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    Cang-ai volatile oil improves depressive-like behaviors and regulates DA and 5-HT metabolism in the brains of CUMS-induced rats. Chen Bojun,Li Jijun,Xie Yuhuan,Ming Xi,Li Gang,Wang Jinjin,Li Meng,Li Xiaohong,Xiong Lei Journal of ethnopharmacology ETHNOPHARMACOLOGICAL RELEVANCE:Cang-ai volatile oil (CAVO) is a traditional Chinese medicine (TCM) inhalational preparation for the treatment of some depressive and emotive disorders. AIM OF THE STUDY:This research aimed to evaluate the efficiency and possible mechanism of intranasal CAVO administration on depression in chronic unpredictable mild stress (CUMS)-induced rats compared to lavender volatile oil (LVO) treatment after CUMS exposure and bilateral olfactory bulb impairment (OBI) in rats. MATERIALS AND METHODS:Forty depressive-like model rats induced by CUMS were evaluated by the forced swim test (FST), open field test (OFT), and sucrose preference test (SPT). The model rats were divided into five groups: CUMS (n = 8), CAVOh + CUMS (n = 8), CAVOl + CUMS (n = 8), LVO + CUMS (n = 8), and OBI + CAVO + CUMS (n = 8). The CUMS-induced rats were treated for a period of 4 weeks. The other healthy rats were regarded as the control (CTR, n = 8) subjects. The levels of serotonin (5-HT) and dopamine (DA) and their respective metabolites homovanillic acid (HVA) and 5-hydroxyindol acetic acid (5-HIAA) were measured in brain tissue homogenates of CUMS-induced rats using enzyme-linked immunosorbent assay (ELISA). RESULTS:CAVO ameliorated depressive-like behaviors (p < 0.05). The levels of DA in the CUMS group were lower than those in the CTR and CAVOh groups (**p < 0.01 and *p < 0.05). The levels of HVA were lower in the CUMS group than in the CTR, LVO, OBI + CAVOh and CAVOh groups (**p < 0.01 and *p < 0.05) and lower in the OBI + CAVOh group than in the CAVOh group (**p < 0.01). The levels of 5-HT in the CUMS group were lower than those in the CTR and CAVOh groups (**p < 0.01). The levels of 5-HIAA were lower in the CUMS and OBI + CAVOh groups than in the CTR, LVO and CAVOh groups (**p < 0.01). CONCLUSIONS:CAVO can improve depressive-like behaviors concomitant with the regulation of DA and 5-HT metabolism in the brains of CUMS-induced rats. 10.1016/j.jep.2019.112088
    The neural cell adhesion molecules L1 and CHL1 are cleaved by BACE1 protease in vivo. Zhou Lujia,Barão Soraia,Laga Mathias,Bockstael Katrijn,Borgers Marianne,Gijsen Harry,Annaert Wim,Moechars Diederik,Mercken Marc,Gevaert Kris,Gevaer Kris,De Strooper Bart The Journal of biological chemistry The β-site amyloid precursor protein-cleaving enzyme BACE1 is a prime drug target for Alzheimer disease. However, the function and the physiological substrates of BACE1 remain largely unknown. In this work, we took a quantitative proteomic approach to analyze the secretome of primary neurons after acute BACE1 inhibition, and we identified several novel substrate candidates for BACE1. Many of these molecules are involved in neuronal network formation in the developing nervous system. We selected the adhesion molecules L1 and CHL1, which are crucial for axonal guidance and maintenance of neural circuits, for further validation as BACE1 substrates. Using both genetic BACE1 knock-out and acute pharmacological BACE1 inhibition in mice and cell cultures, we show that L1 and CHL1 are cleaved by BACE1 under physiological conditions. The BACE1 cleavage sites at the membrane-proximal regions of L1 (between Tyr(1086) and Glu(1087)) and CHL1 (between Gln(1061) and Asp(1062)) were determined by mass spectrometry. This work provides molecular insights into the function and the pathways in which BACE1 is involved, and it will help to predict or interpret possible side effects of BACE1 inhibitor drugs in current clinical trials. 10.1074/jbc.M112.377465
