Neural Cell Adhesion Molecule Research Articles

L1 Syndrome Prenatal Diagnosis Supplemented by Functional Analysis of One L1CAM Gene Missense Variant

L1 syndrome, a complex X-linked neurological disorder, is caused by mutations in the L1 cell adhesion molecule (L1CAM) gene. L1CAM molecule is a member of immunoglobulin (Ig) superfamily of neural cell adhesion molecules (CAMs), which plays a pivotal role in the developing nervous system. In this study, a L1CAM gene exonic missense variant (c.1108G > A, p.G370R) was identified in two induced fetuses (abnormal fetuses), who presented corpus callosum agenesis accompanied with hydrocephalus. Clinical data, published literature, online database, and bioinformatic analysis suggest that the single-nucleotide variant of L1CAM gene is a likely pathogenic mutation. In vitro assays were performed to evaluate the effects of this variant. Based on NSC-34/COS-7 cells transfected with wild-type (L1-WT) and mutated (L1-G370R) plasmids, the L1CAM gene exonic missense variant (c.1108G > A, p.G370R) reduced cell surface expression, induced partial endoplasmic reticulum retention, affected posttranslational modification, and reduced protein’s homophilic adhesive ability, but did not induce endoplasmic reticulum stress, which might probably associate with L1 syndrome. Finally, 35 isolated fetuses were screened for L1CAM gene variants by Sanger sequencing. These cases all prenatally suspected of corpus callosum agenesis accompanied with hydrocephalus, which may relate to L1 syndrome. Consequently, one L1CAM gene single missense variant (c.550C > T, p.R184W) was detected in one fetus. Our results provided evidence that the L1CAM gene missense variant (c.1108G > A, p.G370R) may relate to L1 syndrome. The findings of this study suggest a potential possibility of L1CAM gene screening for prenatal diagnoses for fetuses presented corpus callosum agenesis accompanied with hydrocephalus.

Alpha-synuclein as a biomarker in Parkinson's disease: focus on neural derived extracelluar vesicles.

Alpha-synuclein as a biomarker in Parkinson's disease: focus on neural derived extracelluar vesicles.

Protective effects of polysialic acids (PSAs) and its mimics on the nervous system after injury

Polysialic acid (PSA), a polymer of alpha-2,8 linked sialic acid residues, is a negatively charged macromolecular glycan mainly attached to neural cell adhesion molecules (NCAM). Studies have shown that PSA is not only essential for the development of normal brain circulation, but also for synaptic plasticity, learning and memory in adults. Although the occurrence, features, biosynthesis, and physiological roles of PSA and related effects on related diseases, including schizophrenia, bipolar disorder, neurodegenerative diseases and cancer, have been well reviewed, the important roles of PSA and its mimics in the regeneration of the nervous system following injury have not been well discussed. As a consequence, this article comprehensively reviews the effects of small organic compounds that simulate PSA, such as tegaserod and 5-nonyloxytryptamine (5-NOT), on the nervous system of mammals, suggesting that these mimetics may have tremendous therapeutic potential, especially for strategies aimed at tissue repair after injury of the nervous system.

Variation in muscle and neuromuscular junction morphology between atrophy-resistant and atrophy-prone muscles supports failed re-innervation in aging muscle atrophy.

