Neuronal Cell Adhesion Research Articles

Structural insights into selective interaction between type IIa receptor protein tyrosine phosphatases and Liprin-\u03b1

Synapse formation is induced by transsynaptic interaction of neuronal cell-adhesion molecules termed synaptic organizers. Type IIa receptor protein tyrosine phosphatases (IIa RPTPs) function as presynaptic organizers. The cytoplasmic domain of IIa RPTPs consists of two phosphatase domains, and the membrane-distal one (D2) is essential for synapse formation. Liprin-α, which is an active zone protein critical for synapse formation, interacts with D2 via its C-terminal domain composed of three tandem sterile alpha motifs (tSAM). Structural mechanisms of this critical interaction for synapse formation remain elusive. Here, we report the crystal structure of the complex between mouse PTPδ D2 and Liprin-α3 tSAM at 1.91 Å resolution. PTPδ D2 interacts with the N-terminal helix and the first and second SAMs (SAM1 and SAM2, respectively) of Liprin-α3. Structure-based mutational analyses in vitro and in cellulo demonstrate that the interactions with Liprin-α SAM1 and SAM2 are essential for the binding and synaptogenic activity.

Alternative Splicing of Nrcam Gene in Dorsal Root Ganglion Contributes to Neuropathic Pain

NrCAM, a neuronal cell adhesion molecule in the L1 family of the immunoglobulin superfamily, is subjected to extensively alternative splicing and involved in neural development and some disorders. The aim of this study was to explore the role of Nrcam mRNA alternative splicing in neuropathic pain. A next generation RNA sequencing analysis of dorsal root ganglions (DRGs) showed the differential expression of two splicing variants of Nrcam, Nrcam+10 and Nrcam−10, in the injured DRG after the fourth lumbar spinal nerve ligation (SNL) in mice. SNL increased the exon 10 insertion, resulting in an increase in the amount of Nrcam+10 and a corresponding decrease in the level of Nrcam−10 in the injured DRG. An antisense oligonucleotide (ASO) that specifically targeted exon 10 of Nrcam gene (Nrcam ASO) repressed RNA expression of Nrcam+10 and increased RNA expression of Nrcam−10 in in vitro DRG cell culture. Either DRG microinjection or intrathecal injection of Nrcam ASO attenuated SNL-induced the development of mechanical allodynia, thermal hyperalgesia, or cold allodynia. Nrcam ASO also relieved SNL- or chronic compression of DRG (CCD)-induced the maintenance of pain hypersensitivities in male and female mice. PerspectiveWe conclude that the relative levels of alternatively spliced Nrcam variants are critical for neuropathic pain genesis. Targeting Nrcam alternative splicing via the antisense oligonucleotides may be a new potential avenue in neuropathic pain management.

The impact of ademetionine and ipidacrine/phenibut on the NCAM distribution and behavior in the rat model of drug-induced liver injury

