In search of a function for the TIS21/PC3/BTG1/TOB family

miR-92b-3p protects retinal tissues against DNA damage and apoptosis by targeting BTG2 in experimental myopia

BACKGROUND

Myopia is one of the eye diseases that can damage the vision of young people. This study aimed to explore the protective role of miR-92b-3p against DNA damage and apoptosis in retinal tissues of negative lens-induced myopic (LIM) guinea pigs by targeting BTG2.

METHODS

Biometric measurements of ocular parameters, flash electroretinogram (FERG), and retinal thickness (RT) were performed after miR-92b-3p intravitreal injection in LIM guinea pigs. The apoptotic rate was detected by Annexin V-FITC/PI double staining, and the change in mitochondrial membrane potential was measured by JC-1 staining. Retinal apoptosis and expression of p53, BTG2, and CDK2 were explored by TdT-mediated dUTP-biotin nick labeling (TUNEL) and immunofluorescence staining assays, respectively. BTG2 and its upstream and downstream molecules at gene and protein levels in retinal tissues were measured by real-time quantitative PCR (qPCR) and Western blotting.

RESULTS

Compared with normal controls (NC), the ocular axial length of LIM guinea pig significantly increased, whereas refraction decreased. Meanwhile, dMax-a and -b wave amplitudes of ERG declined, retinal thickness was decreased, the number of apoptotic cells and apoptotic rate in LIM eyes was exaggerated, and the mitochondrial membrane potential significantly decreased. In addition, results of qPCR and Western blot assays showed that the expression levels of p53, BTG2, CDK2, and BAX in LIM guinea pigs were higher than the levels of the NC group, whereas the BCL-2 expression level was decreased. By contrast, the miR-92b-3p intravitreal injection in LIM guinea pigs could significantly inhibit axial elongation, alleviate DNA damage and apoptosis, and thus protect guinea pigs against myopia.

CONCLUSION

In conclusion, p53 and BTG2 were activated in the retinal tissue of myopic guinea pigs, and the activated BTG2 could elevate the expression of CDK2 and BAX, and attenuate the expression of BCL-2, which in turn promote apoptosis and eventually lead to retinal thinning and impaired visual function in myopic guinea pigs. The miR-92b-3p intravitreal injection can attenuate the elongation of ocular length and retinal thickness, and inhibit the CDK2, BAX, and p53 expression by targeting BTG2, thereby ameliorating DNA damage and apoptosis in LIM guinea pigs and protecting ocular tissues.

Differential expression of TOB/BTG family members in patients with plaque psoriasis: cross-sectional study

TOB/BTG is a family of antiproliferative proteins that play an important role in the regulation of immune responses, acting as lymphocyte activators and macrophage-mediated cytotoxicity. No previous studies have explored their role in patients with psoriasis. The aim of this study was to characterize the expression of TOB/BTG family and their co-localization in skin from patients with psoriasis. This is an exploratory, observational, and cross-sectional study that included 24 plaque psoriasis patients and 15 controls. Gene expression of TOB/BTG family was determinate by RT-PCR. Protein products of TOB/BTG were evaluated by immunohistochemistry and compared with control skin tissues. Holm-Sidak's multiple comparisons test was performed. TOB/BTG family mRNA levels and protein expression were significantly decreased in psoriatic skin tissue compared to non-inflammatory control skin tissue. Double-positive cell TOB1/2, BTG1,2 and BTG4/CD16 expressions were found in normal control skin tissues through epidermis and dermis (p < 0.001) and lesser percentage in patients with mild, almost absent in moderate-severe plaque psoriasis. This is the first report of the TOB/BTG family gene and protein expression in skin tissues by a CD16 + subpopulation in plaque psoriasis. TOB/BTG family protein might represent a new therapeutic target among immune-mediated inflammatory diseases.

MicroRNA-409-3p/BTG2 signaling axis improves impaired angiogenesis and wound healing in obese mice

Wound healing is facilitated by neoangiogenesis, a complex process that is essential to tissue repair in response to injury. MicroRNAs are small, noncoding RNAs that can regulate the wound healing process including stimulation of impaired angiogenesis that is associated with type-2 diabetes (T2D). Expression of miR-409-3p was significantly increased in the nonhealing skin wounds of patients with T2D compared to the non-wounded normal skin, and in the skin of a murine model with T2D. In response to high glucose, neutralization of miR-409-3p markedly improved EC growth and migration in human umbilical vein endothelial cells (HUVECs), promoted wound closure and angiogenesis as measured by increased CD31 in human skin organoids, while overexpression attenuated EC angiogenic responses. Bulk mRNA-Seq transcriptomic profiling revealed BTG2 as a target of miR-409-3p, where overexpression of miR-409-3p significantly decreased BTG2 mRNA and protein expression. A 3' untranslated region (3'-UTR) luciferase assay of BTG2 revealed decreased luciferase activity with overexpression of miR-409-3p, while inhibition had opposite effects. Mechanistically, in response to high glucose, miR-409-3p deficiency in ECs resulted in increased mTOR phosphorylation, meanwhile BTG-anti-proliferation factor 2 (BTG2) silencing significantly decreased mTOR phosphorylation. Endothelial-specific and tamoxifen-inducible miR-409-3p knockout mice (MiR-409IndECKO ) with hyperglycemia that underwent dorsal skin wounding showed significant improvement of wound closure, increased blood flow, granulation tissue thickness (GTT), and CD31 that correlated with increased BTG2 expression. Taken together, our results show that miR-409-3p is a critical mediator of impaired angiogenesis in diabetic skin wound healing.

Monocyte-derived alveolar macrophages are key drivers of smoke-induced lung inflammation and tissue remodeling

Smoking is a leading risk factor of chronic obstructive pulmonary disease (COPD), that is characterized by chronic lung inflammation, tissue remodeling and emphysema. Although inflammation is critical to COPD pathogenesis, the cellular and molecular basis underlying smoking-induced lung inflammation and pathology remains unclear. Using murine smoke models and single-cell RNA-sequencing, we show that smoking establishes a self-amplifying inflammatory loop characterized by an influx of molecularly heterogeneous neutrophil subsets and excessive recruitment of monocyte-derived alveolar macrophages (MoAM). In contrast to tissue-resident AM, MoAM are absent in homeostasis and characterized by a pro-inflammatory gene signature. Moreover, MoAM represent 46% of AM in emphysematous mice and express markers causally linked to emphysema. We also demonstrate the presence of pro-inflammatory and tissue remodeling associated MoAM orthologs in humans that are significantly increased in emphysematous COPD patients. Inhibition of the IRAK4 kinase depletes a rare inflammatory neutrophil subset, diminishes MoAM recruitment, and alleviates inflammation in the lung of cigarette smoke-exposed mice. This study extends our understanding of the molecular signaling circuits and cellular dynamics in smoking-induced lung inflammation and pathology, highlights the functional consequence of monocyte and neutrophil recruitment, identifies MoAM as key drivers of the inflammatory process, and supports their contribution to pathological tissue remodeling.

