Adaptor-related Protein Complex Research Articles

AP3M2: A key regulator from the nervous system modulates autophagy in colorectal cancer

Colorectal cancer (CRC) affects approximately a million people annually with a mortality rate of 50 %, accounting for 8 % of cancer-related deaths globally. Molecular characterization by The Cancer Genome Atlas could be useful in these tumor subtypes to reveal "druggable" genes. Our study focuses on the significance of the AP3M2 gene (adaptor-related protein complex 3 subunit mu 2) as a potential oncogene by employing RNA interference to inactivate AP3M2. AP3M2, inplicated in protein trafficking to lysosomes pathway and specialized organelles in neuronal cells, was amplified in CRC cell lines. The Knockdown of AP3M2 significantly reduced the viability of three CRC cell lines HCT-116, CACO2, and HT29. Intriguingly, our findings revealed an interaction between AP3M2 expression and autophagy-related genes, as well as reactive oxygen species (ROS) levels in CRC cell lines. These results suggest that targeting AP3M2 could provide a powerful strategy for CRC treatment through autophagy-ROS mechanism.

SUMOylation-induced membrane localization of TRPV1 suppresses proliferation and migration in gastric cancer cells

Gastric cancer (GC) remains a significant health challenge due to its high mortality rate and the limited efficacy of current targeted therapies. A critical barrier in developing more effective treatments is the lack of understanding of specific mechanisms driving GC progression. This study investigates the role of Transient Receptor Potential Vanilloid 1 (TRPV1), a non-selective cation channel known for its high Ca2+ permeability and tumor-suppressive properties in gastrointestinal cancers. Specifically, we explore the impact of SUMOylation—a dynamic and reversible post-translational modification—on TRPV1’s function in GC. We demonstrate that SUMOylation of TRPV1 inhibits cell proliferation and migration in MGC-803 and AGS GC cells. By mutating amino acids near TRPV1’s existing SUMO motif (slKpE), we created a bidirectional SUMO motif (EψKψE) that enhances TRPV1 SUMOylation, resulting in further suppression of GC cell proliferation and migration. In vivo studies support these findings, showing that TRPV1 SUMOylation prevents spontaneous tumorigenesis in a mouse GC model. Further investigation reveals that TRPV1 SUMOylation increases the protein’s membrane expression by inhibiting its interaction with the adaptor-related protein complex 2 mu 1 subunit (AP2M1). This elevated membrane expression leads to increased intracellular Ca2+ influx, activating the AMP-activated protein kinase (AMPK) pathway, which in turn inhibits the proliferation and migration of GC cells.

Revising pathogenesis of AP1S1-related MEDNIK syndrome: a missense variant in the AP1S1 gene as a causal genetic lesion.

MEDNIK syndrome is a rare autosomal recessive disease characterized by mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis, and keratoderma, and caused by variants in the adaptor-related protein complex 1 subunit sigma 1 (AP1S1) gene. This gene encodes the σ1A protein, which is a subunit of the adaptor protein complex 1 (AP-1), a key component of the intracellular protein trafficking machinery. Previous work identified three AP1S1 nonsense, frameshift and splice-site variants in MEDNIK patients predicted to encode truncated σ1A proteins, with consequent AP-1 dysfunction. However, two AP1S1 missense variants (c.269T > C and c.346G > A) were recently reported in patients who presented with severe enteropathy but no additional symptoms of MEDNIK. This condition was described as a novel non-syndromic form of congenital diarrhea caused specifically by the AP1S1 missense variants. In this study, we report two patients with the same c.269T > C variant, who, contrary to the previous cases, presented as complete MEDNIK syndrome. These data substantially revise the presentation of disorders associated with AP1S1 gene variants and indicate that all the identified pathogenic AP1S1 variants result in MEDNIK syndrome. We also provide a series of functional analyses that elucidate the impact of the c.269T > C variant on σ1A function, contributing to a better understanding of the molecular pathogenesis of MEDNIK syndrome. KEY MESSAGES: A missense AP1S1 c.269T > C (σ1A L90P) variant causes full MEDNIK syndrome. The σ1A L90P variant is largely unable to assemble into the AP-1 complex. The σ1A L90P variant fails to bind [DE]XXXL[LI] sorting motifs. The σ1A L90P variant results in loss-of-function of the protein.