In advanced age, there is an accelerated decline in skeletal muscle mass that appears to be secondary to repeated cycles of denervation-reinnervation and eventually, failed reinnervation. However, whether variation in reinnervation capacity explains why some muscles are less vulnerable to age-related atrophy has not been addressed. In this study we examined changes in neuromuscular junction (NMJ) morphology, fiber cross-sectional area (CSA) and fiber type, accumulation of severely atrophied myofibers, and expression of a marker of denervation in four muscles that exhibit differences in the degree of age-related atrophy and which span the extremes of fiber type composition in 8 mo old (8M) and 34 mo old (34M) male Fischer 344 Brown Norway F1 hybrid rats. Aging muscle atrophy was most pronounced in the fast twitch gastrocnemius (Gas; 25%) and similar between extensor digitorum longus (EDL) and slow-twitch soleus (Sol) muscle (14-15%), whereas the slow-twitch adductor longus (AL) increased in mass by 21% between 8M and 34M (P<0.05 for all). Only the Sol exhibited significant alterations in fiber type with aging, and there was a decrease in fiber CSA in the Gas, EDL, and Sol (P<0.05) with aging that was not seen in the AL. Muscles that atrophied had an increased fraction of severely atrophic myofibers (P<0.05), but this was not observed in the AL. The Gas and EDL both demonstrated a similar degree of age-related remodeling of pre- and post-synaptic NMJ components. On the other hand, pre- and post-synaptic morphology underwent greater changes with aging in the AL, and many of these same morphological variables were already greater in the Sol vs AL at 8M, suggesting the Sol had already undergone substantial remodeling and may be nearing its adaptive limits. Consistent with this idea, analysis of NMJ morphology in Sol from 3M rats exhibited similar values as 8M AL, and the Sol demonstrated greater expression of the denervation marker neural cell adhesion molecule (NCAM) compared to the AL at 34M. Collectively, our results are consistent with NMJ remodeling capacity being finite with aging and that maintained remodeling potential confers atrophy protection in aging skeletal muscle by reducing the degree of persistent denervation.

INSM1, a Novel Biomarker for Detection of Neuroendocrine Neoplasms: Cytopathologists' View.

Background: Insulinoma-associated protein 1 (INSM1) has been considered as a novel immunostain for neuroendocrine tumors (NETs) and is hypothesized to be more reliable than first-generation NET biomarkers, such as CGA (chromogranin A), SYP (synaptophysin) and CD56 (neural cell adhesion molecule). In this review, we summarize existing literature on INSM1′s reliability as an immunostain for detection of various NETs, its results in comparison to first-generation NET biomarkers, and its expression in both non-NETs and benign tissues/cells on cytology specimens (cell blocks/smears).

Evidence for Quantum Chemical Effects in Receptor-Ligand Binding Between Integrin and Collagen Fragments - A Computational Investigation With an Impact on Tissue Repair, Neurooncolgy and Glycobiology.

The collagen-integrin interactions are mediated by the doubly charged Mg2+ cation. In nature this cation seems to have the optimal binding strength to stabilize this complex. It is essential that the binding is not too weak so that the complex becomes unstable, however, it is also of importance that the ligand-receptor binding is still labile enough so that the ligand can separate from the receptor in a suited environment. In the case of crystal growing for experimentally useful integrin-collagen fragment complexes it turned out that Co2+ cations are ideal mediators to form stable complexes for such experiments. Although, one can argue that Co2+ is in this context an artificial cation, however, it is now of special interest to test the impact of this cation in cell-culture experiments focusing on integrin-ligand interactions. In order to examine, in particular, the role cobalt ions we have studied a Co2+ based model system using quantum chemical calculations. Thereby, we have shown that hybrid and long-range corrected functional, which are approximations provide already a sufficient level of accuracy. It is of interest to study a potential impact of cations on the binding of collagen-fragments including collagens from various species because different integrins have numerous biological functions (e.g. Integrin – NCAM (Neural cell adhesion molecule) interactions) and are triggered by intact and degraded collagen fragments. Since integrin–carbohydrate interactions play a key role when bio-medical problems such as tumor cell adhesion and virus-host cell infections have to be addressed on a sub-molecular level it is essential to understand the interactions with heavy-metal ions also at the sub-atomic level. Our findings open new routes, especially, in the fields of tissue repair and neuro-oncology for example for cell-culture experiments with different ions. Since Co2+ ions seem to bind stronger to integrin than Mg2+ ions it should be feasible to exchange these cations in suited tumor tissues although different cations are present in other metalloproteins which are active in such tissues. Various staining methods can be applied to document the interactions of integrins with carbohydrate chains and other target structures. Thereby, it is possible to study a potential impact of these interactions on biological functions. It was therefore necessary to figure out first which histological–glycobiological experimental settings of tumor cells are suited for our purpose. Since the interactions of several metalloproteins (integrin, ADAM12) with polysialic acid and the HNK-1 epitope play a crucial role in tumor tissues selected staining methods are proper tools to obtain essential information about the impact of the metal ions under study.

Farnesol Ameliorates Demyelinating Phenotype in a Cellular and Animal Model of Charcot-Marie-Tooth Disease Type 1A.

