MAL2 reprograms lipid metabolism in intrahepatic cholangiocarcinoma via EGFR/SREBP-1 pathway based on single-cell RNA sequencing.

Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive cancer characterized by a poor prognosis and resistance to chemotherapy. In this study, utilizing scRNA-seq, we discovered that the tetra-transmembrane protein mal, T cell differentiation protein 2 (MAL2), exhibited specific enrichment in ICC cancer cells and was strongly associated with a poor prognosis. The inhibition of MAL2 effectively suppressed cell proliferation, invasion, and migration. Transcriptomics and metabolomics analyses suggested that MAL2 promoted lipid accumulation in ICC by stabilizing EGFR membrane localization and activated the PI3K/AKT/SREBP-1 axis. Molecular docking and Co-IP proved that MAL2 interacted directly with EGFR. Based on constructed ICC organoids, the downregulation of MAL2 enhanced apoptosis and sensitized ICC cells to cisplatin. Lastly, we conducted a virtual screen to identify sarizotan, a small molecule inhibitor of MAL2, and successfully validated its ability to inhibit MAL2 function. Our findings highlight the tumorigenic role of MAL2 and its involvement in cisplatin sensitivity, suggesting the potential for novel combination therapeutic strategies in ICC.

MAL expression downregulation through suppressive H3K27me3 marks at the promoter in HPV16-related cervical cancers is prognostically relevant and manifested by the interplay of novel MAL antisense long noncoding RNA AC103563.8, E7 oncoprotein and EZH2.

BACKGROUND: MAL (T-lymphocyte maturation-associated protein) is highly downregulated in most cancers, including cervical cancer (CaCx), attributable to promoter hypermethylation. Long noncoding RNA genes (lncGs) play pivotal roles in CaCx pathogenesis, by interacting with human papillomavirus (HPV)-encoded oncoproteins, and epigenetically regulating coding gene expression. Hence, we attempted to decipher the impact and underlying mechanisms of MAL downregulation in HPV16-related CaCx pathogenesis, by interrogating the interactive roles of MAL antisense lncRNA AC103563.8, E7 oncoprotein and PRC2 complex protein, EZH2. RESULTS: Employing strand-specific RNA-sequencing, we confirmed the downregulated expression of MAL in association with poor overall survival of CaCx patients bearing HPV16, along with its antisense long noncoding RNA (lncRNA) AC103563.8. The strength of positive correlation between MAL and AC103563.8 was significantly high among patients compared to normal individuals. While downregulated expression of MAL was significantly associated with poor overall survival of CaCx patients bearing HPV16, AC103563.8 did not reveal any such association. We confirmed the enrichment of chromatin suppressive mark, H3K27me3 at MAL promoter, using ChIP-qPCR in HPV16-positive SiHa cells. Subsequent E7 knockdown in such cells significantly increased MAL expression, concomitant with decreased EZH2 expression and H3K27me3 marks at MAL promoter. In silico analysis revealed that both E7 and EZH2 bear the potential of interacting with AC103563.8, at the same binding domain. RNA immunoprecipitation with anti-EZH2 and anti-E7 antibodies, respectively, and subsequent quantitative PCR analysis in E7-silenced and unperturbed SiHa cells confirmed the interaction of AC103563.8 with EZH2 and E7, respectively. Apparently, AC103563.8 seems to preclude EZH2 and bind with E7, failing to block EZH2 function in patients. Thereby, enhanced EZH2 expression in the presence of E7 could potentially inactivate the MAL promoter through H3K27me3 marks, corroborating our previous results of MAL expression downregulation in patients. CONCLUSION: AC103563.8-E7-EZH2 axis, therefore, appears to crucially regulate the expression of MAL, through chromatin inactivation in HPV16-CaCx pathogenesis, warranting therapeutic strategy development.

Molecular predictors for decitabine efficacy in meningiomas - a pilot study.

