Rat hepatocytes secrete free oligosaccharides.

We recently established a method for the isolation of serum-free oligosaccharides, and characterized various features of their structures. However, the precise mechanism for how these glycans are formed still remains unclarified. To further investigate the mechanism responsible for these serum glycans, here, we utilized rat primary hepatocytes to examine whether they are able to secrete free glycans. Our findings indicated that a diverse array of free oligosaccharides such as sialyl/neutral free N-glycans (FNGs), as well as sialyl lactose/LacNAc-type glycans, were secreted into the culture medium by primary hepatocytes. The structural features of these free glycans in the medium were similar to those isolated from the sera of the same rat. Further evidence suggested that an oligosaccharyltransferase is involved in the release of the serum-free N-glycans. Our results indicate that the liver is indeed secreting various types of free glycans directly into the serum.

Identification of a buried ß-strand as a novel disease-related motif in the human polysialyltransferases.

The polysialyltransferases ST8SIA2 and ST8SIA4 and their product, polysialic acid (polySia), are known to be related to cancers and mental disorders. ST8SIA2 and ST8SIA4 have conserved amino acid (AA) sequence motifs essential for the synthesis of the polySia structures on the neural cell adhesion molecule. To search for a new motif in the polysialyltransferases, we adopted the in silico Individual Meta Random Forest program that can predict disease-related AA substitutions. The Individual Meta Random Forest program predicted a new eight-amino-acids sequence motif consisting of highly pathogenic AA residues, thus designated as the pathogenic (P) motif. A series of alanine point mutation experiments in the pathogenic motif (P motif) showed that most P motif mutants lost the polysialylation activity without changing the proper enzyme expression levels or localization in the Golgi. In addition, we evaluated the enzyme stability of the P motif mutants using newly established calculations of mutation energy, demonstrating that the subtle change of the conformational energy regulates the activity. In the AlphaFold2 model, we found that the P motif was a buried ß-strand underneath the known surface motifs unique to ST8SIA2 and ST8SIA4. Taken together, the P motif is a novel buried ß-strand that regulates the full activity of polysialyltransferases from the inside of the molecule.

Survival impact of microsatellite instability in stage II gastric cancer patients who received S-1 adjuvant monotherapy after curative resection.

Adjuvant S-1 monotherapy is the standard of care for stage II gastric cancer (GC) after curative resection in Japan, but its efficacy for microsatellite instability-high (MSI-H) tumors has remained unknown. Among a multi-institutional cohort of patients with stage II GC who underwent R0 resection followed by S-1 adjuvant chemotherapy between February 2008 and December 2018, we assessed MSI status with an MSI-IVD Kit (Falco). MSI status was assessable for 184 (88.5%) of the 208 enrolled patients, with MSI-H being identified in 24 (13.0%) individuals. Although neither relapse-free survival (RFS) (hazard ratio [HR] = 1.00, p = 0.997) nor overall survival (OS) (HR = 0.66, p = 0.488) differed between MSI-H versus microsatellite-stable (MSS) patients, MSI-H patients showed a nonsignificant but better RFS (HR = 0.34, p = 0.064) and OS (HR = 0.22, p = 0.057) than did MSS patients after adjustment for background characteristics by propensity score (PS) analysis. Gene expression analysis in the PS-matched cohort suggested that recurrence was associated with the immunosuppressive microenvironment in MSI-H tumors but with expression of cancer/testis antigen genes in MSS tumors. Our data reveal a better adjusted survival for MSI-H versus MSS stage II GC treated with S-1 adjuvant therapy, and they suggest that mechanisms of recurrence differ between MSI-H and MSS tumors.

The Effects of the Use of Diluted Bupivacaine in Sequential Combined Spinal and Epidural Anesthesia for Cesarean Delivery on Maternal Hypotension and Motor Block after Surgery: A Retrospective Observational Study.

