Assessment of Neural Cell Adhesion Molecule (NCAM) in Autistic Serum and Postmortem Brain

Studies have identified structural abnormalities in areas of the autistic brain, with a pattern suggesting that a neurodevelopmental anomaly took place. Neural cell adhesion molecule (NCAM), which is involved in development of the central nervous system, was previously shown to be decreased in the serum of autistic individuals. In the present study, we measured NCAM protein in the sera from controls, patients with autism, siblings of autistic patients, and individuals with other neurologic disorders, but found no significant differences. We also measured NCAM protein in autistic postmortem brain samples and found the longest isoform, NCAM-180, to be significantly decreased. In addition, we investigated the mRNA expression of NCAM in these brain samples using cDNA microarrays and RT-PCR. Results show that NCAM mRNA levels are not altered in autism.     

Low-level lead exposure attenuates the expression of three major isoforms of neural cell adhesion molecule

Toxic lead (Pb) exposure poses serious risks to human health, especially to children at developmental stages, even at low exposure levels. Neural cell adhesion molecule (NCAM) is considered to be a potential early target in the neurotoxicity of Pb due to its role in cell adhesion, neuronal migration, synaptic plasticity, and learning and memory. However, the effect of low-level Pb exposure on the specific expression of NCAM isoforms has not been reported. In the present study, we found that Pb could concentration-dependently (1-100 nM) inhibit the expression of three major NCAM isoforms (NCAM-180, -140, and -120) in primary cultured hippocampal neurons. Furthermore, it was verified that levels of all three major isoforms of NCAM were reduced by Pb exposure in human embryonic kidney (HEK)-293 cells transiently transfected with NCAM-120, -140, or -180 isoform cDNA constructs. In addition, low-level Pb exposure delayed the neurite outgrowth and reduced the survival rate of cultured hippocampal neurons at different time-points. Together, our results demonstrate that developmental low-level Pb exposure can attenuate the expression of all three major NCAM isoforms, which may contribute to the observed Pb-mediated neurotoxicity.     

Effects of neonatal stress on markers of synaptic plasticity in the hippocampus: Implications for spatial memory

Early stressful adverse situations may increase the vulnerability to cognitive deficits and psychiatric disorders, such as depression. Maternal separation (MS) has been used as an animal model to study changes in neurochemistry and behavior associated with exposure to early‐life stress. This study investigated the effects of neonatal stress (MS) on the expression of synaptic plasticity markers in the hippocampus and a purported relationship to cognitive processes. Spatial learning (Morris water maze) significantly increased the expression of total levels of the neural cell adhesion molecule (NCAM), as well as its three major isoforms (NCAM‐120, ‐140, and ‐180) both in the control and MS groups. Interestingly, these increases in NCAM expression after learning were lower in MS animals when compared with control rats. MS induced a significant decrease in total levels of NCAM, and specifically, in the NCAM‐140 isoform expression. In the hippocampus of MS rats there was a significant decrease in brain‐derived neurotrophic factor and synaptophysin mRNA densities. Cell proliferation, measured as BrdU‐positive cells, was also decreased in the dentate gyrus of MS rats. Altogether these results suggest that MS can alter normal brain development, providing a potential mechanism by which early environmental stressors may influence vulnerability to show cognitive impairments later in life. © 2009 Wiley‐Liss, Inc.     

Increased NCAM-180 immunoreactivity and maintenance of L1 immunoreactivity in injured optic fibers of adult mice

The injury related expression of two axon-growth promoting cell adhesion molecules (CAMs), NCAM-180 which is developmentally downregulated and L1 which is regionally restricted, were compared in optic fibers in the adult mouse. The neuron-specific isoform of NCAM (NCAM-180) is present at very low levels in unlesioned adult optic axons. At 7 days after nerve crush, immunoreactivity was strongly and uniformly increased in optic axons within the nerve and throughout retina. Reactivity in surviving axons had returned to control levels at 4 weeks. To induce regrowth of adult retinal ganglion cell axons retinal explants were placed in culture. Strong NCAM-180 staining was observed on these regenerating optic axons. The neuronal cell adhesion molecule L1 is restricted to retina and to the unmyelinated segment of the optic nerve near the optic nerve head in unlesioned adult animals. Following nerve crush, L1 immunoreactivity was retained within retina and proximal nerve and novel staining was detected in the more distal segment of the optic nerve up to the lesion site where it persisted for at least eight months. The capacity of optic fibers to show increased NCAM-180 immunoreactivity and maintain L1 expression after a lesion may explain why these fibers exhibit relatively good potential for regeneration.     

