Itm2a, a target gene of GATA-3, plays a minimal role in regulating the development and function of T cells

Dupilumab-associated head and neck dermatitis shows a pronounced type 22 immune signature mediated by oligoclonally expanded T cells

Dupilumab, an IL4R-blocking antibody, has shown clinical efficacy for atopic dermatitis (AD) treatment. In addition to conjunctivitis/blepharitis, the de novo appearance of head/neck dermatitis is now recognized as a distinct side effect, occurring in up to 10% of patients. Histopathological features distinct from AD suggest a drug effect, but exact underlying mechanisms remain unknown. We profiled punch biopsies from dupilumab-associated head and neck dermatitis (DAHND) by using single-cell RNA sequencing and compared data with untreated AD and healthy control skin. We show that dupilumab treatment was accompanied by normalization of IL-4/IL-13 downstream activity markers such as CCL13, CCL17, CCL18 and CCL26. By contrast, we found strong increases in type 22-associated markers (IL22, AHR) especially in oligoclonally expanded T cells, accompanied by enhanced keratinocyte activation and IL-22 receptor upregulation. Taken together, we demonstrate that dupilumab effectively dampens conventional type 2 inflammation in DAHND lesions, with concomitant hyperactivation of IL22-associated responses.

Exosomal miRNA-166-5p derived from G-MDSCs promotes proliferation by targeting ITM3E in colorectal cancer

BACKGROUND

The immune milieu of colorectal cancer is a complex phenomenon. It is imperative to investigate the crucial immune factors that promote the progression of colorectal cancer. Immune suppressor cells are granulocytic myeloid-derived suppressor cells (G-MDSCs). However, they also increased cancer growth in other ways that need to be investigated further.

METHODS

Using flow cytometry, we isolated G-MDSCs from colorectal cancer tissues. Ultracentrifugation was used to separate exosomes from the supernatant of G-MDSCs, and western blotting, transmission electron microscopy (TEM), and flow cytometry were used to confirm their presence. RNA sequencing was used to identify unique miRNAs and transcripts, which were subsequently confirmed by RT-qPCR (real-time quantitative real-time PCR). The CCK-8 test was used to determine the rate of proliferation. Lentiviral vectors were employed to manipulate the expression of miRNAs and genes in order to investigate their role in the development of colorectal cancer.

RESULTS

Colorectal cancer tissues have been found to contain granulocyte-myeloid-derived suppressor cells (G-MDSCs) that secrete exosomes. These exosomes have been shown to accelerate cancer progression by promoting cell proliferation. Further research has identified microRNA-166-5p as a target from G-MDSC-derived exosomes. This downregulation leads to the inhibition of integral membrane protein 2B (ITM3E) transcription, which in turn activates the PI3K/Akt signaling pathway. This pathway promotes cell proliferation and can be inhibited using deguelin. The accelerated development of colorectal cancer has been further confirmed in mice models.

CONCLUSION

The primary results of this work show that exosomes produced from G-MDSCs and the miR-166-5p/ITM3E axis have therapeutic and diagnostic promise in colorectal cancer.

Review of T cell proliferation regulatory factors in treatment and prognostic prediction for solid tumors

T cell proliferation regulators (Tcprs), which are positive regulators that promote T cell function, have made great contributions to the development of therapies to improve T cell function. CAR (chimeric antigen receptor) -T cell therapy, a type of adoptive cell transfer therapy that targets tumor cells and enhances immune lethality, has led to significant progress in the treatment of hematologic tumors. However, the applications of CAR-T in solid tumor treatment remain limited. Therefore, in this review, we focus on the development of Tcprs for solid tumor therapy and prognostic prediction. We summarize potential strategies for targeting different Tcprs to enhance T cell proliferation and activation and inhibition of cancer progression, thereby improving the antitumor activity and persistence of CAR-T. In summary, we propose means of enhancing CAR-T cells by expressing different Tcprs, which may lead to the development of a new generation of cell therapies.

