Polysialic acid on SynCAM 1 in NG2 cells and on neuropilin‐2 in microglia is confined to intracellular pools that are rapidly depleted upon stimulation

NG2 cells comprise a heterogeneous precursor population but molecular markers distinguishing between the assumed NG2 cell subpopulations are lacking. Previously, we described that a subfraction of the synaptic cell adhesion molecule SynCAM 1 is modified with the glycan polysialic acid (polySia) in NG2 cells. As for its major carrier, the neural cell adhesion molecule NCAM, polySia attenuates SynCAM 1 adhesion. Functions, as well as cellular and subcellular distribution of polySia‐SynCAM 1 are elusive. Using murine glial cultures we now demonstrate that polySia‐SynCAM 1 is confined to the Golgi compartment of a subset of NG2 cells and transiently recruited to the cell surface in response to depolarization. NG2 cells with Golgi‐confined polySia were NCAM‐negative, but positive for markers of oligodendrocyte precursor cells (OPCs). Consistent with previous data on polySia‐SynCAM 1, polySia in Ncam^?/? NG2 cells was exclusively attached to N‐glycans and synthesized by ST8SIA2, one out of two mammalian polysialyltransferases. Unexpectedly, Golgi‐confined polySia was also detected in Ncam^?/? microglia, but this fraction resided on O‐glycans and was produced by the second polysialyltransferase, ST8SIA4, indicating the presence of yet another polySia carrier in microglia. Searching for this carrier, we identified polysialylated neuropilin‐2, so far only known from dendritic cells and exudate macrophages. Microglia activation by LPS, but not interleukin‐4, caused a transient translocation of Golgi‐localized polySia to the cell surface, resulting in complete depletion. Finally, NO‐production of LPS‐stimulated microglia was attenuated by addition of polySia suggesting that the observed loss of polySia‐neuropilin‐2 is involved in negative feedback regulation of pro‐inflammatory microglia polarization. GLIA 2015;63:1240–1255     

Polysialic acid expression is not necessary for motor neuron target selectivity

Introduction: Recovery after peripheral nerve lesions depends on guiding axons back to their targets. Polysialic acid upregulation by regrowing axons has been proposed recently as necessary for this target selectivity. Methods: We reexamined this proposition using a cross‐reinnervation model whereby axons from obturator motor neurons that do not upregulate polysialic acid regenerated into the distal femoral nerve. Our aim was to assess their target selectivity between pathways to muscle and skin. Results: After simple cross‐repair, obturator motor neurons showed no pathway preference, but the same repair with a shortened skin pathway resulted in selective targeting of these motor neurons to muscle by a polysialic acid–independent mechanism. Conclusion: The intrinsic molecular differences between motor neuron pools can be overcome by manipulation of their access to different peripheral nerve pathways such that obturator motor neurons preferentially project to a terminal nerve branch to muscle despite not upregulating the expression of polysialic acid. Muscle Nerve 47: 364–371, 2013     

Differential gene expression identifies subgroups of renal cell carcinoma

Clear cell carcinoma of the kidney, the most common subtype of renal cell cancer, displays different biological behavior in different patients. This heterogeneity cannot be recognized by light microscopy. In this study, gene expression in 16 clear cell renal cell carcinoma samples and 17 non-malignant tissue types comprising 539 samples was determined using oligonucleotide microarrays representing approximately 40,000 known genes and ESTs. Differences in gene expression were quantified as the fold change in gene expression between the various sets of samples. A set of genes was identified that was overexpressed in the renal cell carcinoma samples compared with the normal kidney samples. Principle component analysis of the set of renal cell carcinomas using this set of genes overexpressed in renal cell cancer revealed the existence of 2 major subgroups among the renal carcinomas. A series of principle component analyses of the set of renal cell carcinomas using different gene sets composed of genes involved in different metabolic pathways also revealed the same 2 major subgroups of the renal cell cancers. Eisen clustering using the same genes also revealed the same 2 major renal cell cancer subsets. Review of the pathology suggested that these 2 subgroups differed in pathologic grade. Genes differentially expressed between the 2 renal cell cancer subsets were identified. Examination of gene expression in each renal cell cancer subset and the pool of renal cell carcinoma samples compared with that in 17 different normal tissues revealed genes specifically overexpressed in renal cell cancer compared with these normal tissues. The authors conclude that gene expression patterns may be useful in helping to further classify subtypes of renal cell carcinoma that may have clinical significance. In addition, the genes identified as overexpressed in each set of clear cell renal cell carcinomas compared with normal tissues may represent useful targets for therapy.     