Charcot-Marie-Tooth disease (CMT) is a genetically heterogeneous disease affecting the peripheral nervous system that is caused by either the demyelination of Schwann cells or degeneration of the peripheral axon. Currently, there are no treatment options to improve the degeneration of peripheral nerves in CMT patients. In this research, we assessed the potency of farnesol for improving the demyelinating phenotype using an animal model of CMT type 1A. In vitro treatment with farnesol facilitated myelin gene expression and ameliorated the myelination defect caused by PMP22 overexpression, the major causative gene in CMT. In vivo administration of farnesol enhanced the peripheral neuropathic phenotype, as shown by rotarod performance in a mouse model of CMT1A. Electrophysiologically, farnesol-administered CMT1A mice exhibited increased motor nerve conduction velocity and compound muscle action potential compared with control mice. The number and diameter of myelinated axons were also increased by farnesol treatment. The expression level of myelin protein zero (MPZ) was increased, while that of the demyelination marker, neural cell adhesion molecule (NCAM), was reduced by farnesol administration. These data imply that farnesol is efficacious in ameliorating the demyelinating phenotype of CMT, and further elucidation of the underlying mechanisms of farnesol’s effect on myelination might provide a potent therapeutic strategy for the demyelinating type of CMT.

DNMT3B regulates proliferation of A549 cells through the microRNA-152-3p/NCAM1 pathway.

The purpose of the present study was to examine the epigenetic mechanism by which microRNA (miR)-152-3p regulates proliferation in non-small cell lung cancer A549 cells via neural cell adhesion molecule 1 (NCAM1). Bisulfite sequencing PCR (BSP), the gold standard for methylation detection, uses bisulfite-treated DNA to determine its pattern of methylation. Treatment of DNA with bisulfite converts cytosine residues to uracil, but leaves 5-methylcytosine residues unaffected. It was conducted and demonstrated a relatively high level of methylation in the miR-152-3p promoter region. Chromatin immunoprecipitation was combined with PCR to detect the binding of DNA methyltransferase 3B (DNMT3B) protein to miR-152-3p, which tends to occur in the core region of the miR-152-3p gene in A549 cells. Luciferase assay identified NCAM1 as the target gene of miR-152-3p. MTT, colony formation and Transwell assays indicated that miR-152-3p could decrease cell proliferation and invasion and in addition to reducing the expression level of NCAM1. Overexpression of NCAM1 could attenuate the effect of miR-152-3p. DNMT3B knockdown decreased the proliferative ability of A549 cells and increased the expression of miR-152-3p, while decreased that of NCAM1. After treatment with miR-152-3p inhibitor, these effects were attenuated and the NCAM1 expression level was upregulated. The results indicated that miR-152-3p may suppress the proliferation of A549 cells by downregulating NCAM1. In addition, DNMT3B negatively regulated the expression of miR-152-3p via modulation of the methylation level in the miR-152-3p core region, thus mediating the proliferation of lung tumor cells.

MiR-23a suppression accelerates functional decline in the rNLS8 mouse model of TDP-43 proteinopathy

Skeletal muscle dysfunction may contribute to the progression and severity of amyotrophic lateral sclerosis (ALS). In the present study, we characterized the skeletal muscle pathophysiology in an inducible transgenic mouse model (rNLS8) that develops a TAR-DNA binding protein (TDP-43) proteinopathy and ALS-like neuropathology and disease progression; representative of >90% of all familial and sporadic ALS cases. As we previously observed elevated levels of miR-23a in skeletal muscle of patients with familial and sporadic ALS, we also investigated the effect of miR-23a suppression on skeletal muscle pathophysiology and disease severity in rNLS8 mice. Five weeks after disease onset TDP-43 protein accumulation was observed in tibialis anterior (TA), quadriceps (QUAD) and diaphragm muscle lysates and associated with skeletal muscle atrophy. In the TA muscle TDP-43 was detected in muscle fibres that appeared atrophied and angular in appearance and that also contained β-amyloid aggregates. These fibres were also positive for neural cell adhesion molecule (NCAM), but not embryonic myosin heavy chain (eMHC), indicating TDP-43/ β-amyloid localization in denervated muscle fibres. There was an upregulation of genes associated with myogenesis and NMJ degeneration and a decrease in the MURF1 atrophy-related protein in skeletal muscle. Suppression of miR-23a impaired rotarod performance and grip strength and accelerated body weight loss during early stages of disease progression. This was associated with increased AchRα mRNA expression and decreased protein levels of PGC-1α. The TDP-43 proteinopathy-induced impairment of whole body and skeletal muscle functional performance is associated with muscle wasting and elevated myogenic and NMJ stress markers. Suppressing miR-23a in the rNLS8 mouse model of ALS contributes to an early acceleration of disease progression as measured by decline in motor function.