Introduction. Recently, more attention is being paid to the drug-induced liver injury (DILI) as a consequence of the tuberculos is treatment and the need for new medicine is emphasized. The use of isoniazid and rifampicin has a potentiating effect, which increases the risk of substancial liver damage. In turn, systemic accumulation of toxic metabolites leads to negative changes in various organs, including the brain. It causes an imbalance in biochemical and neurophysiological processes in the brain, ultimately giving the onset to the development of hepatic encephalopathy. Aim. The effects of rifampicin and isoniazid on the central nervous system have not been studied before and we aimed to evaluate the impact these two substances have on the neuronal cell adhesion molecules (NCAM) distribution and animal behavior in the rat model of DILI. Material and methods. The 24 male Wistar rats, weighing 180-220 g were used for the experiment and divided to the groups (n=6): 1 – control; 2 – rats with experimental DILI; 3 – rats with DILI plus the intravenous infusion of S-adenosyl-L-methionine at a dose of 35 mg/kg; 4 – rats with DILI plus a fixed combination of ipidacrine hydrochloride at a dose 1 mg/kg body weight and phenibut at a dose 60 mg/kg body weight daily for the last 14 days of the experiment. All experimental procedures were carried out in the accordance with the principles outlined in the current Guide to the Care and Use of Experimental Animals. The locomotor and research activities were studied in the open field test. The activity of aspartate aminotransferase (AST, ЕС 2.6.1.1) and alanine aminotransferase (ALT, ЕС 2.6.1.2) in the serum of rats were tested to confirm the liver damage. The quantitative analyses of soluble and membrane forms of NCAM were performed with ELISA. The ANOVA followed by a Tukey post-hoc test was used to assess statistical differences between groups. Results. Our investigation in the open field test revealed a significant decrease in the locomotor and research activity of rats after 28 days of rifampicin and isoniazid administration. The recovery of investigated parameters was observed in groups of animals treated with ademetionine (AD group) or combination of ipidacrine and phenibut (IP/PB group). We also observed that changes in rats’ behavior were consistent with alterations of the NCAM levels in the thalamus and hippocampus. Thus, the level of membrane NCAM was significantly decreased under DILI in both investigated brain regions (thalamus and hippocampus), while both AD and IP/PB treatments restored membrane NCAM levels towards those observed in the control group at least in the hippocampus. Conclusion. Obtained data suggests that both ademetionine and combinated drug containing ipidacrine and phenibut possesses neuroprotective properties and could prevent the decline in synaptic plasticity under antitubercular therapy.

CHL1 and NrCAM are Primarily Expressed in Low Grade Pediatric Neuroblastoma.

BackgroundNeural cell adhesion molecules like close homolog of L1 protein (CHL1) and neuronal glia related cell adhesion molecule (NrCAM) play an important role in development and regeneration of the central nervous system. However, they are also associated with cancerogenesis and progression in adult malignancies, thus gain increasing importance in cancer research. We therefore studied the expression of CHL1 and NrCAM according to the course of disease in children with neuroblastoma.MethodsCHL1 and NrCAM expression levels were histologically assessed by tissue microarrays from surgically resected neuroblastoma specimens of 56 children. Expression of both markers was correlated to demographics as well as clinical data including metastatic dissemination and survival.ResultsCHL1 was expressed in 9% and NrCAM in 51% of neuroblastoma tissue samples. Expression of CHL1 was higher in patients with low Hughes grade 1a/b (p=0.01). NrCAM was more often detected in patients with a low International Staging System (INSS) score 1/2 (p=0.04).ConclusionCHL1 and NrCAM expression was associated with low-grade pediatric neuroblastoma. These adhesion molecules may play a role in early tumor development of neuroblastoma.

Selective Regulation of Neurons, Glial Cells, and Neural Stem/Precursor Cells by Poly(allylguanidine)-Coated Surfaces.

Poly(allylguanidine) (PAG) was synthesized and characterized as a polycationic coating material for culturing neurons, glial cells, and neural stem/precursor cells (NSPCs) to apply PAG for neural tissue engineering. For comparison, poly-d-lysine (PDL), the golden benchmark of the neuron cell culture system, was also used in this study. When PAG was subjected to a mixed culture of neurons and glial cells, cell adhesion and neurite extension of neuronal cells were clearly observed but only few glial cells could be found alongside the neurons. Compared to PDL, the significantly lower density of the glial fibrillary acidic protein-positive cells implied that PAG suppressed the glial cell development. Likewise, PAG was demonstrated to dominate the differentiation of NSPCs principally into neurons. To investigate whether the different effects of PAG and PDL on neuron and glial cell behaviors resulted from the difference of guanidinium cations and ammonium cations, poly-l-arginine (PLA) was included and compared in this study. Similar to PDL, PLA supported high neuron and glial cell viability simultaneously. Consequently, glial cell growth and viability restrained on PAG was not only affected by the side-chain guanidino groups but also by the backbone structure property. The absence of the peptide structure in the backbone of PAG and the conformation of coated PAG on tissue culture polystyrene possibly determined the polycationic biomaterial to limit the growth of glial cells.