AP3B1 facilitates PDIA3/ERP57 function to regulate rabies virus glycoprotein selective degradation and viral entry

ABSTRACT Rabies virus causes an estimated 59,000 annual fatalities worldwide and promising therapeutic treatments are necessary to develop. In this study, affinity tag-purification mass spectrometry was employed to delineate RABV glycoprotein and host protein interactions, and PDIA3/ERP57 was identified as a potential inhibitor of RABV infection. PDIA3 restricted RABV infection with follow mechanisms: PDIA3 mediated the degradation of RABV G protein by targeting lysine 332 via the selective macroautophagy/autophagy pathway; The PDIA3 interactor, AP3B1 (adaptor related protein complex 3 subunit beta 1) was indispensable in PDIA3-triggered selective degradation of the G protein; Furthermore, PDIA3 competitively bound with NCAM1/NCAM (neural cell adhesion molecule 1) to block RABV G, hindering viral entry into host cells. PDIA3 190-199 aa residues bound to the RABV G protein were necessary and sufficient to defend against RABV. These results demonstrated the therapeutic potential of biologics that target PDIA3 or utilize PDIA3 190-199 aa peptide to treat clinical rabies. Abbreviation: aa: amino acids; ANXA2: annexin A2; AP-MS: affinity tag purification-mass spectrometry; AP3B1: adaptor related protein complex 3 subunit beta 1; ATP6V1A: ATPase H+ transporting V1 subunit A; ATP6V1H: ATPase H+ transporting V1 subunit H; BafA1: bafilomycin A1; CHX: cycloheximide; co-IP: co-immunoprecipitation; DDX17: DEAD-box helicase 17; DmERp60: drosophila melanogaster endoplasmic reticulum p60; EBOV: Zaire ebolavirus virus; EV: empty vector; GANAB: glucosidase II alpha subunit; G protein: glycoprotein; GRM2/mGluR2: glutamate metabotropic receptor 2; HsPDIA3: homo sapiens protein disulfide isomerase family A member 3; IAV: influenza virus; ILF2: interleukin enhancer binding factor 2; KO: knockout; MAGT1: magnesium transporter 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MmPDIA3: mus musculus protein disulfide isomerase associated 3; NCAM1/NCAM: neural cell adhesion molecule 1; NGFR/p75NTR: nerve growth factor receptor; NGLY1: N-glycanase 1; OTUD4: OTU deubiquitinase 4; PDI: protein disulfide isomerase; PPIs: protein-protein interactions; RABV: rabies virus; RUVBL2: RuvB like AAA ATPase 2; SCAMP3: secretory carrier membrane protein 3; ScPdi1: Saccharomyces cerevisiae s288c protein disulfide isomerase 1; SLC25A6: solute carrier family 25 member 6; SQSTM1/p62: sequestosome 1; VSV: vesicular stomatitis virus.

A clathrin mediated endocytosis scaffolding protein, Intersectin 1, changes in an isoform, brain region, and sex specific manner in Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia and is characterized by the accumulation of amyloid-beta (Aβ) plaques and neurofibrillary Tau tangles in the brain. We previously identified a set of candidate AD microRNAs (miRNAs) in human cerebrospinal fluid (CSF) and used a target prediction pipeline to identify mRNAs and pathways that could potentially be regulated by the miRNAs. Of these pathways, clathrin mediated endocytosis (CME) was selected for further investigation. CME is altered in multiple brain cell types in AD and is implicated in early cellular phenotypes such as enlarged early endosomes and pathogenic processing of Aβ. However, a comprehensive evaluation of major CME hub proteins in humans with AD across multiple brain regions is lacking. Thus, we used immunoblots to evaluate human post-mortem AD and control (CTL) frontal cortex (FC; AD n = 22, CTL n = 23) and hippocampus (HP; AD n = 34, CTL n = 22) for changes in Intersectin 1 (ITSN1), Phosphatidylinositol Binding Clathrin Assembly Protein gene (PICALM), Clathrin Light Chain (CLT), FCH and Mu Domain Containing Endocytic Adaptor 1 (FCHO1), Adaptor Related Protein Complex 2 (AP2) Subunit Alpha 1 (AP2A1), and Dynamin 2 (DNM2). Of these, we found that in AD, ITSN1-long (ITSN1-L) was decreased in the FC of males and HP of females, while ITSN1-short was increased in the HP of both males and females. We further evaluated ITSN1-L levels in cortex (CTX) and HP of the 5xFAD mouse model of Aβ pathology at different timepoints during aging and disease progression by immunoblot (n = 5-8 per group). At 3 months, female 5xFAD exhibited an increase of ITSN1-L in CTX but a decrease at 6 and 9 months. Additionally, immunofluorescent staining of 5xFAD primary HP neurons showed an increase of ITSN1-L in matured 5xFAD neurons at 21 and 28 days in vitro. Together, our studies show that in AD, isoforms of ITSN1 change in a brain region-and sex-dependent manner. Further, changes in ITSN1-L are transient with levels increasing during early Aβ accumulation and decreasing during later progression. These findings suggest that ITSN1 expression, and consequently CME activity, may change depending on the stage of disease progression.