BACKGROUND: Maternal hypotension is a common hemodynamic consequence of spinal anesthesia during cesarean delivery, but low-dose spinal anesthesia (<9 mg bupivacaine) ensures stable hemodynamics and reduces motor block. The purpose of this retrospective observational study was to examine the effects of baricity of intrathecal administration of diluted bupivacaine in combined spinal-epidural anesthesia (CSEA) for cesarean delivery on maternal hypotension and motor block after surgery. METHODS: The anesthesia and nursing records of 35 patients who had given birth by cesarean delivery under CSEA with intrathecal administration of plain or hyperbaric bupivacaine diluted in cerebrospinal fluid were reviewed. All patients were assigned to who received hyperbaric bupivacaine (hyperbaric group) or plain bupivacaine (plain group). Definition of feasibility of cesarean delivery by diluted low dose bupivacaine was set as no requirement of epidural administration of levobupivacaine during surgery. The incidences of hypotension (nadir blood pressure less than 80% of preanesthetic value) and motor block were reviewed. RESULTS: In 24 of the patients (68%), no additional epidural anesthesia was needed during surgery. One patient (3%) required additional epidural anesthesia before delivery. Feasibility of cesarean delivery was not different between hyperbaric group and plain group (p>0.99). Eighteen of the patients (51%) did not require vasopressors, while 17 (49%) developed hypotension. There was no difference in incidence of maternal hypotension between hyperbaric and plain group. Only 6 patients (17%) required more than 3 times of administration of vasopressors among all patients. Modified Bromage scale scores were recorded in 28 of the patients (80%); scores of 0 (no motor block) were recorded in seven of them, and 1 in eight of them. CONCLUSION: Low-dose either plain or hyperbaric bupivacaine diluted in cerebrospinal fluid to approximately twice the volume may provide sufficient analgesia, fast motor recovery. Incidence of maternal hypotension was similar in hyperbaric and plain group.

Endoscopic Findings and Treatment of Gastric Neoplasms in Familial Adenomatous Polyposis.

PURPOSE: Gastric neoplasia is a common manifestation of familial adenomatous polyposis (FAP). This study aimed to elucidate the clinical characteristics, endoscopic features including fundic gland polyposis (FGPsis), and treatment outcomes of gastric neoplasms (GNs) in patients with FAP. MATERIALS AND METHODS: A total of 35 patients diagnosed with FAP, including nine patients from four pedigrees who underwent esophagogastroduodenoscopy (EGD), were investigated regarding patient characteristics, GN morphology, and treatment outcomes. RESULTS: Twenty-one patients (60.0%) had 38 GNs; 33 (86.8%) and 5 (13.2%) were histologically diagnosed with adenocarcinoma and adenoma, respectively. There were no specific patient characteristics related to GNs. Nodule-type GNs were more prevalent in patients with FGP than without (52.2% vs. 0.0%, P=0.002) in the upper body of the stomach. Conversely, depressed-type GNs were fewer in patients with FGPsis than in those without (13.0% vs. 73.3%, P<0.001). Slightly elevated-type GNs were observed in both groups (34.8% vs. 20.0%, P=0.538). Even within pedigrees, the background gastric mucosa and types of GNs varied. In total, 24 GNs were treated with endoscopic submucosal dissection (ESD) and eight with endoscopic mucosal resection (EMR). EMR was selected for GNs with FGPsis because of the technical difficulty of ESD, resulting in a lower en bloc resection rate (62.5% vs. 100%, P=0.014). CONCLUSIONS: Our study indicates the necessity of routine EGD surveillance in patients diagnosed with FAP. Notably, the morphology and location of GNs differed between patients with and without FGPsis. Endoscopic treatment and outcomes require more attention in cases of FGPsis.

CmLec4, a lectin from the fungus Cordyceps militaris, controls host infection and fruiting body formation.

Fungi belonging to the Ascomycete genus Cordyceps are endoparasitoids and parasites, mainly of insects and other arthropods. Cordyceps militaris has been used as a therapeutic drug for cancer patients. However, the infection, parasitism, and fruiting body formation mechanisms of this fungus are still unknown. Based on our hypothesis that lectin(s) is involved in the interaction between the C. militaris fungi and insects, we partially purified and characterized a new lectin from C. militaris, designated CmLec4. In addition, we searched for substance(s) in the infected silkworm extracts that could bind to CmLec4, and succeeded in purifying the sex-specific storage protein 2 as a specific binding target. To examine function of the binding protein during the process of parasitism, we investigated the effect of recombinant CmLec4 on silkworms by inoculating the protein into silkworm pupae, and found that it significantly delayed emergence compared to the control. Furthermore, cmlec4 gene knockout strains constructed in this study produced markedly lower amounts of fruiting body than the wild-type strain. All the results revealed that the lectin CmLec4 produced by C. militaris would be involved in the infection into silkworm and fruiting body formation from the host.

Comprehensive Analysis of Oligo/Polysialylglycoconjugates in Cancer Cell Lines.

