Lysosome-associated Membrane Protein 3 Research Articles

Lysosome-Associated Membrane Protein-3 (LAMP3) Expression in Oral Squamous Cell Carcinoma and Its Relationship With Clinicopathological Parameters: A Cross-Sectional Study

Lysosome-Associated Membrane Protein-3 (LAMP3) Expression in Oral Squamous Cell Carcinoma and Its Relationship With Clinicopathological Parameters: A Cross-Sectional Study

ALKBH5 regulates chicken adipogenesis by mediating LCAT mRNA stability depending on m6A modification

BackgroundPrevious studies have demonstrated the role of N6-methyladenosine (m6A) RNA methylation in various biological processes, our research is the first to elucidate its specific impact on LCAT mRNA stability and adipogenesis in poultry.ResultsThe 6 100-day-old female chickens were categorized into high (n = 3) and low-fat chickens (n = 3) based on their abdominal fat ratios, and their abdominal fat tissues were processed for MeRIP-seq and RNA-seq. An integrated analysis of MeRIP-seq and RNA-seq omics data revealed 16 differentially expressed genes associated with to differential m6A modifications. Among them, ELOVL fatty acid elongase 2 (ELOVL2), pyruvate dehydrogenase kinase 4 (PDK4), fatty acid binding protein 9 (PMP2), fatty acid binding protein 1 (FABP1), lysosomal associated membrane protein 3 (LAMP3), lecithin-cholesterol acyltransferase (LCAT) and solute carrier family 2 member 1 (SLC2A1) have ever been reported to be associated with adipogenesis. Interestingly, LCAT was down-regulated and expressed along with decreased levels of mRNA methylation methylation in the low-fat group. Mechanistically, the highly expressed ALKBH5 gene regulates LCAT RNA demethylation and affects LCAT mRNA stability. In addition, LCAT inhibits preadipocyte proliferation and promotes preadipocyte differentiation, and plays a key role in adipogenesis.ConclusionsIn conclusion, ALKBH5 mediates RNA stability of LCAT through demethylation and affects chicken adipogenesis. This study provides a theoretical basis for further understanding of RNA methylation regulation in chicken adipogenesis.

Amplified Type I Interferon Response in Sjögren's Disease via Ectopic Toll-Like Receptor 7 Expression in Salivary Gland Epithelial Cells Induced by Lysosome-Associated Membrane Protein 3.

Lysosome-associated membrane protein 3 (LAMP3) misexpression in salivary gland epithelial cells plays a causal role in the development of salivary gland dysfunction and autoimmunity associated with Sjögren's disease (SjD). This study aimed to clarify how epithelial LAMP3 misexpression is induced in SjD. To explore upstream signaling pathways associated with LAMP3 expression, we conducted multiple RNA sequencing analyses of minor salivary glands from patients with SjD, submandibular glands from a mouse model of SjD, and salivary gland epithelial cell lines. A hypothesis generated by the RNA sequencing analyses was further tested by in vitro and in vivo assays with gene manipulation. Transcriptome analysis suggested LAMP3 expression was associated with enhanced type I interferon (IFN) and IFNγ signaling pathways in patients with SjD. In vitro studies showed that type I IFN but not IFNγ stimulation could induce LAMP3 expression in salivary gland epithelial cells. Moreover, we discovered that LAMP3 overexpression could induce ectopic Toll-like receptor 7 (TLR-7) expression and type I IFN production in salivary gland epithelial cells both in vitro and in vivo. TLR-7 knockout mice did not develop any SjD-related symptoms following LAMP3 induction. Epithelial LAMP3 misexpression can be induced through enhanced type I IFN response in salivary glands. In addition, LAMP3 can promote type I IFN production via ectopic TLR-7 expression in salivary gland epithelial cells. This positive feedback loop can contribute to maintaining LAMP3 misexpression and amplifying type I IFN production in salivary glands, which plays an essential role in the pathophysiology of SjD.