    Impairment of novelty detection in mice targeted for the Chl1 gene. Pratte Michel,Jamon Marc Physiology & behavior A deficit in cell adhesion molecules including the human Chl1 (close homologue of the L1 cell adhesion molecule) gene may cause impairment of cognitive processes. Aberrant connectivity in the CA3 region of the hippocampus has been reported in mice lacking the CHL1 protein after Chl1 gene targeting. Previous studies have observed a deficit in the processing of novel information by CHL1-deficient mice. We investigated deficits in spatial discrimination and object discrimination in three groups of mice--Chl1(+/+), Chl1(+/-) and Chl1(-/-)--performing spatial and object novelty tasks. The results indicated that wild-type mice easily recognized objects that were either "displaced" or "substituted". Chl1(-/-) mice showed severe impairment of the capacity to react to both spatial and non-spatial novelty. Chl1(+/-) mice were severely restricted in their ability to detect spatial changes, but succeeded in novel object discrimination. A dose-dependent sensitivity of the organization of the CA3 layer to the CHL1 protein may explain this result. However, the observations suggest that a dysfunction of parts of the brain other than the hippocampus may be involved in the impairment. 10.1016/j.physbeh.2009.03.009
    CHL1 cooperates with PAK1-3 to regulate morphological differentiation of embryonic cortical neurons. Demyanenko G P,Halberstadt A I,Rao R S,Maness P F Neuroscience The cell adhesion molecule close homologue of L1 (CHL1) is important for apical dendritic projection and laminar positioning of pyramidal neurons in caudal regions of the cerebral cortex. The p21-activated kinase (PAK1-3) subfamily of serine/threonine kinases has also been implicated in regulating cell adhesion, migration, and morphology. Immunofluorescence staining in mouse embryonic brain showed that PAK1-3 was expressed in embryonic cortex and colocalized with CHL1 during neuronal migration and differentiation. To investigate a cooperative function for CHL1 and PAK in pyramidal cell differentiation or migration, a dominant-negative PAK mutant (PAK1 AID) that inhibits PAK1-3 kinase activity while coexpressing a green fluorescent protein (GFP) reporter was electroporated into the lateral ventricles of wild type (WT) and CHL1 null mutant mouse embryos (E14.5), then brain slices were cultured and neurons analyzed for laminar positioning and morphology by confocal microscopy after 3 days in vitro. Expression of PAK1 AID in CHL1 mutant cortex inactivated PAK and caused embryonic cortical neurons to branch profusely in the intermediate zone (IZ) and cortical plate (CP). The number of nodes, terminals and length of leading processes/apical dendrites of CHL1 mutant embryos expressing PAK1 AID increased dramatically, compared to CHL1 mutants without PAK1 AID, or WT embryos with or without PAK1 AID. These findings suggest that CHL1 and PAK1-3 kinase cooperate, most likely in independent pathways, in regulating morphological development of the leading process/apical dendrite of embryonic cortical neurons. 10.1016/j.neuroscience.2009.09.077
    Phosphatidylinositol 3-kinase/protein kinase Cdelta activation induces close homolog of adhesion molecule L1 (CHL1) expression in cultured astrocytes. Wu Junfang,Wrathall Jean R,Schachner Melitta Glia Upregulation of expression of the close homolog of adhesion molecule L1 (CHL1) by reactive astrocytes in the glial scar reduces axonal regeneration and inhibits functional recovery after spinal cord injury (SCI). Here, we investigate the molecular mechanisms underlying upregulation of CHL1 expression by analyzing the signal transduction pathways in vitro. We show that astrogliosis stimulated by bacterial lipopolysaccharide (LPS) upregulates CHL1 expression in primary cultures of mouse cerebral astrocytes, coinciding with elevated protein synthesis and translocation of protein kinase delta (PKCdelta) from cytosol to the membrane fraction. Blocking PKCdelta activity pharmacologically and genetically attenuates LPS-induced elevation of CHL1 protein expression through a phosphatidylinositol 3-kinase (PI3K) dependent pathway. LPS induces extracellular signal-regulated kinases (ERK1/2) phosphorylation through PKCdelta and blockade of ERK1/2 activation abolishes upregulation of CHL1 expression. LPS-triggered upregulation of CHL1 expression mediated through translocation of nuclear factor kappaB (NF-kappaB) to the nucleus is blocked by a specific NF-kappaB inhibitor and by inhibition of PI3K, PKCdelta, and ERK1/2 activities, implicating NF-kappaB as a downstream target for upregulation of CHL1 expression. Furthermore, the LPS-mediated upregulation of CHL1 expression by reactive astrocytes is inhibitory for hippocampal neurite outgrowth in cocultures. Although the LPS-triggered NO-guanylate cyclase-cGMP pathway upregulates glial fibrillary acid protein expression in cultured astrocytes, we did not observe this pathway to mediate LPS-induced upregulation of CHL1 expression. Our results indicate that elevated CHL1 expression by reactive astrocytes requires activation of PI3K/PKCdelta-dependent pathways and suggest that reduction of PI3K/PKCdelta activity represents a therapeutic target to downregulate CHL1 expression and thus benefit axonal regeneration after SCI. 10.1002/glia.20925