Non-Coding RNAs and Gut Microbiota in the Pathogenesis of Cardiac Arrhythmias: The Latest Update

Non-coding RNAs (ncRNAs) are indispensable for adjusting gene expression and genetic programming throughout development and for health as well as cardiovascular diseases. Cardiac arrhythmia is a frequent cardiovascular disease that has a complex pathology. Recent studies have shown that ncRNAs are also associated with cardiac arrhythmias. Many non-coding RNAs and/or genomes have been reported as genetic background for cardiac arrhythmias. In general, arrhythmias may be affected by several functional and structural changes in the myocardium of the heart. Therefore, ncRNAs might be indispensable regulators of gene expression in cardiomyocytes, which could play a dynamic role in regulating the stability of cardiac conduction and/or in the remodeling process. Although it remains almost unclear how ncRNAs regulate the expression of molecules for controlling cardiac conduction and/or the remodeling process, the gut microbiota and immune system within the intricate networks might be involved in the regulatory mechanisms. This study would discuss them and provide a research basis for ncRNA modulation, which might support the development of emerging innovative therapies against cardiac arrhythmias.

CircRNAs and RNA-Binding Proteins Involved in the Pathogenesis of Cancers or Central Nervous System Disorders

Circular RNAs (circRNAs), a newly recognized group of noncoding RNA transcripts, have established widespread attention due to their regulatory role in cell signaling. They are covalently closed noncoding RNAs that form a loop, and are typically generated during the splicing of precursor RNAs. CircRNAs are key post-transcriptional and post-translational regulators of gene expression programs that might influence cellular response and/or function. In particular, circRNAs have been considered to function as sponges of specific miRNA, regulating cellular processes at the post-transcription stage. Accumulating evidence has shown that the aberrant expression of circRNAs could play a key role in the pathogenesis of several diseases. Notably, circRNAs, microRNAs, and several RNA-binding proteins, including the antiproliferative (APRO) family proteins, could be indispensable gene modulators, which might be strongly linked to the occurrence of diseases. In addition, circRNAs have attracted general interest for their stability, abundance in the brain, and their capability to cross the blood–brain barrier. Here, we present the current findings and theragnostic potentials of circRNAs in several diseases. With this, we aim to provide new insights to support the development of novel diagnostic and/or therapeutic strategies for these diseases.

BTG1 inactivation drives lymphomagenesis and promotes lymphoma dissemination through activation of BCAR1

Understanding the functional role of mutated genes in cancer is required to translate the findings of cancer genomics into therapeutic improvement. BTG1 is recurrently mutated in the MCD/C5 subtype of diffuse large B-cell lymphoma (DLBCL), which is associated with extranodal dissemination. Here, we provide evidence that Btg1 knock out accelerates the development of a lethal lymphoproliferative disease driven by Bcl2 overexpression. Furthermore, we show that the scaffolding protein BCAR1 is a BTG1 partner. Moreover, after BTG1 deletion or expression of BTG1 mutations observed in patients with DLBCL, the overactivation of the BCAR1-RAC1 pathway confers increased migration ability in vitro and in vivo. These modifications are targetable with the SRC inhibitor dasatinib, which opens novel therapeutic opportunities in BTG1 mutated DLBCL.

Proper regulation of β-adrenergic signal requires Btg2 gene for lipolysis and thermogenesis in response to starvation or cold acclimation in female mice

Mammals maintain constant body temperature in cold environment by activating thermogenesis via adrenergic/protein kinase A (PKA) signaling. B-cell translocation gene 2 (BTG2^/Tis21), induced by PKA signaling, regulates glucose and lipid metabolism in liver, yet its role in lipolysis and in thermogenesis is not explored. Here, Btg2-knockout (KO) mice failed to maintain body temperature under starvation, or in cold acclimation. And norepinephrine-induced thermogenic response was turned off earlier in the KO mice. Gender specifically, gonadal white adipose tissues (gWAT) of female-KO were very active in lipolysis in fed state, however, the fat degradation was diminished upon fasting or cold acclimation. Also, insulin sensitivity was increased in female-KO, but not in male-KO mice, along with the low bone mineral density and small brown adipose tissues (BAT). In the mechanistic aspect, expressions of UCP1 and lipases (LPL, ATGL, HSL) in gWAT of female-KO mice were significantly reduced in response to adrenergic signals. Here, we present some data that Btg2 gene is essential for properly respond to β-adrenergic signals, and plays as a negative regulator of insulin signaling in female mice.

A budding concept with certain microbiota, anti-proliferative family proteins, and engram theory for the innovative treatment of colon cancer

Inflammatory bowel disease (IBD) is a multifactorial chronic disease. Patients with IBD have an increased risk of developing colorectal cancer which has become a major health concern. IBD might exert a role of engrams for making the condition of specific inflammation in the gut. Dysregulation of immune cells induced by the command of engrams might be crucial in the pathogenesis of damages in gut epithelium. The anti-proliferative (APRO) family of anti-proliferative proteins characterized by immediate early responsive gene-products that might be involved in the machinery of the carcinogenesis in IBD. Herein, it is suggested that some probiotics with specific bacteria could prevent the development and/or progression of the IBD related tumors. In addition, consideration regarding the application of studying APRO family proteins for the comprehension of IBD related tumors has been presented. It is hypothesized that overexpression of Tob1, a member of APRO family proteins, in the epithelium of IBD could suppress the function of adjacent cytotoxic immune cells possibly via the paracrine signaling.

B-Cell Translocation Gene 2 Upregulation Is Associated with Favorable Prognosis in Lung Adenocarcinoma and Prolonged Patient Survival

The tumor suppressor protein B-cell translocation gene 2 (BTG2) is downexpressed in lung adenocarcinoma (LUAD); however, its role in LUAD survival remains unknown. This investigation is aimed at exploring the activity of BTG2 in LUAD. We analyzed BTG2 expression in LUAD datasets of the TCGA database and examined that BTG2 was markedly downregulated in comparison with adjacent normal tissues. The prognostic analysis suggested that higher expression of BTG2 protein correlates with prolonged survival in patients. Vectors expressing BTG2 were stably transduced into lung adenocarcinoma A549 cells. The overexpression of BTG2 in A549 cells causes cellular G1 phase arrest but did not affect cell proliferation, accompanied by increased activation of NF-κB. Our data indicate that BTG2 overexpression may trigger an autoregulatory prosurvival NF-κB pathway, which is resistant to environmental intervention owing to an increased level of BTG2.

Expression and functional analysis of CsA-IPT5 splice variants during shoot branching in Camellia sinensis

Alternative splicing (AS) is a process by which several functional splice variants are generated from the same precursor mRNA. In our recent study, five CsA-IPT5 splice variants with various numbers of ATTTA motifs in the untranslated regions (UTRs) were cloned. Meanwhile, their transient expression, as well as the expression and functional analysis in the two shoot branching processes were studied. Here, we examined how these splice variants regulate the other three important shoot branching processes, including the spring tea development, the distal branching of new shoots, and the shoot branching induced by 2,3,5-triiodobenzoic acid (TIBA) spraying, and thus unraveling the key CsA-IPT5 transcripts which play the most important roles in the shoot branching of tea plants. The results showed that the increased expression of 5' UTR AS3, 3' UTR AS1 and 3' UTR AS2 could contribute to the increased synthesis of tZ/iP-type cytokinins (CKs), thus promoting the spring tea development. Meanwhile, in the TIBA-induced shoot branching or in the distal branching of the new shoots, CsA-IPT5 transcripts regulated the synthesis of CsA-IPT5 protein and CKs through transcriptional regulation of the ratios of its splice variants. Moreover, 3' UTR AS1 and 3' UTR AS2 both play key roles in these two processes. In summary, it is revealed that 3' UTR AS1 and 3' UTR AS2 of CsA-IPT5 might act as the predominant splice variants in shoot branching of the tea plant, and they both can serve as gene resources for tea plant breeding.

