Alterations of Perineuronal Net Expression and Abnormal Social Behavior and Whisker-dependent Texture Discrimination in Mice Lacking the Autism Candidate Gene Engrailed 2.

GABAergic interneurons and perineuronal nets (PNNs) are important regulators of plasticity throughout life and their dysfunction has been implicated in the pathogenesis of several neuropsychiatric conditions, including autism spectrum disorders (ASD). PNNs are condensed portions of the extracellular matrix (ECM) that are crucial for neural development and proper formation of synaptic connections. We previously showed a reduced expression of GABAergic interneuron markers in the hippocampus and somatosensory cortex of adult mice lacking the Engrailed2 gene (En2-/- mice), a mouse model of ASD. Since alterations in PNNs have been proposed as a possible pathogenic mechanism in ASD, we hypothesized that the PNN dysfunction may contribute to the neural and behavioral abnormalities of En2-/- mice. Here, we show an increase in the PNN fluorescence intensity, evaluated by Wisteria floribunda agglutinin, in brain regions involved in social behavior and somatosensory processing. In addition, we found that En2-/- mice exhibit altered texture discrimination through whiskers and display a marked decrease in the preference for social novelty. Our results raise the possibility that altered expression of PNNs, together with defects of GABAergic interneurons, might contribute to the pathogenesis of social and sensory behavioral abnormalities.

Role of Wisteria floribunda agglutinin binding glycans in carcinogenesis and metastasis of cholangiocarcinoma.

Aberrant glycosylation is an important factor in facilitating tumor progression and therapeutic resistance. In this study, using Wisteria floribunda agglutinin (WFA), we examined the expression of WFA-binding glycans (WFAG) in cholangiocarcinoma (CCA). The results showed that WFAG was highly detected in precancerous and cancerous lesions of human CCA tissues, although it was rarely detected in normal bile ducts. The positive signal of WFAG in the cancerous lesion accounted for 96.2% (50/52) of the cases. Overexpression of WFAG was significantly associated with lymph node and distant metastasis (P < 0.05). The study using the CCA hamster model showed that WFAG is elevated in preneoplastic and neoplastic bile ducts as early as 1 month after being infected with liver fluke and exposed to N-nitrosodimethylamine. Functional analysis was performed to reveal the role of WFAG in CCA. The CCA cell lines KKU-213A and KKU-213B were treated with WFA, followed by migration assay. Our data suggested that WFAG facilitates the migration of CCA cells via the activation of the Akt and ERK signaling pathways. In conclusion, we have demonstrated the association of WFAG with carcinogenesis and metastasis of CCA, suggesting its potential as a target for the treatment of the disease.

Tamoxifen-resistant breast cancer cells exhibit reactivity with Wisteria floribunda agglutinin.

Glycosylation is one of the most important post-translational modifications of cell surface proteins involved in the proliferation, metastasis and treatment resistance of cancer cells. However, little is known about the role of glycosylation as the mechanism of breast cancer cell resistance to endocrine therapy. Herein, we aimed to identify the glycan profiles of tamoxifen-resistant human breast cancer cells, and their potential as predictive biomarkers for endocrine therapy. We established tamoxifen-resistant cells from estrogen receptor-positive human breast cancer cell lines, and their membrane-associated proteins were subjected to lectin microarray analysis. To confirm differential lectin binding to cellular glycoproteins, we performed lectin blotting analyses after electrophoretic separation of the glycoproteins. Mass spectrometry of the tryptic peptides of the lectin-bound glycoproteins was further conducted to identify glycoproteins binding to the above lectins. Finally, expression of the glycans that were recognized by a lectin was investigated using clinical samples from patients who received tamoxifen treatment after curative surgery. Lectin microarray analysis revealed that the membrane fractions of tamoxifen-resistant breast cancer cells showed increased binding to Wisteria floribunda agglutinin (WFA) compared to tamoxifen-sensitive cells. Glycoproteins seemed to be responsible for the differential WFA binding and the results of mass spectrometry revealed several membrane glycoproteins, such as CD166 and integrin beta-1, as candidates contributing to increased WFA binding. In clinical samples, strong WFA staining was more frequently observed in patients who had developed distant metastasis during tamoxifen treatment compared with non-relapsed patients. Therefore, glycans recognized by WFA are potentially useful as predictive markers to identify the tamoxifen-resistant and relapse-prone subset of estrogen receptor-positive breast cancer patients.