    Loss of cell adhesion molecule CHL1 improves homeostatic adaptation and survival in hypoxic stress. Huang X,Sun J,Rong W,Zhao T,Li D H,Ding X,Wu L Y,Wu K,Schachner M,Xiao Z C,Zhu L L,Fan M Cell death & disease Close homologue of L1 (CHL1) is a transmembrane cell adhesion molecule that is critical for brain development and for the maintenance of neural circuits in adults. Recent studies revealed that CHL1 has diverse roles and is involved in the regulation of recovery after spinal cord injury. CHL1 expression was downregulated in the cerebral cortex, hypothalamus, and brain stem after the induction of acute hypoxia (AH). In the current study, we sought to address the role of CHL1 in regulating homeostasis responses to hypoxia using CHL1-knockout (CHL1(-/-)) mice. We found that, compared with wild-type littermates, CHL1(-/-) mice showed a dramatically lower mortality rate and an augmented ventilatory response after they were subjected to AH. Immunofluorescence staining revealed that CHL1 was expressed in the carotid body (CB), the key oxygen sensor in rodents, and CHL1 expression level in the CB as assayed by western blot was decreased after hypoxic exposure. The number of glomus cells and the expression of tyrosine hydroxylase (a marker for glomus cells) in the CB of CHL1(-/-) mice appeared to be increased compared with CHL1(+/+) mice. In addition, in the ex vivo CB preparation, hypoxia induced a significantly greater afferent nerve discharge in CHL1(-/-) mice compared with CHL1(+/+) mice. Furthermore, the arterial blood pressure and plasma catecholamine levels of CHL1(-/-) mice were also significantly higher than those of CHL1(+/+) mice. Our findings first demonstrate that CHL1 is a novel intrinsic factor that is involved in CB function and in the ventilatory response to AH. 10.1038/cddis.2013.284
    Chronic mild stress impairs latent inhibition and induces region-specific neural activation in CHL1-deficient mice, a mouse model of schizophrenia. Buhusi Mona,Obray Daniel,Guercio Bret,Bartlett Mitchell J,Buhusi Catalin V Behavioural brain research Schizophrenia is a neurodevelopmental disorder characterized by abnormal processing of information and attentional deficits. Schizophrenia has a high genetic component but is precipitated by environmental factors, as proposed by the 'two-hit' theory of schizophrenia. Here we compared latent inhibition as a measure of learning and attention, in CHL1-deficient mice, an animal model of schizophrenia, and their wild-type littermates, under no-stress and chronic mild stress conditions. All unstressed mice as well as the stressed wild-type mice showed latent inhibition. In contrast, CHL1-deficient mice did not show latent inhibition after exposure to chronic stress. Differences in neuronal activation (c-Fos-positive cell counts) were noted in brain regions associated with latent inhibition: Neuronal activation in the prelimbic/infralimbic cortices and the nucleus accumbens shell was affected solely by stress. Neuronal activation in basolateral amygdala and ventral hippocampus was affected independently by stress and genotype. Most importantly, neural activation in nucleus accumbens core was affected by the interaction between stress and genotype. These results provide strong support for a 'two-hit' (genes x environment) effect on latent inhibition in CHL1-deficient mice, and identify CHL1-deficient mice as a model of schizophrenia-like learning and attention impairments. 10.1016/j.bbr.2017.06.033