Critical role of epigenetic modification in the pathogenesis of atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease characterised by recurrent eczema-like lesions and severe pruritus, along with drying and decrustation of skin. Current research relates the pathogenesis of atopic dermatitis mainly to genetic susceptibility, abnormal skin barrier function, immune disorders, Staphylococcus aureus colonisation, microbiological dysfunction and vitamin D insufficiency. Epigenetic modifications are distinct genetic phenotypes resulting from environment-driven changes in chromosome functions in the absence of nuclear DNA sequence variation. Classic epigenetic events include DNA methylation, histone protein modifications and non-coding RNA regulation. Increasing evidence has indicated that epigenetic events are involved in the pathogenesis of atopic dermatitis by their effects on multiple signalling pathways which in turn influence the above factors. This review primarily analyses the function of epigenetic regulation in the pathogenesis of atopic dermatitis. In addition, it tries to make recommendations for personalised epigenetic treatment strategies for atopic dermatitis in the future.

Identification of potential biomarkers in active Lyme borreliosis

OBJECTIVES

Lyme serology does not readily discriminate an active Lyme borreliosis (LB) from a previous Borrelia infection or exposure. Here, we aimed to investigate a large number of immunological protein biomarkers to search for an immunological pattern typical for active LB, in contrast to patterns found in healthy blood donors, a proportion of whom were previously exposed to Borrelia.

METHODS

Serum samples from well-characterised adult patients with ongoing LB and healthy blood donors were included and investigated using a proximity extension assay (provided by Olink®) by which 92 different immune response-related human protein biomarkers were analysed simultaneously.

RESULTS

In total, 52 LB patients and 75 healthy blood donors were included. The blood donors represented both previously Borrelia exposed (n = 34) and not exposed (n = 41) based on anti-Borrelia antibody status. Ten of the examined 92 proteins differed between patients and blood donors and were chosen for further logistic regression (p<0.1). Six proteins were statistically significantly different between LB patients and blood donors (p<0.05). These six proteins were then combined in an index and analysed using receiver-operating-characteristic curve analysis showing an area under the curve of 0.964 (p<0.001).

CONCLUSIONS

The results from this study suggest that there is an immunological protein pattern that can distinguish a present Borrelia infection from a previous exposure as well as anti-Borrelia antibody negative blood donors. Although this method is not adapted for routine clinical use at this point, the possibility is interesting and may open new diagnostic opportunities improving the laboratory diagnostics of LB.

Tumor-associated macrophages-derived exo-let-7a promotes osteosarcoma metastasis via targeting C15orf41 in osteosarcoma

BACKGROUND

Osteosarcoma (OS) immune environment is complexed and the immune factors-related to OS progression need to be explored. Tumor-associated macrophages (TAMs) are regarded as immune suppressive and tumor-promoting cells. However, the underlying mechanisms through which TAMs function are still fragmentary. Here, we aim to explore the underlying mechanisms by which TAMs regulate OS progression.

METHODS

TAMs from OS tissues were isolated by flow cytometry. Exosomes derived from TAMs were separated using ultracentrifugation and western blotting. Transmission electron microscopy (TEM), and flow cytometry were constructed to characterize TAMs-derived exosomes. Additionally, the differential MicroRNAs (miRNAs) and genes were detected through RNA sequencing, and further validated using real-time PCR (RT-PCR). OS cell metastasis ability was assessed using transwell invasion and scratch wound healing assays. MiRNAs mimic and lentiviral vectors were utilized to explore the effects on OS progression.

RESULTS

Exosome secreted by TAMs accelerated the OS metastasis. Let-7a level was upregulated in TAMs derived exosomes, which downregulated C15orf41 by targeting 3'-untranslated region (UTR). Furthermore, overexpressing let-7a enhanced invasion and migration by blocking the transcription of C15orf41. In consistent, up-regulating let-7a promoted OS progression and made the prognosis to be worse, which can be reversed by C15orf41 overexpression.

CONCLUSION

This study highlighted the critical role of TAMs-derived exosomes in OS progression and explored the potential value of the let-7a/C15orf41 axis as an indicator or target for OS.

Association of ITM2A rs1751094 polymorphism on X chromosome in Korean pediatric patients with autoimmune thyroid disease

Background

Autoimmune thyroid disease (AITD) manifests with a female predominance, and much attention has been directed towards the integral membrane protein 2 A (ITM2A) gene located on the X chromosome.