Regulation of perineuronal net components in the synaptic bouton vicinity on lumbar α-motoneurons in the rat after spinalization and locomotor training: New insights from spatio-temporal changes in gene, protein expression and WFA labeling.

Chondroitin sulfate proteoglycans (CSPGs) consist of core proteins and glycosaminoglycan side chains. Tenascins, and hyaluronan and proteoglycan link protein 1 (HAPLN), link CSPGs with a hyaluronan backbone to constitute perineuronal nets (PNNs), which ensheath preferentially highly active neurons to maintain architecture and stabilize synapses, but restrict repair plasticity. Spinal cord injury increases CSPG core protein levels in the lesion proximity, limiting permissiveness of the extracellular milieu for fiber regrowth, however regulation of PNNs structure in the vicinity of distant α-motoneurons (MNs) in the course of degeneration and reorganization of their inputs requires research. Here, we examined early and late changes in CSPGs, HAPLN1, tenascin-R, and glial activation along the spinal cord in male rats with complete spinal cord transection (Th10), and their impact on PNNs ensheathing lumbar MNs innervating ankle extensor and flexor muscles, which are in different loading states in paraplegic rats. We show that (1) distance from the lesion site and time after injury (2-5 weeks) differentiate degree of changes in transcription rates (measured with RT-qPCR) of PNNs proteins with increased CSPGs and decreased HAPLN1 transcripts, suggesting long-term PNN destabilization in majority of spinal segments, (2) in lumbar segments PNN composition is not MN-class (extensor vs flexor) specific, both showing early decrease and late upregulation of Wisteria floribunda agglutinin (WFA) labeling in vicinity of synaptic boutons on MNs, (3) long-term locomotor training tends to reduce WFA(+) PNNs, but not their protein components (immunofluorescence measurements) around MNs. Our results suggest that training-induced regulation may target glycan structures of CSPGs.

The fungal Clitocybe nebularis lectin binds distinct cell surface glycoprotein receptors to induce cell death selectively in Jurkat cells.

Clitocybe nebularis lectin (CNL) is a GalNAcß1-4GlcNAc-binding lectin that exhibits an antiproliferative effect exclusively on the Jurkat leukemic T cell line by provoking homotypic aggregation and dose-dependent cell death. Cell death of Jurkat cells exhibited typical features of early apoptosis, but lacked the activation of initiating and executing caspases. None of the features of CNL-induced cell death were effectively blocked with the pan-caspase inhibitor or different cysteine peptidase inhibitors. Furthermore, CNL binding induced Jurkat cells to release the endogenous damage-associated molecular pattern molecule high-mobility group box 1 (HMGB1). A plant lectin with similar glycan-binding specificity, Wisteria floribunda agglutinin (WFA) showed less selective toxicity and induced cell death in Jurkat, Tall-104, and Hut-87 cell lines. HMGB1 release was also detected when Jurkat cells were treated with WFA. We identified the CD45 and CD43 cell surface glycoproteins on Jurkat cells as the main targets for CNL binding. However, the blockade of CD45 phosphatase activity failed to block either CNL-induced homotypic agglutination or cell death. Overall, our results indicate that CNL triggers atypical cell death selectively on Jurkat cells, suggesting the potential applicability of CNL in novel strategies for treating and/or detecting acute T cell leukemia.

Sensitive New Assay System for Serum Wisteria floribunda Agglutinin-Reactive Ceruloplasmin That Distinguishes Ovarian Clear Cell Carcinoma from Endometrioma.