TOB1 Blocks Intestinal Mucosal Inflammation Through Inducing ID2-Mediated Suppression of Th1/Th17 Cell Immune Responses in IBD

BACKGROUND & AIMS

TOB1 is an anti-proliferative protein of Tob/BTG family and typically involved in the tumorigenesis and T cell activation. Although TOB1 is associated with T helper 17 cell-related autoimmunity, its role in modulating T cell-mediated immune responses in IBD remains poorly understood. Here, we explored its expression and the underlying mechanisms involved in the pathogenesis of inflammatory bowel disease (IBD).

METHODS

TOB1 and ID2 expression in IBD patients was examined by quantitative real time polymerase chain reaction and immunohistochemistry. IBD CD4⁺ T cells were transfected with lentivirus expressing TOB1, ID2, TOB1 short hairpin RNA and ID2 short hairpin RNA, respectively, and Tob1^-/-CD4⁺ T cells were transfected with lentivirus expressing Id2. Experimental colitis was established in Tob1^-/- mice by trinitrobenzene sulfonic acid enema and in Rag1^-/- mice reconstituted with Tob1^-/-CD45RB^highCD4⁺ T cells to further explore the role of Tob1 in intestinal mucosal inflammation. Splenic CD4⁺ T cells of Tob1^-/- mice were sorted to determine transcriptome differences by RNA sequencing.

RESULTS

TOB1 expression was decreased in inflamed mucosa and peripheral blood CD4⁺ T cells of IBD patients compared with healthy subjects. Overexpression of TOB1 downregulated IBD CD4⁺ T cells to differentiate into Th1/Th17 cells compared with control subjects. Severe colitis was observed in Tob1^-/- mice through trinitrobenzene sulfonic acid enema or in Rag1^-/- mice reconstituted with Tob1^-/-CD45RB^highCD4⁺ T cells, compared with control animals. RNA sequencing analysis revealed ID2 as functional target of TOB1 to inhibit IBD CD4⁺ T cell differentiation into Th1/Th17 cells. Mechanistically, TOB1 was associated with Smad4/5 to induce ID2 expression and restrain Th1/Th17 cell differentiation.

CONCLUSIONS

TOB1 restrains intestinal mucosal inflammation through suppressing Th1/Th17 cell-mediated immune responses via the Smad4/5-ID2 pathway. It may serve as a novel therapeutic target for treatment of human IBD.

Urinary Exosomal miRNAs as biomarkers of bladder Cancer and experimental verification of mechanism of miR-93-5p in bladder Cancer

Background

Bladder cancer (BC) is one of the most common malignancies globally. Early diagnosis of it can significantly improve patients’ survival and quality of life. Urinary exosomes (UEs)-derived miRNAs might be a promising biomarker for BC detection.

Method

A total of 12 patients with BC and 4 non-cancerous participants (as healthy control) were recruited from a single center between March 2018 and December 2019 as the discovery set. Midstream urine samples from each participants were collected and high-throughput sequencing and differentially expression analysis were conducted. Combined with miRNA expression profile of BC tissue from The Cancer Genome Atlas (TCGA), miRNAs biomarkers for BC were determined. Candidate miRNAs as biomarkers were selected followed by verification with a quantitative reverse-transcription polymerase chain reaction assay in an independent validation cohort consisting of 53 BC patients and 51 healthy controls. The receiver-operating characteristic (ROC) curve was established to evaluate the diagnostic performance of UE-derived miRNAs. The possible mechanism of miRNAs were revealed by bioinformatic analysis and explored in vitro experiments.

Results

We identified that miR-93-5p, miR-516a-5p were simultaneously significantly increased both in UEs from BC compared with healthy control and BC tissue compared with normal tissue, which were verified by RT-qPCR in the validation cohort. Subsequently, the performance to discover BC of the miR-93-5p, miR-516a-5p was further verified with an area under ROC curve (AUC) of 0.838 and 0.790, respectively, which was significantly higher than that of urine cytology (AUC = 0.630). Moreover, miR-93-5p was significantly increased in muscle-invasive BC compared with non-muscle-invasive BC with an AUC of 0.769. Bioinformatic analysis revealed that B-cell translocation gene 2(BTG2) gene may be the hub target gene of miR-93-5p. In vitro experiments verified that miR-93-5p suppressed BTG2 expression and promoted BC cells proliferation, invasion and migration.

Conclusion

Urine derived exosomes have a distinct miRNA profile in BC patients, and urinary exosomal miRNAs could be used as a promising non-invasive tool to detect BC. In vitro experiments suggested that miR-93-5p overexpression may contribute to BC progression via suppressing BTG2 expression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08926-x.

Reduced TREM2 activation in microglia of patients with Alzheimer's disease

Loss-of-function variants of triggering receptor expressed on myeloid cells 2 (TREM2) increase the risk of developing Alzheimer's disease (AD). The mechanism through which TREM2 contributes to the disease (TREM2 activation vs inactivation) is largely unknown. Here, we analyzed changes in a gene set downstream of TREM2 to determine whether TREM2 signaling is modified by AD progression. We generated an anti-human TREM2 agonistic antibody and defined TREM2 activation in terms of the downstream expression changes induced by this antibody in microglia developed from human induced pluripotent stem cells (iPSC). Differentially expressed genes (DEGs) following TREM2 activation were compared with the gene set extracted from microglial single nuclear RNA sequencing data of patients with AD, using gene set enrichment analysis. We isolated an anti-TREM2-specific agonistic antibody, Hyb87, from anti-human TREM2 antibodies generated using binding and agonism assays, which helped us identify 300 upregulated and 251 downregulated DEGs. Pathway enrichment analysis suggested that TREM2 activation may be associated with Th2-related pathways. TREM2 activation was lower in AD microglia than in microglia from healthy subjects or patients with mild cognitive impairment. TREM2 activation also showed a significant negative correlation with disease progression. Pathway enrichment analysis of DEGs controlled by TREM2 activity indicated that TREM2 activation in AD may lead to anti-apoptotic signaling, immune response, and cytoskeletal changes in the microglia. We showed that TREM2 activation decreases with AD progression, in support of a protective role of TREM2 activation in AD. In addition, the agonistic anti-TREM2 antibody can be used to identify TREM2 activation state in AD microglia.

Reactive oxygen species may influence on the crossroads of stemness, senescence, and carcinogenesis in a cell via the roles of APRO family proteins

Excessive reactive oxygen species (ROS) may cause oxidative stress which is involved in aging and in the pathogenesis of various human diseases. Whereas unregulated levels of the ROS may be harmful, regulated basal level of ROS are even necessary to support cellular functions as a second messenger for homeostasis under physiological conditions. Therefore, redox medicine could develop as a new therapeutic concept for human health-benefits. Here, we introduce the involvement of ROS on the crossroads of stemness, senescence, and carcinogenesis in a stem cell and cancer cell biology. Amazingly, the anti-proliferative (APRO) family anti-proliferative proteins characterized by immediate early growth responsive genes may also be involved in the crossroads machinery. The biological functions of APRO proteins (APROs) seem to be quite intricate, however, which might be a key modulator of microRNAs (miRNAs). Given the crucial roles of ROS and APROs for pathophysiological functions, upcoming novel therapeutics should include vigilant modulation of the redox state. Next generation of medicine including regenerative medicine and/or cancer therapy will likely comprise strategies for altering the redox environment with the APROs via the modulation of miRNAs as well as with the regulation of ROS of cells in a sustainable manner.