Neither alpha-synuclein fibril strain nor host murine genotype influences seeding efficacy

Parkinson’s disease (PD) is a neurodegenerative disease characterized by progressive motor symptoms and alpha-synuclein (αsyn) aggregation in the nervous system. For unclear reasons, PD patients with certain GBA1 mutations (GBA-PD) have a more aggressive clinical progression. Two testable hypotheses that can potentially account for this phenomenon are that GBA1 mutations promote αsyn spread or drive the generation of highly pathogenic αsyn polymorphs (i.e., strains). We tested these hypotheses by treating homozygous GBA1 D409V knockin (KI) mice with human α-syn-preformed fibrils (PFFs) and treating wild-type mice (WT) with several αsyn-PFF polymorphs amplified from brain autopsy samples collected from patients with idiopathic PD and GBA-PD patients with either homozygous or heterozygous GBA1 mutations. Robust phosphorylated-αsyn (PSER129) positive pathology was observed at the injection site (i.e., the olfactory bulb granule cell layer) and throughout the brain six months following PFF injection. The PFF seeding efficiency and degree of spread were similar regardless of the mouse genotype or PFF polymorphs. We found that PFFs amplified from the human brain, regardless of patient genotype, were generally more effective seeders than wholly synthetic PFFs (i.e., non-amplified); however, PFF concentration differed between these two studies, which might also account for the observed differences. To investigate whether the molecular composition of pathology differed between different seeding conditions, we performed Biotinylation by Antibody Recognition on PSER129 (BAR-PSER129). We found that for BAR-PSER129, the endogenous PSER129 pool dominated identified interactions, and thus, very few potential interactions were explicitly identified for seeded pathology. However, we found Dynactin Subunit 2 (Dctn2) interaction was shared across all PFF conditions, and NCK Associated Protein 1 (Nckap1) and Adaptor Related Protein Complex 3 Subunit Beta 2 (Ap3b2) were unique to PFFs amplified from GBA-PD brains of heterozygous mutation carriers. In conclusion, both the genotype and αsyn strain had little effect on overall seeding efficacy and global PSER129-interactions.

Host proteins interact with viral elements and affect the life cycle of highly pathogenic avian influenza A virus H7N9

Host-virus interactions can significantly impact the viral life cycle and pathogenesis; however, our understanding of the specific host factors involved in highly pathogenic avian influenza A virus H7N9 (HPAI H7N9) infection is currently restricted. Herein, we designed and synthesized 65 small interfering RNAs targeting host genes potentially associated with various aspects of RNA virus life cycles. Afterward, HPAI H7N9 viruses were isolated and RNA interference was used to screen for host factors likely to be involved in the life cycle of HPAI H7N9. Moreover, the research entailed assessing the associations between host proteins and HPAI H7N9 proteins. Twelve key host proteins were identified: Annexin A (ANXA)2, ANXA5, adaptor related protein complex 2 subunit sigma 1 (AP2S1), adaptor related protein complex 3 subunit sigma 1 (AP3S1), ATP synthase F1 subunit alpha (ATP5A1), COPI coat complex subunit alpha (COP)A, COPG1, heat shock protein family A (Hsp70) member 1A (HSPA)1A, HSPA8, heat shock protein 90 alpha family class A member 1 (HSP90AA1), RAB11B, and RAB18. Co-immunoprecipitation revealed intricate interactions between viral proteins (hemagglutinin, matrix 1 protein, neuraminidase, nucleoprotein, polymerase basic 1, and polymerase basic 2) and these host proteins, presumably playing a crucial role in modulating the life cycle of HPAI H7N9. Notably, ANXA5, AP2S1, AP3S1, ATP5A1, HSP90A1, and RAB18, were identified as novel interactors with HPAI H7N9 proteins rather than other influenza A viruses (IAVs). These findings underscore the significance of host-viral protein interactions in shaping the dynamics of HPAI H7N9 infection, while highlighting subtle variations compared with other IAVs. Deeper understanding of these interactions holds promise to advance disease treatment and prevention strategies.