Neural cell adhesion molecule (NCAM) and polysialic acid–NCAM expression in developing ICR mice

Abstract Background Coexpression of polysialic acid (PSA)–neuronal cell adhesion molecule (NCAM) with immature neuronal markers is used to indicate the developmental state of neurons generated in the subgranular zone (SGZ) of adult hippocampus. PSA–NCAM is highly expressed throughout the embryonic and juvenile mammalian brain, but heavily downregulated in adult brain. Objective To visualize the expression profiles of NCAM/PSA–NCAM in the dentate SGZ of the hippocampus in developing ICR mice. Methods Cellular distribution, expression, and developmental changes of NCAM/PSA–NCAM were studied in ICR mice at embryonic age 17 days (E17); and similarly at postnatal ages P3, P5, and P7. The SGZ was studied using NCAM and PSA–NCAM immunoreactive staining with or without hematoxylin counterstaining. Western blotting was used to confirm protein expression levels. Results NCAM expression was localized to the surface of neurons and glia and was higher in postnatal mice than it was in embryonic mice. PSA–NCAM was found in cytoplasm and membrane of neural cells, more densely staining in the dentate SGZ at P7, but no staining found at E17. Western blotting of brain tissues also showed expression of both PSA–NCAM and NCAM increased significantly at P5 and P7 compared with expression at P3. Conclusions Progressive increase in NCAM expression occurs in the SGZ during embryogenic and postnatal development. PSA–NCAM was not expressed in embryonic ICR mice, but was increased after birth and highly localized in the SGZ at P7. This NCAM expression pattern in the developing brain indicating structural plasticity and neurogenesis may be useful for study of brain repair.

Profile of neuronal exosomes in HIV cognitive impairment exposes sex differences

To use plasma neuron-derived exosomes (NDEs) to detect proteins that diagnose HIV-associated neurocognitive disorders (HAND). To compare NDE cargo from HAND with Alzheimer's disease. Eighty plasma samples were assayed including men (n = 29) and women (n = 51) with and without HAND. Plasma NDEs were isolated by immunoadsorption with neuron specific L1 cell adhesion molecule antibody. NDE proteins were quantified by ELISA and proximity extension assays for 184 targets. Neuronal enrichment of NDE was confirmed with elevated synaptophysin and normalized to the exosomal marker, apoptosis-linked gene-2-interacting protein X (ALIX). NDE from men and women had significant divergent results. High mobility group box 1 and neurofilament light were significantly increased in NDE from cognitively impaired men and were unchanged in women. NDE from HIV+ men had decreased p-T181-tau, a marker increased in Alzheimer's disease, compared with no difference in women. NDE amyloid beta was not increased in cognitive impairment. Proximity extension assays analysis showed 25 proteins were differentially expressed in HIV infection alone. Seven proteins identified asymptomatic and mild cognitive impairment in HIV+ women. NDE from women had significantly decreased cathepsin S, total tau, neuronal cell adhesion molecule and contactin 5 in mild impairment. Twelve proteins were increased in NDE from cognitively impaired men, including carboxypeptidase M, cadherin 3, colony stimulating factor 2 receptor alpha subunit and mesencephalic astrocyte-derived neurotropic factor. NDE proteins differ in HIV infection alone and cognitive impairment between men and women suggesting mechanistic sex differences associated with HAND. Several NDE targets are different from that reported for Alzheimer's disease.

Prognostic Markers Identification in Glioma by Gene Expression Profile Analysis.