LAMP3 is a potent uterine corpus endometrial carcinoma prognostic biomarker associated with immune behavior.

Uterine corpus endometrial carcinoma (UCEC) is one of the most common gynecological malignancies and its incidence and mortality continue apace. Lysosome-associated membrane protein 3 (LAMP3) is the third member of the LAMP family and its overexpression has been described to be involved in the progression of breast, ovarian and cervical cancers, but there has been an absence of research focusing on its role in UCEC. WGCNA, TIMER, LinkedOmics, GSEA, Cytoscape, Kaplan-Meier plotter, GDC, GeneMANIA, cBioPortal, PDB, RNAinter, miRNet were applied in this research. Our study uncovers that LAMP3 possesses higher expression levels in UCEC compared to normal tissues, and this differential expression profile is tightly aligned with clinical and pathological features, and patients demonstrating high LAMP3 expression tend to have a shorter survival expectancy. The high expression of LAMP3 is modulated by the designated ceRNA network. LAMP3 is engaged in UCEC progression by functioning in a variety of biological roles of relevance to immunity. Furthermore, we predicted several prospering drugs based on drug sensitivity. Finally, we also constructed possible docking patterns of LAMP3 with ABCA3, RAB9A, and SGTB. LAMP3 is a formidable biomarker for UCEC and could be a prospective candidate for the diagnosis, treatment and prognostic assessment of UCEC.

KDM6A Promotes Angiogenesis, Migration, and Invasion of Pancreatic Cancer by Activating LAMP3.

Lysine demethylase 6A (KDM6A) is abnormally expressed in various cancer. This study aimed to investigate the potential of KDM6A in pancreatic cancer (PC). mRNA expression was calculated by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Protein expression was detected by Western blot. Cell viability was measured by Cell Counting Kit (CCK-8) assay. Cell angiogenesis was determined by tube formation assay. Cell migration and invasion were determined by Transwell assay. We found that KDM6A was upregulated in PC patients and cells. Interestingly, KDM6A deficiency inhibited the proliferation and angiogenesis of PC cells. Moreover, KDM6A knockdown suppressed the migration and invasion of PC cells. Additionally, KDM6A upregulated the expression of lysosomal associated membrane protein 3 (LAMP3) via driving demethylation of H3K27me3. Overexpression of LAMP3 reversed the effects of KDM6A knockdown and contributed to the angiogenesis and aggressiveness of PC cells. In summary, KDM6A-mediated demethylation of tri-methylation at lysine 27 of histone H3 (H3K27me3) promotes the transcription of LAMP3, resulting the angiogenesis and aggressiveness of PC. Therefore, targeting KDM6A may be an anti-angiogenetic strategy for PC.

A pan-cancer analysis of prognostic significance and immunological role of lysosomal-associated membrane protein 3.

Lysosomal dysfunction can drive carcinogenesis. Lysosomal-associated membrane protein 3 (LAMP3), is a member of the Lysosome Associated Membrane Proteins and is involved in the malignant phenotype such as tumour metastasis and drug resistance, while the mechanisms that regulate the malignant progression of tumour remain vague. Our study aims to provide a more systematic and comprehensive understanding of the role of LAMP3 in the progression of various cancers by various databases.We explored the role of LAMP3 in pan-cancer using The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) database. Multiple online web platforms and software were used for data analysis, including HPA, TIMER, TISIDB, GEPIA, UALCAN, Kaplan-Meier plotter, DAVID and TIGER. The immunohistochemistry was used to quantify the LAMP3 and PD-L1 expression levels in cancer.High LAMP3 expression was found in most cancers and differentially expressed across molecular and immune subtypes. The expression of LAMP3 was involved in the immune-associated processes of Antigen processing and presentation, Th17 cell differentiation, Th1 and Th2 cell differentiation, and the immune-associated pathways of T cell receptor and B cell receptor signalling pathways in most cancers. It also correlated with genetic markers of immunomodulators in various cancers. LAMP3 and PD-L1 expression in BRCA and HNSC tissues was higher than that in corresponding adjacent normal tissues by immunohistochemistry. There is a significant correlation between the expression of LAMP3 and PD-L1.Our study elucidates that LAMP3 has different expression patterns and genetic alteration patterns in different tumours. It is a potential biomarker for immune-related cancer diagnosis, prognosis and efficacy prediction.