Proteomic characterization of hUC-MSC extracellular vesicles and evaluation of its therapeutic potential to treat Alzheimer’s disease

In recent years, human umbilical cord mesenchymal stem cell (hUC-MSC) extracellular vesicles (EVs) have been used as a cell replacement therapy and have been shown to effectively overcome some of the disadvantages of cell therapy. However, the specific mechanism of action of EVs is still unclear, and there is no appropriate system for characterizing the differences in the molecular active substances of EVs produced by cells in different physiological states. We used a data-independent acquisition (DIA) quantitative proteomics method to identify and quantify the protein composition of two generations EVs from three different donors and analysed the function and possible mechanism of action of the proteins in EVs of hUC-MSCs via bioinformatics. By comparative proteomic analysis, we characterized the different passages EVs. Furthermore, we found that adaptor-related protein complex 2 subunit alpha 1 (AP2A1) and adaptor-related protein complex 2 subunit beta 1 (AP2B1) in hUC-MSC-derived EVs may play a significant role in the treatment of Alzheimer's disease (AD) by regulating the synaptic vesicle cycle signalling pathway. Our work provides a direction for batch-to-batch quality control of hUC-MSC-derived EVs and their application in AD treatment.

Spatiotemporal expression of AP-2/myosin Ⅵ in mouse cochlear IHCs and correlation with auditory function

Background Recycling of synaptic vesicles plays an important role in vesicle pool replenishment, neurotransmitter release and synaptic plasticity. Clathrin-mediated endocytosis (CME) is considered to be the main mechanism for synaptic vesicle replenishment. AP-2 (adaptor-related protein complex 2) and myosin Ⅵ are known as key proteins that regulate the structure and dynamics of CME. Objective This study aims to reveal the spatiotemporal expression of AP-2/myosin Ⅵ in inner hair cells (IHCs) of the mouse cochlea and its correlation with auditory function. Material and Methods Immunofluorescence was used to detect the localization and expression of AP-2 and myosin Ⅵ in cochlear hair cells (HCs) of CBA/CaJ mice of various ages. qRT-PCR was used to verify the differential expression of AP-2 and myosin Ⅵ mRNA in the mouse cochlea, and ABR tests were administered to mice of various ages. A preliminary analysis of the correlation between AP-2/myosin Ⅵ levels and auditory function was conducted. Results AP-2 was located in the cytoplasmic region of IHCs and was mainly expressed in the basal region of IHCs and the area near ribbon synapses, while myosin Ⅵ was expressed in the cytoplasmic region of IHCs and OHCs. Furthermore, AP-2 and myosin Ⅵ were not significant detected in the cochleae of P7 mice; the expression level reached a peak at P35 and then decreased significantly with age. The expression patterns and expression levels of AP-2 and myosin Ⅵ in the cochleae of the mice were consistent with the development of the auditory system. Conclusions and Significance AP-2 and myosin Ⅵ protein expression may differ in mice of different ages, and this variation probably leads to a difference in the efficiency in CME; it may also cause a defect in IHC function.

Prognostic and immunological role of adaptor related protein complex 3 subunit mu2 in colon cancer

The expression levels and prognostic role of AP3M2 in colorectal adenocarcinoma (CRAC) have yet to be fully unveiled. Our study comprehensively investigated the clinical significance of AP3M2 in colorectal cancer through an extensive bioinformatics data mining process (TCGA, GEO, GEPIA, Timer, Ualcan, ROCPLOT, and David), followed by experimental validation. We found AP3M2 is a cancer gene, which can be used to distinguish between colorectal cancer and colorectal adenomas, liver metastasis, lung metastasis, colorectal polyp. Higher AP3M2 expression levels were associated with longer overall survival in colon adenocarcinoma. AP3M2 might be the primary biomarker for oxaliplatin in colon cancer and an acquired resistance biomarker for oxaliplatin and 5-fu. AP3M2 was positively associated with CD274, CTLA4. AP3M2 might be associated with T-cell, NF-kappaB transcription factor activity, and response to hypoxia. AP3M2 could predict chemotherapy effectiveness and prognosis for colon cancer patients. AP3M2 might inhibit tumor growth via influencing tumor-infiltrating immune cells in the context of Tumor microenvironment. AP3M2 plays as an oncogene in CRAC and is suggested as a new potential biotarget for therapy.