Wisteria floribunda agglutinin (WFA)-reactive ceruloplasmin (CP) is a candidate marker for ovarian clear cell carcinoma (CCC) reported in our previous paper. Herein, a new measurement system was developed to investigate its potential as a serum marker for CCC. Site-specific glycome analysis using liquid chromatography/mass spectrometry showed that WFA-CP from CCC binds to WFA via the GalNAcß1,4GlcNAc (LDN) structure. We used mutant recombinant WFA (rWFA), which has a high specificity to the LDN structure, instead of native WFA, to increase the specificity of the serum sample measurement. To improve the sensitivity, we used a surface plasmon field-enhanced fluorescence spectroscopy immunoassay system, which is approximately 100 times more sensitive than the conventional sandwich enzyme-linked immunosorbent assay system. With these two improvements, the specificity and sensitivity of the serum rWFA-CP measurement were dramatically improved, clearly distinguishing CCC from endometrioma, from which CCC originates. This rWFA-CP assay can be used clinically for the serodiagnosis of early-stage CCC, which is difficult to detect with existing serum markers.

Wisteria floribunda Agglutinin-Positive Mac-2 Binding Protein as a Screening Tool for Significant Liver Fibrosis in Health Checkup.

Chronic liver disease is generally widespread, and a test for screening fibrotic subjects in a large population is needed. The ability of Wisteria floribunda agglutinin-positive mac-2 binding protein (WFA+-M2BP) to detect significant fibrosis was investigated in health checkup subjects in this research. Of 2021 health checkup subjects enrolled in this prospective cross-sectional study, those with WFA+-M2BP ≥ 1.0 were defined as high risk. Liver fibrosis was evaluated using magnetic resonance elastography (MRE) in subjects with high risk. The primary outcome was the positive predictive value (PPV) of WFA+-M2BP for significant fibrosis (liver stiffness ≥ 2.97 kPa by MRE). This trial was registered with the UMIN clinical trial registry, UMIN000036175. WFA+-M2BP ≥ 1.0 was observed in 5.3% of the 2021 subjects. The PPV for significant fibrosis with the threshold of WFA+-M2BP at ≥1.0, ≥1.1, ≥1.2, ≥1.3, ≥1.4, and ≥1.5 was 29.2%, 36.4%, 43.5%, 42.9%, 62.5%, and 71.4%, respectively. A WFA+-M2BP of 1.2 was selected as the optimal threshold for significant fibrosis among high-risk subjects, and the PPV, negative predictive value, sensitivity, and specificity for significant fibrosis were 43.5%, 84.0%, 71.4%, and 61.8%, respectively. WFA+-M2BP ≥ 1.2 was significantly associated with significant fibrosis, with an odds ratio (OR) of 4.04 (95% confidence interval (CI): 1.1-16, p = 0.04), but not FIB-4 ≥ 2.67 (OR: 2.40, 95%CI: 0.7-8.6, p-value = 0.2). In conclusion, WFA+-M2BP is associated with significant fibrosis and could narrow down potential subjects with liver fibrosis. The strategy of narrowing down fibrosis subjects using WFA+-M2BP may be used to screen for fibrotic subjects in a large population.

Wisteria floribunda agglutinin-positive Mac-2-binding protein as a diagnostic biomarker in liver cirrhosis: an updated meta-analysis.

Wisteria floribunda agglutinin-positive Mac-2-binding protein (WFA+-M2BP) had been suggested as a possible glycobiomarker for assessing liver fibrosis. Here, we conducted this updated meta-analysis to systematically investigate the predictive accuracy of WFA+-M2BP for diagnosing liver fibrosis and hepatocellular carcinoma (HCC) by comparing with multiple non-invasive indicators. We searched relevant literatures from Pubmed, Web of Science, EMBASE and Cochrane Library and enrolled 36 eligible studies involving 7,362 patients. Summary results were calculated using bivariate random effects model. The pooled sensitivities, specificities and areas under the summary receiver operating characteristic curves (AUSROCs) of WFA+-M2BP for identifying mild fibrosis, significant fibrosis, advanced fibrosis, cirrhosis, and HCC were 0.70/0.68/0.75, 0.71/0.75/0.79, 0.75/0.76/0.82, 0.77/0.86/0.88, and 0.77/0.80/0.85, respectively. The accuracy of WFA+-M2BP was strongly affected by etiology and it was not better than other non-invasive indicators for predicting early fibrosis. It showed similar diagnostic performance to hyaluronic acid and FibroScan for cirrhosis, but was equivalent to α-fetoprotein for HCC. In conclusion, WFA+-M2BP was suitable to diagnose late stage of liver fibrosis, especially cirrhosis. Individual cutoff value of WFA+-M2BP could be used to grade liver fibrosis in different etiology. Combined diagnostic model was suggested to improve its predictive accuracy for HCC.