This study aimed to explore more gene markers associated with glioma or its prognosis. The glioma-related RNAseq data from the Gene Expression Omnibus database and The Cancer Genome Atlas dataset in UCSC Xena database were downloaded. There was a total of 971 tumor samples and 102 normal samples in the 2 datasets. The differentially expressed genes (DEGs) data between tumor and normal samples were analyzed, on which were then performed function and pathway enrichment analyses. Pearson correlation coefficient between DEGs was calculated to construct the coexpression network. Finally, prognostic genes were screened. A total of 634 upregulated and 769 downregulated DEGs were identified between tumor and control groups. These DEGs were significantly involved in 15 upregulated pathways, such as p53 signaling pathway, and 16 downregulated pathways, such as neuroactive ligand-receptor interaction, and cell adhesion molecules. In the coexpression network, pseudouridine synthase 7 (PUS7), EFR3 homolog B (EFR3B), and neuronal cell adhesion molecule (NRCAM) had the top three highest degrees. Additionally, 17 prognostic genes were selected, such as thrombospondin-1 (THBS1), caspase-8 (CASP8), glutamate ionotropic receptor AMPA type subunit 2 (GRIA2), GRIA4, and ADCYAP receptor type I (ADCYAP1R1). Pathways of p53 signaling pathway and neuroactive ligand-receptor interaction may play important roles in glioma progression. PUS7, EFR3B, and NRCAM may be potential biomarkers of glioma. THBS1, CASP8, GRIA2, GRIA4, and ADCYAP1R1 may serve as prognostic markers in glioma.

The Inhibition of Polysialyltranseferase ST8SiaIV Through Heparin Binding to Polysialyltransferase Domain (PSTD)

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. Heparin has been found to be effective in inhibiting the ST8Sia IV activity, but no clear molecular rationale. It has been found that polysialyltransferase domain (PSTD) in polyST plays a significant role in influencing polyST activity, and thus it is critical for NCAM polysialylation based on the previous studies. To determine whether the three different types of heparin (unfractionated hepain (UFH), low molecular heparin (LMWH) and heparin tetrasaccharide (DP4)) is bound to the PSTD; and if so, what are the critical residues of the PSTD for these binding complexes? Fluorescence quenching analysis, the Circular Dichroism (CD) spectroscopy, and NMR spectroscopy were used to determine and analyze interactions of PSTD-UFH, PSTD-LMWH, and PSTD-DP4. The fluorescence quenching analysis indicates that the PSTD-UFH binding is the strongest and the PSTD-DP4 binding is the weakest among these three types of the binding; the CD spectra showed that mainly the PSTD-heparin interactions caused a reduction in signal intensity but not marked decrease in α-helix content; the NMR data of the PSTD-DP4 and the PSTDLMWH interactions showed that the different types of heparin shared 12 common binding sites at N247, V251, R252, T253, S257, R265, Y267, W268, L269, V273, I275, and K276, which were mainly distributed in the long α-helix of the PSTD and the short 3-residue loop of the C-terminal PSTD. In addition, three residues K246, K250 and A254 were bound to the LMWH, but not to DP4. This suggests that the PSTD-LMWH binding is stronger than the PSTD-DP4 binding, and the LMWH is a more effective inhibitor than DP4. The findings in the present study demonstrate that PSTD domain is a potential target of heparin and may provide new insights into the molecular rationale of heparin-inhibiting NCAM polysialylation.

Abstract 241: An efficient cell-based assay for quantification of cellular polysialic acid in neuroblastoma