Neural cell adhesion molecule function is regulated by metalloproteinase-mediated ectodomain release

The neural cell adhesion molecule (NCAM) is involved in development of the nervous system, in brain plasticity associated with learning and memory, and in neuronal regeneration. NCAM regulates these processes by influencing cell adhesion, cell migration, and neurite outgrowth. NCAM activates intracellular signaling upon homophilic NCAM binding, and this is a prerequisite for NCAM-stimulated neurite outgrowth. NCAM is synthesized in three main membrane-bound isoforms, NCAM-120, NCAM-140, and NCAM-180. Soluble forms of NCAM in blood and cerebrospinal fluid have also been found, although the functional significance of these forms remains unclear. In this report, we demonstrate that NCAM can be released from primary hippocampal neurons in culture. The release was enhanced by application of ATP and inhibited by the metalloproteinase inhibitor BB-3103. ATP also induced metalloproteinase-dependent release of all three major NCAM isoforms from NCAM-transfected fibroblastoid L-cells. In this model system, the extracellular ATP-binding site of NCAM was shown not to be necessary for ATP-induced NCAM release. Furthermore, inhibition of serine, cysteine, and aspartic proteinases could not prevent ATP-induced down-regulation of NCAM in L-cells, suggesting that NCAM is cleaved directly by a metalloproteinase. Aggregation of hippocampal neurons in culture was increased in the presence of the metalloproteinase inhibitor GM 6001, consistent with a metalloproteinase-dependent shedding of NCAM occurring in these cells. Moreover, NCAM-dependent neurite outgrowth was significantly reduced by application of GM 6001. Taken together, these results suggest that membrane-bound NCAM can be cleaved extracellularly by a metalloproteinase and that metalloproteinase-dependent shedding of NCAM regulates NCAM-mediated neurite outgrowth.     

Increase in polysialyltransferase gene expression following LTP in adult rat dentate gyrus

Neural cell adhesion molecule (NCAM) is frequently associated with polysialic acid (PSA), and its function is highly dependent on this polysialylation. PSA‐NCAM plays an important role in synaptic plasticity in the hippocampus. STX and PST are the enzymes responsible for NCAM polysialylation. We investigated whether unilateral long‐term potentiation (LTP) induction in vivo, in adult rat dentate gyrus (DG), triggered NCAM polysialylation by STX and PST produced in the hippocampus. We found that levels of STX and PST mRNA increased strongly since the early stage of hippocampal LTP and remained high during the maintenance of DG‐LTP for 4 h. This rapid increase in polysialyltransferase gene expression occurred in both the hippocampi, probably resulting from bilateral LTP induction by strong unilateral HFS. Thus, LTP triggers interhemispheric molecular changes in the hippocampal network. This study is the first to describe the effects of LTP induction and maintenance on polysialyltransferases in vivo. Our findings suggest that hippocampal synaptic remodeling requires NCAM polysialylation. ©2010 Wiley Periodicals, Inc.     

电针对SAMP8小鼠海马NCAM和NF-κB表达的影响

目的 研究电针对阿尔茨海默病(AD)模型小鼠海马神经细胞黏附分子(NCAM)和核转录因子κB(NF-κB)的影响,从神经细胞黏附角度探讨电针治疗AD的作用机制.方法 快速老化模型小鼠(SAMP8)24只采用随机数字表法分为模型组、模型+针刺组(简称模针组),每组12只;抗快速老化模型小鼠(SAMR1)12只为空白组,每日一次电针模针组小鼠"百会"、"涌泉"穴,连续治疗21 d.应用免疫组织化学染色、原位杂交方法 检测各组小鼠海马组织NCAM、NF-κB蛋白及mRNA的表达.结果 与模型组比较,模针组小鼠NCAM(0.231±0.007)、NF-κB蛋白(0.367±0.012)及mRNA(0.528±0.016,0.308±0.001)阳性表达明显增强,差异有统计学意义(P<0.05).结论 电针可通过提高NF-κB的表达,诱导NCAM的合成,促进神经细胞黏附.     