In cancer cells, cell-surface sialylation is altered, including a change in oligo/polysialic acid (oligo/polySia) structures. Since they are unique and rarely expressed in normal cells, oligo/polySia structures may serve as promising novel biomarkers and targets for therapies. For the diagnosis and treatment of the disease, a precise understanding of the oligo/polySia structures in cancer cells is necessary. In this study, flow cytometric analysis and gene expression datasets were obtained from sixteen different cancer cell lines. These datasets demonstrated the ability to predict glycan structures and their sialylation status. Our results also revealed that sialylation patterns are unique to each cancer cell line. Thus, we can suggest promising combinations of antibody and cancer cell for glycan prediction. However, the precise prediction of minor glycans need to be further explored.

The α2,8-sialyltransferase 6 (St8sia6) localizes in the ER and enhances the anchorage-independent cell growth in cancer.

Sialylation, the final stage of post-translational modification of proteins, is achieved in the Golgi apparatus and is related to the malignant phenotype of cancer. Disialylation of ganglioside (GD3) by St8sia1 and polysialylation by St8sia2 and 4 have been shown to be related to malignant phenotypes; however, di/oligosialylation by St8sia6 is still unknown. In this study, we analyzed the malignant phenotype of St8sia6 and found that upregulation of St8sia6 in melanoma B16 cells increased anchorage-independent cell growth, which was not due to sialic acid cleavage by a sialidase. Moreover, unlike other sialyltransferases, St8sia6 localized to the endoplasmic reticulum (ER). We found that the localization to the Golgi apparatus could be regulated by swapping experiments using St8sia2; however, the malignant phenotype did not change. These data demonstrate that the enhancement of anchorage-independent cell growth by St8sia6 is not due to its localization of ER, but is due to the expression of the protein itself.

Analysis of biochemical features of ST8 α-N-acetyl-neuraminide α2,8-sialyltransferase (St8sia) 5 isoforms.

Gangliosides are important components of the membrane and are involved in many biological activities. St8sia5 is an α2,8-sialyltransferase involved in ganglioside synthesis, and has three isoforms. In this study, we analyzed the features of three isoforms, St8sia5-S, -M, and -L that had not been analyzed, and found that only St8sia5-L was localized in the Golgi, while the majority of St8sia5-M and -S were localized in the ER. The localization of Golgi of St8sia5 depended on the stem region. In addition, the incorporation of exogenous GD3 was upregulated only in St8sia5-L expressing cells. Taken together, the localization of St8sia5 is important for the activity of the enzyme.

MAPT R406W increases tau T217 phosphorylation in absence of amyloid pathology.

OBJECTIVE: Tau hyperphosphorylation at threonine 217 (pT217) in cerebrospinal fluid (CSF) has recently been linked to early amyloidosis and could serve as a highly sensitive biomarker for Alzheimer's disease (AD). However, it remains unclear whether other tauopathies induce pT217 modifications. To determine if pT217 modification is specific to AD, CSF pT217 was measured in AD and other tauopathies. METHODS: Using immunoprecipitation and mass spectrometry methods, we compared CSF T217 phosphorylation occupancy (pT217/T217) and amyloid-beta (Aß) 42/40 ratio in cognitively normal individuals and those with symptomatic AD, progressive supranuclear palsy, corticobasal syndrome, and sporadic and familial frontotemporal dementia. RESULTS: Individuals with AD had high CSF pT217/T217 and low Aß42/40. In contrast, cognitively normal individuals and the majority of those with 4R tauopathies had low CSF pT217/T217 and normal Aß 42/40. We identified a subgroup of individuals with increased CSF pT217/T217 and normal Aß 42/40 ratio, most of whom were MAPT R406W mutation carriers. Diagnostic accuracies of CSF Aß 42/40 and CSF pT217/T217, alone and in combination were compared. We show that CSF pT217/T217 × CSF Aß 42/40 is a sensitive composite biomarker that can separate MAPT R406W carriers from cognitively normal individuals and those with other tauopathies. INTERPRETATION: MAPT R406W is a tau mutation that leads to 3R+4R tauopathy similar to AD, but without amyloid neuropathology. These findings suggest that change in CSF pT217/T217 ratio is not specific to AD and might reflect common downstream tau pathophysiology common to 3R+4R tauopathies.

Durable response to EGFR tyrosine kinase inhibitors in a patient with non-small cell lung cancer harboring an EGFR kinase domain duplication.