目的基因NCAM1在人神经管缺陷中的差异表达的研究

目的探究NCAM1在人类神经管畸形胚胎中的作用机制。方法提取NTDs组以及同周对照组胚胎脑组织，应用人类基因组U133Plus2．0芯片杂交，比较得出差异表达谱。所有差异表达基因按照功能分类。检测目的基因NCAM1的差异表达，并应用半定量RT—PCR方法以及免疫组化验证其mRNA及蛋白的改变。结果芯片显示出NTDs较正常对照组基因谱有较大的差异改变，总共检测到22209条基因的改变，其中2倍以上增高表达的74条，2倍以上降低表达的387条，分属于物质代谢、基因表达调控、信号转导、凋亡等途径。NCAM1呈21．8倍高表达。RT—PCR以及免疫组化也验证其mRNA及蛋白呈现高表达结果（P〈0．01）。结论人类神经管畸形是不同阶段发展的复杂事件，作为细胞表面粘附分子的NCAM1在神经管畸形的发生发展过程中起了重要的作用。     

The NCAM1 gene set is linked to depressive symptoms and their brain structural correlates in healthy individuals

Depressive symptoms exist on a continuum, the far end of which is found in depressive disorders. Utilizing the continuous spectrum of depressive symptoms may therefore contribute to the understanding of the biological underpinnings of depression. Gene set enrichment analysis (GSEA) is an important tool for the identification of gene groups linked to complex traits, and was applied in the present study on genome-wide association study (GWAS) data of depression scores and their brain-level structural correlates in healthy young individuals. On symptom level (i.e. depression scores), robust enrichment was identified for two gene sets: NCAM1 Interactions and Collagen Formation. Depression scores were also associated with decreased fractional anisotropy (FA) – a brain white matter property – within the forceps minor and the left superior temporal longitudinal fasciculus. Within each of these tracts, mean FA value of depression score-associated voxels was used as a phenotype in a subsequent GSEA. The NCAM1 Interactions gene set was significantly enriched in these tracts. By linking the NCAM1 Interactions gene set to depression scores and their structural brain correlates in healthy participants, the current study contributes to the understanding of the molecular underpinnings of depressive symptomatology.     

脑梗死后神经细胞黏附分子的动态变化及滋补肝肾复方复健片的干预效应

[目的]观察复健片在不同时间点对脑梗死大鼠脑组织神经细胞黏附分子表达的影响,探讨其促进神经功能恢复的作用机制.[方法] 240只Wistar大鼠随机分为正常对照组、假手术组、模型组和药物组共4个大组,并根据脑梗死病程每组又分为3、7、14、28、42 d共5个亚组,每个亚组动物数为12只.用改良的Longa EZ法制备大脑中动脉阻塞大鼠模型,药物组灌胃给予复健片水溶液,余各组分别灌胃给予同剂量的蒸馏水.用免疫组织化学法观察模型大鼠梗死周边区脑组织神经细胞黏附分子的表达.[结果]模型组大鼠脑梗死后脑内的神经细胞黏附分子(NCAM)表达逐渐增高,在28 d时达到高峰,后逐渐下降,其与正常对照组各时相比较有非常显著性差异(P<0.01).药物组在3 d时出现高表达,14 d时其表达达到高峰,持续至28 d时开始下降,药物组的NCAM表达与模型组同时间点比较有非常显著性差异(P<0.01).[结论]复健片可增加NCAM的表达,有助于轴突生长和靶向迁移,促进神经功能恢复.     

海人酸诱导颞叶癫癎大鼠海马中GAP-43和NCAM的表达变化以及托吡酯的干预作用

目的研究海人酸（KA）对大鼠海马中生长相关蛋白-43（GAP-43）和神经细胞粘附分子（NCAM）表达的影响，以及托吡酯（TPM）对其的干预作用。方法将48只大鼠随机分成生理盐水（NS）组、4mgKA组、10mgKA组和10mgKA＋TPM组（n=12），建立KA诱导颞叶癫癎大鼠模型和TPM干预模型，观察大鼠行为学改变，并通过RT-PCR和WesternBlot的方法测定各组大鼠海马中GAP-43及NCAM的mRNA和蛋白表达水平。结果大鼠建模成功；4mgKA组、10mgKA组大鼠GAP-43及NCAM的mRNA和蛋白表达水平明显高于NS组（P〈0．01），且10mgKA组高于4nagKA组（P〈0．01）；10mgKA＋TPM组大鼠的GAP-43和NCAM表达明显低于10mgKA组（P〈0．01）。结论KA能够诱导致癎大鼠海马GAP-43和NCAM表达上调，且与KA剂量有关，而TPM能够抑制KA诱导的GAP-43和NCAM的表达上调。     