Abstract Introduction Polysialic acid (polySia) decorates the surface of NCAM (neuronal cell adhesion molecule) on neuroendocrine tumors, notably neuroblastoma and small cell lung cancer, and is strongly associated with poor prognosis and aggressive disease in patients in the clinic [1]. PolySia modulates tumor cell-cell and cell-matrix adhesion, migration, invasion and metastasis. SiRNA knockdown of polysialyltransferase (polyST) ST8SiaII, the enzyme primarily responsible for polySia synthesis in tumors, abrogates tumor cell migration and invasion. PolyST is a selective and largely unexplored therapeutic target for neuroblastoma dissemination [1]. Methods and Results We describe the development of a cell-based assay that quantifies the formation of polySia on the cell surface of neuroblastoma cells. This is a sensitive assay that detects the polySia that is released after pH adjustment, organic precipitation and acid hydrolysis. PolySia was first separated from cell lysate by mild acid hydrolysis and acetone precipitation. It was then purified by ethanol precipitation. We further analysed the role of lactonisation of polySia during organic precipitation. The purified polySia is further hydrolysed into sialic acid monomers, followed by DMB labelling and RPLC-fluorescence analysis. This method was validated by analysis of polySia in C6-ST8SiaII cells, following treatment with Endo-NF in a various concentrations. This method proved to be useful to assess polySia changes after treatment of cells with novel polyST inhibitors. The effect of lactonisation of polySia during organic precipitation was also investigated. It was found that lactonised polySia was mainly soluble in 90% acetone/90% ethanol, while natural polySia (non-lactonised) can be precipitated by ethanol in the presence salts. Based on the different solubility of polySia, a cost-efficient assay was designed to purify polySia released from cells with a low level of non-polySia-derived sialic acid contamination before further acid hydrolysis. With this method we quantified the different levels of cell-surface polySia-derived sialic acid between polySia-positive and polySia-negative cell lines. Furthermore, we successfully validated this method by Endo-NF treatment in C6-ST8SiaII cells: the EC50 of Endo-NF digestion of polySia in C6-ST8SiaII cells was approximately 5.4 pM. The assay has been successfully utilised to evaluate novel polyST inhibitors in vitro. [1] Falconer, R.A. et al., Curr. Cancer Drug Targets, 2012, 12, 925-939; [2] Al-Saraireh YMJ et al., PLoS ONE, 2013, 8:e73366. Citation Format: Xiaoxiao Guo, Francis Mprah Barnieh, Jodie Malcolm, Amanda D Race, Goreti Ribeiro Morais, Steven D Shnyder, Paul M Loadman, Laurence H Patterson, Robert A. Falconer. An efficient cell-based assay for quantification of cellular polysialic acid in neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 241.

Abstract 209: Metastatic colonization in the perivascular niche: A mechanotransduction perspective

Abstract Metastases are responsible for majority cancer related deaths. Disseminated tumor cells (DTCs) gain a diverse array of metastatic traits in order to adapt to and survive within different microenvironments, making them very difficult to therapeutically target. Remarkably, regardless of the secondary organ, DTCs survive and thrive in perivascular niches. Using xenograft and syngeneic models of metastasis in mouse, we found that upon extravasation, neuronal cell adhesion molecule L1 (L1CAM) expressed by DTCs engages the vascular basal lamina in order to amplify integrin β1 and integrin linked kinase (ILK) signaling in DTCs. ILK promotes actin polymerization for cell spreading and subsequent activation of mechanotransduction effector transcription factors YAP and MRTF. We found that activation of YAP and MRTF coincides with DTCs ability to dislodge resident pericytes from the perivascular niche and is an essential step in the metastatic colonization regardless of dormancy state. Therefore, these results provided us a unifying molecular mechanism that governs cancer progression from metastatic seeding to overt colonization. Ongoing studies will determine how mechanotransduction and pericyte-DTC interactions can be manipulated to prevent metastatic colonization by potentiating the immune response and exposing their biophysical vulnerabilities. Citation Format: Ekrem Emrah Er, Maria Tello-Lafoz, Jing Hu, Morgan Huse, Joan Massagué. Metastatic colonization in the perivascular niche: A mechanotransduction perspective [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 209.

Graphene oxide substrates with N-cadherin stimulates neuronal growth and intracellular transport