Epidermal growth factor receptor (EGFR) kinase domain duplication (KDD) has been identified as an oncogenic driver in 0.05% to 0.14% of non-small cell lung cancer (NSCLC) patients. However, little is known of the efficacy of EGFR tyrosine kinase inhibitors (TKIs) for such patients. Here, we report the case of a 45-year-old Japanese woman with NSCLC positive for EGFR-KDD (duplication of exons 18-25) who developed carcinomatous meningitis and showed a marked response to the EGFR-TKIs erlotinib and osimertinib. As far as we are aware, this is the first report of EGFR-TKI efficacy for carcinomatous meningitis in a NSCLC patient harboring EGFR-KDD.

Identification and functional characterization of a Siglec-7 counter-receptor on K562 cells.

Sialic acid (Sia)-binding immunoglobulin-like lectin 7 (Siglec-7) is an inhibitory receptor primarily expressed on natural killer (NK) cells and monocytes. Siglec-7 is known to negatively regulate the innate immune system through Sia binding to distinguish self and nonself; however, a counter-receptor bearing its natural ligand remains largely unclear. Here, we identified a counter-receptor of Siglec-7 using K562 hematopoietic carcinoma cells presenting cell surface ligands for Siglec-7. We affinity-purified the ligands using Fc-ligated recombinant Siglec-7 and diSia-dextran polymer, a strong inhibitor for Siglec-7. We then confirmed the counter-receptor for Siglec-7 as leukosialin (CD43) through mass spectrometry, immunoprecipitation, and proximity labeling. Additionally, we demonstrated that the cytotoxicity of NK cells toward K562 cells was suppressed by overexpression of leukosialin in a Siglec-7-dependent manner. Taken together, our data suggest that leukosialin on K562 is a counter-receptor for Siglec-7 on NK cells and that a cluster of the Sia-containing glycan epitope on leukosialin is key as trans-ligand for unmasking the cis-ligand.

Clinical Application of the FoundationOne CDx Assay to Therapeutic Decision-Making for Patients with Advanced Solid Tumors.

BACKGROUND: Implementation of personalized medicine requires the accessibility of tumor molecular profiling in order to allow prioritization of appropriate targeted therapies for individual patients. Our aim was to study the role of comprehensive genomic profiling assays that may inform treatment recommendations for patients with solid tumors. MATERIALS AND METHODS: We performed a prospective study to evaluate the feasibility of application of the FoundationOne CDx panel-which detects substitutions, insertions and deletions, and copy number alterations in 324 genes, select gene rearrangements, and genomic signatures including microsatellite instability and tumor mutation burden (TMB)-to patients with advanced or recurrent solid tumors before its approval in Japan. RESULTS: A total of 181 samples were processed for genomic testing between September 2018 and June 2019, with data being successfully obtained for 175 of these samples, yielding a success rate of 96.7%. The median turnaround time was 41 days (range, 21-126 days). The most common known or likely pathogenic variants were TP53 mutations (n = 113), PIK3CA mutations (n = 33), APC mutations (n = 32), and KRAS mutations (n = 29). Among the 153 patients assessed for TMB, the median TMB was 4 mutations/Mb, and tumors with a high TMB (≥10 mutations/Mb) were more prevalent for lung cancer (11/32) than for other solid tumor types (9/121, Fisher's exact test p < .01). No clear trend toward increased efficacy for immune checkpoint inhibitor (ICI) monotherapy or ICI combination chemotherapy in patients with a high programmed cell death-ligand 1 tumor proportion score or a high TMB was apparent. Among the 174 patients found to harbor known or likely pathogenic actionable alterations, 24 individuals (14%) received matched targeted therapy. CONCLUSION: The FoundationOne CDx assay was performed with formalin-fixed, paraffin-embedded tumor specimens with a success rate of >95%. Such testing may inform the matching of patients with cancer with investigational or approved targeted drugs. IMPLICATIONS FOR PRACTICE: This prospective cohort study was initiated to investigate the feasibility and utility of clinical application of FoundationOne CDx. A total of 181 samples were processed for genomic testing between September 2018 and June 2019, with data being successfully obtained for 175 of these samples, yielding a success rate of 96.7%, and 24 individuals (14%) received matched targeted therapy.

Polysialylation and disease.