Therapeutic targets for endometriosis: Genome-wide Mendelian randomization and colocalization analyses

BackgroundEndometriosis (EM) greatly affects women's reproductive health, identifying new drug targets for EM is urgently needed. This study utilizes comprehensive genome-wide Mendelian randomization (MR) and colocalization analyses, using genomic data, to identify potential therapeutic approaches for EM. MethodsGenome-wide cis-expression quantitative trait loci (cis-eQTL) data were obtained from GTEx V8, which included 838 participants across 49 tissues or cells, and the eQTLGen consortium, which included 31,684 participants. Genome-wide association analysis (GWAS) data for EM were sourced from the FinnGen study, which consisted of 8,288 cases and 68,969 controls, as well as the UK Biobank study, which included 1,496 cases and 359,698 controls. This study utilized MR analysis to assess the correlation between genes and the risk of EM. Subsequently, colocalization analysis was conducted to investigate potential shared causal variants between the identified genes and EM. ResultsAfter conducting MR and colocalization analyses, we identified a total of 13 genes that showed significant evidence of colocalization. These genes are considered promising therapeutic candidates for treating EM. Among them, inner membrane mitochondrial protein (IMMT), src kinase associated phosphoprotein 1 (SKAP1), lysine methyltransferase 5A (KMT5A), KLF transcription factor 12 (KLF12), GRB10 interacting GYF protein 1 (GIGYF1), Wnt family member 7A (WNT7A), Sad1 and UNC84 domain containing 1 (SUN1), and poly (ADP-ribose) polymerase family member 3 (PARP3) were found to have positive associations with the risk of EM. On the other hand, progestin and adipoQ receptor family member 8 (PAQR8), adaptor related protein complex 3 subunit mu 1 (AP3M1), surfeit 6 (SURF6), TUB bipartite transcription factor (TUB), and DNA polymerase delta interacting protein 2 (POLDIP2) were found to have inverse relationships with the risk of EM. ConclusionsThrough genome-wide MR studies, a comprehensive set of genes associated with EM has been identified. Among them, IMMT, PAQR8, SKAP1, KMT5A, AP3M1, SURF6, KLF12, GIGYF1, TUB, WNT7A, SUN1, POLDIP2, and PARP3 show potential as therapeutic targets for EM treatment. Nonetheless, it is crucial to conduct further rigorous investigations to validate these prospects.

Downregulation of AP1S1 causes the lysosomal degradation of EGFR in non-small cell lung cancer.

Matrix stiffness has been shown to play a critical role in cancer progression by influencing various cellular processes, including epidermal growth factor (EGF) signaling. However, the underlying molecular mechanisms are not fully understood. Here, we investigated the role of adaptor-related protein complex 1 subunit sigma 1 (AP1S1), a component of adaptor protein complex-1, in the regulation of EGF receptor (EGFR) intracellular trafficking during cancer cell progression. We found that AP1S1 expression was upregulated under stiff matrix conditions, resulting in the regulation of EGFR trafficking in non-small cell lung adenocarcinoma cells. Knockout of AP1S1 caused the lysosomal degradation of EGFR, leading to suppressed EGF-induced anaplastic lymphoma receptor tyrosine kinase phosphorylation. In addition, the downregulation of AP1S1 increased the sensitivity of H1975 cancer cells, which are resistant to tyrosine kinase inhibitors, to erlotinib. Collectively, our results suggest that AP1S1 could regulate EGFR recycling under stiff matrix conditions, and AP1S1 inhibition could be a novel strategy for treating cancer cells resistant to EGFR-targeted anticancer drugs.

Current management of generalized pustular psoriasis.

Generalized pustular psoriasis (GPP) is a rare subset of psoriasis involving episodes of sterile pustules accompanied by inflammation and, often, systemic involvement. The inflammatory nature of GPP has potential for severe multisystem complications including high-output cardiac failure, infections, digestive system issues, and disfiguring or lethal acute flare episodes. The disease tends to have higher prevalence in females and Asians. The IL-1/IL-36 inflammatory pathway is a critical facet of GPP's pathology. Genetic mutations that are associated with GPP include modifications of Interleukin 36 Receptor Antagonist (IL36RN), Caspase Recruitment Domain Family Member 14 (CARD14), Adaptor Related Protein Complex 1 Subunit Sigma 3 (AP1S3), Myeloperoxidase (MPO) and Serpin Peptidase Inhibitor Clade A Member 3 (SERPINA3) genes. Treatment guidelines for GPP are not well-entrenched. Currently, only one GPP-specific treatment, the interleukin-36 receptor antagonist (IL-36Ra) spesolimab, has been approved for use in the United States. Additional anti-IL-36 pathway therapies are currently being developed. Other treatment options include other biologic therapies such as IL-17 inhibitors, IL-23 inhibitors and TNFα inhibitors. Non-biologic therapeutic options include retinoids, cyclosporine and methotrexate. Treatment options differ throughout the world; most countries utilize retinoids, cyclosporine and methotrexate as first-line non-biologic options. China and United Kingdom have no GPP-specific biologic therapies approved for use, while several biologic therapies are approved for use in Japan. This review aims to serve as an update on the current global management of GPP while also including relevant aspects of disease pathogenesis, diagnosis, clinical presentation, histopathology, aetiology and epidemiology.