Wisteria floribunda Agglutinin-Positive Mac-2 Binding Protein but not α-fetoprotein as a Long-Term Hepatocellular Carcinoma Predictor.

Identification of high-risk patients for hepatocellular carcinoma (HCC) after sustained virological responses (SVR) is necessary to define candidates for long-term surveillance. In this study, we examined whether serum markers after 1 year of SVR could predict subsequent HCC development. Total 734 chronic hepatitis C patients without a history of HCC who achieved SVR with direct-acting antivirals were included. The regular surveillance for HCC started from 24 weeks after the end of treatment (SVR24). Factors at SVR24 and 1 year after SVR24 were analyzed for predicting HCC development. During the mean observation period of 19.7 ± 10 months, 24 patients developed HCC. At SVR24, Wisteria floribunda agglutinin-positive mac-2 binding protein (WFA±M2BP) ≥ 1.85 and α-fetoprotein (AFP) ≥ 6.0 ng/mL were independent factors of HCC development. However, at 1 year after SVR24, WFA±M2BP ≥ 1.85 was associated with subsequent HCC development (hazard ratio: 23.5, 95% confidence interval: 2.68-205) but not AFP. Among patients with WFA±M2BP ≥ 1.85 at SVR24, 42% had WFA±M2BP < 1.85 at 1 year after SVR24 (WFA±M2BP declined group). Subsequent HCC development was significantly lower in the declined group than in the non-declined group (1 year HCC rate: 0% vs. 9.4%, p = 0.04). In conclusion, WFA±M2BP but not AFP could identify high and no-risk cases of HCC at 1 year after SVR. Therefore, it was useful as a real-time monitoring tool to identify the candidates for continuous surveillance for HCC.

Noise exposure alters MMP9 and brevican expression in the rat primary auditory cortex.

BACKGROUND: This study aimed to investigate the changes in molecules related to perineuronal nets (PNNs) and synaptic transporters in the primary auditory cortices of rats with noise-induced hearing loss. Female Sprague-Dawley rats at postnatal day 7 were divided into the noise and control groups. Four hours of 115 dB SPL white noise was delivered for 10 days to the noise group. Thirty days after noise exposure, the primary auditory cortex and the inferior colliculus were harvested. The expression levels of vesicular glutamatergic transporter (VGLUT)1, VGLUT2, vesicular GABA transporter (VGAT), glutamate decarboxylase (GAD)67, brevican, aggrecan, MMP9, and MMP14 were evaluated using real-time reverse transcription polymerase chain reaction or western blot. An immunofluorescence assay was conducted to assess parvalbumin (PV), Wisteria floribunda agglutinin (WFA), and brevican. The immune-positive cells were counted in the primary auditory cortex. RESULTS: The expression level of VGLUT1 in the primary auditory cortex was decreased in the noise group. The expression level of VGLUT2 in the inferior colliculus was elevated in the noise group. The expression levels of brevican and PV + WFA in the primary auditory cortex were decreased in the noise group. The expression level of MMP9 in the primary auditory cortex was increased in the noise group. CONCLUSION: Noise-induced hearing loss during the precritical period impacted PNN expression in the primary auditory cortex. Increased MMP9 expression may have contributed to the decrease in brevican expression. These changes were accompanied by the attenuation of glutamatergic synaptic transporters.