MiR-526b-3p enhances sensitivity of head and neck squamous cell carcinoma cells to radiotherapy via suppressing exosomal LAMP3-mediated autophagy

Lysosomal associated membrane protein 3 (LAMP3) has been reported to be a tumour promoter in multiple cancer types by modulating tumour cell autophagy. However, the potential mechanism of LAMP3 in radio-resistance of head and neck squamous cell carcinoma (HNSCC) remains unknown. Therefore, our current study aims to detect the impacts of LAMP3 on the resistance of HNSCC cells to radiotherapy and meanwhile explore its functional mechanism. Through RT-Qpcr examination, LAMP3 expression was identified to be expressed at a significantly high level in irradiation-resistant HNSCC cell lines compared with irradiation-sensitive HNSCC cell lines. Functional assays including CCK-8, colony formation and Transwell assays demonstrated that LAMP3 enhanced the radio-resistance through inducing autophagy to promote HNSCC cell growth. Furthermore, irradiation-resistant HNSCC cells could transfer exosomal LAMP3 to elevate LAMP3 expression in irradiation-sensitive HNSCC cells. Mechanistically, microRNA (miRNA) miR-526b-3p could inhibit LAMP3 expression so as to strengthen sensitivity of HNSCC cells to radiotherapy. In a word, exosomal LAMP3 expression promoted radioresistance of HNSCC cells via inducing autophagy, while this effect could be suppressed by miR-526b-3p in a targeted manner.

Lysosome-Associated Membrane Protein 3 Induces Lysosome-Dependent Cell Death by Impairing Autophagic Caspase 8 Degradation in the Salivary Glands of Individuals With Sjögren's Disease.

Lysosome-associated membrane protein 3 (LAMP3) overexpression is implicated in the development and progression of Sjögren's disease (SjD) by inducing lysosomal membrane permeabilization (LMP) and apoptotic cell death in salivary gland epithelium. The aim of this study was to clarify the molecular details of LAMP3-induced lysosome-dependent cell death and to test lysosomal biogenesis as a therapeutic intervention. Human labial minor salivary gland biopsies were analyzed using immunofluorescence staining for LAMP3 expression levels and galectin-3 puncta formation, a marker of LMP. Expression level of caspase 8, an initiator of LMP, was determined by Western blotting in cell culture. Galectin-3 puncta formation and apoptosis were evaluated in cell cultures and a mouse model treated with glucagon-like peptide 1 receptor (GLP-1R) agonists, a known promoter of lysosomal biogenesis. Galectin-3 puncta formation was more frequent in the salivary glands of SjD patients compared to control glands. The proportion of galectin-3 puncta-positive cells was positively correlated with LAMP3 expression levels in the glands. LAMP3 overexpression increased caspase 8 expression, and knockdown of caspase 8 decreased galectin-3 puncta formation and apoptosis in LAMP3-overexpressing cells. Inhibition of autophagy increased caspase 8 expression, while restoration of lysosomal function using GLP-1R agonists decreased caspase 8 expression, which reduced galectin-3 puncta formation and apoptosis in both LAMP3-overexpressing cells and mice. LAMP3 overexpression induced lysosomal dysfunction, resulting in lysosome-dependent cell death via impaired autophagic caspase 8 degradation, and restoring lysosomal function using GLP-1R agonists could prevent this. These findings suggested that LAMP3-induced lysosomal dysfunction is central to disease development and is a target for therapeutic intervention in SjD.