The expression of neural cell adhesion molecule and the microenvironment of pituitary neuroendocrine tumours.

The neural cell adhesion molecule (NCAM) has previously been studied in pituitary neuroendocrine tumours (PitNETs), but its role in tumour biology and aggressiveness remains controversial, and its relationship with the tumour microenvironment remains unknown. We aimed to characterise NCAM expression in PitNETs, to correlate this with clinico-pathological features, and to assess the role of various microenvironment components on NCAM expression. NCAM and immune cells were investigated by immunohistochemistry in 16human non-functioning-PitNETs (NF-PitNETs) and eight somatotrophinomas, including macrophages (CD68, CD163, HLA-DR), cytotoxic (CD8) and T helper (CD4) lymphocytes, regulatory T cells (FOXP3), B cells (CD20), and neutrophils (neutrophil elastase). Five normal pituitaries were included for comparison. The cytokine secretome from these PitNETs and from PitNET-derived tumour-associated fibroblasts (TAFs) were assessed on culture supernatants using a multiplex immunoassay panel. There were no significant NCAM expression differences between PitNETs and normal pituitary, and no difference between types of pituitary tumours (NF-PitNETs vs. somatotrophinomas). There was no association between NCAM expression and different clinico-pathological features, including cavernous sinus invasion and Ki-67, nor with serum hormone levels. NCAM immunoreactivity correlated negatively with PitNET-derived CXCL10 (rho=-0.417; p=.042) and CX3CL1 (rho=-0.423; p=.040) levels. NCAM immunoreactivity was negatively correlated with TAF-derived fibroblast growth factor (FGF)-2 (rho=-0.632; p=.009), but not with other TAF-derived cytokines. Within the PitNET cohort, there were no correlations between NCAM immunoreactivity and immune infiltrates or ratios, although, within NF-PitNETs, NCAM expression was higher in tumours with more FOXP3+ cells. NCAM expression does not differ between PitNETs and normal pituitary, and does not appear to relate to tumour invasiveness or proliferation. However, our data suggest a possible role for cytokines in the modulation of NCAM expression in PitNETs, particularly CXCL10, CX3CL1 and FGF-2, but not for immune cell infiltrates.

Development and validation of a prognostic nomogram model for Chinese patients with primary small cell carcinoma of the esophagus.

BACKGROUNDPrimary small cell carcinoma of the esophagus (PSCE) is a highly invasive malignant tumor with a poor prognosis compared with esophageal squamous cell carcinoma. Due to the limited samples size and the short follow-up time, there are few reports on elucidating the prognosis of PSCE, especially on the establishment and validation of a survival prediction nomogram model covering general information, pathological factors and specific biological proteins of PSCE patients.AIMTo establish an effective nomogram to predict the overall survival (OS) probability for PSCE patients in China.METHODSThe nomogram was based on a retrospective study of 256 PSCE patients. Univariate analysis and multivariate Cox proportional hazards regression analysis were used to examine the prognostic factors associated with PSCE, and establish the model for predicting 1-, 3-, and 5-year OS based on the Akaike information criterion. Discrimination and validation were assessed by the concordance index (C-index) and calibration curve and decision curve analysis (DCA). Histology type, age, tumor invasion depth, lymph node invasion, detectable metastasis, chromogranin A, and neuronal cell adhesion molecule 56 were integrated into the model.RESULTSThe C-index was prognostically superior to the 7th tumor node metastasis (TNM) staging in the primary cohort [0.659 (95%CI: 0.607-0.712) vs 0.591 (95%CI: 0.517-0.666), P = 0.033] and in the validation cohort [0.700 (95%CI: 0.622-0.778) vs 0.605 (95%CI: 0.490-0.721), P = 0.041]. Good calibration curves were observed for the prediction probabilities of 1-, 3-, and 5-year OS in both cohorts. DCA analysis showed that our nomogram model had a higher overall net benefit compared to the 7th TNM staging .CONCLUSIONOur nomogram can be used to predict the survival probability of PSCE patients, which can help clinicians to make individualized survival predictions.