Growth hormone promotes hepatic gluconeogenesis by enhancing BTG2-YY1 signaling pathway

Growth hormone (GH) is one of the critical factors in maintaining glucose metabolism. B-cell translocation gene 2 (BTG2) and yin yang 1 (YY1) are key regulators of diverse metabolic processes. In this study, we investigated the link between GH and BTG2–YY1 signaling pathway in glucose metabolism. GH treatment elevated the expression of hepatic Btg2 and Yy1 in primary mouse hepatocytes and mouse livers. Glucose production in primary mouse hepatocytes and serum blood glucose levels were increased during GH exposure. Overexpression of hepatic Btg2 and Yy1 induced key gluconeogenic enzymes phosphoenolpyruvate carboxykinase 1 (PCK1) and glucose-6 phosphatase (G6PC) as well as glucose production in primary mouse hepatocytes, whereas this phenomenon was markedly diminished by knockdown of Btg2 and Yy1. Here, we identified the YY1-binding site on the Pck1 and G6pc gene promoters using reporter assays and point mutation analysis. The regulation of hepatic gluconeogenic genes induced by GH treatment was clearly linked with YY1 recruitment on gluconeogenic gene promoters. Overall, this study demonstrates that BTG2 and YY1 are novel regulators of GH-dependent regulation of hepatic gluconeogenic genes and glucose production. BTG2 and YY1 may be crucial therapeutic targets to intervene in metabolic dysfunction in response to the GH-dependent signaling pathway.

MicroRNA miR-92a-3p regulates breast cancer cell proliferation and metastasis via regulating B-cell translocation gene 2 (BTG2)

MicroRNAs (miRNAs) dysregulation contributes to tumorigenesis, and it is reported that abnormal miR-92a-3p expression participates in multiple cancers’ occurrence and progression. This study focuses on miR-92a-3p’s functions and regulatory mechanism in breast cancer (BC). The current study proved miR-92a-3p expression was enhanced in BC tissues and cells, and its high expression was related to increased TNM stage and larger tumor size of BC patients. Functionally, transfection of miR-92a-3p mimics facilitated BC cell proliferation and metastasis, yet transfection of miR-92a-3p inhibitors functioned oppositely. In addition, BTG2 was verified as a direct miR-92a-3p target in BC cells. This research indicated that miR-92a-3p facilitates BC cell proliferation and metastasis through repressing BTG2 expression.

A conserved motif in human BTG1 and BTG2 proteins mediates interaction with the poly(A) binding protein PABPC1 to stimulate mRNA deadenylation

Antiproliferative BTG/Tob proteins interact directly with the CAF1 deadenylase subunit of the CCR4-NOT complex. This binding requires the presence of two conserved motifs, boxA and boxB, characteristic of the BTG/Tob APRO domain. Consistently, these proteins were shown to stimulate mRNA deadenylation and decay in several instances. Two members of the family, BTG1 and BTG2, were reported further to associate with the protein arginine methyltransferase PRMT1 through a motif, boxC, conserved only in this subset of proteins. We recently demonstrated that BTG1 and BTG2 also contact the first RRM domain of the cytoplasmic poly(A) binding protein PABPC1. To decipher the mode of interaction of BTG1 and BTG2 with partners, we performed nuclear magnetic resonance experiments as well as mutational and biochemical analyses. Our data demonstrate that, in the context of an APRO domain, the boxC motif is necessary and sufficient to allow interaction with PABPC1 but, unexpectedly, that it is not required for BTG2 association with PRMT1. We show further that the presence of a boxC motif in an APRO domain endows it with the ability to stimulate deadenylation in cellulo and in vitro. Overall, our results identify the molecular interface allowing BTG1 and BTG2 to activate deadenylation, a process recently shown to be necessary for maintaining T-cell quiescence.

Rethinking peripheral T cell tolerance: checkpoints across a T cell's journey

Following their exit from the thymus, T cells are endowed with potent effector functions but must spare host tissue from harm. The fate of these cells is dictated by a series of checkpoints that regulate the quality and magnitude of T cell-mediated immunity, known as tolerance checkpoints. In this Perspective, we discuss the mediators and networks that control the six main peripheral tolerance checkpoints throughout the life of a T cell: quiescence, ignorance, anergy, exhaustion, senescence and death. At the naive T cell stage, two intrinsic checkpoints that actively maintain tolerance are quiescence and ignorance. In the presence of co-stimulation-deficient T cell activation, anergy is a dominant hallmark that mandates T cell unresponsiveness. When T cells are successfully stimulated and reach the effector stage, exhaustion and senescence can limit excessive inflammation and prevent immunopathology. At every stage of the T cell's journey, cell death exists as a checkpoint to limit clonal expansion and to terminate unrestrained responses. Here, we compare and contrast the T cell tolerance checkpoints and discuss their specific roles, with the aim of providing an integrated view of T cell peripheral tolerance and fate regulation.

Expression of TOB/BTG family members in patients with inflammatory bowel disease

In recent years, the role of anti-proliferative TOB proteins in the regulation of immune response by inhibiting T cell activation has been demonstrated. Nevertheless, no previous studies have explored their expression in patients with IBD. The aim of the study was to characterize the gene and protein expression of the TOB/BTG family in intestinal tissue of patients with IBD. This is an observational and cross-sectional study that included 63 IBD patients. Gene expression of TOB/BTG family was measured by RT-PCR. Protein expression of TOB/CD16 and BTG/Ki-67 was evaluated by immunohistochemistry. TOB/BTG family mRNAs were detected and quantitated by RT-qPCR in rectal and ileum biopsies from UC patients and CD patients, respectively, and non-inflammatory control tissues. Results showed that TOB1 and BTG1 gene expression was decreased in the colonic mucosa from patients with UC compared with the control group. The TOB2 and BTG2 genes were over-expressed in the colonic mucosa of patients with UC in remission compared with the active UC and control group. The high TOB2 gene expression was associated with histological remission (P = .01). TOB1/CD16, TOB2/CD16, BTG1/Ki-67, BTG2/Ki-67 and BTG4/Ki-67 single and double positive cells were mostly NK, macrophages, epithelial cells, connective tissue cells and perivascular inflammatory infiltrates in tissues from patients with UC and CD. This is the first depiction of the TOB/BTG family gene and protein expression in rectal and ileum tissues by a CD16⁺ subpopulation in IBD.