RPL21 interacts with LAMP3 to promote colorectal cancer invasion and metastasis by regulating focal adhesion formation

BackgroundMetastasis is the leading cause of death among patients with colorectal cancer (CRC). Therefore, it is important to explore the molecular mechanisms of metastasis to develop effective therapeutic targets for CRC. In the present study, ribosomal protein L21 (RPL21) was considered as being involved in promoting CRC metastasis, yet the underlying mechanism requires further investigation.MethodsImmunohistochemistry, western blotting, and quantitative reverse transcription polymerase chain reaction were performed to measure the expression of RPL21 and lysosome-associated membrane protein 3 (LAMP3) in CRC tissues and cells. Wound healing, transwell migration, and invasion assays were performed to study the migration and invasion of cultured CRC cells. An orthotopic CRC mouse model was developed to investigate the metastatic ability of CRC. Transcriptome sequencing was conducted to identify the genes related to RPL21. The dual-luciferase reporter gene assay was performed to determine the transcriptional activity of transcription factor EB (TFEB). The GST/His pull-down assay was performed to investigate the specific binding sites of RPL21 and LAMP3. The cell adhesion assay was performed to determine the adhesion ability of CRC cells. Immunofluorescence staining was performed to observe focal adhesions (FAs).ResultsRPL21 was highly expressed in CRC, contributing to tumor invasiveness and poor patient prognosis. Functionally, RPL21 promoted the migration and invasion of CRC cells in vitro and tumor metastasis in vivo. Moreover, LAMP3 was identified as being highly related to RPL21 and was essential in promoting the migration and invasion of CRC cells. Mechanistically, RPL21 activated the transcriptional function of TFEB to upregulate LAMP3 expression. RPL21 directly bound to the aa 341–416 domain of LAMP3 via its aa 1–40 and aa 111–160 segments. The combination of RPL21 and LAMP3 enhanced the stability of the RPL21 protein by suppressing the degradation of the ubiquitin–proteasome system. Furthermore, RPL21 and LAMP3 promoted the formation of immature FAs by activating the FAK/paxillin/ERK signaling pathway.ConclusionsRPL21 promoted invasion and metastasis by regulating FA formation in a LAMP3-dependent manner during CRC progression. The interaction between RPL21 and LAMP3 may function as a potential therapeutic target against CRC.

Salivary gland LAMP3 mRNA expression is a possible predictive marker in the response to hydroxychloroquine in Sjögren's disease.

Hydroxychloroquine (HCQ) is a lysosomotropic agent that is commonly used for treating Sjögren's disease (SjD). However, its efficacy is controversial because of the divergent response to the drug among patients. In a subgroup of SjD patients, lysosome-associated membrane protein 3 (LAMP3) is elevated in expression in the salivary glands and promotes lysosomal dysregulation and lysosome-dependent apoptotic cell death. In this study, chloroquine (CQ) and its derivative HCQ were tested for their ability to prevent LAMP3-induced apoptosis, in vitro and on a mouse model of SjD. In addition, efficacy of HCQ treatment was retrospectively compared between high LAMP3 mRNA expression in minor salivary glands and those with LAMP3 mRNA levels comparable with healthy controls. Study results show that CQ treatment stabilized the lysosomal membrane in LAMP3-overexpressing cells via deactivation of cathepsin B, resulting in decreased apoptotic cell death. In mice with established SjD-like phenotype, HCQ treatment also significantly decreased apoptotic cell death and ameliorated salivary gland hypofunction. Retrospective analysis of SjD patients found that HCQ tended to be more effective in improving disease activity index, symptom severity and hypergammaglobulinemia in patients with high LAMP3 expression compared those with normal LAMP3 expression. Taken together, these findings suggested that by determining salivary gland LAMP3 mRNA level, a patient's response to HCQ treatment could be predicted. This finding may provide a novel strategy for guiding the development of more personalized medicine for SjD.