PURPOSE: Effective chemotherapeutical agents for the treatment of meningiomas are still lacking. Previous in-vitro analyses revealed efficacy of decitabine (DCT), a DNA methyltransferase (DNMT) inhibitor established in the treatment of leukemia, in a yet undefined subgroup of meningiomas. METHODS: Effects of DCT on proliferation and viability was analyzed in primary meningioma cells by immunofluorescence and MTT assays, and cases were classified as drug responders and non-responders. Molecular preconditions for efficacy were analyzed using immunofluorescence for Ki67, DNMT1, and five oncogenes (TRIM58, FAM84B, ELOVL2, MAL2, LMO3) previously found to be differentially methylated after DCT exposition, as well as by genome-wide DNA methylation analyses. RESULTS: Efficacy of DCT (10µM) was found in eight (62%) of 13 meningioma cell lines 48 h after drug exposition (p < .05). DCT significantly reduced DNMT1 expression in all but two cell lines, and median ΔDNMT1 reduction 48 h after drug exposition was lower in DCT-resistant (-11.1%) than in DCT-sensitive (-50.5%, p = .030) cells. Rates of cell lines responsive to DCT exposition distinctly decreased to 25% after 72 h. No significant correlation of the patients´ age, sex, histological subtype, location of the paternal tumor, expression of Ki67, DNMT1 or the analyzed oncogenes with treatment response was found (p > .05, each). DCT efficacy was further independent of the methylation class and global DNA methylation of the paternal tumor. CONCLUSION: Early effects of DCT in meningiomas are strongly related with DNMT1 expression, while clinical, histological, and molecular predictors for efficacy are sparse. Kinetics of drug efficacy might indicate necessity of repeated exposition and encourage further analyses.

LINC00460 Facilitates Cell Proliferation and Inhibits Ferroptosis in Breast Cancer Through the miR-320a/MAL2 Axis.

Background: Emerging evidence suggests that long noncoding RNAs (lncRNAs) play an important role in the progression of multiple human cancers including breast cancer. In this study, we aimed to research novel functions of long intergenic noncoding RNA 460 (LINC00460) on cell proliferation and ferroptosis in breast cancer. Method: UALCAN, TANRIC, and GSE16446 data were used to analyze the expression of LINC00460 in breast cancer tissues. Furthermore, real-time quantitative PCR, western blot, cell proliferation assay, iron assay, and malondialdehyde (MDA) assay were applied to detect the function and mechanism of particular molecules. Results: The LINC00460 expression was significantly increased in breast cancer tissues compared with normal tissues. Importantly, patients with high LINC00460 expression showed a longer overall survival rate. LINC00460 knockdown markedly suppressed the proliferation of breast cancer cells and promoted ferroptosis. Mechanistic analysis revealed that LINC00460 promoted myelin and lymphocyte protein 2 (MAL2) expression by sponging miR-320a. Moreover, both miR-320a knockdown and MAL2 overexpression could reverse the effects of LINC00460 silencing on cell proliferation and ferroptosis. Conclusions: In summary, our results reveal an alternative mechanism by which breast cancer cells can acquire resistance to ferroptosis via the LINC00460/miR-320a/MAL2 axis.

Developing and validating a survival prediction model based on blood exosomal ceRNA network in patients with PAAD.

BACKGROUND: Among the most lethal cancers, pancreatic adenocarcinoma (PAAD) is an essential component of digestive system malignancies that still lacks effective diagnosis and treatment methods. As exosomes and competing endogenous RNA (ceRNA) regulatory networks in tumors go deeper, we expect to construct a ceRNA regulatory network derived from blood exosomes of PAAD patients by bioinformatics methods and develop a survival prediction model based on it. METHODS: Blood exosome sequencing data of PAAD patients and normal controls were downloaded from the exoRbase database, and the expression profiles of exosomal mRNA, lncRNA, and circRNA were differentially analyzed by R. The related mRNA, circRNA, lncRNA, and their corresponding miRNA prediction data were imported into Cytoscape software to visualize the ceRNA network. Then, we conducted GO and KEGG enrichment analysis of mRNA in the ceRNA network. Genes that express differently in pancreatic cancer tissues compared with normal tissues and associate with survival (P < 0.05) were determined as Hub genes by GEPIA. We identified optimal prognosis-related differentially expressed mRNAs (DEmRNAs) and generated a risk score model by performing univariate and multivariate Cox regression analyses. RESULTS: 205 DEmRNAs, 118 differentially expressed lncRNAs (DElncRNAs), and 98 differentially expressed circRNAs (DEcircRNAs) were screened out. We constructed the ceRNA network, and a total of 26 mRNA nodes, 7 lncRNA nodes, 6 circRNA nodes, and 16 miRNA nodes were identified. KEGG enrichment analysis showed that the DEmRNAs in the regulatory network were mainly enriched in Human papillomavirus infection, PI3K-Akt signaling pathway, Osteoclast differentiation, and ECM-receptor interaction. Next, six hub genes (S100A14, KRT8, KRT19, MAL2, MYO5B, PSCA) were determined through GEPIA. They all showed significantly increased expression in cancer tissues compared with control groups, and their high expression pointed to adverse survival. Two optimal prognostic-related DEmRNAs, MYO5B (HR = 1.41, P < 0.05) and PSCA (HR = 1.10, P < 0.05) were included to construct the survival prediction model. CONCLUSION: In this study, we successfully constructed a ceRNA regulatory network in blood exosomes from PAAD patients and developed a two-gene survival prediction model that provided new targets which shall aid in diagnosing and treating PAAD.