Glioblastoma-Associated Microglia Reprogramming Is Mediated by Functional Transfer of Extracellular miR-21

Gliomas are primary, diffusely infiltrating brain tumors. Microglia are innate immune cells in the CNS and make up a substantial portion of the tumor mass. Glioma cells shape their microenvironment, communicating with and reprogramming surrounding cells, resulting in enhanced angiogenesis, immune suppression, and remodeling of the extracellular matrix. Glioma cells communicate with microglia, in part by releasing extracellular vesicles (EVs). Mouse glioma cells stably expressing a palmitoylated GFP to label EVs were implanted intracranially into syngeneic miR-21-null mice. Here, we demonstrate functional delivery of miR-21, regulating specific downstream mRNA targets in microglia after uptake of tumor-derived EVs. These findings attest to EV-dependent microRNA delivery as studied in an in vivo-based model and provide insight into the reprograming of microglial cells by tumor cells to create a favorable microenvironment for cancer progression.

Tob2 phosphorylation regulates global mRNA turnover to reshape transcriptome and impact cell proliferation

Tob2, an anti-proliferative protein, promotes deadenylation through recruiting Caf1 deadenylase to the mRNA poly(A) tail by simultaneously interacting with both Caf1 and poly(A)-binding protein (PABP). Previously, we found that changes in Tob2 phosphorylation can alter its PABP-binding ability and deadenylation-promoting function. However, it remained unknown regarding the relevant kinase(s). Moreover, it was unclear whether Tob2 phosphorylation modulates the transcriptome and whether the phosphorylation is linked to Tob2's anti-proliferative function. In this study, we found that c-Jun amino-terminal kinase (JNK) increases phosphorylation of Tob2 at many Ser/Thr sites in the intrinsically disordered region (IDR) that contains two separate PABP-interacting PAM2 motifs. JNK-induced phosphorylation or phosphomimetic mutations at these sites weaken the Tob2-PABP interaction. In contrast, JNK-independent phosphorylation of Tob2 at serine 254 (S254) greatly enhances Tob2 interaction with PABP and its ability to promote deadenylation. We discovered that both PAM2 motifs are required for Tob2 to display these features. Combining mass spectrometry analysis, poly(A) size-distribution profiling, transcriptome-wide mRNA turnover analyses, and cell proliferation assays, we found that the phosphomimetic mutation at S254 (S254D) enhances Tob2's association with PABP, leading to accelerated deadenylation and decay of mRNAs globally. Moreover, the Tob2-S254D mutant accelerates the decay of many transcripts coding for cell cycle related proteins and enhances anti-proliferation function. Our findings reveal a novel mechanism by which Ccr4-Not complex is recruited by Tob2 to the mRNA 3' poly(A)-PABP complex in a phosphorylation dependent manner to promote rapid deadenylation and decay across the transcriptome, eliciting transcriptome reprogramming and suppressed cell proliferation.

NUSAP1 knockdown inhibits cell growth and metastasis of non-small-cell lung cancer through regulating BTG2/PI3K/Akt signaling

Non-small-cell lung cancer (NSCLC) is the most common malignancy along with high mortality rate worldwide. Recently, nucleolar and spindle-associated protein 1 (NUSAP1) has been reported to be involved in the malignant progression of several cancers. However, in NSCLC, the biological function of NUSAP1 and its molecular mechanism have not been reported. Here, our findings indicated that the NUSAP1 messenger RNA expression level was remarkably upregulated in NSCLC tissues compared with that of adjacent normal tissues. We also found that NUSAP1 gene expression was notably upregulated in NSCLC cell lines (A549, 95-D, H358, and H1299) compared with that of normal human bronchial epithelial cell line (16HBE). Subsequently, the biological function of NUSAP1 was investigated in A549 and H358 cells transfected with NUSAP1 small interfering RNA (siRNA), respectively. Results showed that NUSAP1 knockdown inhibited NSCLC cell proliferation, and promoted cell apoptosis. Furthermore, the number of cell migration and invasion was significantly suppressed by NUSAP1 knockdown. In addition, our results indicated that NUSAP1 knockdown increased the gene expression of B-cell translocation gene 2 (BTG2), but decreased the expression levels of phosphoinositide 3-kinase (PI3K) and phosphorylated serine/threonine kinase (p-AKT). BTG2 siRNA partly abrogates the effect of NUSAP1 knockdown on BTG2 gene expression. Fumonisin B1 (FB1), a AKT activator, reversed the effect of NUSAP1 knockdown on the biological function in NSCLC. Taken together, NUSAP1 knockdown promotes NSCLC cell apoptosis, and inhibits cell proliferation, cell migration, and invasion, which is associated with regulating BTG2/PI3K/Akt signal pathway. Our findings suggest that NUSAP1 is a promising molecular target for NSCLC treatment.

MicroRNA-519c-3p promotes tumor growth and metastasis of hepatocellular carcinoma by targeting BTG3

Tumor recurrence and metastasis after surgical resection are the major causes for the cancer-related death of hepatocellular carcinoma (HCC). Thus, better understanding the mechanisms involved in tumor progression will benefit to improve HCC treatment. Accumulating evidence demonstrates that microRNAs (miRNAs) play critical roles in the development and progression of HCC. However, the function of miR-519c-3p in HCC and its related mechanism remain unexplored. Here, we reported that miR-519c-3p was strongly overexpressed in HCC tissues, which was significantly correlated with poor prognosis and clinicopathological features including tumor size ≥5 cm, vascular invasion and advanced tumor-node-metastasis (TNM) stages (III + IV). Furthermore, the elevated levels of miR-519c-3p were observed in HCC cell lines. Subsequently, gain- or loss-of-function assays demonstrated that miR-519c-3p promoted HCC cell proliferation, migration as well as invasion in vitro, and facilitated the growth and metastasis of HCC cells in vivo. Mechanistically, B-cell translocation gene 3 (BTG3) was identified as a direct downstream target of miR-519c-3p. The level of BTG3 mRNA was downregulated in HCC and negatively correlated with miR-519c-3p expression. Western blotting confirmed that BTG3 was negatively regulated by miR-519c-3p in HCC cells. Luciferase reporter assays illustrated the direct interaction between miR-519c-3p and the 3'UTR of BTG3 mRNA. Recuse experiments demonstrated that BTG3 mediated the promoting effects of miR-519c-3p on the proliferation and motility of HCC cells. Collectively, our results suggest that miR-519c-3p functions as a tumor promotor in regulating the growth and metastasis of HCC by targeting BTG3, and potentially serves as a novel therapeutic target for HCC.

Autophagy inhibition prevents glucocorticoid-increased adiposity via suppressing BAT whitening