Prognostic Role of Serum Wisteria Floribunda Agglutinin-Positive Mac-2 Binding Protein Level in Early Stage Hepatocellular Carcinoma.

The purpose of this study is to evaluate the prognostic value of preoperative Wisteria floribunda agglutinin-positive Mac-2 binding protein (WFA+-M2BP) in predicting overall survival for patients with hepatitis B- and hepatitis C-related early-stage hepatocellular carcinoma (ESHCC) after liver resection. Post-operative survival rates were compared according to WFA+-M2BP level and tumor stage. Six hundred and ten patients were identified and 198 were removed after application of the exclusion criteria; the median follow-up time was 4.33 years, and cancer-related death occurred in 117 (28.4%) patients. Age (p = 0.03), fibrosis grade (p = 0.042), cancer stage (p = 0.01), and WFA+-M2BP level (p = 0.001) were identified as independent risk factors for poor overall survival. The overall survival rates at 3 and 5 years for patients with WFA+-M2BP ≤ 1.12 were 0.92 and 0.90, respectively, and 0.76 and 0.61 for patients with WFA+-M2BP > 1.12 (p < 0.001). During the analysis of survival prediction, serum WFA+-M2BP level exhibited a higher log-likelihood and a lower AIC value compared to TNM stage (log likelihood: -638; AIC: 1279). Pre-operative serum WFA+-M2BP level provided important prognostic information after curative hepatic resection in our study.

Visualization of Perineuronal Nets in Central Nervous System Tissue Sections.

The perineuronal net (PNN) is a specialized extracellular matrix structure that surrounds subpopulations of neurons in the central nervous system (CNS). The appearance of PNNs on the cell surface marks the closure of the critical period during development and has been observed to reduce synaptic plasticity. Perineuronal nets comprise hyaluronan, chondroitin sulfate proteoglycans (CSPGs), link proteins, tenascin-R, and other components, some of which are substrates for a disintegrin-like and metalloprotease domain with thrombospondin type 1 motifs (ADAMTS) proteases. There is a high heterogeneity of PNNs in the CNS. Depending on which part of the CNS is studied, the PNNs may be observed surrounding the soma, or both the soma and proximal dendrites. The most robust marker for PNN is a lectin called Wisteria floribunda agglutinin. Here, we describe a method for preparing tissue for visualization of PNNs in CNS.

Serum Wisteria floribunda agglutinin-positive human Mac-2 binding protein level predicts recurrence of hepatitis B virus-related hepatocellular carcinoma after curative resection.

BACKGROUND/AIMS: To investigate whether serum Wisteria floribunda agglutinin-positive human Mac-2-binding protein (WFA+-M2BP) can predict the recurrence of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) after curative resection. METHODS: Patients with chronic hepatitis B (CHB) who underwent curative resection for HCC between 2004 and 2015 were eligible for the study. Recurrence was sub-classified as early (<2 years) or late (≥2 years). RESULTS: A total of 170 patients with CHB were selected. During the follow-up period (median, 22.6 months), 64 (37.6%) patients developed recurrence. In multivariate analyses, WFA+-M2BP level was an independent predictor of overall (hazard ratio [HR]=1.490), early (HR=1.667), and late recurrence (HR=1.416), together with male sex, des-gamma carboxyprothrombin level, maximal tumor size, portal vein invasion, and satellite nodules (all P<0.05). However, WFA+- M2BP level was not predictive of grade B-C posthepatectomy liver failure. The cutoff value that maximized the sum of sensitivity (30.2%) and specificity (90.6%) was 2.14 (area under receiver operating characteristic curve=0.632, P=0.010). Patients with a WFA+-M2BP level >2.14 experienced recurrence more frequently than those with a WFA+-M2BP level ≤2.14 (P=0.011 by log-rank test), and had poorer postoperative outcomes than those with a WFA+-M2BP level ≤2.14 in terms of overall recurrence (56.0 vs. 34.5%, P=0.047) and early recurrence (52.0 vs. 20.7%, P=0.001). CONCLUSION: WFA+-M2BP level is an independent predictive factor of HBV-related HCC recurrence after curative resection. Further studies should investigate incorporation of WFA+-M2BP level into tailored postoperative surveillance strategies for patients with CHB.