Construction and Validation of a Prognostic Model Based on mRNAsi-Related Genes in Breast Cancer.

Background: Breast cancer is a big threat to the women across the world with substantial morbidity and mortality. The pressing matter of our study is to establish a prognostic gene model for breast cancer based on mRNAsi for predicting patient's prognostic survival. Methods: From The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, we downloaded the expression profiles of genes in breast cancer. On the basis of one-class logistic regression (OCLR) machine learning algorithm, mRNAsi of samples was calculated. Kaplan-Meier (K-M) and Kruskal-Wallis (K-W) tests were utilized for the assessment of the connection between mRNAsi and clinicopathological variables of the samples. As for the analysis on the correlation between mRNAsi and immune infiltration, ESTIMATE combined with Spearman test was employed. The weighted gene coexpression network analysis (WGCNA) network was established by utilizing the differentially expressed genes in breast cancer, and the target module with the most significant correlation with mRNAsi was screened. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted to figure out the biological functions of the target module. As for the construction of the prognostic model, univariate, least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analyses were performed on genes in the module. The single sample gene set enrichment analysis (ssGSEA) and tumor mutational burden were employed for the analysis on immune infiltration and gene mutations in the high- and low-risk groups. As for the analysis on whether this model had the prognostic value, the nomogram and calibration curves of risk scores and clinical characteristics were drawn. Results: Nine mRNAsi-related genes (CFB, MAL2, PSME2, MRPL13, HMGB3, DCTPP1, SHCBP1, SLC35A2, and EVA1B) comprised the prognostic model. According to the results of ssGSEA and gene mutation analysis, differences were shown in immune cell infiltration and gene mutation frequency between the high- and low-risk groups. Conclusion: Nine mRNAsi-related genes screened in our research can be considered as the biomarkers to predict breast cancer patients' prognoses, and this model has a potential relationship with individual somatic gene mutations and immune regulation. This study can offer new insight into the development of diagnostic and clinical treatment strategies for breast cancer.

Transcriptional expressions of hsa-mir-183 predicted target genes as independent indicators for prognosis in bladder urothelial carcinoma.

OBJECTIVE: To uncover novel prognostic and therapeutic targets for BLCA, our study is the first to investigate the role of hsa-mir-183 and its up-regulated predicted target genes in bladder urothelial carcinoma. METHODS: To address this issue, our study explored the roles of hsa-mir-183 predicted target genes in the prognosis of BLCA via UALCAN, Metascape, Kaplan-Meier plotter, Human Protein Atlas, TIMER2.0, cBioPortal and Genomics of Drug Sensitivity in Cancer databases. RESULTS: High transcriptional expressions of PDCD6, GNG5, PHF6 and MAL2 were markedly relevant to favorable OS in BLCA patients, whereas SLC25A15 and PTDSS1 had opposite expression significance. Additionally, high transcriptional expression of PDCD6, GNG5, PHF6, MAL2, SLC25A15 and PTDSS1 were significantly correlated with BLCA individual cancer stages and molecular subtypes. Furthermore, high mutation rate of PDCD6, MAL2, SLC25A15 and PTDSS1 were observed. Finally, TP53 mutation of PDCD6, GNG5, PHF6, MAL2, SLC25A15 and PTDSS1 has guiding significance for drug selection in BLCA. CONCLUSIONS: PDCD6, GNG5, PHF6, MAL2, SLC25A15 and PTDSS1 could be the advanced independent indicators for prognosis of BLCA patients, and TP53-mutation might be a biomarker for drug option in BLCA patients.

Lipid raft-mediated and upregulated coordination pathways assist transport of glycocholic acid-modified nanoparticle in a human breast cancer cell line of SK-BR-3.