The mechanisms underlying glucocorticoid (GC)-increased adiposity are poorly understood. Brown adipose tissue (BAT) acquires white adipose tissue (WAT) cell features defined as BAT whitening under certain circumstances. The aim of our current study was to investigate the possibility and mechanisms of GC-induced BAT whitening. Here, we showed that one-week dexamethasone (Dex) treatment induced BAT whitening, characterized by lipid droplet accumulation, in vitro and in vivo. Furthermore, autophagy and ATG7 (autophagy related 7) expression was induced in BAT by Dex, and treatment with the autophagy inhibitor chloroquine or adenovirus-mediated ATG7 knockdown prevented Dex-induced BAT whitening and fat mass gain. Moreover, Dex-increased ATG7 expression and autophagy was mediated by enhanced expression of BTG1 (B cell translocation gene 1, anti-proliferative) that stimulated activity of CREB1 (cAMP response element binding protein 1). The importance of BTG1 in this regulation was further demonstrated by the observed BAT whitening in adipocyte-specific BTG1-overexpressing mice and the attenuated Dex-induced BAT whitening and fat mass gain in mice with BTG1 knockdown in BAT. Taken together, we showed that Dex induces a significant whitening of BAT via BTG1- and ATG7-dependent autophagy, which might contribute to Dex-increased adiposity. These results provide new insights into the mechanisms underlying GC-increased adiposity and possible strategy for preventing GC-induced side effects via the combined use of an autophagy inhibitor.Abbreviations: ACADL: acyl-Coenzyme A dehydrogenase, long-chain; ACADM: acyl-Coenzyme A dehydrogenase, medium-chain; ACADS: acyl-Coenzyme A dehydrogenase, short-chain; ADIPOQ: adiponectin; AGT: angiotensinogen; Atg: autophagy-related; BAT: brown adipose tissue; BTG1: B cell translocation gene 1, anti-proliferative; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; CIDEA: cell death-inducing DNA fragmentation factor, alpha subunit-like effector A; CPT1B: carnitine palmitoyltransferase 1b, muscle; CPT2: carnitine palmitoyltransferase 2; CQ: chloroquine; Dex: dexamethasone; eWAT: epididymal white adipose tissue; FABP4: fatty acid binding protein 4, adipocyte; FFAs: free fatty acids; GCs: glucocorticoids; NRIP1: nuclear receptor interacting protein 1; OCR: oxygen consumption rate; PBS: phosphate-buffered saline; PPARA: peroxisome proliferator activated receptor alpha; PPARG: peroxisome proliferator activated receptor gamma; PPARGC1A: peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; PRDM16: PR domain containing 16; PSAT1: phosphoserine aminotransferase 1; RB1: RB transcriptional corepressor 1; RBL1/p107: RB transcriptional corepressor like 1; SQSTM1: sequestosome 1; sWAT: subcutaneous white adipose tissue; TG: triglycerides; UCP1: uncoupling protein 1 (mitochondrial, proton carrier); WT: wild-type.

Estradiol Prevents High Glucose-Induced β-cell Apoptosis by Decreased BTG2 Expression

Hyperglycemia stimulates several pathways to induce pancreatic β-cell apoptosis. In our previous study by mRNA analysis, we demonstrated that B-cell translocation gene 2 (BTG₂) expression was up-regulated in INS-1 cells cultured under high glucose conditions, but this effect was reversed by estrogen. In the present study, we demonstrated that BTG₂ mRNA and protein expressions in both INS-1 cells and mouse pancreatic islets increased under high glucose conditions compared to those cultured under basal glucose conditions, while in the presence of estrogen, the BTG₂ mRNA and protein expressions decreased. SiRNA-BTG₂ significantly reduced cell apoptosis, cleaved-caspase 3, and Bax, compared to the siRNA-control in INS-1 cultured under high glucose conditions. We further demonstrated that BTG₂ promoter activity was activated under high glucose conditions whereas estrogen significantly reduced it. The effects of estrogen on BTG₂ expression were inhibited by estrogen receptor inhibitors. Also, under high glucose conditions, p53 and Bax mRNA and protein expressions increased, but they decreased in the presence of estrogen. Again, the effect of estrogen on p53 and Bax expression was inhibited by estrogen receptor inhibitors. Taken together, this study demonstrates that estrogen reduces pancreatic β-cell apoptosis under high glucose conditions via suppression of BTG2, p53, and Bax expressions.

Investigation of copy number variations on chromosome 21 detected by comparative genomic hybridization (CGH) microarray in patients with congenital anomalies

Background

The clinical features of Down syndrome vary among individuals, with those most common being congenital heart disease, intellectual disability, developmental abnormity and dysmorphic features. Complex combination of Down syndrome phenotype could be produced by partially copy number variations (CNVs) on chromosome 21 as well. By comparing individual with partial CNVs of chromosome 21 with other patients of known CNVs and clinical phenotypes, we hope to provide a better understanding of the genotype-phenotype correlation of chromosome 21.

Methods

A total of 2768 pediatric patients sample collected at the Genetics Laboratory at Oklahoma University Health Science Center were screened using CGH Microarray for CNVs on chromosome 21.

Results

We report comprehensive clinical and molecular descriptions of six patients with microduplication and seven patients with microdeletion on the long arm of chromosome 21. Patients with microduplication have varied clinical features including developmental delay, microcephaly, facial dysmorphic features, pulmonary stenosis, autism, preauricular skin tag, eye pterygium, speech delay and pain insensitivity. We found that patients with microdeletion presented with developmental delay, microcephaly, intrauterine fetal demise, epilepsia partialis continua, congenital coronary anomaly and seizures.

Conclusion

Three patients from our study combine with four patients in public database suggests an association between 21q21.1 microduplication of CXADR gene and patients with developmental delay. One patient with 21q22.13 microdeletion of DYRK1A shows association with microcephaly and scoliosis. Our findings helped pinpoint critical genes in the genotype-phenotype association with a high resolution of 0.1 Mb and expanded the clinical features observed in patients with CNVs on the long arm of chromosome 21.

Tumor suppressor BTG1 limits activation of BCL6 expression downstream of ETV6-RUNX1

Translocation t(12;21) (p13;q22), giving rise to the ETV6-RUNX1 fusion gene, is the most common genetic abnormality in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). This translocation usually arises in utero, but its expression is insufficient to induce leukemia and requires other cooperating genetic lesions for BCP-ALL to develop. Deletions affecting the transcriptional coregulator BTG1 are frequently observed in ETV6-RUNX1-positive leukemia. Here we report that Btg1 deficiency enhances the self-renewal capacity of ETV6-RUNX1-positive mouse fetal liver-derived hematopoietic progenitors (FL-HPCs). Combined expression of the fusion protein and a loss of BTG1 drive upregulation of the proto-oncogene Bcl6 and downregulation of BCL6 target genes, such as p19Arf and Tp53. Similarly, ectopic expression of BCL6 promotes the self-renewal and clonogenic replating capacity of FL-HPCs, by suppressing the expression of p19Arf and Tp53. Together these results identify BCL6 as a potential driver of ETV6-RUNX1-mediated leukemogenesis, which could involve loss of BTG1-dependent suppression of ETV6-RUNX1 function.

The many faces of IKZF1 in B-cell precursor acute lymphoblastic leukemia

Transcription factor IKZF1 (IKAROS) acts as a critical regulator of lymphoid differentiation and is frequently deleted or mutated in B-cell precursor acute lymphoblastic leukemia. IKZF1 gene defects are associated with inferior treatment outcome in both childhood and adult B-cell precursor acute lymphoblastic leukemia and occur in more than 70% of BCR-ABL1-positive and BCR-ABL1-like cases of acute lymphoblastic leukemia. Over the past few years, much has been learned about the tumor suppressive function of IKZF1 during leukemia development and the molecular pathways that relate to its impact on treatment outcome. In this review, we provide a concise overview on the role of IKZF1 during normal lymphopoiesis and the pathways that contribute to leukemia pathogenesis as a consequence of altered IKZF1 function. Furthermore, we discuss different mechanisms by which IKZF1 alterations impose therapy resistance on leukemic cells, including enhanced cell adhesion and modulation of glucocorticoid response.