Re-Expression of Poly/Oligo-Sialylated Adhesion Molecules on the Surface of Tumor Cells Disrupts Their Interaction with Immune-Effector Cells and Contributes to Pathophysiological Immune Escape.

Simple SummaryThe immune system consists of various mechanisms contributing to the battle against cancer cells or hazardous pathogens. However, in cancer progression the immune system is often unable to eliminate neoplastic cells, although immune effector cells infiltrate the tumor environment. The current paper reviews the causes for this immune escape. Specifically, we comprehensively discuss various roles of sialic acids in this process. Specific focus is given to adhesion molecules re-expressed on membranes of tumor cells, which carry oligo- and polysialic acid chains. These carrier proteins loaded with sialic acids direct the interaction between immune effector and tumor cells and thus prevent the “kiss of death” between the latter and the former cells. We also discuss strategies suited to reduce the degree of sialic acid presence on the surface of tumor cells, which can be the basis for future therapeutic intervention.Glycans linked to surface proteins are the most complex biological macromolecules that play an active role in various cellular mechanisms. This diversity is the basis of cell–cell interaction and communication, cell growth, cell migration, as well as co-stimulatory or inhibitory signaling. Our review describes the importance of neuraminic acid and its derivatives as recognition elements, which are located at the outermost positions of carbohydrate chains linked to specific glycoproteins or glycolipids. Tumor cells, especially from solid tumors, mask themselves by re-expression of hypersialylated neural cell adhesion molecule (NCAM), neuropilin-2 (NRP-2), or synaptic cell adhesion molecule 1 (SynCAM 1) in order to protect themselves against the cytotoxic attack of the also highly sialylated immune effector cells. More particularly, we focus on α-2,8-linked polysialic acid chains, which characterize carrier glycoproteins such as NCAM, NRP-2, or SynCam-1. This characteristic property correlates with an aggressive clinical phenotype and endows them with multiple roles in biological processes that underlie all steps of cancer progression, including regulation of cell–cell and/or cell–extracellular matrix interactions, as well as increased proliferation, migration, reduced apoptosis rate of tumor cells, angiogenesis, and metastasis. Specifically, re-expression of poly/oligo-sialylated adhesion molecules on the surface of tumor cells disrupts their interaction with immune-effector cells and contributes to pathophysiological immune escape. Further, sialylated glycoproteins induce immunoregulatory cytokines and growth factors through interactions with sialic acid-binding immunoglobulin-like lectins. We describe the processes, which modulate the interaction between sialylated carrier glycoproteins and their ligands, and illustrate that sialic acids could be targets of novel therapeutic strategies for treatment of cancer and immune diseases.

Galectins and Their Ligand Glycoconjugates in the Central Nervous System Under Physiological and Pathological Conditions.