High expression of AP2M1 correlates with worse prognosis by regulating immune microenvironment and drug resistance to R-CHOP in diffuse large B cell lymphoma.

First-line treatment with R-CHOP has cured 50%-60% patients of diffuse large B cell lymphoma (DLBCL), and more than one-third patients will eventually progressed to relapsed/refractory disease with dismal outcomes. Adaptor Related Protein Complex 2 Subunit Mu 1 (AP2M1) is required for the activity of a vacuolar ATPase and may also play an important role in regulating the intracellular trafficking and function of CTLA-4 protein. Herein, using both public databases and our own tumor samples, we aimed to demonstrate the prognostic role of AP2M1 and the potential tumor-promoting mechanisms in DLBCL. Using public datasets of DLBCL from both GEO and TCGA databases, we analyzed the role of AP2M1 in mediating chemoresistance to R-CHOP and its correlation with various clinical parameters and prognosis. By using various R packages, we evaluated the role of AP2M1 on regulating tumor immune microenvironment. Moreover, tumor samples of DLBCL from Beijing TongRen Hospital were used to validate our findings by immunohistochemistry staining. Expression of AP2M1 was significantly increased in DLBCL, which was correlated with poor prognosis and a variety of clinical indicators. On the basis of enrichment analysis, it was found that AP2M1 may be related to intracellular receptor signaling pathway. Through immune analysis and drug prediction, we found that the expression of AP2M1 affected the immune environment and drug response of DLBCL, which further revealed the important role of AP2M1 in DLBCL. By analyzing 61 patients treated uniformly with R-CHOP regimen in our center, we validated the above findings that high expression of AP2M1 correlated with inferior survival outcomes and affected sensitivity to R-CHOP treatment. Expression of AP2M1 may affect the prognosis of DLBCL patients probably by affecting the immune environment and the responses to many drugs in treating DLBCL, indicating AP2M1 as a potential therapy target in DLBCL.

AP3S1 is a Novel Prognostic Biomarker and Correlated With an Immunosuppressive Tumor Microenvironment in Pan-Cancer.

Background: Adaptor-related protein complex 3, sigma one subunit (AP3S1) is one of the encoding subunits of the adaptor complex AP-3. However, its role in various tumor types and relationship with the tumor immune microenvironment (TIME) remains unclear. Methods: AP3S1 expression was analyzed using datasets from The Cancer Genome Atlas, Genotype-Tissue Expression, UALCAN, and HPA databases. Then, we performed a systematic analysis of the genetic alterations, clinical features, and prognostic value of AP3S1 in pan-cancer. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used to identify the signaling pathways associated with AP3S1. The correlation between immune cell infiltration and AP3S1 expression was analyzed using immune cell infiltration data from the ImmuCellAI, TIMER2, and a previous study. Finally, we analyzed the association of AP3S1 with tumor mutational burden (TMB), microsatellite instability (MSI), and immune-related genes. Results: We found AP3S1 overexpression in most tumors and a significant association with low survival rates. GSEA and GSVA results show that AP3S1 is involved in tumor progression and associated with immune pathways in different tumor types. We also found that AP3S1 expression was positively correlated with the level of infiltration of immunosuppressive cells (tumor-associated macrophages, cancer-associated fibroblasts, Tregs) and negatively correlated with immune killer cells, including NK cells and CD8+ T cells, in pan-cancer. The expression of AP3S1 could affect TMB and MSI in various cancers. In addition, AP3S1 was positively correlated with most immunosuppressive genes, including PD-1, PD-L1, CTLA4, LAG3 and TIGIT in most cancer types. Conclusion: Our study reveals that AP3S1 is a potential pan-cancer oncogene and plays an essential role in tumorigenesis and cancer immunity. Elevated expression of AP3S1 indicates an immunosuppressive microenvironment and can be used as a potential prognostic biomarker and a target for immunotherapy.