Inhibition of TNFα-interacting protein α (Tipα)-associated gastric carcinogenesis by BTG2/TIS21 via downregulating cytoplasmic nucleolin expression

To understand the regulation of Helicobacter pylori (H. pylori)-associated gastric carcinogenesis, we examined the effect of B-cell translocation gene 2 (BTG2) expression on the biological activity of Tipα, an oncoprotein secreted from H. pylori. BTG2, the human ortholog of mouse TIS21 (BTG2/TIS21), has been reported to be a primary response gene that is transiently expressed in response to various stimulations. Here, we report that BTG2 is constitutively expressed in the mucous epithelium and parietal cells of the gastric gland in the stomach. Expression was increased in the mucous epithelium following H. pylori infection in contrast to its loss in human gastric adenocarcinoma. Indeed, adenoviral transduction of BTG2/TIS21 significantly inhibited Tipα activity in MKN-1 and MGT-40, human and mouse gastric cancer cells, respectively, thereby downregulating tumor necrosis factor-α (TNFα) expression and Erk1/2 phosphorylation by reducing expression of nucleolin, a Tipα receptor. Chromatin immunoprecipitation proved that BTG2/TIS21 inhibited Sp1 expression and its binding to the promoter of the nucleolin gene. In addition, BTG2/TIS21 expression significantly reduced membrane-localized nucleolin expression in cancer cells, and the loss of BTG2/TIS21 expression induced cytoplasmic nucleolin availability in gastric cancer tissues, as evidenced by immunoblotting and immunohistochemistry. Higher expression of BTG2 and lower expression of nucleolin were accompanied with better overall survival of poorly differentiated gastric cancer patients. This is the first report showing that BTG2/TIS21 inhibits nucleolin expression via Sp1 binding, which might be associated with the inhibition of H. pylori-induced carcinogenesis. We suggest that BTG2/TIS21 is a potential inhibitor of nucleolin in the cytoplasm, leading to inhibition of carcinogenesis after H. pylori infection.

PRMT5 promotes cell proliferation by inhibiting BTG2 expression via the ERK signaling pathway in hepatocellular carcinoma

Increasing evidence suggests that PRMT5, a protein arginine methyltransferase, has roles in cell growth regulation and cancer development. However, the role of PRMT5 in hepatocellular carcinoma (HCC) progression remains unclear. Here, we showed that PRMT5 expression was frequently upregulated in HCC tissues, and its expression was inversely correlated with overall survival in HCC patients. PRMT5 knockdown markedly inhibited in vitro HCC proliferation and in vivo tumorigenesis. We revealed that the mechanism of PRMT5‐induced proliferation was partially mediated by BTG downregulation, leading to cell cycle arrest during the G1 phase in HCC cells. Ectopic BTG2 overexpression decreased HCC growth, caused cell cycle arrest at the G1 phase, and downregulated Cyclin D1 and Cyclin E1 protein expression. Furthermore, we found that PRMT5‐induced ERK phosphorylation regulated BTG2 expression in HCC cells, whereas pretreatment with a selective ERK1/2 inhibitor (PD184352) significantly reversed the effect of PRMT5 on BTG2 expression. Our results indicated that PRMT5 promotes HCC proliferation by downregulating BTG2 expression via the ERK pathway.

MiR-27a-3p functions as an oncogene in gastric cancer by targeting BTG2

microRNA-27a (miR-27a) is frequently dysregulated in human carcinoma, including gastric cancer. The B-cell translocation gene 2 (BTG2) has been implicated in gastric carcinogenesis. However, till now, the link between miR-27a and BTG2 in gastric cancer has not been reported. Here, we found that two isoforms of mature miR-27a, miR-27a-5p and miR-27-3p, were both frequently overexpressed in gastric cancer tissues and cell lines, whereas the expression level of miR-27-3p in gastric cancer was significantly higher than that of miR-27a-5p. And overexpression of miR-27a-3p, but not miR-27a-5p, markedly promoted gastric cancer cell proliferation in vitro as well as tumor growth in vivo. Further experiments revealed that BTG2 was a direct and functional target of miR-27a-3p in gastric cancer and miR-27a-3p inhibition obviously up-regulated the expression of BTG2. In turn, overexpression of BTG2 triggered G1/S cell cycle arrest, induced subsequent apoptosis, and inhibited C-myc activation following Ras/MEK/ERK signaling pathway, which involved in the biological effects of miR-27a-3p/BTG2 axis on gastric carcinogenesis and cancer progression. Overall, these results suggested that the miR-27a-3p/BTG2 axis might represent a promising diagnostic biomarker for gastric cancer patients and could be a potential therapeutic target in the management of gastric cancer.

Expression and prognosis analyses of the Tob/BTG antiproliferative (APRO) protein family in human cancers

Background

Despite advances in early diagnosis and treatment, cancer remains the major cause of mortality in the world. The Tob/BTG antiproliferative (APRO) protein family is reported to participate in diverse human diseases. However, there’s little known about their expression and prognostic values in most human cancers.

Methods

We performed a detailed cancer vs. normal analysis. The mRNA expression levels of APRO family in various cancers were analyzed via the Oncomine database. Moreover, the Kaplan-Meier Plotter and PrognScan databases were used to evaluate the prognostic values.

Results

We observed that the mRNA expression levels of TOB1-2 and BTG2 were decreased in most cancers compared with normal tissues, while BTG3 was upregulated in most cancers. In survival analyses based on Kaplan-Meier Plotter, TOB1, BTG1 and BTG4 showed significant associations with survival outcome of different subtypes of breast cancer. Decreased BTG2 was related with poor relapse free survival (RFS) in all subtypes of breast cancer. Especially, besides RFS, reduced BTG2 also indicated worse overall survival and distant metastasis free survival in breast cancer patients who were classified as luminal A. Significant prognostic effects of the whole APRO family were also found in lung adenocarcinoma, but not in squamous cell lung carcinoma. In addition, potential correlations between some APRO family members and survival outcomes were also observed in ovarian, colorectal and brain cancer.

Conclusions

Some members of APRO family showed significant expression differences between cancer and normal tissues, and could be prognostic biomarkers for defined cancer types.

miR-511 promotes the proliferation of human hepatoma cells by targeting the 3'UTR of B cell translocation gene 1 (BTG1) mRNA

Aberrant expression of miR-511 is involved in the development of cancer, but the role of miR-511 in hepatocellular carcinoma (HCC) is not well documented. In this study, we explored the molecular mechanisms of miR-511 in hepatocarcinogenesis. Our results of bioinformatics analysis suggested that B cell translocation gene 1 (BTG1), a member of anti-proliferative gene family, was one of the putative targets of miR-511. The expression levels of miR-511 were significantly higher in 30 clinical HCC tissues than in corresponding peritumor tissues, and were negatively correlated with those of BTG1 in the HCC tissues (r=-0.6105, P<0.01). In human hepatoma cell lines HepG2 and H7402, overexpression of miR-511 dose-dependently inhibited the expression of BTG1, whereas knockdown of miR-511 dose-dependently increased the expression of BTG1. Luciferase reporter gene assays verified that miR-511 targeted the 3'UTR of BTG1 mRNA. In the hepatoma cells, overexpression of miR-511 significantly decreased BTG1-induced G₁ phase arrest, which was rescued by overexpression of BTG1. Furthermore, overexpression of miR-511 promoted the proliferation of the hepatoma cells, which was rescued by overexpression of BTG1. Conversely, knockdown of miR-511 inhibited cell proliferation, which was reversed by knockdown of BTG1. In conclusion, miR-511 promotes the proliferation of human hepatoma cells in vitro by targeting the 3'UTR of BTG1 mRNA.