LAMP3 transfer via extracellular particles induces apoptosis in Sjögren’s disease

Sjögren’s disease (SjD) is an autoimmune disease that affects exocrine tissues and is characterized by increased apoptosis in salivary and lacrimal glands. Although the pathogenic mechanism triggering SjD is not well understood, overexpression of lysosome-associated membrane protein 3 (LAMP3) is associated with the disease in a subset of SjD patients and the development of SjD-like phenotype in mice. In this study, histological analysis of minor salivary glands of SjD patients suggested that LAMP3-containing material is being ejected from cells. Follow-on in vitro experiments with cells exposed to extracellular particles (EPs) derived from LAMP3-overexpressing cells showed increased apoptosis. Proteomics identified LAMP3 as a major component of EPs derived from LAMP3-overexpressing cells. Live-cell imaging visualized release and uptake of LAMP3-containing EPs from LAMP3-overexpressing cells to naïve cells. Furthermore, experiments with recombinant LAMP3 protein alone or complexed with Xfect protein transfection reagent demonstrated that internalization of LAMP3 was required for apoptosis in a caspase-dependent pathway. Taken together, we identified a new role for extracellular LAMP3 in cell-to-cell communication via EPs, which provides further support for targeting LAMP3 as a therapeutic approach in SjD.

LAMP3/CD63 Expression in Early and Late Endosomes in Human Vaginal Epithelial Cells Is Associated with Enhancement of HSV-2 Infection.

Herpes simplex virus 2 (HSV-2) is a lifelong sexually transmitted virus that disproportionately infects women through heterosexual transmission in the vaginal tract. The vaginal epithelium is known to be highly susceptible to HSV-2 infection; however, the cellular mechanism of HSV-2 uptake and replication in vaginal epithelium has not been extensively studied. Previously, we observed that lysosomal-associated membrane protein-3 (LAMP3/CD63) was among the highly upregulated genes during HSV-2 infection of human vaginal epithelial cell line VK2, leading us to posit that LAMP3/CD63 may play a role in HSV-2 infection. Consequently, we generated two gene-altered VK2-derived cell lines, a LAMP3-overexpressed (OE) line and a LAMP3 knockout (KO) line. The wild-type VK2 and the LAMP3 OE and KO cell lines were grown in air-liquid interface (ALI) cultures for 7 days and infected with HSV-2. Twenty-four hours postinfection, LAMP3 OE cells produced and released significantly higher numbers of HSV-2 virions than wild-type VK2 cells, while virus production was greatly attenuated in LAMP3 KO cells, indicating a functional association between LAMP3/CD63 expression and HSV-2 replication. Fluorescence microscopy of HSV-2-infected cells revealed that HSV-2 colocalized with LAMP3 in both early endosomes and lysosomal compartments. In addition, blocking endosomal maturation or late endosomal/lysosomal fusion using specific inhibitors resulted in reduced HSV-2 replication in VK2 cells. Similarly, LAMP3 KO cells exhibited very low viral entry and association with endosomes, while LAMP3 OE cells demonstrated large amounts of virus that colocalized with LAMP3/CD63 in endosomes and lysosomes. IMPORTANCE Collectively, these results showed that HSV-2 is taken up by human vaginal epithelial cells through an endosomal-lysosomal pathway in association with LAMP3, which plays a crucial role in the enhancement of HSV-2 replication. These findings provide the basis for the future design of antiviral agents for prophylactic measures against HSV-2 infection.

Correction of LAMP3-associated salivary gland hypofunction by aquaporin gene therapy