Galectins are β-galactoside-binding lectins consisting of 15 members in mammals. Galectin-1,-3,-4,-8, and -9 are predominantly expressed in the central nervous system (CNS) and regulate various physiological and pathological events. This review summarizes the current knowledge of the cellular expression and role of galectins in the CNS, and discusses their functions in neurite outgrowth, myelination, and neural stem/progenitor cell niches, as well as in ischemic/hypoxic/traumatic injuries and neurodegenerative diseases such as multiple sclerosis. Galectins are expressed in both neurons and glial cells. Galectin-1 is mainly expressed in motoneurons, whereas galectin-3-positive neurons are broadly distributed throughout the brain, especially in the hypothalamus, indicating its function in the regulation of homeostasis, stress response, and the endocrine/autonomic system. Astrocytes predominantly contain galectin-1, and galectin-3 and−9 are upregulated along with its activation. Activated, but not resting, microglia contain galectin-3, supporting its phagocytic activity. Galectin-1,−3, and -4 are characteristically expressed during oligodendrocyte differentiation. Galectin-3 from microglia promotes oligodendrocyte differentiation and myelination, while galectin-1 and axonal galectin-4 suppress its differentiation and myelination. Galectin-1- and- 3-positive cells are involved in neural stem cell niche formation in the subventricular zone and hippocampal dentate gyrus, and the migration of newly generated neurons and glial cells to the olfactory bulb or damaged lesions. In neurodegenerative diseases, galectin-1,-8, and -9 have neuroprotective and anti-inflammatory activities. Galectin-3 facilitates pro-inflammatory action; however, it also plays an important role during the recovery period. Several ligand glycoconjugates have been identified so far such as laminin, integrins, neural cell adhesion molecule L1, sulfatide, neuropilin-1/plexinA4 receptor complex, triggering receptor on myeloid cells 2, and T cell immunoglobulin and mucin domain. N-glycan branching on lymphocytes and oligodendroglial progenitors mediated by β1,6-N-acetylglucosaminyltransferase V (Mgat5/GnTV) influences galectin-binding, modulating inflammatory responses and remyelination in neurodegenerative diseases. De-sulfated galactosaminoglycans such as keratan sulfate are potential ligands for galectins, especially galectin-3, regulating neural regeneration. Galectins have multitudinous functions depending on cell type and context as well as post-translational modifications, including oxidization, phosphorylation, S-nitrosylation, and cleavage, but there should be certain rules in the expression patterns of galectins and their ligand glycoconjugates, possibly related to glucose metabolism in cells.

Analysis of Global and Local DNA Methylation Patterns in Blood Samples of Patients With Autism Spectrum Disorder.

The goal of this investigation was to determine whether there are alterations in DNA methylation patterns in children with autism spectrum disorder (ASD).Material and Methods: Controlled prospective observational case-control study. Within the ASD group, children were sub-classified based on the presence (AMR subgroup) or absence (ANMR subgroup) of neurodevelopmental regression during the first 2 years of life. We analyzed the global levels of DNA methylation, reflected in LINE-1, and the local DNA methylation pattern in two candidate genes, Neural Cell Adhesion Molecule (NCAM1) and Nerve Growth Factor (NGF) that, according to our previous studies, might be associated to an increased risk for ASD. For this purpose, we utilized blood samples from pediatric patients with ASD (n = 53) and their corresponding controls (n = 45).Results: We observed a slight decrease in methylation levels of LINE-1 in the ASD group, compared to the control group. One of the CpG in LINE-1 (GenBank accession no.X58075, nucleotide position 329) was the main responsible for such reduction, highly significant in the ASD subgroup of children with AMR (p < 0.05). Furthermore, we detected higher NCAM1 methylation levels in ASD children, compared to healthy children (p < 0.001). The data, moreover, showed higher NGF methylation levels in the AMR subgroup, compared to the control group and the ANMR subgroup. These results are consistent with our prior study, in which lower plasma levels of NCAM1 and higher levels of NGF were found in the ANMR subgroup, compared to the subgroup that comprised neurotypically developing children.Conclusions: We have provided new clues about the epigenetic changes that occur in ASD, and suggest two potential epigenetic biomarkers that would facilitate the diagnosis of the disorder. We similarly present with evidence of a clear differentiation in DNA methylation between the ASD subgroups, with or without mental regression.

Role of regulatory C‐terminal motifs in synaptic confinement of LRRTM2

Leucine Rich Repeat Transmembrane proteins (LRRTMs) are neuronal cell adhesion molecules involved in synapse development and plasticity. LRRTM2 is the most synaptogenic isoform of the family, and its expression is strongly restricted to excitatory synapses in mature neurons. However, the mechanisms by which LRRTM2 is trafficked and stabilized at synapses remain unknown. Here, we examine the role of LRRTM2 intracellular domain on its membrane expression and stabilization at excitatory synapses, using a knock-down strategy combined to single molecule tracking and super-resolution dSTORM microscopy. We show that LRRTM2 operates an important shift in mobility after synaptogenesis in hippocampal neurons. Knock-down of LRRTM2 during synapse formation reduced excitatory synapse density in mature neurons. Deletion of LRRTM2 C-terminal domain abolished the compartmentalization of LRRTM2 in dendrites and disrupted its synaptic enrichment. Furtheremore, we show that LRRTM2 diffusion is increased in the absence of its intracellular domain, and that the protein is more dispersed at synapses. Surprisingly, LRRTM2 confinement at synapses was strongly dependent on a YxxC motif in the C-terminal domain, but was independent of the PDZ-like binding motif ECEV. Finally, the nanoscale organization of LRRTM2 at excitatory synapses depended on its C-terminal domain, with involvement of both the PDZ-binding and YxxC motifs. Altogether, these results demonstrate that LRRTM2 trafficking and enrichment at excitatory synapses are dependent on its intracellular domain.