Altered expression of neurotrophic factors in patients with major depression

There is an abundance of evidence suggesting the involvement of altered levels of expression of neurotrophic factors in the pathophysiology of neuropsychiatric disorders. Although postmortem brain studies have indicated the alterations in the expression levels of neurotrophic factors in mood disorder patients, it is unclear whether these changes are state- or trait-dependent. In this study, we examined the expression levels of the members of the glial cell line-derived neurotrophic factor (GDNF) family (GDNF, artemin (ARTN), neurturin, and persephin), brain-derived neurotrophic factor, nerve growth factor, neurotrophin-3 (NT-3), and neurotrophin-4 mRNAs by using quantitative real-time PCR method in peripheral blood cells of patients with major depressive and bipolar disorders in both a current depressive and a remissive states. Reduced expression levels of GDNF, ARTN, and NT-3 mRNAs were found in patients with major depressive disorder in a current depressive state, but not in a remissive state. Altered expressions of these mRNAs were not found in patients with bipolar disorder. Our results suggest that the changes in the expression levels of GDNF, ARTN, and NT-3 mRNAs might be state-dependent and associated with the pathophysiology of major depression.     

Neuroendocrine plasticity in GnRH release during rat estrous cycle: correlation with molecular markers of synaptic remodeling

Morphological changes in the gonadotropin releasing hormone (GnRH) neurons in the preoptic area (POA) and their terminals in the median eminence-arcuate (ME-ARC) region are reported to occur during ovarian cycle that may be involved in the GnRH release into the portal blood during preovulatory surge. However, the neuronal substrates participating in altered GnRH neuronal plasticity are poorly understood. The present study was designed to determine whether morphological changes occurring in the GnRH neuron cell bodies in the POA and their terminals in the ME-ARC region of hypothalamus with pulsatile GnRH release in cycling female rats are associated with expression of intrinsic determinants of neuronal plasticity. The plasticity markers studied are polysialylated neural cell adhesion molecule (PSA-NCAM), high molecular weight isoforms of NCAM, growth associated protein (GAP-43), glial fibrillary acidic protein (GFAP) and synaptophysin. Regularly cycling female rats were sacrificed at diestrous, i.e., when GnRH release is low, and at proestrous, i.e., when preovulatory GnRH surge occurs, using perfusion fixation method for immunohistochemical staining of GnRH cells. GnRH cell bodies and their terminals from the POA and ME-ARC region respectively, were localized using immunohistochemical technique in proestrous and diestrous phase of estrous cycle and our results showed a marked increase in the GnRH nerve terminals length and immunoreactivity in the ME-ARC region from proestrous phase rats as compared to diestrous rats. Immunoblot analyses of the POA and ME-ARC region of the hypothalamus revealed a significant increase in the content of PSA-NCAM, NCAM-180, NCAM-140, GAP-43 and synaptophysin from proestrous phase rats as compared to diestrous phase rats. The ME-ARC region showed more pronounced increase in the protein expression of these markers of neuronal plasticity as compared to the POA, whereas, hippocampal region did not show any significant change in the content of these markers showing specificity of the changes to the GnRH system. GFAP content was significantly decreased in the POA with a marginal increase in the GFAP level from the ME-ARC region. These results demonstrate the involvement of synaptic proteins in the dynamic plasticity of the ME-ARC region of hypothalamus, allowing GnRH nerve terminals to release the neurohormone into the pituitary portal blood on the day of proestrous.     