Sjögren’s disease (SjD) is a chronic autoimmune sialadenitis resulting in salivary gland hypofunction with dry mouth symptom. Previous studies showed that lysosome-associated membrane protein 3 (LAMP3) overexpression is involved in the development of salivary gland hypofunction associated with SjD. However, the molecular mechanisms are still unclear, and no effective treatment exists to reverse gland function in SjD. Analysis on salivary gland samples from SjD patients showed that salivary gland hypofunction was associated with decreased expression of sodium–potassium-chloride cotransporter-1 (NKCC1) and aquaporin 5 (AQP5), which are membrane proteins involved in salivation. Further studies revealed that LAMP3 overexpression decreased their expression levels by promoting endolysosomal degradation. Additionally, we found that LAMP3 overexpression enhanced gene transfer by increasing internalization of adeno-associated virus serotype 2 (AAV2) via the promoted endolysosomal pathway. Retrograde cannulation of AAV2 vectors encoding AQP1 gene (AAV2-AQP1) into salivary glands induced glandular AQP1 expression sufficient to restore salivary flow in LAMP3-overexpressing mice. LAMP3 could play a critical role in the development of salivary gland hypofunction in SjD by promoting endolysosomal degradation of NKCC1 and AQP5. But it also could enhance AAV2-mediated gene transfer to restore fluid movement through induction of AQP1 expression. These findings suggested that AAV2-AQP1 gene therapy is useful in reversing salivary gland function in SjD patients.

Abstract 290: Derivation of immortalized human alveolar epithelial cells for lung adenocarcinoma modeling

Abstract Lung cancer, primarily caused by tobacco smoke exposure, kills more Americans than the next top three cancers combined. The two main histological subtypes are lung adenocarcinoma, which arises in the alveoli, and squamous cell lung cancer, which arises in the airways. In vitro models of squamous cell lung cancer have used human bronchial epithelial cells immortalized with Simian Virus 40 Large T antigen (SV40 LgT) or mutant CDK4R24C combined with telomerase. The derived immortalized human bronchial epithelial cells have been very useful to study the effects of tobacco smoke exposure and oncogene activation. However, to date it has not been possible to develop similar models for lung adenocarcinoma; immortalized human alveolar epithelial cells (AECs) were not available due to the difficulty in establishing alveolar cell lines that proliferate yet remain epithelial. Here we describe a method to derive AEC lines, providing a new resource for in vitro lung adenocarcinoma models. We purified human AECs from de-identified remnant human transplant lungs from deceased subjects and tested numerous conditions to establish immortalized cell lines. We found that the addition of Rho-associated kinase inhibitor (Y27632) to culture media allowed AECs to proliferate so that they could then be transduced with lentivirus. Transduction with CDK4R24C + telomerase did not yield cell lines that grew well. However, transduction with SV40 LgT resulted in well-proliferating cell lines that retained their epithelial morphology. In 2-dimensional (2D) culture the AEC LgT-expressing cell lines grow in cobblestone monolayers and do not express mature alveolar markers. However, in 3-dimensional (3D) culture in Matrigel with fibroblasts the cells form alveolar-like organoids of varying complexity. Immunofluorescence and single cell RNA sequencing indicate that the transition from 2D monolayer to 3D organoids is accompanied by the expression of mature alveolar markers such as aquaporin 5 (AQP5), G-protein-coupled receptor class C, member A (GPRC5A), lysosomal-associated membrane protein 3 (LAMP3) and ATP-binding cassette subfamily A member 3 (ABCA3, involved in surfactant production). In addition, while in 2D culture the cells form a single cluster with homogeneous gene expression patterns, in 3D diverse cell groups appear. Using a 3D culture medium that stimulates alveologenesis induces additional mature alveolar markers. We are using AEC lines to study the effects of environmental exposures such as tobacco smoke and the role of lung cancer driver genes. In addition, we intend to establish AEC lines from individuals of diverse ethnicities to investigate the effects of genetic background on lung cancer development. Our AEC lines provide a valuable new system to model and study the distal lung and associated diseases in vitro. Citation Format: Ite A. Offringa, Evelyn Tran, Tuo Shi, Laurence St.Pierre, Pablo E. Puente, Rong Lu, Crystal N. Marconett, Beiyun Zhou, Zea Borok. Derivation of immortalized human alveolar epithelial cells for lung adenocarcinoma modeling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 290.

Lysosomal exocytosis of HSP70 stimulates monocytic BMP6 expression in Sjögren's syndrome.