Methods

In a study of 166 pediatric patients with autoimmune thyroid disease (AITD), the ITM2A rs1751094 single‐nucleotide polymorphism (SNP) was genotyped. The sample comprised 143 females and 23 males, with 67 patients diagnosed with Hashimoto chronic thyroiditis (HD) and 99 with Graves' disease (GD). In the 99 GD patients, 49 (49.5%) exhibited thyroid‐associated ophthalmopathy (TAO). Among the 85 GD patients, 70.6% (60/85) were considered intractable GD. The results were compared to those from 198 healthy Korean individuals, including 97 females and 101 males.

Results

The frequency of the rs1751094 C allele and CC/AC genotype were higher in AITD, GD and HD patients compared to controls, while the frequency of the A allele and AA genotype were lower. The results were more pronounced in female AITD and GD patients compared to male patients. The association was also found in intractable GD and TAO patients. Target SNP fits Hardy–Weinberg equilibrium.

Conclusions

These findings indicate that the ITM2A gene polymorphism on the X chromosome may contribute to the immunological basis of female‐predominant AITD in Korean children.

Construction of a B cell-related gene pairs signature for predicting prognosis and immunotherapeutic response in non-small cell lung cancer

BACKGROUND

Accumulating evidence indicates that the B cells play important roles in anti-tumor immunity and shaping tumor development. This study aimed to explore the expression profiles of B cell marker genes and construct a B cell-related gene pairs (BRGPs) signature associated with the prognosis and immunotherapeutic efficiency in non-small cell lung cancer (NSCLC) patients.

METHODS

B cell-related marker genes in NSCLC were identified using single-cell RNA sequencing data. TCGA and GEO datasets were utilized to identify the prognostic BRGPs based on a novel algorithm of cyclically single pairing along with a 0-or-1 matrix. BRGPs signature was then constructed using Lasso-Cox regression model. Its prognostic value, associated immunogenomic features, putative molecular mechanism and predictive ability to immunotherapy were investigated in NSCLC patients.

RESULTS

The BRGPs signature was composed of 23 BRGPs including 28 distinct B cell-related genes. This predictive signature demonstrated remarkable power in distinguishing good or poor prognosis and can serve as an independent prognostic factor for NSCLC patients in both training and validation cohorts. Furthermore, BRGPs signature was significantly associated with immune scores, tumor purity, clinicopathological characteristics and various tumor-infiltrating immune cells. Besides, we demonstrated that the tumor mutational burden scores and TIDE scores were positively correlated with the risk score of the model implying immune checkpoint blockade therapy may be more effective in NSCLC patients with high-risk scores.

CONCLUSIONS

This novel BRGPs signature can be used to assess the prognosis of NSCLC patients and may be useful in guiding immune checkpoint inhibitor treatment in our clinical practice.

The Multifaceted Role of Signal Peptide-CUB-EGF Domain-Containing Protein (SCUBE) in Cancer

Signal peptide, CUB, and EGF-like domain-containing proteins (SCUBE) are secretory cell surface glycoproteins that play key roles in the developmental process. SCUBE proteins participate in the progression of several diseases, including cancer, and are recognized for their oncogenic and tumor suppressor functions depending on the cellular context. SCUBE proteins promote cancer cell proliferation, angiogenesis, invasion, or metastasis, stemness or self-renewal, and drug resistance. The association of SCUBE with other proteins alters the expression of signaling pathways, including Hedgehog, Notch, TGF-β/Smad2/3, and β-catenin. Further, SCUBE proteins function as potential prognostic and diagnostic biomarkers for breast cancer, renal cell carcinoma, endometrial carcinoma, and nasopharyngeal carcinoma. This review presents key features of SCUBE family members, and their structure and functions, and highlights their contribution in the development and progression of cancer. A comprehensive understanding of the role of SCUBE family members offers novel strategies for cancer therapy.

Integral membrane protein 2A enhances sensitivity to chemotherapy via notch signaling pathway in cervical cancer

As the second most common cancer among women, cervical cancer is a huge threat to their health all over the world. Integral membrane protein 2A (ITM2A), a member of the Type II Integral Membrane protein (ITM2) family, has been reported to act as a tumor suppressor in breast cancer and ovarian cancer. Moreover, the low expression of ITM2A was associated with cervical adenocarcinoma. However, the function of ITM2A in drug resistance in cervical cancer remains unclear. Here, we used bioinformatics methods to screen differentially expressed genes (DEGs) closely related to chemotherapeutic relapse cervical carcinoma. ITM2A is downregulated in cervical tumor tissues and is associated with poor survival. Furthermore, ITM2A is also downregulated in cervical cancer cells with cisplatin resistance. Overexpression of ITM2A increases the cisplatin sensitivity of cervical cancer cells. Mechanically, ITM2A upregulation mediates the sensitivity of cervical cancer cell through Notch signaling pathway. Our study suggests that ITM2A may serve as a target in mediating cisplatin-resistant cervical cancer.