Intracellular transport is fundamental for neuronal function and development and is dependent on the formation of stable actin filaments. N-cadherin, a cell–cell adhesion protein, is actively involved in neuronal growth and actin cytoskeleton organization. Various groups have explored how neurons behaved on substrates engineered to present N-cadherin; however, few efforts have been made to examine how these surfaces modulate neuronal intracellular transport. To address this issue, we assembled a substrate to which recombinant N-cadherin molecules are physiosorbed using graphene oxide (GO) or reduced graphene oxide (rGO). N-cadherin physisorbed on GO and rGO led to a substantial enhancement of intracellular mass transport along neurites relative to N-cadherin on glass, due to increased neuronal adhesion, neurite extensions, dendritic arborization and glial cell adhesion. This study will be broadly useful for recreating active neural tissues in vitro and for improving our understanding of the development, homeostasis, and physiology of neurons. Statement of SignificanceIntracellular transport of proteins and chemical cues is extremely important for culturing neurons in vitro, as they replenish materials within and facilitate communication between neurons. Various studies have shown that intracellular transport is dependent on the formation of stable actin filaments. However, the extent to which cadherin-mediated cell–cell adhesion modulates intracellular transport is not heavily explored. In this study, N-cadherin was adsorbed onto graphene oxide-based substrates to understand the role of cadherin at a molecular level and the intracellular transport within cells was examined using spatial light interference microscopy. As such, the results of this study will serve to better understand and harness the role of cell–cell adhesion in neuron development and regeneration.

Fabrication of a Biocompatible Liquid Crystal Graphene Oxide-Gold Nanorods Electro- and Photoactive Interface for Cell Stimulation.

For decades, electrode-tissue interfaces are pursued to establish electrical stimulation as a reliable means to control neuronal cells behavior. However, spreading of electrical currents in tissues limits its spatial precision. Thus, optical cues, such as near-infrared (NIR) light, are explored as alternatives. Presently, NIR stimulation requires higher energy input than electrical methods despite introduction of light absorbers, e.g., gold nanoparticles. As potential solution, NIR and electrical costimulation are proposed but with limited interfaces capable of sustaining this stimulation technique. Here, a novel electroactive nanocomposite with photoactive properties in the NIR range is constructed by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysulfosuccinimide sodium (EDC)/NHS conjugation of liquid crystal graphene oxide (LCGO) to protein-coated gold nanorods (AuNR). The liquid crystal graphene oxide-gold nanorod nanocomposite (LCGO-AuNR) is fabricated into a hydrophilic electrode-coating via drop-casting, making it appropriate for versatile electrode-tissue interface fabrication. UV-vis spectrophotometry results demonstrate that LCGO-AuNR presents an absorbance peak at 798 nm (NIR range). Cyclic voltammetry measurements further confirm its electroactive capacitive properties. Furthermore, LCGO-AuNR coating supports cell adhesion, proliferation, and differentiation of NG108-15 neuronal cells. This biocompatible interface is anticipated, with ideal electrical and optical properties for NIR and electrical costimulation, to enable further development of the technique for energy-efficient and precise neuronal cell modulation.

NrCAM is a marker for substrate‐selective activation of ADAM10 in Alzheimer's disease

The metalloprotease ADAM10 is a drug target in Alzheimer's disease, where it cleaves the amyloid precursor protein (APP) and lowers amyloid‐beta. Yet, ADAM10 has additional substrates, which may cause mechanism‐based side effects upon therapeutic ADAM10 activation. However, they may also serve—in addition to APP—as biomarkers to monitor ADAM10 activity in patients and to develop APP‐selective ADAM10 activators. Our study demonstrates that one such substrate is the neuronal cell adhesion protein NrCAM. ADAM10 controlled NrCAM surface levels and regulated neurite outgrowth in vitro in an NrCAM‐dependent manner. However, ADAM10 cleavage of NrCAM, in contrast to APP, was not stimulated by the ADAM10 activator acitretin, suggesting that substrate‐selective ADAM10 activation may be feasible. Indeed, a whole proteome analysis of human CSF from a phase II clinical trial showed that acitretin, which enhanced APP cleavage by ADAM10, spared most other ADAM10 substrates in brain, including NrCAM. Taken together, this study demonstrates an NrCAM‐dependent function for ADAM10 in neurite outgrowth and reveals that a substrate‐selective, therapeutic ADAM10 activation is possible and may be monitored with NrCAM.