Molecular Mechanism of Inhibition of Polysialyltransferase Domain (PSTD) by Heparin.

The polysialic acid (polySia) is a unique carbohydrate polymer produced on the surface of Neuronal Cell Adhesion Molecule (NCAM) in a number of cancer cells, and strongly correlates with the migration and invasion of tumor cells and with aggressive, metastatic disease and poor clinical prognosis in the clinic. Its synthesis is catalyzed by two polysialyltransferases (polySTs), ST8SiaIV (PST) and ST8SiaII (STX). Selective inhibition of polySTs, therefore, presents a therapeutic opportunity to inhibit tumor invasion and metastasis due to NCAM polysialylation. It has been proposed that NCAM polysialylation could be inhibited by two types of heparin inhibitors, low molecular heparin (LMWH) and heparin tetrasaccharide (DP4). This review summarizes how the interactions between Polysialyltransferase Domain (PSTD) in ST8SiaIV and CMP-Sia, and between the PSTD and polySia take place, and how these interactions are inhibited by LMWH and DP4. Our NMR studies indicate that LMWH is a more effective inhibitor than DP4 for inhibition of NCAM polysialylation. The NMR identification of heparin-binding sites in the PSTD may provide insight into the design of specific inhibitors of polysialylation.

Extracellular Matrix Expression in Human Induced Pluripotent Stem Cell-Derived Optic Vesicles

Background: Human tissue/organ development is a complex, highly orchestrated process, regulated in part by the surrounding extracellular matrix (ECM). Every complex tissue, including the retina, has a unique ECM configuration that plays a critical role in cellular differentiation, adhesion, migration, and maturation. Aim: To characterize ECM expression of human induced pluripotent stem cell-derived optic vesicles (iPSC-OVs). Methods: A 3- dimensional (3D) in vitro suspension culture system was used to direct differentiation of human induced pluripotent stem cells (iPSCs) into optic vesicles (OVs). Stepwise differentiation of iPSCs into retinal progenitor cells was confirmed by sequential expression of OTX2, SOX1, SIX6, LHX2, PAX6, and CHX10. Expression of ECM genes in iPSC-derived OVs was analyzed by RT2 ProfilerTM PCR Array, whereas immunofluorescence staining was performed to detect ECM proteins in the OVs. Results: A number of cell adhesion molecules (CAMs) previously reported to be abundantly expressed in iPSCs such as E-cadherin, Intercellular adhesion molecule-1 (ICAM1), Integrin-α L, Integrin-α M, Integrin-α 6 were downregulated while neural and retina specific CAMs including neural cell adhesion molecule 1 (NCAM1), neural plakophilin-related armadillo repeat protein (NPRAP), Integrin-α 1 and Integrin-α 4 were upregulated. Several glycoproteins that have been reported to play key roles during retinogenesis, namely CD44, Tenascin C, Tenascin R, Neurocan, Neuroglycan C, Delta 2 Catenin, Vitronectin, and Reelin were also present. Conclusion: We have identified an array of ECM proteins that were expressed during retinogenesis. Further characterization of these proteins will lead to a better understanding of retinal development.