Maternal atopy and offspring epigenome-wide methylation signature

The increase in the prevalence of allergic diseases is believed to partially depend on environmental changes. DNA methylation is a major epigenetic mechanism, which is known to respond to environmental factors. A number of studies have revealed that patterns of DNA methylation may potentially predict allergic diseases.Here, we examined how maternal atopy is associated with methylation patterns in the cord blood of neonates.We conducted an epigenome-wide association study in a cohort of 96 mother-child pairs. Pregnant women aged not more than 35 years old, not currently smoking or exposed to environmental tobacco smoke, who did not report obesity before conception were considered eligible. They were further tested for atopy. Converted DNA from cord blood was analysed using Infinium MethylationEPIC; for statistical analysis, RnBeads software was applied. Gestational age and sex were included as covariates in the final analysis.83 DM sites were associated with maternal atopy. Within the top DM sites, there were CpG sites which mapped to genes SCD, ITM2C, NT5C3A and NPEPL1. Regional analysis revealed 25 tiling regions, 4 genes, 3 CpG islands and 5 gene promoters, (including PIGCP1, ADAM3A, ZSCAN12P1) associated with maternal atopy. Gene content analysis revealed pointwise enrichments in pathways related to purine-containing compound metabolism, the G1/S transition of the mitotic cell cycle, stem cell division and cellular glucose homoeostasis.These findings suggest that maternal atopy provides a unique intrauterine environment that may constitute the first environment in which exposure is associated with methylation patterns in newborn.

ITM2A as a Tumor Suppressor and Its Correlation With PD-L1 in Breast Cancer

Background

High expression of integral membrane protein 2A (ITM2A) was reported to be associated with favorable prognosis in several solid tumors including breast cancer. This study aimed to investigate the role of ITM2A in breast cancer, especially in respect to tumor microenvironment.

Methods

ITM2A expression was evaluated based on qRT-PCR results on breast cancer specimens, as well as TCGA and GEO datasets. The influence of ITM2A expression on breast cancer cell proliferation and tumor growth were evaluated by CCK-8 assay, clonogenic assay, and murine xenograft models. Transwell assay was performed to observe the changes of invasion and migration capacity in breast cancer cells. To determine the biological functions of ITM2A, differentially expressed genes (DEGs) were screened based on RNA-sequencing data of MCF-7 cells overexpressed ITM2A. Then, functional annotation on DEGs was given by Gene Ontology and KEGG analysis. The stimulation on programmed cell death ligand 1 (PD-L1) expression when ITM2A overexpressed was determined by flow cytometry. Meanwhile, the correlation on expression levels between PD-L1 and ITM2A was tested via qRT-PCR on 24 breast cancer tissues, as well as public database.

Results

We demonstrated that ITM2A was frequently downregulated in breast cancer. Patients with high expression levels of ITM2A had longer overall survival and relapse free survival. Overexpression of ITM2A inhibited proliferation and impaired cells capacity of invasion and migration in vitro and in vivo. The DEGs in breast cancer cells overexpressed ITM2A were found to be associated with immunity responses. Moreover, ITM2A was found to facilitate breast cancer cells to express PD-L1. The correlation between PD-L1 and ITM2A was verified with both qRT-PCR assay and public database. Additionally, it was found that breast cancer had higher ITM2A expression frequently had more tumor-infiltrating lymphocytes (TILs).

Conclusion

In summary, we found that high expression of ITM2A reduced the aggressivity of breast cancer cells and had a favorable effect on outcomes of patients with breast cancer. Moreover, ITM2A induced PD-L1 expression in breast cancer cells was accompanied with higher TILs numbers in tumor microenvironment.