Bile acid transporter-targeting has been proven to be an effective strategy to improve drug delivery to hepatocytes and enterocytes. With increasing discoveries of bile acid transporter expression on tumor cells, bile acid-modified anticancer drugs are gradually attaining interests. In our previous study, we confirmed the efficacy of glycocholic acid-conjugated polystyrene nanoparticles (GCPN) on apical sodium bile acid transporter (ASBT)-expressed SK-BR-3 cells. However, the transport mechanisms remain unknown, due to the nanosized carriers are unlikely to be pumped through the narrow cavities of ASBT. To clarify their transport pathways, in this article, pharmacological inhibition and gene knocking-down studies were performed, which revealed that GCPN were primarily internalized via non-caveolar lipid raft-mediated endocytosis. Proteomics was analyzed to explore the in-depth mechanisms. In total 561 proteins were identified and statistical overrepresentation test was used to analyze the gene ontology (GO) upregulated pathways based on the highly expressed proteins. It was found that multiple pathways were upregulated and might coordinate to assist the location of the GCPN-ASBT complex and the recycling of ASBT. Among the highly expressed proteins, myelin and lymphocyte protein 2 (MAL2) was selected and confirmed to colocalize with GCPN, which further supported the lipid raft-mediated process. These findings will help set up a platform for designing the bile acid-modified nanomedicines and regulating their transport to improve their anticancer efficacy.

Plasmolipin regulates basolateral-to-apical transcytosis of ICAM-1 and leukocyte adhesion in polarized hepatic epithelial cells.

Apical localization of Intercellular Adhesion Receptor (ICAM)-1 regulates the adhesion and guidance of leukocytes across polarized epithelial barriers. Here, we investigate the molecular mechanisms that determine ICAM-1 localization into apical membrane domains of polarized hepatic epithelial cells, and their effect on lymphocyte-hepatic epithelial cell interaction. We had previously shown that segregation of ICAM-1 into apical membrane domains, which form bile canaliculi and bile ducts in hepatic epithelial cells, requires basolateral-to-apical transcytosis. Searching for protein machinery potentially involved in ICAM-1 polarization we found that the SNARE-associated protein plasmolipin (PLLP) is expressed in the subapical compartment of hepatic epithelial cells in vitro and in vivo. BioID analysis of ICAM-1 revealed proximal interaction between this adhesion receptor and PLLP. ICAM-1 colocalized and interacted with PLLP during the transcytosis of the receptor. PLLP gene editing and silencing increased the basolateral localization and reduced the apical confinement of ICAM-1 without affecting apicobasal polarity of hepatic epithelial cells, indicating that ICAM-1 transcytosis is specifically impaired in the absence of PLLP. Importantly, PLLP depletion was sufficient to increase T-cell adhesion to hepatic epithelial cells. Such an increase depended on the epithelial cell polarity and ICAM-1 expression, showing that the epithelial transcytotic machinery regulates the adhesion of lymphocytes to polarized epithelial cells. Our findings strongly suggest that the polarized intracellular transport of adhesion receptors constitutes a new regulatory layer of the epithelial inflammatory response.

MAL2 mediates the formation of stable HER2 signaling complexes within lipid raft-rich membrane protrusions in breast cancer cells.

The lipid raft-resident protein, MAL2, has been implicated as contributing to the pathogenesis of several malignancies, including breast cancer, but the underlying mechanism for its effects on tumorigenesis is unknown. Here, we show that MAL2-mediated lipid raft formation leads to HER2 plasma membrane retention and enhanced HER2 signaling in breast cancer cells. We demonstrate physical interactions between HER2 and MAL2 in lipid rafts using proximity ligation assays. Super-resolution structured illumination microscopy imaging displays the structural organization of the HER2/Ezrin/NHERF1/PMCA2 protein complex. Formation of this protein complex maintains low intracellular calcium concentrations in the vicinity of the plasma membrane. HER2/MAL2 protein interactions in lipid rafts are enhanced in trastuzumab-resistant breast cancer cells. Our findings suggest that MAL2 is crucial for lipid raft formation, HER2 signaling, and HER2 membrane stability in breast cancer cells, suggesting MAL2 as a potential therapeutic target.

The MAL Protein, an Integral Component of Specialized Membranes, in Normal Cells and Cancer.