Influence of IGF-I serum concentration on muscular regeneration capacity in patients with sarcopenia

BackgroundPrevious research has described a neuroprotective effect of IGF-I, supporting neuronal survival, axon growth and proliferation of muscle cells. Therefore, the association between IGF-I concentration, muscle histology and electrophysiological markers in a cohort of patients with sarcopenia dares investigation.MethodsMeasurement of serum concentrations of IGF-I and binding partners, electromyographic measurements with the MUNIX (Motor Unit Number Index) method and muscle biopsies were performed in 31 patients with acute hip fracture older age 60 years. Molecular markers for denervation (neural cell adhesion molecule NCAM) and proliferation markers (Ki67) were assessed by immunofluorescence staining of muscle biopsy tissue. Skeletal muscle mass by bioelectrical impedance analysis and hand-grip strength were measured to assess sarcopenia status according to EWGSOP2 criteria.ResultsThirty-one patients (20 women) with a mean age of 80.6 ± 7.4 years were included. Concentrations of IGF-I and its binding partners were significantly associated with sarcopenia (ß = − 0.360; p = 0.047) and MUNIX (ß = 0.512; p = 0.005). Further, expression of NCAM (ß = 0.380; p = 0.039) and Ki67 (ß = 0.424; p = 0.022) showed significant associations to IGF-I concentrations.ConclusionsThe findings suggest a pathogenetic role of IGF-I in sarcopenia based on muscle denervation.

Nerve bundle formation during the promotion of peripheral nerve regeneration: collagen VI-neural cell adhesion molecule 1 interaction.

The formation of nerve bundles, which is partially regulated by neural cell adhesion molecule 1 (NCAM1), is important for neural network organization during peripheral nerve regeneration. However, little is known about how the extracellular matrix (ECM) microenvironment affects this process. Here, we seeded dorsal root ganglion tissue blocks on different ECM substrates of peripheral nerve ECM-derived matrix-gel, Matrigel, laminin 521, collagen I, and collagen IV, and observed well-aligned axon bundles growing in the peripheral nerve ECM-derived environment. We confirmed that NCAM1 is necessary but not sufficient to trigger this phenomenon. A protein interaction assay identified collagen VI as an extracellular partner of NCAM1 in the regulation of axonal fasciculation. Collagen VI interacted with NCAM1 by directly binding to the FNIII domain, thereby increasing the stability of NCAM1 at the axolemma. Our in vivo experiments on a rat sciatic nerve defect model also demonstrated orderly nerve bundle regeneration with improved projection accuracy and functional recovery after treatment with 10 mg/mL Matrigel and 20 μg/mL collagen VI. These findings suggest that the collagen VI-NCAM1 pathway plays a regulatory role in nerve bundle formation. This study was approved by the Animal Ethics Committee of Guangzhou Medical University (approval No. GY2019048) on April 30, 2019.

Transcriptome Analysis Reveals an Inhibitory Effect of Dihydrotestosterone-Treated 2D- and 3D-Cultured Dermal Papilla Cells on Hair Follicle Growth.

Dermal papillae are a target of androgen action in patients with androgenic alopecia, where androgen acts on the epidermis of hair follicles in a paracrine manner. To mimic the complexity of the dermal papilla microenvironment, a better culture model of human dermal papilla cells (DPCs) is needed. Therefore, we evaluated the inhibitory effect of dihydrotestosterone (DHT)-treated two-dimensional (2D)- and 3D-cultured DPCs on hair follicle growth. 2D- and 3D-cultured DPC proliferation was inhibited after co-culturing with outer root sheath (ORS) cells under DHT treatment. Moreover, gene expression levels of β-catenin and neural cell adhesion molecules were significantly decreased and those of cleaved caspase-3 significantly increased in 2D- and 3D-cultured DPCs with increasing DHT concentrations. ORS cell proliferation also significantly increased after co-culturing in the control-3D model compared with the control-2D model. Ki67 downregulation and cleaved caspase-3 upregulation in DHT-treated 2D and 3D groups significantly inhibited ORS cell proliferation. Sequencing showed an increase in the expression of genes related to extracellular matrix synthesis in the 3D model group. Additionally, the top 10 hub genes were identified, and the expression of nine chemokine-related genes in DHT-treated DPCs was found to be significantly increased. We also identified the interactions between transcription factor (TF) genes and microRNAs (miRNAs) with hub genes and the TF–miRNA coregulatory network. Overall, the findings indicate that 3D-cultured DPCs are more representative of in vivo conditions than 2D-cultured DPCs and contribute to our understanding of the molecular mechanisms underlying androgen-induced alopecia.