    Interaction of the cell adhesion molecule CHL1 with vitronectin, integrins, and the plasminogen activator inhibitor-2 promotes CHL1-induced neurite outgrowth and neuronal migration. Katic Jelena,Loers Gabriele,Kleene Ralf,Karl Nicole,Schmidt Carsten,Buck Friedrich,Zmijewski Jaroslaw W,Jakovcevski Igor,Preissner Klaus T,Schachner Melitta The Journal of neuroscience : the official journal of the Society for Neuroscience The cell adhesion molecule close homolog of L1 (CHL1) plays important functional roles in the developing and adult nervous system. In search of the binding partners that mediate the diverse and sometimes opposing functions of CHL1, the extracellular matrix-associated proteins vitronectin and plasminogen activator inhibitor-2 (PAI-2) were identified as novel CHL1 interaction partners and tested for involvement in CHL1-dependent functions during mouse cerebellar development. CHL1-induced cerebellar neurite outgrowth and cell migration at postnatal days 6-8 were inhibited by a CHL1-derived peptide comprising the integrin binding RGD motif, and by antibodies against vitronectin or several integrins, indicating a vitronectin-dependent integrin-mediated pathway. A PAI-2-derived peptide, or antibodies against PAI-2, urokinase type plasminogen activator (uPA), uPA receptor, and several integrins reduced cell migration. CHL1 colocalized with vitronectin, PAI-2, and several integrins in cerebellar granule cells, suggesting an association among these proteins. Interestingly, at the slightly earlier age of 4-5 d, cerebellar neurons did not depend on CHL1 for neuritogenesis and cell migration. However, differentiation of progenitor cells into neurons at this stage was dependent on homophilic CHL1-CHL1 interactions. These observations indicate that homophilic CHL1 trans-interactions regulate differentiation of neuronal progenitor cells at early postnatal stages, while heterophilic trans-interactions of CHL1 with vitronectin, integrins, and the plasminogen activator system regulate neuritogenesis and neuronal cell migration at a later postnatal stage of cerebellar morphogenesis. Thus, within very narrow time windows in postnatal cerebellar development, distinct types of molecular interactions mediated by CHL1 underlie the diverse functions of this protein. 10.1523/JNEUROSCI.3280-13.2014
    Age-dependent loss of parvalbumin-expressing hippocampal interneurons in mice deficient in CHL1, a mental retardation and schizophrenia susceptibility gene. Schmalbach Barbara,Lepsveridze Eka,Djogo Nevena,Papashvili Giorgi,Kuang Fang,Leshchyns'ka Iryna,Sytnyk Vladimir,Nikonenko Alexander G,Dityatev Alexander,Jakovcevski Igor,Schachner Melitta Journal of neurochemistry In humans, deletions/mutations in the CHL1/CALL gene are associated with mental retardation and schizophrenia. Juvenile CHL1-deficient (CHL1(-/-) ) mice have been shown to display abnormally high numbers of parvalbumin-expressing (PV(+) ) hippocampal interneurons and, as adults, display behavioral traits observed in neuropsychiatric disorders. Here, we addressed the question whether inhibitory interneurons and synaptic plasticity in the CHL1(-/-) mouse are affected during brain maturation and in adulthood. We found that hippocampal, but not neocortical, PV(+) interneurons were reduced with age in CHL1(-/-) mice, from a surplus of +27% at 1 month to a deficit of -20% in adulthood compared with wild-type littermates. This loss occurred during brain maturation, correlating with microgliosis and enhanced interleukin-6 expression. In parallel with the loss of PV(+) interneurons, the inhibitory input to adult CA1 pyramidal cells was reduced and a deficit in short- and long-term potentiation developed at CA3-CA1 excitatory synapses between 2 and 9 months of age in CHL1(-/-) mice. This deficit could be abrogated by a GABAA receptor agonist. We propose that region-specific aberrant GABAergic synaptic connectivity resulting from the mutation and a subsequently enhanced synaptic elimination during brain maturation lead to microgliosis, increase in pro-inflammatory cytokine levels, loss of interneurons, and impaired synaptic plasticity. Close homolog of L1-deficient (CHL1(-/-) ) mice have abnormally high numbers of parvalbumin (PV)-expressing hippocampal interneurons in juvenile animals, but in adult animals a loss of these cells is observed. This loss correlates with an increased density of microglia (M), enhanced interleukin-6 (IL6) production and a deficit in short- and long-term potentiation at CA3-CA1 excitatory synapses. Furthermore, adult CHL1(-/-) mice display behavioral traits similar to those observed in neuropsychiatric disorders of humans. 10.1111/jnc.13284