PB2170: HIGH EXPRESSION OF AP2M1 CORRELATES WITH WORSE PROGNOSIS BY REGULATING IMMUNE MICROENVIRONMENT AND DRUG RESPONSE TO R-CHOP IN DLBCL

Background: DLBCL (diffuse large B cell lymphoma) is the most common subtype of non-Hodgkin lymphoma (NHL). After anthracycline-based chemotherapy, more than 70% of DLBCL patients can get complete response or partial response, but only 50% - 60% of patients can survive for a long time. Adaptor Related Protein Complex 2 Subunit Mu 1 (AP2M1) encodes a subunit of the hetero tetrameric coat assembly protein complex 2 (AP2), which required for the activity of a vacuolar ATPase and may also play an important role in regulating the intracellular trafficking and function of CTLA-4 protein. There are few reports on the relationship between DLBCL and AP2M1. Meanwhile, it is unclear whether it is related to the pathogenesis of DLBCL. Aims: Here, in this study, the relationship between DLBCL and AP2M1 and its effect in DLBCL chemotherapy were studied. Methods: Using public datasets of DLBCL from both GEO and TCGA databases, we analyzed the role of AP2M1 in mediating chemoresistance to R-CHOP and its correlation with various clinical parameters and prognosis. By using various R packages, we evaluated the role of AP2M1 on regulating tumor immune microenvironment. Moreover, FFPE samples of DLBCL from Beijing Tongren Hospital were used to valiate our findings. Results: We found that the expression of AP2M1 was significantly increased in DLBCL, which was correlated with poor prognosis and a variety of clinical indicators. On the basis of enrichment analysis, it was found that AP2M1 may be related to intracellular receptor signaling pathway. Through immune analysis and drug prediction, we found that the expression of AP2M1 affected the immune environment and drug response of DLBCL, which further revealed the important role of AP2M1 in DLBCL. Using FFPE DLBCL samples from patients treated in our center, we validated the above findings that high expression of AP2M1 correlated with inferior survival outcomes and affected sensitivity to R-CHOP treatment. Image:Summary/Conclusion: In this study, we found that the expression of AP2M1 could affect the prognosis of DLBCL patients by affecting the immune environment, and the expression of AP2M1 affected the response of many drugs in DLBCL treatment, indicating AP2M1 as a potential therapy target in DLBCL.

NRF1-mediated microglial activation triggers high-altitude cerebral edema.

High-altitude cerebral edema (HACE) is a potentially fatal encephalopathy associated with a time-dependent exposure to the hypobaric hypoxia of altitude. The formation of HACE is affected by both vasogenic and cytotoxic edema. The over-activated microglia potentiate the damage of blood–brain barrier (BBB) and exacerbate cytotoxic edema. In light with the activation of microglia in HACE, we aimed to investigate whether the over-activated microglia were the key turning point of acute mountain sickness to HACE. In in vivo experiments, by exposing mice to hypobaric hypoxia (7000 m above sea level) to induce HACE model, we found that microglia were activated and migrated to blood vessels. Microglia depletion by PLX5622 obviously relieved brain edema. In in vitro experiments, we found that hypoxia induced cultured microglial activation, leading to the destruction of endothelial tight junction and astrocyte swelling. Up-regulated nuclear respiratory factor 1 (NRF1) accelerated pro-inflammatory factors through transcriptional regulation on nuclear factor kappa B p65 (NF-κB p65) and mitochondrial transcription factor A (TFAM) in activated microglia under hypoxia. NRF1 also up-regulated phagocytosis by transcriptional regulation on caveolin-1 (CAV-1) and adaptor-related protein complex 2 subunit beta (AP2B1). The present study reveals a new mechanism in HACE: hypoxia over-activates microglia through up-regulation of NRF1, which both induces inflammatory response through transcriptionally activating NF-κB p65 and TFAM, and enhances phagocytic function through up-regulation of CAV-1 and AP2B1; hypoxia-activated microglia destroy the integrity of BBB and release pro-inflammatory factors that eventually induce HACE.

System Analysis of Adaptor-Related Protein Complex 1 Subunit Mu 2 (AP1M2) on Malignant Tumors: A Pan-Cancer Analysis.