Identification of glycogene-type and validation of ST3GAL6 as a biomarker predicts clinical outcome and cancer cell invasion in urinary bladder cancer

Background: Urinary bladder cancer (UBC) is one of the most common causes of morbidity and mortality worldwide characterized by a high risk of invasion and metastasis; however, the molecular classification biomarkers and underlying molecular mechanisms for UBC patient stratification on clinical outcome need to be investigated. Methods: A systematic transcriptomic analysis of 185 glycogenes in the public UBC datasets with survival information and clinicopathological parameters were performed using unsupervised hierarchical clustering. The gene signature for glycogene-type classification was identified using Limma package in R language, and correlated to 8 known molecular features by Gene Set Variation Analysis (GSVA). The clinical relevance and function of a glycogene was characterized by immunohistochemistry in UBC patient samples, and quantitative RT-PCR, Western blotting, promoter activity, MAL II blotting, immunofluorescence staining, wound healing, and transwell assays in UBC cells. Results: A 14-glycogene signature for glycogene-type classification was identified. Among them, ST3GAL6, a glycotransferase to transfer sialic acid to 3'-hydroxyl group of a galactose residue, showed a significant negative association with the subtype with luminal feature in UBC patients (n=2,130 in total). Increased ST3GAL6 was positively correlated to tumor stage, grade, and survival in UBCs from public datasets or our cohort (n=52). Transcription factor GATA3, a luminal-specific marker for UBC, was further identified as a direct upstream regulator of ST3GAL6 to negatively regulate its transactivation. ST3GAL6 depletion decreased MAL II level, cell invasion and migration in 5637 and J82 UBC cells. ST3GAL6 could reverse the effects of GATA3 on global sialylation and cell invasion in SW780 cells. Conclusions: Herein, we successfully identified a novel 14-gene signature for glycogene-type classification of UBC patients. ST3GAL6 gene, from this signature, was demonstrated as a potential biomarker for poor outcomes and cell invasion in UBCs.

Urinary Cell Transcriptome Profiling and Identification of ITM2A, SLAMF6, and IKZF3 as Biomarkers of Acute Rejection in Human Kidney Allografts

Identification of a shared gene expression pattern between T cell–mediated rejection (TCMR) and antibody-mediated rejection (AMR) in human kidney allografts may help prioritize targets for the treatment of both types of acute rejection.

Integral membrane protein 2A inhibits cell growth in human breast cancer via enhancing autophagy induction

Background

Breast cancer is a life-threatening disease in females and the leading cause of mortality among the female population, presenting huge challenges for prognosis and treatment. ITM2A is a member of the BRICHOS superfamily, which are thought to have a chaperone function. ITM2A has been identified to related to ovarian cancer progress recently. However, the biological role of ITM2A in breast cancer remains largely unclear.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR), western blotting assay and immunohistochemistry staining were used to analyzed the expression level of ITM2A. The patient overall survival versus ITM2A expression level was evaluated by Kaplan-Meier analysis. MTT assay, EdU incorporation assay and colony formation assay were used to evaluated the role of ITM2A on breast cancer cell proliferation. Autophagy was explored through autophagic flux detection using a confocal microscope and autophagic vacuoles investigation under a transmission electron microscopy (TEM). In vitro kinase assay was used to investigated the phosphorylation modification of ITM2A by HUNK.

Results

Our data showed that the expression of integral membrane protein 2A (ITM2A) was significantly down-regulated in human breast cancer tissues and cell lines. Kaplan-Meier analysis indicated that patients presenting with reduced ITM2A expression exhibited poor overall survival, and expression significantly correlated with age, progesterone receptor status, TNM classification and tumor stage. ITM2A overexpression significantly inhibited the proliferation of breast cancer cells. By studying several autophagic markers and events in human breast cancer SKBR-3 cells, we further demonstrated that ITM2A is a novel positive regulator of autophagy through an mTOR-dependent manner. Moreover, we found that ITM2A was phosphorylated at T35 by HUNK, a serine/threonine kinase significantly correlated with human breast cancer overall survival and HER2-induced mammary tumorigenesis.

Conclusion

Our study provided evidence that ITM2A functions as a novel prognostic marker and represents a potential therapeutic target.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0422-7) contains supplementary material, which is available to authorized users.