    Increased temporal discounting after chronic stress in CHL1-deficient mice is reversed by 5-HT2C agonist Ro 60-0175. Buhusi Mona,Olsen Kaitlin,Buhusi Catalin V Neuroscience Schizophrenia is a neurodevelopmental disorder in which impaired decision-making and goal-directed behaviors are core features. One of the genes associated with schizophrenia is the Close Homolog of L1 (CHL1); CHL1-deficient mice are considered a model of schizophrenia-like deficits, including sensorimotor gating, interval timing and spatial memory impairments. Here we investigated temporal discounting in CHL1-deficient (KO) mice and their wild-type littermates. Although no discounting differences were found under baseline conditions, CHL1-KO mice showed increased impulsive choice following chronic unpredictable stress (fewer % larger-later choices, and reduced area under the discounting curve). Stressed CHL1-KO mice also showed decreased neuronal activation (number of cFos positive neurons) in the discounting task in the prelimbic cortex and dorsal striatum, areas thought to be part of executive and temporal processing circuits. Impulsive choice alterations were reversed by the 5-HT2C agonist Ro 60-0175. Our results provide evidence for a gene x environment, double-hit model of stress-related decision-making impairments, and identify CHL1-deficient mice as a mouse model for these deficits in regard to schizophrenia-like phenotypes. 10.1016/j.neuroscience.2017.05.047
    Interaction between DISC1 and CHL1 in regulation of neurite outgrowth. Ren Jun,Zhao Tian,Xu Yiliang,Ye Haihong Brain research Disrupted-in-schizophrenia 1 (DISC1), a gene susceptible for major mental illnesses, including schizophrenia, plays multiple roles in neural development, including neuronal proliferation, maturation, migration and neurite outgrowth. DISC1 regulates neurite length via interaction with several intracellular proteins, such as NDEL1, FEZ1 and dysbindin. However, the signal transduction mechanism upstream of DISC1 in regulating neurite outgrowth remains to be elucidated. Here we show that DISC1 interacts with the intracellular domain of close homolog of L1 (CHL1), a member of the L1 family of neural cell adhesion molecules. DISC1 and CHL1 proteins co-localize in growth cones of cortical neurons. Moreover, in neurite outgrowth assay, CHL1 rescues the inhibitory effect of DISC1 on the initial phase of neurite outgrowth. Considering the fact that CHL1 also plays crucial roles in neural development, and its coding gene is associated with schizophrenia, our findings indicate that DISC1 and CHL1 may engage in physical and functional interaction in neural development, supporting the notion that DISC1 regulates neurite outgrowth with a receptor belonging to the neural cell adhesion molecules, and disruption of such interaction may contribute to increased risk for schizophrenia. 10.1016/j.brainres.2016.06.033
    BACE1 elevation engendered by GGA3 deletion increases β-amyloid pathology in association with APP elevation and decreased CHL1 processing in 5XFAD mice. Kim WonHee,Ma Liang,Lomoio Selene,Willen Rachel,Lombardo Sylvia,Dong Jinghui,Haydon Philip G,Tesco Giuseppina Molecular neurodegeneration BACKGROUND:β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is the rate-limiting enzyme in the production of amyloid beta (Aβ), the toxic peptide that accumulates in the brains of Alzheimer's disease (AD) patients. Our previous studies have shown that the clathrin adaptor Golgi-localized γ-ear-containing ARF binding protein 3 (GGA3) plays a key role in the trafficking of BACE1 to lysosomes, where it is normally degraded. GGA3 depletion results in BACE1 stabilization both in vitro and in vivo. Moreover, levels of GGA3 are reduced and inversely related to BACE1 levels in post-mortem brains of AD patients. METHOD:In order to assess the effect of GGA3 deletion on AD-like phenotypes, we crossed GGA3 -/- mice with 5XFAD mice. BACE1-mediated processing of APP and the cell adhesion molecule L1 like protein (CHL1) was measured as well as levels of Aβ42 and amyloid burden. RESULTS:In 5XFAD mice, we found that hippocampal and cortical levels of GGA3 decreased while BACE1 levels increased with age, similar