Polysialic acid (polySia, PSA) is a unique constituent of the glycocalyx on the surface of bacterial and vertebrate cells. In vertebrates, its biosynthesis is highly regulated, not only in quantity and quality, but also in time and location, which allows polySia to be involved in various important biological phenomena. Therefore, impairments in the expression and structure of polySia sometimes relate to diseases, such as schizophrenia, bipolar disorder, and cancer. Some bacteria express polySia as a tool for protecting themselves from the host immune system during invasion. PolySia is proven to be a biosafe material; polySia, as well as polySia-recognizing molecules, are key therapeutic agents. This review first comprehensive outlines the occurrence, features, biosynthesis, and functions of polySia and subsequently focuses on the related diseases.

Comparative Studies of Polysialic Acids Derived from Five Different Vertebrate Brains.

Polysialic acid (polySia/PSA) is a linear homopolymer of sialic acid (Sia) that primarily modifies the neural cell adhesion molecule (NCAM) in mammalian brains. PolySia-NCAM not only displays an anti-adhesive function due to the hydration effect, but also possesses a molecule-retaining function via a direct binding to neurologically active molecules. The quality and quantity of polySia determine the function of polySia-NCAM and are considered to be profoundly related to the maintenance of normal brain functions. In this study, to compare the structures of polySia-NCAM in brains of five different vertebrates (mammals, birds, reptiles, amphibians, and fish), we adopted newly developed combinational methods for the analyses. The results revealed that the structural features of polySia considerably varied among different species. Interestingly, mice, as a mammal, possess eminently distinct types of polySia, in both quality and quantity, compared with those possessed by other animals. Thus, the mouse polySia is of larger quantities, of longer and more diverse chain lengths, and of a larger molecular size with higher negative charge, compared with polySia of other species. These properties might enable more advanced brain function. Additionally, it is suggested that the polySia/Sia ratio, which likely reflects the complexity of brain function, can be used as a new promising index to evaluate the intelligence of different vertebrate brains.

Combinational Analyses with Multiple Methods Reveal the Existence of Several Forms of Polysialylated Neural Cell Adhesion Molecule in Mouse Developing Brains.

Polysialic acid (polySia/PSA) is an anionic glycan polymer of sialic acid, and it mostly modifies the neural cell adhesion molecule (NCAM) in mammalian brains. Quality and quantity of the polySia of the polySia-NCAM is spatio-temporally regulated in normal brain development and functions, and their impairments are reported to be related to diseases, such as psychiatric disorders and cancers. Therefore, precise understanding of the state of polySia-NCAM structure would lead to the diagnosis of diseases for which their suitable evaluation methods are necessary. In this study, to develop these evaluation methods, structures of polySia-NCAM from mouse brains at six different developmental stages were analyzed by several conventional and newly developed methods. Integrated results of these experiments clearly demonstrated the existence of different types of polySia-NCAMs in developing brains. In addition, combinational analyses were shown to be useful for precise understanding of the quantity and quality of polySia, which can provide criteria for the diagnosis of diseases.

Regional correlation of biochemical measures of amyloid and tau phosphorylation in the brain.

Alzheimer's disease (AD) neuropathologic change is characterized by amyloid plaques and neurofibrillary tangles (NFTs) that consist of aggregated amyloid beta (Abeta) and hyperphosphorylated tau proteins (p-tau), respectively. Although the global relationship between Abeta and p-tau has been studied for decades, it is still unclear whether a regional correlation exists between Abeta and p-tau in the human brain. Recent studies in cerebrospinal fluid (CSF) have suggested that tau phosphorylation at specific sites such as T217 is modified at an early stage of AD when amyloid plaques become detectable. We applied biochemical and mass spectrometry methods in human brain samples with and without Abeta plaque pathology to measure site-specific phosphorylation occupancies in soluble and insoluble tau. Our quantitative results identified multiple residues specifically hyper-phosphorylated in AD, including at sites T111, T153, S184 (or S185), T205, S208, T217, S262, and S285 in brain soluble tau. In contrast, the most enriched phosphorylated residues in brain insoluble tau were T111, S113, T153, T181, S199, S202, T205, T217, T231, S262, and S396. Tau phosphorylation occupancies in the insoluble fraction were relatively constant across brain regions, suggesting that tau has a consistent phosphorylation pattern once it has aggregated into NFTs. We did not find regional association between Abeta42 and insoluble tau. However, the phosphorylation profile of soluble tau in AD brain was highly correlated to that in AD CSF, which was analyzed in a previous study. We also found a higher regional association between total Abeta42 and soluble tau phosphorylation occupancy at residues T111, T153 and T217 in the brain. This study provides insights into regional interactions between amyloidosis and specific tau phosphorylated residues in the human brain and may explain the specific increases of tau species phosphorylation observed in AD CSF.