Activation of CB1 cannabinoid receptors impairs memory consolidation and hippocampal polysialylated neural cell adhesion molecule expression in contextual fear conditioning

We investigated the role of CB1 receptors in hippocampal-dependent memory consolidation mediated by polysialylated neural cell adhesion molecule (PSA-NCAM) during contextual fear conditioning (CFC). The CB1 receptor agonist 3-(1,1-dimethylheptyl)-(-)-11-hydroxy-Δ⁸-tetrahydrocannabinol (HU-210) (0.1 mg/kg) was given immediately after training during the memory consolidation phase, and freezing behavior was measured 24 h after conditioning. Administration of HU-210 attenuated freezing behavior measured in CFC. Western blot analysis showed that CFC induced a decrease in the expression of NCAM-180, but did not change the level of NCAM-140 and increased PSA-NCAM expression measured 24 h after training in the rat hippocampus. HU-210 (0.1 mg/kg) injection did not affect the reduction in NCAM-180 levels induced by CFC, but it blocked the increase in PSA-NCAM expression. Since the dentate gyrus (DG) of the hippocampus is known to be involved in memory consolidation and expresses a high level of PSA-NCAM protein, we measured the effects of CFC and HU-210 administration on PSA-NCAM-immunoreactive (IR) cells in the DG. CFC caused an increase in the number of PSA-NCAM-IR cells in the DG, but not K_i-67- or doublecortin (DCX)-IR cells. This increase in PSA-NCAM-IR cells was abolished by HU-210 injection. Administration of the CB1 receptor antagonist N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM-251) (3 mg/kg immediately before HU-210) inhibited the effects of HU-210 on freezing behavior and PSA-NCAM expression in the DG. These results indicate that activation of CB1 receptors disturbs consolidation of fear memory in CFC, likely by affecting PSA-NCAM expression in the DG, which plays an important role in synaptic rearrangement during the formation of memory traces.     

托吡酯对癫痫大鼠认知功能及海马组织中NCAM的mRNA表达影响

目的研究托吡酯（TPM）对癫痫大鼠认知功能的影响以及使用TPM后大鼠海马组织中神经细胞粘附分子（NCAM）的mRNA表达变化。方法将大鼠随机分成生理盐水（NS）组、癫痫（EP）组、癫痫＋托吡酯治疗1周（TPM1周）组和癫痫＋托吡酯治疗4周（TPM4周）组,建立匹罗卡品诱导癫痫大鼠模型和TPM干预模型,观察大鼠的行为学改变,通过Morris水迷宫实验测试大鼠的学习记忆能力,并通过Real—TimePCR检测大鼠海马组织中NCAM的mRNA表达水平。结果EP组大鼠的逃避潜伏期大于NS组,原平台象限游泳时间百分比小于NS组,海马NCAM的mRNA表达水平高于NS组（P〈0．01）;TPM1周组和TPM4周组大鼠的逃避潜伏期大于EP组,原平台象限游泳时间百分比小于EP组,海马NCAM的mRNA表达水平低于EP组（P〈0.01）;TPM4周组大鼠的逃避潜伏期大于TPM1周组,原平台象限游泳时间百分比小于TPM1周组,海马NCAM的mRNA表达水平低于TPMI周组（P〈0.05）。结论大鼠产生癫痫持续状态后认知功能明显下降,海马NCAM的mRNA表达上调;使用大剂量TPM短期治疗后其认知功能进一步下降,海马NCAM的mRNA表达受抑,且下降与受抑程度与TPM的持续使用时间有关。     

Early nephron formation in the developing mouse kidney

This paper reports 3-dimensional confocal microscopy observations on how nephrogenic aggregates form from the NCAM- and Pax2-positive caps (4–5 cells deep) of condensed metanephric mesenchyme surrounding the duct tips of the mouse kidney. Aggregates of 6–8 cells are first seen at ∼E12.5–12.75 immediately proximal to this cap, closely abutting the duct surface. As the tip advances, NCAM expression is maintained in the cap but is otherwise restricted to aggregates whose cells rapidly epithelialise, forming tubules that invade the duct epithelium. Pax2 expression studies shows how the rind of nephrogenic blastemal cells forms: as duct tips extend towards the kidney surface, the associated Pax2+ cells form patches of cells on the kidney surface. These observations revise our knowledge of the timing and process of nephron initiation.