The MAL gene encodes a 17-kDa protein containing four putative transmembrane segments whose expression is restricted to human T cells, polarized epithelial cells and myelin-forming cells. The MAL protein has two unusual biochemical features. First, it has lipid-like properties that qualify it as a member of the group of proteolipid proteins. Second, it partitions selectively into detergent-insoluble membranes, which are known to be enriched in condensed cell membranes, consistent with MAL being distributed in highly ordered membranes in the cell. Since its original description more than thirty years ago, a large body of evidence has accumulated supporting a role of MAL in specialized membranes in all the cell types in which it is expressed. Here, we review the structure, expression and biochemical characteristics of MAL, and discuss the association of MAL with raft membranes and the function of MAL in polarized epithelial cells, T lymphocytes, and myelin-forming cells. The evidence that MAL is a putative receptor of the epsilon toxin of Clostridium perfringens, the expression of MAL in lymphomas, the hypermethylation of the MAL gene and subsequent loss of MAL expression in carcinomas are also presented. We propose a model of MAL as the organizer of specialized condensed membranes to make them functional, discuss the role of MAL as a tumor suppressor in carcinomas, consider its potential use as a cancer biomarker, and summarize the directions for future research.

MAL2 interacts with IQGAP1 to promote pancreatic cancer progression by increasing ERK1/2 phosphorylation.

Pancreatic cancer is a digestive tract malignancy characterized by an occult onset and rapid progression. The genetic heterogeneity of pancreatic cancer is closely related to its highly malignant biological behavior. The myelin and lymphocyte protein 2 (MAL2) is upregulated in multiple cancers at the transcriptional level. However, the exact role of MAL2 in pancreatic cancer remains elusive. In this study, we demonstrated that MAL2 protein and mRNA levels were upregulated in pancreatic cancer. MAL2 overexpression was significantly associated with poor prognosis in patients with pancreatic cancer. We further showed that MAL2 interacted with IQGAP1 to increase ERK1/2 phosphorylation levels, which promoted pancreatic cancer progression. Therefore, these results suggest that MAL2 could be a novel therapeutic target for pancreatic cancer.

FTO modifies the m6A level of MALAT and promotes bladder cancer progression.

BACKGROUND: Nearly a half million people around the world are diagnosed with bladder cancer each year, and an incomplete understanding of its pathogenicity and lack of efficient biomarkers having been discovered lead to poor clinical management of bladder cancer. Fat mass and obesity-associated protein (FTO) is a critical player in carcinogenesis. We, here, explored the role of FTO and unraveled the mechanism of its function in bladder cancer. METHODS: Identification of the correlation of FTO with bladder cancer was based on both bioinformatics and clinical analysis of tissue samples collected from a cohort of patients at a hospital and microarray data. Gain-of-function and loss-of-function assays were conducted in vivo and in vitro to assess the effect of FTO on bladder carcinoma tumor growth and its impact on the bladder carcinoma cell viability. Moreover, the interactions of intermediate products were also investigated to elucidate the mechanisms of FTO function. RESULTS: Bladder tumor tissues had increased FTO expression which correlated with clinical bladder cancer prognosis and outcomes. Both in vivo and in vitro, it played the function of an oncogene in stimulating the cell viability and tumorigenicity of bladder cancer. Furthermore, FTO catalyzed metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) demethylation, regulated microRNA miR-384 and mal T cell differentiation protein 2 (MAL2) expression, and modulated the interactions among these processes. CONCLUSIONS: The interplay of these four clinically relevant factors contributes to the oncogenesis of bladder cancer. FTO facilitates the tumorigenesis of bladder cancer through regulating the MALAT/miR-384/MAL2 axis in m6A RNA modification manner, which ensures the potential of FTO for serving as a diagnostic or prognostic biomarker in bladder cancer.

Differentiation and activation of human CD4 T cells is associated with a gradual loss of myelin and lymphocyte protein.