Structural characterization of the third scavenger receptor cysteine-rich domain of murine neurotrypsin

Neurotrypsin (NT) is a multi-domain serine protease of the nervous system with only one known substrate: the large proteoglycan Agrin. NT has seen to be involved in the maintenance/turnover of neuromuscular junctions and in processes of synaptic plasticity in the central nervous system. Roles which have been tied to its enzymatic activity, localized in the C-terminal serine-protease (SP) domain. However the purpose of NT's remaining 3-4 scavenger receptor cysteine-rich (SRCR) domains is still unclear. We have determined the crystal structure of the third SRCR domain of murine NT (mmNT-SRCR3), immediately preceding the SP domain and performed a comparative structural analysis using homologous SRCR structures. Our data and the elevated degree of structural conservation with homologous domains highlight possible functional roles for NT SRCRs. Computational and experimental analyses suggest the identification of a putative binding region for Ca²⁺ ions, known to regulate NT enzymatic activity. Furthermore, sequence and structure comparisons allow to single out regions of interest that, in future studies, might be implicated in Agrin recognition/binding or in interactions with as of yet undiscovered NT partners.

Regulatory network of GATA3 in pediatric acute lymphoblastic leukemia

GATA3 polymorphisms were reported to be significantly associated with susceptibility of pediatric B-lineage acute lymphoblastic leukemia (ALL), by impacting on GATA3 expression. We noticed that ALL-related GATA3 polymorphism located around in the tissue-specific enhancer, and significantly associated with GATA3 expression. Although the regulatory network of GATA3 has been well reported in T cells, the functional status of GATA3 is poorly understood in B-ALL. We thus conducted genome-wide gene expression association analyses to reveal expression associated genes and pathways in nine independent B-ALL patient cohorts. In B-ALL patients, 173 candidates were identified to be significantly associated with GATA3 expression, including some reported GATA3-related genes (e.g., ITM2A) and well-known tumor-related genes (e.g., STAT4). Some of the candidates exhibit tissue-specific and subtype-specific association with GATA3. Through overexpression and down-regulation of GATA3 in leukemia cell lines, several reported and novel GATA3 regulated genes were validated. Moreover, association of GATA3 expression and its targets can be impacted by SNPs (e.g., rs4894953), which locate in the potential GATA3 binding motif. Our findings suggest that GATA3 may be involved in multiple tumor-related pathways (e.g., STAT/JAK pathway) in B-ALL to impact leukemogenesis through epigenetic regulation.

MicroRNA-146a Overexpression Impairs the Positive Selection during T Cell Development

MicroRNAs play crucial roles in modulating immune system. miR-146a, a potent feedback suppressor of NF-κB signaling, was shown to limit the innate immune response and myelopoiesis in a knockout mouse model. Here, we observed high lymphopoiesis demonstrated as mild splenomegaly and severe lymphadenopathy in a miR-146a transgenic mouse model. Overexpression of miR-146a resulted in enhanced proliferation and reduced apoptosis of T cells. More activated CD4⁺ T cells or effector memory T cells were observed in transgenic mice even under physiological conditions. Importantly, as one of the key steps to generate central tolerance, the positive selection of thymocytes is impaired in transgenic mice, resulting in more CD4⁺CD8⁺ double-positive thymocytes but fewer CD4⁺CD8⁻ and CD4⁻CD8⁺ single-positive thymocytes. The maturation of selected CD4⁻CD8⁺ thymocytes was also impaired, leading to more severe loss of CD4⁻CD8⁺ than CD4⁺CD8⁻ thymocytes in thymus of transgenic mice. Gene expression profiling analysis identified nine positive selection-associated genes, which were downregulated in transgenic mice, including genes encoding major histocompatibility complex class I/II molecules, IL-7 receptor α chain, and Gimap4, whose downregulation may contribute to the impairment of positive selection. Gimap4 was verified as a novel target of miR-146a. These findings further extend our understanding of the function of miR-146a in T cell biology and identify a novel regulatory mechanism underlying the positive selection during T cell development.