Expression of the heparin-binding growth factors Midkine and pleiotrophin during ocular development

Midkine (MDK) and Pleiotrophin (PTN) belong to a group of heparin-binding growth factors that has been shown to have pleiotropic functions in various biological processes during development and disease. Development of the vertebrate eye is a multistep process that involves coordinated interactions between neuronal and non-neuronal cells, but very little is known about the potential function of MDK and PTN in these processes. In this study, we demonstrate by section in situ hybridization, the spatiotemporal expression of MDK and PTN during ocular development in chick and mouse. We show that MDK and PTN are expressed in dynamic patterns that overlap in a few non-neuronal tissues in the anterior eye and in neuronal cell layers of the posterior eye. We show that the expression patterns of MDK and PTN are only conserved in a few tissues in chick and mouse but they overlap with the expression of some of their receptors LRP1, RPTPZ, ALK, NOTCH2, ITGβ1, SDC1, and SDC3. The dynamic expression patterns of MDK, PTN and their receptors suggest that they function together during the multistep process of ocular development and they may play important roles in cell proliferation, adhesion, and migration of neuronal and non-neuronal cells.

PTPRD: neurobiology, genetics, and initial pharmacology of a pleiotropic contributor to brain phenotypes.

Receptor-type protein tyrosine phosphatase, receptor type D (PTPRD) has likely roles as a neuronal cell adhesion molecule and synaptic specifier. Interest in its neurobiology and genomics has been stimulated by results from human genetics and mouse models for phenotypes related to addiction, restless leg syndrome, neurofibrillary pathology in Alzheimer's disease, cognitive impairment/intellectual disability, mood lability, and obsessive-compulsive disorder. We review PTPRD's discovery, gene family, candidate homomeric and heteromeric binding partners, phosphatase activities, brain distribution, human genetic associations with nervous system phenotypes, and mouse model data relevant to these phenotypes. We discuss the recently reported discovery of the first small molecule inhibitor of PTPRD phosphatase, the identification of its addiction-related effects, and the implications of these findings for the PTPRD-associated brain phenotypes. In assembling PTPRD neurobiology, human genetics, and mouse genetic and pharmacological datasets, we provide a compelling picture of the roles played by PTPRD, its variation, and its potential as a target for novel therapeutics.

Plasma neuronal exosomes serve as biomarkers of cognitive impairment in HIV infection and Alzheimer's disease.

Plasma neuronal exosomes serve as biomarkers of cognitive impairment in HIV infection and Alzheimer's disease.

SU116 - ASSOCIATION BETWEEN THE NEURONAL CELL ADHESION MOLECULE (NrCAM) GENE VARIANTS, WORKING MEMORY AND COGNITION IN METHAMPHETAMINE ABUSE

Background The recent development of molecular genetic techniques is promoting the study of the genetic basis of drug abuse. It is possible that personality factor mediates intermediately in the genetic contributions to drug abuse. Classical genetic studies document strong complex genetic contributions to abuse of multiple addictive substances, to mnemonic processes that are likely to include those involved in substance dependence, and to the volumes of brain gray matter in regions that are likely to contribute to mnemonic/cognitive and to addictive processes. [1] Several lines of evidence support a role of the neuronal cell adhesion molecule (NrCAM) in polysubstance abuse vulnerability in humans, as well as in the rewarding effects of abused drugs in animals. [2] This gene, which encodes a receptor involved in nervous system development, is expressed in the central nervous system and located in the 7q region. Polymorphisms in NrCAM have been reported to be associated with addiction susceptibility and with substance abuse, implicating NrCAM in reward circuitry. Methods Thirty-seven male methamphetamine abusers(age=43.3±7.8) and thirty unrelated controls (16 males, 14 females; age=59.8±10.4) were enrolled into the study from the Bugok National Hospital drug abuse clinic for one year. They underwent a blood sample collection for NRCAM gene variants genotyping. Wizard Genomic DNA Purification Kit was used for extracting DNA from patient's blood collected in EDTA tubes. 10 single nucleotide polymorphisms(SNPs) in NrCAM gene were selected for variant analysis. We evaluated working memory dimensions with Hinting Task(HT), Eye Task (ET), Picture Sequencing (PS), Emotion Attribution Task (EAT), Emotion Recognition 40 (ER40), Wisconsin Card Sorting Test (WCST). We assessed cognitive dimensions with Iowa Gambling Task (IGT) and Game of Dice Tast (GDT). Results The distribution of one NRCAM gene SNP genotypes and alleles significantly differed between patients and controls.(rs1990162; p=0.0418) Five NRCAM gene SNP genotypes and alleles were associated with some working memory dimensions in the patients.(rs2142325, rs381318, rs1269621, rs2072546, rs1269634) Of those SNP rs1269634 was associated with three working memory dimensions comprehensively.(PS-M, EAT, WCST-PE) Two NRCAM gene SNP genotypes and alleles were associated with some cognitive dimensions in the patients.(rs2142325, rs722519) Both SNPs were associated with four cognitive dimensions comprehensively.(IGT-A, B, C, D, B3, B5) Only one SNPs(rs2142325) was associated with both working memory and cognitive dimensions. Discussion These findings support the idea that NRCAM gene polymorphisms could play a part in the genetic susceptibility to methamphetamine abuse, and it seems to be involved in predisposing addictive patients to a more disturbed addictive behavior influencing on each working memory and cognitive factor. Considering the important role of the NRCAM gene in brain development, our results therefore replicate that the NRCAM gene is one of the strong candidate genes for drug abuse.