Diagnostic Accuracy of Acoustic Radiation Force Impulse (ARFI) and Wisteria floribunda Agglutinin-Positive Mac-2-Binding Protein (WFA⁺-M2BP) in Patients with Chronic Liver Disease.

BACKGROUND The present study assessed and compared the diagnostic accuracy of elastography (acoustic radiation force impulse, ARFI) with that of Wisteria floribunda agglutinin-positive Mac-2-binding protein (WFA⁺-M2BP) for estimating the stage of hepatic fibrosis in chronic liver disease patients. MATERIAL AND METHODS This retrospective cross-sectional study enrolled 70 chronic liver disease patients who underwent hepatectomy for hepatic tumors. ARFI and WFA⁺-M2BP serum level, underlying liver disease, and laboratory data for all patients were recorded. The stage of fibrosis was determined from a surgical specimen. The area under the receiver operating characteristic (ROC) curves (AUC) was measured to compare the diagnostic accuracy. RESULTS The ARFI and serum WFA⁺-M2BP levels had good performances for detecting severe fibrosis (≥F3). The AUC in characterization of fibrosis stage ≥F3 was 0.79 for ARFI and 0.71 for serum WFA⁺-M2BP levels. When comparing the diagnostic performances between ARFI and serum WFA⁺-M2BP levels for the severity of fibrosis stage, no significant differences were found. Then all patients were divided into 2 subgroups, the AUC for serum WFA⁺-M2BP levels was higher in the hepatitis C virus (HCV) subgroup than in the hepatitis B virus (HBV) subgroup when characterizing fibrosis stages ≥F3. CONCLUSIONS WFA⁺-M2BP is an accurate biomarker and is as good as ARFI in detecting severe fibrosis for chronic liver disease patients.

Wisteria floribunda agglutinin-positive mac-2 binding protein as an age-independent fibrosis marker in nonalcoholic fatty liver disease.

The assessment of liver fibrosis is essential because it correlates with mortality risk in nonalcoholic fatty liver disease (NAFLD). This study aims to examine whether serum fibrosis markers could identify candidate patients likely to have advanced fibrosis. We enrolled 352 patients with NAFLD and performed liver biopsies in 97 patients. The area under the receiver operating characteristic curve (AUROC) of liver stiffness by magnetic resonance elastography for histological advanced fibrosis was 0.910, and the optimal cutoff value was 4.07 kPa. To predict severe liver stiffness (≥4.07 kPa), the AUROC for Wisteria floribunda agglutinin-positive mac-2 binding protein (WFA+-M2BP) and FIB-4 were 0.897 (cutoff value, 1.08) and 0.880 (cutoff value, 2.53), respectively. After stratification of patients into four age groups as quartile, the optimal cutoff values of WFA+-M2BP for predicting severe liver stiffness were similar in each group (1.09, 1.08, 1.10, and 1.12). On the other hand, those of FIB-4 increased in parallel with age (1.47, 2.19, 2.99, and 3.88). In conclusion, WFA+-M2BP was precise for estimating severe liver stiffness in NAFLD with single cutoff value independent of age. Hence, identifying high-risk cases using WFA+-M2BP from a large number of NAFLD patients is clinically significant.

Novel Serum Biomarkers for Noninvasive Diagnosis and Screening of Nonalcoholic Fatty Liver Disease-Related Hepatic Fibrosis.