to what is observed in human AD brains. GGA3 deletion prevented age-dependent elevation of BACE1 in GGA3KO;5XFAD mice. We also found that GGA3 deletion resulted in increased hippocampal levels of Aβ42 and amyloid burden in 5XFAD mice at 12 months of age. While levels of BACE1 did not change with age and gender in GGAKO;5XFAD mice, amyloid precursor protein (APP) levels increased with age and were higher in female mice. Moreover, elevation of APP was associated with a decreased BACE1-mediated processing of CHL1 not only in 12 months old 5XFAD mice but also in human brains from subjects affected by Down syndrome, most likely due to substrate competition. CONCLUSION:This study demonstrates that GGA3 depletion is a leading candidate mechanism underlying elevation of BACE1 in AD. Furthermore, our findings suggest that BACE1 inhibition could exacerbate mechanism-based side effects in conditions associated with APP elevation (e.g. Down syndrome) owing to impairment of BACE1-mediated processing of CHL1. Therefore, therapeutic approaches aimed to restore GGA3 function and to prevent the down stream effects of its depletion (e.g. BACE1 elevation) represent an attractive alternative to BACE inhibition for the prevention/treatment of AD. 10.1186/s13024-018-0239-7
    The cell adhesion molecule CHL1 interacts with patched-1 to regulate apoptosis during postnatal cerebellar development. Katic Jelena,Loers Gabriele,Tosic Jelena,Schachner Melitta,Kleene Ralf Journal of cell science The immunoglobulin superfamily adhesion molecule close homolog of L1 (CHL1) plays important roles during nervous system development. Here, we identified the hedgehog receptor patched-1 (PTCH1) as a novel CHL1-binding protein and showed that CHL1 interacts with the first extracellular loop of PTCH1 via its extracellular domain. Colocalization and co-immunoprecipitation of CHL1 with PTCH1 suggest an association of CHL1 with this major component of the hedgehog signaling pathway. The -interaction of CHL1 with PTCH1 promotes neuronal survival in cultures of dissociated cerebellar granule cells and of organotypic cerebellar slices. An inhibitor of the PTCH1-regulated hedgehog signal transducer, smoothened (SMO), and inhibitors of RhoA and Rho-associated kinase (ROCK) 1 and 2 prevent CHL1-dependent survival of cultured cerebellar granule cells and survival of cerebellar granule and Purkinje cells in organotypic cultures. In histological sections from 10- and 14-day-old CHL1-deficient mice, enhanced apoptosis of granule, but not Purkinje, cells was observed. The results of the present study indicate that CHL1 triggers PTCH1-, SMO-, RhoA- and ROCK-dependent signal transduction pathways to promote neuronal survival after cessation of the major morphogenetic events during mouse cerebellar development. 10.1242/jcs.194563
    Cell Adhesion Molecule Close Homolog of L1 (CHL1) Guides the Regrowth of Regenerating Motor Axons and Regulates Synaptic Coverage of Motor Neurons. Guseva Daria,Jakovcevski Igor,Irintchev Andrey,Leshchyns'ka Iryna,Sytnyk Vladimir,Ponimaskin Evgeni,Schachner Melitta Frontiers in molecular neuroscience The close homolog of L1 (CHL1) is a cell adhesion molecule involved in regulation of neuronal differentiation and survival, neurite outgrowth and axon guidance during development. In the mature nervous system, CHL1 regulates synaptic activity and plasticity. The aim of the present study was to evaluate the influence of CHL1 on peripheral nerve regeneration after trauma. Using the established model of mouse femoral nerve regeneration, CHL1 knock-out mice were investigated in comparison to the wild type littermates. First, non-injured mice of both genotypes were compared regarding the synaptic phenotypes in the corresponding spinal cord segment. While no differences in phenotypes were detectable in the femoral nerve, corresponding segments in the spinal cord were observed to differ in that inhibitory perisomatic innervation of motor neurons was increased in CHL1-deficient mice, and numbers of perisomatic cholinergic synapses on motor neuronal somata were reduced. Regarding the femoral nerve after injury, CHL1-deficient mice demonstrated preferential motor axon regrowth into the saphenous vs. quadriceps branch after nerve transection upstream of the nerve bifurcation by 8 weeks