Upon generation of monoclonal antibodies to the T cell antigen receptor/CD3 (TCR/CD3) complex, we isolated mAb MT3, whose reactivity correlates inversely with the production of IFN-γ by human peripheral blood T lymphocytes. Using eukaryotic expression cloning, we identified the MT3 antigen as myelin-and-lymphocyte (MAL) protein. Flow cytometry analysis demonstrates high surface expression of MAL on all naïve CD4+ T cells whereas MAL expression is diminished on central memory- and almost lost on effector memory T cells. MAL- T cells proliferate strongly in response to stimulation with CD3/CD28 antibodies, corroborating that MAL+ T cells are naïve and MAL- T cells memory subtypes. Further, resting MAL- T cells harbor a larger pool of Ser59- and Tyr394- double phosphorylated lymphocyte-specific kinase (Lck), which is rapidly increased upon in vitro restimulation. Previously, lack of MAL was reported to prevent transport of Lck, the key protein tyrosine kinase of TCR/CD3 signaling to the cell membrane, and to result in strongly impaired human T cell activation. Here, we show that knocking out MAL did not significantly affect Lck membrane localization and immune synapse recruitment, or transcriptional T cell activation. Collectively, our results indicate that loss of MAL is associated with activation-induced differentiation of human T cells but not with impaired membrane localization of Lck or TCR signaling capacity.

Clostridium perfringens epsilon toxin binds to erythrocyte MAL receptors and triggers phosphatidylserine exposure.

Epsilon toxin (ETX) is a 33-kDa pore-forming toxin produced by type B and D strains of Clostridium perfringens. We previously found that ETX caused haemolysis of human red blood cells, but not of erythrocytes from other species. The cellular and molecular mechanisms of ETX-mediated haemolysis are not well understood. Here, we investigated the effects of ETX on erythrocyte volume and the role of the putative myelin and lymphocyte (MAL) receptors in ETX-mediated haemolysis. We observed that ETX initially decreased erythrocyte size, followed by a gradual increase in volume until lysis. Moreover, ETX triggered phosphatidylserine (PS) exposure and enhanced ceramide abundance in erythrocytes. Cell shrinkage, PS exposure and enhanced ceramide abundance were preceded by increases in intracellular Ca2+ concentration. Interestingly, lentivirus-mediated RNA interference studies in the human erythroleukaemia cell line (HEL) cells confirmed that MAL contributes to ETX-induced cytotoxicity. Additionally, ETX was shown to bind to MAL in vitro. The results of this study recommend that ETX-mediated haemolysis is associated with MAL receptor activation in human erythrocytes. These data imply that interventions affecting local MAL-mediated autocrine and paracrine signalling may prevent ETX-mediated erythrocyte damage.

The Role of CADM1 and MAL Promoter Methylation in Inflammation and Cervical Intraepithelial Neoplasia.

Aims: This study investigated the presence of human papillomavirus (HPV) infection and the methylation status of the promoters of the cell adhesion molecule 1 (CADM1) gene and T lymphocyte maturation associated protein (MAL) gene in patients with cervicitis/inflammation and cervical intraepithelial neoplasia (CIN). Materials and Methods: Cervical specimens (n = 47) were collected from women with normal cervical cytology (n = 21) and those with cervical abnormalities (n = 26). The presence of HPV infection was confirmed by an HPV DNA test and an HPV mRNA test (Aptima HPV test). Methylation levels of the CADM1 and MAL promoters were evaluated by pyrosequencing. Results: Compared with the HPV DNA test, the Aptima HPV test improved specificity from 57% to 70% for the detection of inflammation and/or CIN type 1 (CIN1) or more advanced conditions (CIN1+). The methylation level of the CADM1 and MAL promoters was 1.5 times higher in inflammatory samples, compared with normal cervical cytology (p < 0.05). Conclusion: Selected 5'-C-phosphate-G-3' islands within the promoters of the CADM1 and MAL genes were differentially methylated in the inflammatory samples compared with the CIN samples. These results suggested that methylation likely occurred following tissue disruption, and the detection of persistent inflammation might be associated with a higher risk of lesion progression.

Herpes Simplex Virus 1 Spread in Oligodendrocytic Cells Is Highly Dependent on MAL Proteolipid.