Nonalcoholic fatty liver disease (NAFLD) is a growing global public health concern and becoming the leading cause of liver disease worldwide. The estimated global prevalence of NAFLD is ∼25% depending on the country and the assessment method used to establish the diagnosis. Meta-analyses suggest that the highest prevalence is in the Middle East (31.8%) and South America (30.4%), and the lowest in Africa (13.5%). In the United States, between 75 and 100 million individuals were estimated to have NAFLD. This important disease is associated with increased incidence of liver-related deaths, hepatocarcinoma, and overall mortality. Fibrosis stage, among other histological characteristics, is the most critical factor in predicting all-cause and disease-specific mortality in NAFLD. The ability to detect fibrosis early in NAFLD patients is critical in controlling mortality associated with this highly prevalent disease. We present here an expert review on recent advances in novel blood biomarkers, for example, the Wisteria floribunda agglutinin-positive mac-2 binding protein (WFA+-M2BP), type IV collagen 7S, chitinase 3 like 1 (CHI3L1; YKL-40), and insulin-like growth factor-1 (IGF-1). Algorithms using multiple biomarkers such as alpha-2-macroglobulin, mir34a, YKL-40, and hemoglobin A1c (HbA1c; NIS4), enhanced liver fibrosis (ELF), Hepascore, FibroMeter, FibroTest, FIBROSpect, FIB-C3, and ADPAPT are highlighted. Novel technologies such as tandem mass spectrometry to directly measure protein turnover rate of the key proteins involved in hepatic fibrosis, as an indicator of fibrogenesis, are also discussed. In conclusion, NAFLD is a growing global health problem that warrants long-term funding, research, and training of scholars across the fields of public health diagnostics, systems sciences, nutrition, hepatology, and clinical oncology.

Identification of mammalian glycoproteins with type-I LacdiNAc structures synthesized by the glycosyltransferase B3GALNT2.

The type-I LacdiNAc (LDN; GalNAcß1-3GlcNAc) has rarely been observed in mammalian cells except in the O-glycan of α-dystroglycan, in contrast to type-II LDN structures (GalNAcß1-4GlcNAc) in N- and O-glycans that are present in many mammalian glycoproteins, such as pituitary and hypothalamic hormones. Although a ß1,3-N-acetylgalactosaminyltransferase 2 (B3GALNT2; type-I LDN synthase) has been cloned, the function of type-I LDN in mammalian cells is still unclear, as its carrier protein(s) has not been identified. In this study, using HeLa cells, we demonstrate that inhibition of Golgi-resident glycosyltransferase increases the abundance of B3GALNT2-synthesized type-I LDN structures, recognized by Wisteria floribunda agglutinin (WFA). Using isotope-coded glycosylation site-specific tagging (IGOT)-LC/MS analysis of Lec8 Chinese hamster cells lacking galactosylation and of cells transfected with the B3GALNT2 gene, we identified the glycoproteins that carry B3GALNT2-generated type-I LDN in their N-glycans. Our results further revealed that LDN presence on low-density lipoprotein receptor-related protein 1 and nicastrin depends on B3GALNT2, indicating the occurrence of type-I LDN in vivo in mammalian cells. Our analysis also uncovered that most of the identified glycoproteins localize to intracellular organelles, particularly to the endoplasmic reticulum. Whereas B4GALNT3 and B4GALNT4 synthesized LDN on extracellular glycoproteins, B3GALNT2 primarily transferred LDN to intracellular glycoproteins, thereby clearly delineating proteins that carry type-I or type-II LDNs. Taken together, our results indicate the presence of mammalian glycoproteins carrying type-I LDN on N-glycans and suggest that type-I and type-II LDNs have different roles in vivo.

Adult vitamin D deficiency disrupts hippocampal-dependent learning and structural brain connectivity in BALB/c mice.

