the serotonin_2A (5-HT_2A) receptor is involved in cerebellar functions. However, the expression of 5-HT_2A receptors in the developing cerebellum has not been elucidated to date. In the present immunohistochemical study, we examined developmental changes of the distribution of 5-HT_2A receptors in Purkinje cells of the rat cerebellum from embryonic day 18 (E18) to postnatal day 21 (P21). The weak immunoreaction to 5-HT_2A receptors was found in the deep cerebellar nuclei on E19. In the cerebellar cortex of the hemisphere and the posterior vermis, somata of Purkinje cells became weakly immunoreactive on P0. With the dendritic elongation and arborization, the immunoreaction appeared in the proximal parts of Purkinje cell dendrites. Distal parts of the dendrites became immunoreactive after P12, and were strongly immunolabeled by P21. The present study may provide a structural basis to investigate the roles of 5-HT_2A receptors during the cerebellar development.     

维生素D3受体对hsp90β基因表达的调控作用

鉴于热休克蛋白９０β（ｈｓｐ９０β）基因内含子中含有维生素Ｄ３受体（ＶＤＲ）结合位点，为探讨作为核受体家族成员的ＶＤＲ是否对核受体特异分子伴侣的ｈｓｐ９０β基因的表达具有调控作用，我们开展了本项研究。分别将野生型ＶＤＲ、含Ｎ端（１～１３３氨基酸残基）及Ｃ端（２８１～４２７氨基酸残基）片段的ＶＤＲ突变体真核表达质粒与人ｈｓｐ９０β基因调控片段（－１０３９／＋１５３１）介导的氯霉素乙酰基转移酶（ＣＡＴ）报告基因质粒共转染Ｊｕｒｋａｔ细胞，检测正常及经热休克（４２℃，１ｈ）处理后细胞裂解液中ＣＡＴ活性。结果表明ＶＤＲＮ端增强、而Ｃ端抑制ｈｓｐ９０β的组成性表达；在热诱导条件下野生型ＶＤＲ对ｈｓｐ９０β的表达有一定的抑制作用，而其Ｃ端片段的抑制较强。为进一步研究ＶＤＲ对细胞内源性热休克基因表达的影响，我们用ＲＴＰＣＲ方法研究了ＶＤＲ的对细胞内ｈｓｐ９０β基因ｍＲＮＡ水平的影响，发现ＶＤＲ过表达对ｈｓｐ９０β的热诱导表达明显抑制。结果提示ＶＤＲ对ｈｓｐ９０β基因的组成性和热诱导表达的调控机制不同。     

Distribution of galanin-binding sites in the monkey and human telencephalon: preliminary observations

Summary Using X-ray film autoradiography the distribution of ¹²⁵I-galanin binding sites was studied in the forebrain of monkey and man. In the monkey a high density was found in all areas of the neocortex, especially layer 4, and in certain subfields in the hippocampal region. Also in the human brain high activity was seen in neocortex, mainly layer 6 and in hippocampal areas, as well as in amygdala, piriform cortex and hypothalamus. These results suggest that the 29-amino acid peptide galanin may be involved in the regulation of higher cortical functions in primates.     

Differential sensitivity to Arg side chain modification of IL-1β binding to type I and type II receptors

The central role of interleukin-1 (IL-1) in several disease processes, including fever and inflammation, makes the characterization of ligand-receptor interaction of prime importance.The role of arginine (Arg) side chains of hr-IL-1 in receptor recognition was studied by the modification of Arg residues with the specific reagent 1,2-cyclohexanedione. It was found that chemical modification of Arg residues decreased the binding potential of IL-1 to type I receptor dramatically (by 230-fold) while the affinity to type II receptor was reduced only moderately (by 10-fold), with an insignificant reduction of the dissociation rate.These studies suggest that intact Arg side chains of IL-1 may be necessary for high affinity binding to type I IL-1 receptor, but have less importance for the interaction of IL-1 with type II IL-1 receptor.This observation may be useful in the study of type II IL-1 receptor-mediated biological responses and design of receptor-subtype specific ligands as well.     

Monocyte chemotactic protein-3 (MCP3) interacts with multiple leukocyte receptors: binding and signaling of MCP3 through shared as well as unique receptors on monocytes and neutrophils

The diversity of monocyte chemotactic protein (MCP)3 target cell types, as well as the capacity of MCP3 to desensitize leukocyte responses to other CC chemokines, suggested that MCP3 may interact with multiple CC chemokine receptors. The purpose of this study is to establish how MCP3 binds and activates monocytes and neutrophils. We show that human monocytes exhibit high-affinity binding for ¹²⁵I-MCP3 with an estimated Kd of 1–3 nM and about 10000 binding sites/cell. The binding of ¹²⁵I-MCP3 to monocytes was progressively less well competed by CC chemokines macrophage inflammatory protein (MIP)lα (Kd = 5–10 nM), RANTES (Kd = 5–10 nM), MCP1 (monocyte chemoattractant and activating factor, or MCAF) (Kd = 60 nM) and MIP1β (Kd > 100 nM). On the other hand, unlabeled MCP3 displaced the binding of radiolabeled MIP1α, RANTES, MCP1 and MIP1β as effectively as the isologous CC chemokines. In agreement with the binding data, pretreatment of monocytes with MCP3 completely desensitized the calcium flux in response to MIP1α and RANTES. However, MIP1α and RANTES failed to desensitize the response of monocytes to MCP3. MCP3 and MCP1 partially desensitized each other's effects on monocytes. These binding and cross-desensitization results suggest that MCP3 binds and signals through other binding sites in addition to those shared with MIP1α, RANTES and MCP1. The unidirectional competition for MIP1β binding and signaling by MCP3 suggests the existence of an as-yet unidentified site for MCP3 shared with MIP1β. The existence of another unique binding site(s) for MCP3 was further shown by the failure of any of the other CC chemokines to compete effectively for MCP3 binding on neutrophils. MCP3 in our study was also the only human CC chemokine that consistently chemoattracted neutrophils. These results suggest that MCP3 is a ligand that can bind and activate a broad range of target cells through receptors shared by other CC chemokines as well as its own receptor.