Blood plasma phosphorylated-tau isoforms track CNS change in Alzheimer's disease.

Highly sensitive and specific plasma biomarkers for Alzheimer's disease (AD) have the potential to improve diagnostic accuracy in the clinic and facilitate research studies including enrollment in prevention and treatment trials. We recently reported CSF tau hyperphosphorylation, especially on T217, is an accurate predictor of ß-amyloidosis at asymptomatic and symptomatic stages. In the current study, we determine by mass spectrometry the potential utility of plasma p-tau isoforms to detect AD pathology and investigate CSF and plasma tau isoforms' profile relationships. Plasma tau was truncated as previously described in CSF. CSF and plasma measures of p-tau-217 and p-tau-181 were correlated. No correlation was found between CSF and plasma on total-tau levels and pS202 measures. We found p-tau-217 and p-tau-181 were highly specific for amyloid plaque pathology in the discovery cohort (n = 36, AUROC = 0.99 and 0.98 respectively). In the validation cohort (n = 92), p-tau-217 measures were still specific to amyloid status (AUROC = 0.92), and p-tau-181 measures were less specific (AUROC = 0.75).

PSA-NCAM Colocalized with Cholecystokinin-Expressing Cells in the Hippocampus Is Involved in Mediating Antidepressant Efficacy.

The extracellular glycan polysialic acid linked to neural cell adhesion molecule (PSA-NCAM) is principally expressed in the developing brain and the adult neurogenic regions. Although colocalization of PSA-NCAM with cholecystokinin (CCK) was found in the adult brain, the role of PSA-NCAM remains unclear. In this study, we aimed to elucidate the functional significance of PSA-NCAM in the CA1 region of the male mouse hippocampus. Combined fluorescence in situ hybridization and immunohistochemistry showed that few vesicular glutamate transporter 3-negative/CCK-positive (VGluT3-/CCK+) cells were colocalized with PSA-NCAM, but most of the VGluT3+/CCK+ cells were colocalized with PSA-NCAM. The somata of PSA-NCAM+/CCK+ cells were highly innervated by serotonergic boutons than those of PSA-NCAM-/CCK+ cells. The expression ratios of 5-HT3A receptors and p11, a serotonin receptor-interacting protein, were higher in PSA-NCAM+/CCK+ cells than in PSA-NCAM-/CCK+ cells. Pharmacological digestion of PSA-NCAM impaired the efficacy of antidepressant fluoxetine (FLX), a selective serotonin reuptake inhibitor, but not the efficacy of benzodiazepine anxiolytic diazepam. A Western blot showed that restraint stress decreased the expressions of p11 and mature brain-derived neurotrophic factor (BDNF), and FLX increased them. Interestingly, the FLX-induced elevation of expression of p11, but not mature BDNF, was impaired by the digestion of PSA-NCAM. Quantitative reverse transcription-polymerase chain reaction showed that restraint stress reduced the expression of polysialyltransferase ST8Sia IV and FLX elevated it. Collectively, PSA-NCAM colocalized with VGluT3+/CCK+ cells in the CA1 region of the hippocampus may play a unique role in the regulation of antidepressant efficacy via the serotonergic pathway.SIGNIFICANCE STATEMENT Polysialic acid (PSA) is composed of eight or more α2,8-linked sialic acids. Here, we examined the functional significance of polysialic acid linked to the neural cell adhesion molecule (PSA-NCAM) in the adult mouse hippocampus. Few vesicular glutamate transporter 3-negative/cholecystokinin-positive (VGluT3-/CCK+) cells were colocalized with PSA-NCAM, but most of the VGluT3+/CCK+ cells were colocalized with PSA-NCAM. The expression ratios of 5-HT3A receptors and p11, a serotonin receptor-interacting protein, were higher in PSA-NCAM+/CCK+ cells than in PSA-NCAM-/CCK+ cells. The efficacy of antidepressants, but not anxiolytics, was impaired by the digestion of PSA-NCAM. The antidepressant-induced increase in p11 expression was inhibited following PSA-NCAM digestion. We hence hypothesize that PSA-NCAM colocalized with VGluT3+/CCK+ cells may play a unique role in regulating antidepressant efficacy.