Objective To identify new tumor marker genes available for early tumor screening, differentially expressed gene profiles of multiple tumors were compared using Genotype-Tissue Expression (GTEx), Cancer Cell Line Encyclopedia (CCLE), and The Cancer Genome Atlas (TCGA) databases. As AP1M2 was highly and differentially expressed in invasive breast carcinoma, the purpose of this study was to explore the association of AP1M2 gene with the survival, immune invasion, and tumor neoantigens of patients on a pan-cancer basis. Methods The expression and distribution of AP1M2 gene in tumor tissues and the corresponding normal control tissues were analyzed using the pan-cancer databases GTEx, CCLE, and TCGA. Kaplan-Meyer survival plots and proportional hazards model (COX) were employed to evaluate actions of AP1M2 on the clinical prognosis of tumor patients. Subsequently, the association of AP1M2 expression with immune invasion in different tumor types was explored. Simultaneously, the investigation of the interrelationship of AP1M2 and tumor neoantigens of the immune system, unstable microsatellite, DNA repair genes, and DNA methyltransferases were explored, and the mutation frequency of AP1M2 gene in diverse tumors was studied. Several tumor types were analyzed using gene-set enrichment analysis (GSEA). Results AP1M2 was abundantly expressed in a wide range of cancers, and its expression level was positively correlated with the outcome of tumor victims. Through a study on AP1M2 action on clinical prognosis and immune infiltration in tumor patients, AP1M2 expression in breast-infiltrating carcinoma was found to be highly associated with patients' overall survival and infiltration levels of macrophages, dendritic cells, T cells (CD4+ and CD8+), and B cells. Also, AP1M2 expression was positively correlated with tumor immune neoantigens and microsatellite instability in breast invasive carcinoma. The effect of AP1M2 on tumors was analyzed by GSEA, and findings demonstrated that AP1M2 expression levels in most tumors influenced the activation of tumor-associated pathways and immune-associated pathways. Conclusions These findings suggest that AP1M2 expression levels are significantly correlated to patients' outcomes and levels of immune infiltration in most cancer types, including T cells (CD8+ and CD4+), macrophages, neutrophils, and dendritic cells (DCs), particularly in breast cancer. The results indicate that AP1M2 may influence the tumor environment of invasive breast cancer patients and it may be a target contributing to early screening and treatment for breast cancer, helping improve the efficiency of early screening and overall survival rate in invasive breast cancer patients.

Long noncoding RNA SNHG8 accelerates acute gouty arthritis development by upregulating AP3D1 in mice

ABSTRACT Gout can affect the quality of life of patients due to monosodium urate monohydrate (MSU) crystals. Numerous studies have proposed that long noncoding RNAs (lncRNAs) regulate gout. We aimed to reveal the function of lncRNA small nucleolar RNA host gene 8 (SNHG8) in acute gouty arthritis (GA). A GA mouse model was established by injection of MSU into footpads. The levels of SNHG8, miR-542-3p and adaptor-related protein complex 3 subunit delta 1 (AP3D1) in footpads were detected via polymerase chain reaction analysis. Hematoxylin–eosin staining revealed the paw swelling in mice. Enzyme-linked immunosorbent assay and western blot analysis were applied to determine the concentrations of proinflammatory cytokines. SNHG8 expression was identified to be upregulated after MSU treatment. Ablation of SNHG8 decreased the MSU-induced enhancement of paw swelling and foot thickness. In addition, SNHG8 depletion decreased the protein levels of proinflammatory factors in GA mice. Mechanically, SNHG8 was verified to be a sponge of miR-542-3p, and miR-542-3p targeted AP3D1 3ʹ untranslated region. SNHG8 competitively bound with miR-542-3p to upregulate AP3D1 expression. Finally, results of rescue assays illustrated that AP3D1 upregulation offset the SNHG8-mediated inhibition on paw swelling and protein levels of proinflammatory factors in GA mice. In conclusion, SNHG8 accelerates acute GA development by upregulating AP3D1 in an miR-542-3p-dependent way in mice, providing an effective therapeutic approach to treat acute GA.

Planar cell polarity protein Vangl2 and its interacting protein Ap2m1 regulate dendritic branching in cortical neurons.

Van Gogh-like 2 (Vangl2) is a mammalian homolog of Drosophila core planar cell polarity (PCP) protein Vang/Strabismus, which organizes asymmetric cell axes for developmental proliferation, fate determination, and polarized movements in multiple tissues, including neurons. Although the PCP pathway has an essential role for dendrite and dendritic spine formation, the molecular mechanism remains to be clarified. To investigate the mechanism of Vangl2-related neuronal development, we screened for proteins that interact with the Vangl2 cytosolic N-terminus from postnatal day 9 mouse brains using a yeast two-hybrid system. From 61 genes, we identified adaptor-related protein complex 2, mu 1 subunit (Ap2m1) as the Vangl2 N-terminal binding protein. Intriguingly, however, the pull-down assay demonstrated that Vangl2 interacted with Ap2m1 not only at its N-terminus but also at the C-terminal Prickle binding domain. Furthermore, we verified that the downregulation of Ap2m1 in the developing cortical neurons reduced the dendritic branching similar to what occurs in a knockdown of Vangl2. From these results, we suggest that the membrane internalization regulated by the PCP pathway is required for the developmental morphological change in neurons.