Enhanced Adhesion of Fish Ovarian Germline Stem Cells on Solid Surfaces by Mussel-Inspired Polymer Coating.

Development of advanced cell culture methods has gained increasing attention because it allows for efficient genetic engineering and precise regulation of animal reproduction on a cellular basis. Numerous studies have attempted to develop an advanced cell culture method. Previous studies have altered cell culture media and pretreated culture plates with functional molecules. Among them, a mussel-inspired polymer coating has been extensively utilized owing to its wide applicability. For instance, adhesion of human embryonic stem cells and neuronal cells on solid surfaces has been improved. Despite the excellent capability of the mussel-inspired polymer coating, most studies have primarily focused on mammalian cells. However, the efficacy of these coatings on the adhesion of other cell lines is yet unclear. This study aimed to assess the potential of the mussel-inspired polymer coating in the regulation of the adhesion of fish ovarian germline stem cells on solid surfaces. Solid surfaces were coated by polydopamine and poly-L-lysine, and the effect of the coatings on cellular behaviors was investigated.

Neuronal cell adhesion molecule regulating neural systems underlying addiction.

AimsThe human NRCAM gene is associated with polysubstance use. Nrcam knockout mice do not acquire a preference for addictive substances. We aimed to elucidate the role of Nrcam in specific neural circuits underlying congenital preference for substances and the acquisition of addiction.MethodsWe analyzed gene expression patterns of neural molecules to find a common addiction pathway dependent on Nrcam function. We examined monoaminergic, glutamatergic, and GABAergic systems in the brains of Nrcam knockout mice following treatment with methamphetamine (METH) or saline (SAL) using micro‐array gene expression analysis, which was replicated using TaqMan gene expression analysis. To find a common addiction pathway, we examined similarities and differences between the expression patterns of molecules in METH‐treated mice and in Nrcam knockout mice treated with cocaine (COC).ResultsGlutaminase expression in brain was reduced in Nrcam heterozygous mice after METH and COC treatment, consistent with our previous study. Metabotropic glutamate receptor 2 expression was reduced in Nrcam heterozygous mice that received either METH or COC treatment. Several other molecules could act in independent addiction pathways involving METH or COC. We also found that GABA receptor subunit g2 expression was reduced in Nrcam heterozygous mice that underwent SAL treatment, and that METH treatment attenuated this reduction.ConclusionNrcam differentially regulates glutamatergic and GABAergic molecules in naive brains and in brains of animals with acquired addiction. Elucidating the complex neural mechanisms underlying polysubstance use will uncover biological features of addiction and may contribute to the development of effective pharmaceutical treatments.