after transection, indicating decreased preferential motor re-innervation. Furthermore, in injured wild-type mice, enhanced CHL1 expression was observed in regenerating axons in the proximal nerve stump upstream of the bifurcation at days 1, 3, 5, 7 and 14, and in the distal stump at days 7 and 14 after injury, when compared to non-injured mice. Injury-related upregulation of CHL1 expression was more pronounced in axons than in Schwann cells. Despite a more pronounced capacity for preferential motor axon regrowth in wild-type vs. mutant mice, only a tendency for difference in recovery of motor functions was observed between genotypes, without statistical significance Taken together, these results indicate that CHL1 is involved in peripheral nerve regeneration, because it guides regrowing axons into the appropriate nerve branch and regulates synaptic coverage in the spinal cord. 10.3389/fnmol.2018.00174
    Downregulation of Adhesion Molecule CHL1 in B Cells but Not T Cells of Patients with Major Depression and in the Brain of Mice with Chronic Stress. Yang C R,Ning L,Zhou F H,Sun Q,Meng H P,Han Z,Liu Y,Huang W,Liu S,Li X H,Zheng B,Ming Dong,Zhou Xin-Fu Neurotoxicity research Depression is a common serious mental disorder with unclear pathogenesis. Currently, specific diagnostic biomarkers are yet to be characterized. The close homolog of L1 (CHL1) is a L1 family cell adhesion molecule involved in the regulation of neuronal survival and growth. Although genome-wide expression profiling of human lymphoblastoid cell lines (LCLs) reported neural cell adhesion molecule (NCAM) L1 as a tentative biomarker for selective serotonin reuptake inhibitor (SSRI) antidepressant response, the involvement of CHL1 in depression is unclear. In this study, using a well-established chronic unpredictable mild stress (CUMS) depression mouse model, we examined the mRNA and protein expression of CHL1 in normal control, CUMS, vehicle (VEH), fluoxetine (FLU), and clozapine (CLO) groups. We found that in the CUMS group, both mRNA and protein expression of CHL1 were downregulated in both the hippocampus and the cortex. Treatment of CUMS mice with FLU and CLO reversed CHL1 mRNA and protein expression. In the human study, we showed that CHL1 expression was significantly downregulated in monocytes of unipolar and bipolar depressive patients compared with healthy donors (HD) at both mRNA and protein levels. Consistently, ELISA showed that CHL1 levels in the serum of patients with depression were reduced and negatively correlated with their HRSD-21 scores. Further flow cytometry studies showed that the reduced number of CHL1 positive CD19 and CD20 B cells of patients with depression was subsequently reversed with antidepressant treatment. Our findings suggested that downregulation of CHL1 from both immune cells and the brain may be linked to the immunopathogenesis of depression. In conclusion, CHL1 may be an important predictive marker for both diagnosis and treatment outcome of depression. 10.1007/s12640-020-00234-9
    Misguided axonal projections, neural cell adhesion molecule 180 mRNA upregulation, and altered behavior in mice deficient for the close homolog of L1. Montag-Sallaz M,Schachner M,Montag D Molecular and cellular biology Cell recognition molecules are involved in nervous system development and participate in synaptic plasticity in the adult brain. The close homolog of L1 (CHL1), a recently identified member of the L1 family of cell adhesion molecules, is expressed by neurons and glia in the central nervous system and by Schwann cells in the peripheral nervous system in a pattern overlapping, but distinct from, the other members of the L1 family. In humans, CHL1 (also referred to as CALL) is a candidate gene for 3p- syndrome-associated mental impairment. In the present study, we generated and analyzed CHL1-deficient mice. At the morphological level, these mice showed alterations of hippocampal mossy fiber organization and of olfactory axon projections. Expression of the mRNA of the synapse-specific neural cell adhesion molecule 180 isoform was upregulated in adult CHL1-deficient mice, but the mRNA levels of several other recognition molecules were not changed. The behavior of CHL1-deficient mice in the open field, the elevated plus maze, and the Morris water maze indicated that the mutant animals reacted differently to their environment. Our data show that the permanent absence of CHL1 results in misguided axonal projections and aberrant axonal connectivity and alters the exploratory behavior in novel environments, suggesting deficits in information processing in CHL1-deficient mice. 10.1128/mcb.22.22.7967-7981.2002