Systemic Cell Adhesion Molecules in Severe Mental Illness: Potential Role of Intercellular CAM-1 in Linking Peripheral and Neuroinflammation

BackgroundCell adhesion molecules (CAMs) orchestrate leukocyte trafficking and could link peripheral and neuroinflammation in patients with severe mental illness (SMI), by promoting inflammatory and immune-mediated responses and mediating signals across blood-brain barrier. We hypothesized that CAMs would be dysregulated in SMI and evaluated plasma levels of different vascular and neural CAMs. Dysregulated CAMs in plasma were further evaluated in vivo in leukocytes and brain tissue and in vitro in induced pluripotent stem cells.MethodsWe compared plasma soluble levels of different vascular (VCAM-1, ICAM-1, P-SEL) and neural (JAM-A, NCAD) CAMs in circulating leukocytes in a large SMI sample of schizophrenia (SCZ) spectrum disorder (n = 895) and affective disorder (n = 737) and healthy control participants (n = 1070) controlling for age, sex, body mass index, C-reactive protein, and freezer storage time. We also evaluated messenger RNA expression of ICAM1 and related genes encoding ICAM-1 receptors in leukocytes using microarray (n = 842) and in available RNA sequencing data from the CommonMind Consortium (CMC) in postmortem samples from the dorsolateral prefrontal cortex (n = 474). The regulation of soluble ICAM-1 in induced pluripotent stem cell–derived neurons and astrocytes was assessed in patients with SCZ and healthy control participants (n = 8 of each).ResultsOur major findings were 1) increased soluble ICAM-1 in patients with SMI compared with healthy control participants; 2) increased ITGB2 messenger RNA, encoding the beta chain of the ICAM-1 receptor, in circulating leukocytes from patients with SMI and increased prefrontal cortex messenger RNA expression of ICAM1 in SCZ; and 3) enhanced soluble ICAM-1 release in induced pluripotent stem cell–derived neurons from patients with SCZ.ConclusionsOur results support a systemic and cerebral dysregulation of soluble ICAM-1 expression in SMI and especially in patients with SCZ.     

Acute stress-induced impairment of spatial memory is associated with decreased expression of neural cell adhesion molecule in the hippocampus and prefrontal cortex.

BACKGROUND: There is an extensive literature describing how stress disturbs cognitive processing and can exacerbate psychiatric disorders. There is, however, an insufficient understanding of the molecular mechanisms involved in stress effects on brain and behavior. METHODS: Rats were given spatial memory training in a hippocampus-dependent water maze task. We investigated how a fear-provoking experience (predator exposure) would affect their spatial memory and neural cell adhesion molecule (NCAM) levels in the hippocampus, prefrontal cortex (PFC), amygdala, and cerebellum. RESULTS: Whereas the control (nonstress) group exhibited excellent memory for the hidden platform location in the water maze, the cat-exposed (stress) group exhibited a profound impairment of memory and a marked suppression of levels of the NCAM-180 isoform in the hippocampus. Predator stress produced a more global reduction of NCAM levels in the PFC but had no effect on NCAM levels in the amygdala and cerebellum. CONCLUSIONS: This work provides a novel perspective into dynamic and structure-specific changes in the molecular events involved in learning, memory, and stress. The selective suppression of NCAM-180 in the hippocampus and the more general suppression of NCAM in the PFC provide insight into the mechanisms underlying the great sensitivity of these two structures to be disturbed by stress.     

Quantitative proton magnetic resonance spectroscopy of the basal ganglia in patients with affective disorders

Proton magnetic resonance spectra were recorded from a subcortical region containing the basal ganglia in 40 patients with affective disorders (18 with bipolar disorder and 22 with major depression) and in 20 normal controls. The absolute concentration of the choline-containing compounds (Cho) in the patients with bipolar disorder in the depressive state was significantly higher than that in the normal controls. The patients with bipolar disorder had significantly higher levels of the Cho/creatine + phosphocreatine (Cr) and Cho/N-acetly-l-aspartate (NAA) peak ratio compared with the normal controls in both the depressive and euthymic states, with a tendency to higher levels in the depressive state. The Cho/NAA peak ratio was also significantly higher in the patients with major depression compared with the normal controls. These results suggest that the membrane phospholipid metabolism in the basal ganglia is altered in affective disorders. Received: 26 June 1997 / Accepted: 5 August 1997     

Cell adhesion molecules of the immunoglobulin superfamily in axonal regeneration and neural repair