BMP6 is a central cytokine in the induction of Sjögren’s syndrome–associated (SS-associated) secretory hypofunction. However, the upstream initiation leading to the production of this cytokine in SS is unknown. In this study, RNA ISH on salivary gland sections taken from patients with SS indicated monocytic lineage cells as a cellular source of BMP6. RNA-Seq data on human salivary glands suggested that TLR4 signaling was an upstream regulator of BMP6, which was confirmed by in vitro cell assays and single-cell transcriptomics of human PBMCs. Further investigation showed that HSP70 was an endogenous natural TLR4 ligand that stimulated BMP6 expression in SS. Release of HSP70 from epithelial cells could be triggered by overexpression of lysosome-associated membrane protein 3 (LAMP3), a protein also associated with SS in several transcriptome studies. In vitro studies supported the idea that HSP70 was released as a result of lysosomal exocytosis initiated by LAMP3 expression, and reverse transcription PCR on RNA from minor salivary glands of patients with SS confirmed a positive correlation between BMP6 and LAMP3 expression. BMP6 expression could be experimentally induced in mice by overexpression of LAMP3, which developed an SS-like phenotype. The newly identified LAMP3/HSP70/BMP6 axis provided an etiological model for SS gland dysfunction and autoimmunity.

Regulation of Lysosomal Associated Membrane Protein 3 (LAMP3) in Lung Epithelial Cells by Coronaviruses (SARS-CoV-1/2) and Type I Interferon Signaling

Abstract Severe Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV-2) infection is a major risk factor for mortality and morbidity in critical care hospitals around the world. Lung epithelial type II cells play a major role in the recognition and clearance of respiratory viruses as well as repair of lung injury in response to environmental toxicants. Gene expression profiling studies revealed that mouse lung epithelial type II cells express several cell-specific markers including surfactant proteins and Lysosomal associated membrane protein 3 (LAMP3) located in lysosomes, endosomes and lamellar bodies. These intracellular organelles are involved in vesicular transport and facilitate viral entry and release of the viral genome into the host cell cytoplasm. In this study, regulation of LAMP3 expression in human lung epithelial cells by several respiratory viruses and type I interferon signaling was investigated. Respiratory viruses including SARS-CoV-1 and SARS-CoV-2 significantly induced LAMP3 expression in lung epithelial cells within 24 hours after infection that required the presence of ACE2 viral entry receptors. Time course experiments revealed that the induced expression of LAMP3 was correlated with the induced expression of Interferon–beta (IFNB1) and STAT1 at mRNA levels. LAMP3 was also induced by direct IFN-beta treatment in multiple lung epithelial cell lines or by infection with influenza virus lacking the non-structural protein1(NS1) in NHBE bronchial epithelial cells. LAMP3 expression was also induced by several respiratory viruses in human lung epithelial cells including RSV and HPIV3. Location in lysosomes and endosomes aswell as induction by respiratory viruses and type I Interferon suggests that LAMP3 may have an important role in inter-organellar regulation of innate immunity and a potential target for therapeutic modulation in health and disease. Furthermore, bioinformatics revealed that a subset of lung type II genes were differentially regulated in the lungs of COVID-19 patients.

LAMP3 inhibits autophagy and contributes to cell death by lysosomal membrane permeabilization

ABSTRACT Sjögren syndrome (SS) is a chronic and progressive autoimmune disease characterized by dry mouth and dry eyes, and characteristic autoantibodies. Evidence of altered macroautophagy/autophagy and apoptosis has been associated with SS, but a mechanistic understanding of the gene expression changes associated with these abnormal processes has not been realized. Recently, increased LAMP3 (lysosomal associated membrane protein 3) expression was found in a subset of SS patients and was associated with increased apoptosis and autoantigen accumulation and release. To better understand how LAMP3 expression might modulate apoptosis, cell biology, and biochemical studies were used to examine the effect of LAMP3 expression in minor salivary gland cells. LAMP3 expression resulted in degradation of LAMP1 increasing lysosomal membrane permeabilization and relocalization of cathepsins to the cytoplasm, resulting in destabilizing autophagic flux and caspase activation. These findings highlight the central role of LAMP3 expression in the pathogenesis of SS.