    CHL1, ITGB3 and SLC6A4 gene expression and antidepressant drug response: results from the Munich Antidepressant Response Signature (MARS) study. Probst-Schendzielorz Kristina,Scholl Catharina,Efimkina Olga,Ersfeld Eva,Viviani Roberto,Serretti Alessandro,Fabbri Chiara,Gurwitz David,Lucae Susanne,Ising Marcus,Paul Anna Maria,Lehmann Marie-Louise,Steffens Michael,Crisafulli Concetta,Calabrò Marco,Holsboer Florian,Stingl Julia Pharmacogenomics AIM:The identification of antidepressant drugs (ADs) response biomarkers in depression is of high clinical importance. We explored CHL1 and ITGB3 expression as tentative response biomarkers. MATERIALS & METHODS:In vitro sensitivity to ADs, as well as gene expression and genetic variants of the candidate genes CHL1, ITGB3 and SLC6A4 were measured in lymphoblastoid cell lines (LCLs) of 58 depressed patients. RESULTS:An association between the clinical remission of depression and the basal expression of CHL1 and ITGB3 was discovered. Individuals whose LCLs expressed higher levels of CHL1 or ITGB3 showed a significantly better remission upon AD treatment. In addition individuals with the CHL1 rs1516338 TT genotype showed a significantly better remission after 5 weeks AD treatment than those carrying a CC genotype. No association between the in vitro sensitivity of LCLs toward AD and the clinical remission could be detected. CONCLUSION:CHL1 expression in patient-derived LCLs correlated with the clinical outcome. Thus, it could be a valid biomarker to predict the success of an antidepressant therapy. Original submitted 8 December 2014; Revision submitted 2 March 2015. 10.2217/pgs.15.31
    Genome-wide expression profiling of human lymphoblastoid cell lines identifies CHL1 as a putative SSRI antidepressant response biomarker. Morag Ayelet,Pasmanik-Chor Metsada,Oron-Karni Varda,Rehavi Moshe,Stingl Julia C,Gurwitz David Pharmacogenomics AIMS:Selective serotonin reuptake inhibitors (SSRIs) are the most commonly used class of antidepressants for treating major depression. However, approximately 30% of patients do not respond sufficiently to first-line antidepressant drug treatment and require alternative therapeutics. Genome-wide studies searching for SSRI response DNA biomarkers or studies of candidate serotonin-related genes so far have given inconclusive or contradictory results. Here, we present an alternative transcriptome-based genome-wide approach for searching antidepressant drug-response biomarkers by using drug-effect phenotypes in human lymphoblastoid cell lines (LCLs). MATERIALS & METHODS:We screened 80 LCLs from healthy adult female individuals for growth inhibition by paroxetine. A total of 14 LCLs with reproducible high and low sensitivities to paroxetine (seven from each phenotypic group) were chosen for genome-wide expression profiling with commercial microarrays. RESULTS:The most notable genome-wide transcriptome difference between LCLs displaying high versus low paroxetine sensitivities was a 6.3-fold lower (p = 0.0000256) basal expression of CHL1, a gene coding for a neuronal cell adhesion protein implicated in correct thalamocortical circuitry, schizophrenia and autism. The microarray findings were confirmed by real-time PCR (36-fold lower CHL1 expression levels in the high paroxetine sensitivity group). Several additional genes implicated in synaptogenesis or in psychiatric disorders, including ARRB1, CCL5, DDX60, DDX60L, ENDOD1, ENPP2, FLT1, GABRA4, GAP43, MCTP2 and SPRY2, also differed by more than 1.5-fold and a p-value of less than 0.005 between the two paroxetine sensitivity groups, as confirmed by real-time PCR experiments. CONCLUSION:Genome-wide transcriptional profiling of in vitro phenotyped LCLs identified CHL1 and additional genes implicated in synaptogenesis and brain circuitry as putative SSRI response biomarkers. This method might be used as a preliminary tool for searching for potential depression treatment biomarkers. 10.2217/pgs.10.185