Myelin and lymphocyte protein (MAL) is a tetraspan integral membrane protein that resides in detergent-insoluble membrane fractions enriched in condensed membranes. MAL is expressed in oligodendrocytes, in Schwann cells, where it is essential for the stability of myelin, and at the apical membrane of epithelial cells, where it has a critical role in transport. In T lymphocytes, MAL is found at the immunological synapse and plays a crucial role in exosome secretion. However, no involvement of MAL in viral infections has been reported so far. Here, we show that herpes simplex virus 1 (HSV-1) virions travel in association with MAL-positive structures to reach the end of cellular processes, which contact uninfected oligodendrocytes. Importantly, the depletion of MAL led to a significant decrease in infection, with a drastic reduction in the number of lytic plaques in MAL-silenced cells. These results suggest a significant role for MAL in viral spread at cell contacts. The participation of MAL in the cell-to-cell spread of HSV-1 may shed light on the involvement of proteolipids in this process.IMPORTANCE Herpes simplex virus 1 (HSV-1) is a neurotropic pathogen that can infect many types of cells and establish latent infections in neurons. HSV-1 may spread from infected to uninfected cells by two main routes: by cell-free virus or by cell-to-cell spread. In the first case, virions exit into the extracellular space and then infect another cell from the outside. In the second case, viral transmission occurs through cell-to-cell contacts via a mechanism that is still poorly understood. A third mode of spread, using extracellular vesicles, also exists. In this study, we demonstrate the important role for a myelin protein, myelin and lymphocyte protein (MAL), in the process of cell-to-cell viral spread in oligodendrocytes. We show that MAL is involved in trafficking of virions along cell processes and that MAL depletion produces a significant alteration in the viral cycle, which reduces cell-to cell spread of HSV-1.

MAL2 promotes proliferation, migration, and invasion through regulating epithelial-mesenchymal transition in breast cancer cell lines.

BACKGROUND: Breast cancer is one of the most common malignant tumors in women. However, the underlying molecular mechanisms of breast cancer are still far to clear. With the development of sequencing technology, we discovered that MAL2 is overexpressed in tumor tissues. But the major function of MAL2 in breast cancer has not to be well confirmed. MATERIALS AND METHODS: We downloaded and analyzed the MAL2 expression in The Cancer Genome Atlas (TCGA) database. Real-time quantitative polymerase chain reaction (RT-qPCR) was conducted to detect the expression of MAL2 in 35 breast cancer patients. Then, we performed proliferation, colony formation, migration, invasion and western blot assays to investigate the role of MAL2 in breast cancer cell lines (MDA-MB-231 and BT-549). RESULTS: In our research, we found that MAL2 is remarkably overexpressed in breast cancer tissues compared to adjacent non-cancer tissues by RT-qPCR (T: N = 5.28 ±â€¯4.34:1.82 ±â€¯1.11, P < 0.001) and high expression of MAL2 has worse overall survival in TCGA cohort (P = 0.0032). Knocked down MAL2 could decrease the ability of proliferation, migration, and invasion of breast cancer cell lines. Our Western Blot assay results investigated that MAL2 could regulate EMT. CONCLUSION: In this study, we demonstrated the function of MAL2 in breast cancer cell lines and it might act as an oncogene in breast cancer.

MiR-129 regulates growth and invasion by targeting MAL2 in papillary thyroid carcinoma.

MAL2, a member of the MAL proteolipid family, is essential for raft-mediated transport. In this study, we investigated the roles and underlying mechanism of MAL2 in the development of papillary thyroid carcinoma (PTC). Up-regulation of MAL2 was found in human PTC tissues and significantly correlated with poor overall survival (OS). Knockdown of MAL2 dramatically suppressed PTC cell proliferation and invasion in vitro and inhibited tumor growth in vivo. We further found that miR-129 suppressed the expression of MLA through directly binding to the 3' untranslated region (3' UTR). While forced miR-129 expression suppressed growth and invasion of PTC cells, re-expression of MAL2 rescued these effects. Taken together, our data indicated that MAL2 acted as an oncogene and was negatively regulated by miR-129, supporting the potential therapeutic strategy against PTC by targeting miR-129-MAL2 axis.

The Cytotoxicity of Epsilon Toxin from Clostridium perfringens on Lymphocytes Is Mediated by MAL Protein Expression.

Epsilon toxin (Etx) from Clostridium perfringens is a pore-forming protein that crosses the blood-brain barrier, binds to myelin, and, hence, has been suggested to be a putative agent for the onset of multiple sclerosis, a demyelinating neuroinflammatory disease. Recently, myelin and lymphocyte (MAL) protein has been identified to be a key protein in the cytotoxic effect of Etx; however, the association of Etx with the immune system remains a central question. Here, we show that Etx selectively recognizes and kills only human cell lines expressing MAL protein through a direct Etx-MAL protein interaction. Experiments on lymphocytic cell lines revealed that MAL protein-expressing T cells, but not B cells, are sensitive to Etx and reveal that the toxin may be used as a molecular tool to distinguish subpopulations of lymphocytes. The overall results open the door to investigation of the role of Etx and Clostridium perfringens on inflammatory and autoimmune diseases like multiple sclerosis.