Lysosome-associated membrane protein 3 misexpression in salivary glands induces a Sjögren’s syndrome-like phenotype in mice

ObjectivesSjögren’s syndrome (SS) is an autoimmune sialadenitis with unknown aetiology. Although extensive research implicated an abnormal immune response associated with lymphocytes, an initiating event mediated by salivary gland epithelial cell...

Association study of MCCC1/LAMP3 and DGKQ variants with Parkinson's disease in patients of Malay ancestry.

Genome-wide association studies (GWAS) have shown that variants in the 3-methylcrotonyl-CoA carboxylase (MCCC1)/lysosome-associated membrane protein 3 (LAMP3) loci (rs10513789, rs12637471, rs12493050) reduce the risk of Parkinson's disease (PD) in Caucasians, Chinese and Ashkenazi-Jews while the rs11248060 variant in the diacylglycerol kinase theta (DGKQ) gene increases the risk of PD in Caucasian and Han Chinese cohorts. However, their roles in Malays are unknown. Therefore, this study aims to investigate the association of these variants with the risk of PD in individuals of Malay ancestry. A total of 1114 subjects comprising of 536 PD patients and 578 healthy controls of Malay ancestry were recruited and genotyped using Taqman® allelic discrimination assays. The G allele of rs10513789 (OR = 0.83, p = 0.001) and A allele of rs12637471 (OR = 0.79, p = 0.007) in the MCCC1/LAMP3 locus were associated with a protective effect against developing PD in the Malay population. A recessive model of penetrance showed a protective effect of the GG genotype for rs10513789 and the AA genotype for rs12637471. No association with PD was found with the other MCCC1/LAMP3 rs12493050 variant or with the DGKQ (rs11248060) variant. No significant associations were found between the four variants with the age at PD diagnosis. MCCC1/LAMP3 variants rs10513789 and rs12637471 protect against PD in the Malay population.

LL-37-Induced Autophagy Contributed to the Elimination of Live Porphyromonas gingivalis Internalized in Keratinocytes.

Porphyromonas gingivalis (P. gingivalis), one of the most important pathogens of periodontitis, is closely associated with the aggravation and recurrence of periodontitis and systemic diseases. Antibacterial peptide LL-37, transcribed from the cathelicidin antimicrobial peptide (CAMP) gene, exhibits a broad spectrum of antibacterial activity and regulates the immune system. In this study, we demonstrated that LL-37 reduced the number of live P. gingivalis (ATCC 33277) in HaCaT cells in a dose-dependent manner via an antibiotic-protection assay. LL-37 promoted autophagy of HaCaT cells internalized with P. gingivalis. Inhibition of autophagy with 3-methyladenine (3-MA) weakened the inhibitory effect of LL-37 on the number of intracellular P. gingivalis. A cluster of orthologous groups (COGs) and a gene ontology (GO) functional analysis were used to individually assign 65 (10%) differentially expressed genes (DEGs) to an “Intracellular trafficking, secretion, and vesicular transport” cluster and 306 (47.08%) DEGs to metabolic processes including autophagy. Autophagy-related genes, a tripartite motif-containing 22 (TRIM22), and lysosomal-associated membrane protein 3 (LAMP3) were identified as potentially involved in LL-37-induced autophagy. Finally, bioinformatics software was utilized to construct and predict the protein–protein interaction (PPI) network of CAMP-TRIM22/LAMP3-Autophagy. The findings indicated that LL-37 can reduce the quantity of live P. gingivalis internalized in HaCaT cells by promoting autophagy in these cells. The transcriptome sequencing and analysis also revealed the potential molecular pathway of LL-37-induced autophagy.