Cell adhesion molecules (CAMs) play important roles in cell-cell and cell-extracellular matrix interactions in both mature and developing nervous system. During development, they are involved in cell migration, axon guidance, target recognition, and synapse formation; while in the mature nervous system, they maintain synaptic connections, cell-cell contacts, and neuron-glial interactions. Injuries to the nervous systems break the stable state of the tissues and the repair of damaged tissues and regeneration of axons require the participation of CAMs both as adhesion molecules and as signal transduction molecules. One group of the well-studied CAMs in the nervous system is the immunoglobulin superfamily including L1 and neural cell adhesion molecule (NCAM). This review will be focussed on the involvement of L1, NCAM, and polysialylated NCAM in neural repair and axon regeneration after nerve injury and their potential applications in the treatment of CNS injury.     

Expressions and possible roles of GDNF receptors in the developing dopaminergic neurons

Glial cell line-derived neurotrophic factor (GDNF) has an essential role in the survival and maturation of the dopaminergic (DA) neurons in the substantia nigra (SN) of mammalian embryonic brain. In addition to Ret, cell adhesion molecules (CAMs) were also proposed to function as transmembrane signaling receptors of GDNF. The present study was to investigate whether these transmembrane receptors of GDNF were correlated with the tyrosine hydroxylase (TH) expression of SN DA neurons during early developmental stage. RT-PCR and Western blot were performed to detect TH expression in SN of perinatal rats at mRNA and protein level respectively; meanwhile, Western blot was performed to detect the expressions of the transmembrane proteins including Ret, neural cell adhesion molecule-140 (NCAM-140), integrin β1 and N-cadherin. The results showed that TH mRNA expression was positively correlated with both Ret and N-cadherin protein, while there was no correlation with NCAM-140 and integrin β1; TH protein expression was correlated with all of these transmembrane molecules. These data suggested that the expression of either TH mRNA or TH protein was subject to the mediation of different transmembrane receptor combinations of GDNF.     

Cytoplasmic domain of NCAM 180 reduces NCAM-mediated neurite outgrowth

The neural cell adhesion molecule (NCAM) is one of the best-characterized cell adhesion molecules of the immunoglobulin superfamily. In the nervous system, NCAM is involved in cell migration, axon fasciculation and in neurite outgrowth. Neurite outgrowth is mediated by homophilic NCAM-NCAM interactions. Alternative splicing generates three major isoforms of NCAM differing in their intracellular portion. Two of them, NCAM 180 and NCAM 140, are transmembrane proteins with large intracellular domains. The present study is concerned with novel details of the intracellular domains of NCAM 140 and NCAM 180. We expressed these NCAM isoforms consisting only of the transmembrane and intracellular domains (without extracellular domains) in PC12 cells and elaborated their function in neurite outgrowth assays. Our data demonstrate that membrane-associated NCAM 180 interferes with neurite outgrowth, whereas membrane-associated NCAM 140 promotes neurite outgrowth.     

Variable alternative spliced exon (VASE)-containing and VASE-lacking neural cell adhesion molecule in the dorsal and ventral hippocampus of SAMP8 mice

The neural cell adhesion molecule (NCAM) is involved in the development and synaptic plasticity of the brain. Differential splicing of the variable alternative spliced exon (VASE) in the fourth immunoglobulin domain can dramatically change the functional properties of NCAM. This paper discusses our analysis of the levels of different expression of VASE-containing NCAM (NCAM-VASE(+)) and VASE-lacking NCAM (NCAM-VASE(-)) mRNAs in the dorsal and ventral hippocampus of senescence-accelerated mice (SAM). We further investigated the individual level of NCAM-VASE(+) and NCAM-VASE(-) in relation to the capacity for spatial learning and memory as assessed by a Morris water maze task. The results showed that the levels of both NCAM-VASE(+) and NCAM-VASE(-) were increased significantly in dorsal but not ventral hippocampus in aged SAMP8 mice. The mean latencies to find the hidden platform of the learning task on the last day were positively correlated with the levels of NCAM-VASE(+) in the dorsal hippocampus of SAMP8, which reveals that the mice with high levels of NCAM-VASE(+) have poor learning performances. These results suggest that the up-regulation of NCAM-VASE(+) could be involved in the impairments of spatial learning and memory.