Converging evidence from human and animal studies support an association between vitamin D deficiency and cognitive impairment. Previous studies have shown that hippocampal volume is reduced in adults with vitamin D deficiency as well as in a range of disorders, such as schizophrenia. The aim of the current study was to examine the effect of adult vitamin D (AVD) deficiency on hippocampal-dependent spatial learning, and hippocampal volume and connectivity in healthy adult mice. Ten-week-old male BALB/c mice were fed a control (vitamin D 1500 IU/kg) or vitamin D-depleted (vitamin D 0 IU/kg) diet for a minimum of 10 weeks. The mice were then tested for hippocampal-dependent spatial learning using active place avoidance (APA) and on tests of muscle and motor coordination (rotarod and grip strength). The mice were perfused and brains collected to acquire ex vivo structural and diffusion-weighted images using a 16.4 T MRI scanner. We also performed immunohistochemistry to quantify perineuronal nets (PNNs) and parvalbumin (PV) interneurons in various brain regions. AVD-deficient mice had a lower latency to enter the shock zone on APA, compared to control mice, suggesting impaired hippocampal-dependent spatial learning. There were no differences in rotarod or grip strength, indicating that AVD deficiency did not have an impact on muscle or motor coordination. AVD deficiency did not have an impact on hippocampal volume. However, AVD-deficient mice displayed a disrupted network centred on the right hippocampus with abnormal connectomes among 29 nodes. We found a reduction in PNN positive cells, but no change in PV, centred on the hippocampus. Our results provide compelling evidence to show that AVD deficiency in otherwise healthy adult mice may play a key role in hippocampal-dependent learning and memory formation. We suggest that the spatial learning deficits could be due to the disruption of right hippocampal structural connectivity.

Changes in Dendritic Spine Density and Inhibitory Perisomatic Connectivity onto Medium Spiny Neurons in L-Dopa-Induced Dyskinesia.

Using bacterial artificial chromosome-double transgenic mice expressing tdTomato in D1 receptor-medium spiny neurons (MSNs) and enhanced green fluorescent protein in D2 receptor-MSNs, we have studied changes in spine density and perisomatic GABAergic boutons density in MSNs of both the D1R and D2R pathways, in an experimental model of parkinsonism (mouse injected with 6-hydroxydopamine in the medial forebrain bundle), both in the parkinsonian and dyskinetic condition induced by L-DOPA treatment. To assess changes in perisomatic GABAergic connectivity onto MSNs, we measured the number of contacts originated from parvalbumin (PV)-containing striatal "fast-spiking" interneurons (FSIs), the major component of a feed-forward inhibition mechanism that regulates spike timing in MSNs, in both cell types as well as the number of vesicular GABA transporter (VGAT) contacts. Furthermore, we determined changes in PV-immunoreactive cell density by PV immunolabeling combined with Wisteria floribunda agglutinin (WFA) labeling to detect FSI in a PV-independent manner. We also explored the differential expression of striatal activity-regulated cytoskeleton-associated protein (Arc) and c-Fos in both types of MSNs as a measure of neuronal activation. Our results confirm previous findings of major structural changes in dendritic spine density after nigrostriatal denervation, which are further modified in the dyskinetic condition. Moreover, the finding of differential modifications in perisomatic GABAergic connectivity and neuronal activation in MSNs suggests an attempt by the system to regain homeostasis after denervation and an imbalance between excitation and inhibition leading to the development of dyskinesia after exposure to L-DOPA.

Precocious deposition of perineuronal nets on Parvalbumin inhibitory neurons transplanted into adult visual cortex.

The end of the critical period for primary visual cortex (V1) coincides with the deposition of perineuronal nets (PNN) onto Parvalbumin (PV) inhibitory neurons. Recently, we found that transplantation of embryonic inhibitory neurons into adult V1 reinstates a new critical period. Here we used Wisteria Floribunda Agglutinin (WFA) staining to compare the deposition of PNNs onto neurons during normal development and following transplantation at equivalent cell ages. In accord with previous findings, PV and PNN expression increases from negligible levels at postnatal day 14 (P14) to mature levels by P70. In contrast to P14, PNNs are found on transplanted PV neurons by 21 days after transplantation and persist to 105 days after transplantation. This precocious deposition was specific to PV neurons and excluded transplanted neurons expressing Somatostatin. Notably, the onset of PV expression in transplanted inhibitory neurons follows the timing of PV expression in juvenile V1. Moreover, transplantation has no discernible effect on host PNNs. The precocious deposition of PNNs onto transplanted PV neurons suggests that PNN expression identified by WFA does not reflect neuronal maturity and may be an inaccurate marker for transplant-induced plasticity of cortical circuits.