Itm2a silencing rescues lamin A mediated inhibition of 3T3-L1 adipocyte differentiation

Dysregulation of adipose tissue metabolism is associated with multiple metabolic disorders. One such disease, known as Dunnigan-type familial partial lipodystrophy (FPLD2) is characterized by defective fat metabolism and storage. FPLD2 is caused by a specific subset of mutations in the LMNA gene. The mechanisms by which LMNA mutations lead to the adipose specific FPLD2 phenotype have yet to be determined in detail. We used RNA-Seq analysis to assess the effects of wild-type (WT) and mutant (R482W) lamin A on the expression profile of differentiating 3T3-L1 mouse preadipocytes and identified Itm2a as a gene that was upregulated at 36 h post differentiation induction in these cells. In this study we identify Itm2a as a novel modulator of adipogenesis and show that endogenous Itm2a expression is transiently downregulated during induction of 3T3-L1 differentiation. Itm2a overexpression was seen to moderately inhibit differentiation of 3T3-L1 preadipocytes while shRNA mediated knockdown of Itm2a significantly enhanced 3T3-L1 differentiation. Investigation of PPARγ levels indicate that this enhanced adipogenesis is mediated through the stabilization of the PPARγ protein at specific time points during differentiation. Finally, we demonstrate that Itm2a knockdown is sufficient to rescue the inhibitory effects of lamin A WT and R482W mutant overexpression on 3T3-L1 differentiation. This suggests that targeting of Itm2a or its related pathways, including autophagy, may have potential as a therapy for FPLD2.

ITM2A Expands Evidence for Genetic and Environmental Interaction in Graves Disease Pathogenesis

CONTEXT

Graves disease (GD) is a common autoimmune disease triggered by genetic predisposition and environmental factors. However, the mechanisms of interaction between genetic and environmental factors contributing to the development of GD remain unknown.

OBJECTIVE

We aimed to identify GD susceptibility variants and genes on Xq21.1 locus and interpret the contribution of interaction between genetic predisposition on Xq21.1 and environmental factors to GD.

DESIGN

We performed refining study on Xq21.1 in a 2-stage study and carried out expression quantitative trait locus analysis of the best association signal with GD.

SETTING AND PARTICIPANTS

A total of 4316 GD patients and 4374 sex-matched controls were collected from the Chinese Han population by cooperation with multiple hospitals.

RESULTS

We identified that rs3827440 or its linkage single nucleotide polymorphisms (SNPs) were probably the causal variant in the Xq21.1 locus, with the most substantial association with GD in our combined cohorts (P = 2.45 × 10-15). The genotypes of rs3827440 were correlated with the expression of ITM2A in monocytes and peripheral blood mononuclear cells (PBMCs) from healthy volunteers. Notably, the expression of ITM2A in monocytes after lipopolysaccharide (LPS) and interferon-γ (INF-γ) stimulation showed substantial difference among the volunteers that carried different genotypes of rs3827440 (P = 9.40 × 10-7 and P = 1.26 × 10-5 for 24 hours' LPS and INF-γ stimulation, respectively). Moreover, ITM2A expression was significantly decreased in PBMCs from untreated GD patients than that from controls.

CONCLUSION

The results suggest that ITM2A might be a susceptibility gene for GD in the Xq21.1 locus, and environmental factors, such as viral and bacterial infections, probably contribute to GD pathogenesis by interacting with the risk SNP rs3827440 mediating the regulation of ITM2A expression.

The integral membrane protein ITM2A, a transcriptional target of PKA-CREB, regulates autophagic flux via interaction with the vacuolar ATPase

The PKA-CREB signaling pathway is involved in many cellular processes including autophagy. Recent studies demonstrated that PKA-CREB inhibits autophagy in yeast; however, the role of PKA-CREB signaling in mammalian cell autophagy has not been fully characterized. Here, we report that the integral membrane protein ITM2A expression is positively regulated by PKA-CREB signaling and ITM2A expression interferes with autophagic flux by interacting with vacuolar ATPase (v-ATPase). The ITM2A promoter contains a CRE element, and mutation at the CRE consensus site decreases the promoter activity. Forskolin treatment and PKA expression activate the ITM2A promoter confirming that ITM2A expression is dependent on the PKA-CREB pathway. ITM2A expression results in the accumulation of autophagosomes and interferes with autolysosome formation by blocking autophagic flux. We demonstrated that ITM2A physically interacts with v-ATPase and inhibits lysosomal function. These results support the notion that PKA-CREB signaling pathway regulates ITM2A expression, which negatively regulates autophagic flux by interfering with the function of v-ATPase.