The interplay between transcription and mRNA degradation in Saccharomyces cerevisiae

The cellular transcriptome is shaped by both the rates of mRNA synthesis in the nucleus and mRNA degradation in the cytoplasm under a specified condition. The last decade witnessed an exciting development in the field of post-transcriptional regulation of gene expression which underscored a strong functional coupling between the transcription and mRNA degradation. The functional integration is principally mediated by a group of specialized promoters and transcription factors that govern the stability of their cognate transcripts by “marking” them with a specific factor termed “coordinator.” The “mark” carried by the message is later decoded in the cytoplasm which involves the stimulation of one or more mRNA-decay factors, either directly by the “coordinator” itself or in an indirect manner. Activation of the decay factor(s), in turn, leads to the alteration of the stability of the marked message in a selective fashion. Thus, the integration between mRNA synthesis and decay plays a potentially significant role to shape appropriate gene expression profiles during cell cycle progression, cell division, cellular differentiation and proliferation, stress, immune and inflammatory responses, and may enhance the rate of biological evolution.

The B-cell translocation gene 1 (CgBTG1) identified in oyster Crassostrea gigas exhibit multiple functions in immune response

B-cell translocation gene 1 (BTG1) is a member of the anti-proliferative gene family, which plays important roles in regulation of cell cycle. In the present study, a B-cell translocation gene 1 molecule homologue (designed CgBTG1) are identified and characterized in oyster Crassostrea gigas. CgBTG1 contains a conserved BTG domain with Box A and Box B motifs, and it shares high similarities with both BTG1 and BTG2 proteins in vertebrates. CgBTG1 mRNA is predominantly expressed in hemocytes, and its expression level in hemocytes is significantly up-regulated at 6 h (5.40-fold, p < 0.01) post Vibrio splendidus stimulation. The apoptosis rate of oyster hemocytes is significantly decreased (p < 0.05) after CgBTG1 interfered by dsRNA (dsCgBTG1). This is indicated that CgBTG1 participated in the regulation of oyster hemocytes apoptosis. Furthermore, CgBTG1 could also induce the apoptosis of cancer cells (HeLa, A549 and BEL7402) in vitro. Compared with normal oysters, both vessel-like structures and muscle fibers in CgBTG1 interfered oysters are severely damaged after V. splendidus challenge in paraffin section, considering that CgBTG1 possessed an analogous feature of angiogenesis for maintenance of vessel-like structures in adductor muscle of oyster. The results suggests that CgBTG1 is a multi-functional molecule involved in the immune response of C. gigas against pathogen infection, which provides more clues for intensive studies of BTG family proteins in invertebrates.

Molecular signature of anastasis for reversal of apoptosis

Anastasis (Greek for "rising to life") is a cell recovery phenomenon that rescues dying cells from the brink of cell death. We recently discovered anastasis to occur after the execution-stage of apoptosis in vitro and in vivo. Promoting anastasis could in principle preserve injured cells that are difficult to replace, such as cardiomyocytes and neurons. Conversely, arresting anastasis in dying cancer cells after cancer therapies could improve treatment efficacy. To develop new therapies that promote or inhibit anastasis, it is essential to identify the key regulators and mediators of anastasis - the therapeutic targets. Therefore, we performed time-course microarray analysis to explore the molecular mechanisms of anastasis during reversal of ethanol-induced apoptosis in mouse primary liver cells. We found striking changes in transcription of genes involved in multiple pathways, including early activation of pro-cell survival, anti-oxidation, cell cycle arrest, histone modification, DNA-damage and stress-inducible responses, and at delayed times, angiogenesis and cell migration. Validation with RT-PCR confirmed similar changes in the human liver cancer cell line, HepG2, during anastasis. Here, we present the time-course whole-genome gene expression dataset revealing gene expression profiles during the reversal of apoptosis. This dataset provides important insights into the physiological, pathological, and therapeutic implications of anastasis.

Molecular signature of anastasis for reversal of apoptosis

Anastasis (Greek for "rising to life") is a cell recovery phenomenon that rescues dying cells from the brink of cell death. We recently discovered anastasis to occur after the execution-stage of apoptosis in vitro and in vivo. Promoting anastasis could in principle preserve injured cells that are difficult to replace, such as cardiomyocytes and neurons. Conversely, arresting anastasis in dying cancer cells after cancer therapies could improve treatment efficacy. To develop new therapies that promote or inhibit anastasis, it is essential to identify the key regulators and mediators of anastasis – the therapeutic targets. Therefore, we performed time-course microarray analysis to explore the molecular mechanisms of anastasis during reversal of ethanol-induced apoptosis in mouse primary liver cells. We found striking changes in transcription of genes involved in multiple pathways, including early activation of pro-cell survival, anti-oxidation, cell cycle arrest, histone modification, DNA-damage and stress-inducible responses, and at delayed times, angiogenesis and cell migration. Validation with RT-PCR confirmed similar changes in the human liver cancer cell line, HepG2, during anastasis. Here, we present the time-course whole-genome gene expression dataset revealing gene expression profiles during the reversal of apoptosis. This dataset provides important insights into the physiological, pathological, and therapeutic implications of anastasis.

Esophageal cancer: Risk factors, genetic association, and treatment

The poor prognosis and rising incidence of esophageal cancer highlight the need for improved detection and prediction methods that are essential prior to treatment. Esophageal cancer is one of the most fatal malignancies worldwide, with a dramatic increase in incidence in the Western world occurring over the past few decades. Despite improvements in the management and treatment of esophageal cancer patients, the general outcome remains very poor for overall 5-year survival rates (∼10%) and 5-year postesophagectomy survival rates (∼15-40%). Esophageal cancer is often diagnosed during its advanced stages, the main reason being the lack of early clinical symptoms. In an attempt to improve the outcome of patients after surgery, such patients are often treated with neoadjuvent concurrent chemoradiotherapy (CCRT) in order to decrease tumor size. However, CCRT may enhance toxicity levels and possibly cause a delay in surgery for patients who respond poorly to CCRT. Thus, precise biomarkers that could predict or identify patients who may or may not respond well to CCRT can assist physicians in choosing the appropriate therapy for patients. Identifying susceptible gene and biomarkers can help in predicting the treatment response of patients while improving their survival rates.

Apoptosis during embryonic tissue remodeling is accompanied by cell senescence

This study re-examined the dying process in the interdigital tissue during the formation of free digits in the developing limbs. We demonstrated that the interdigital dying process was associated with cell senescence, as deduced by induction of β-gal activity, mitotic arrest, and transcriptional up-regulation of p21 together with many components of the senescence-associated secretory phenotype. We also found overlapping domains of expression of members of the Btg/Tob gene family of antiproliferative factors in the regressing interdigits. Notably, Btg2 was up-regulated during interdigit remodeling in species with free digits but not in the webbed foot of the duck. We also demonstrate that oxidative stress promoted the expression of Btg2, and that FGF2 and IGF1 which are survival signals for embryonic limb mesenchyme inhibited Btg2 expression. Btg2 overexpression in vivo and in vitro induced all the observed changes during interdigit regression, including oxidative stress, arrest of cell cycle progression, transcriptional regulation of senescence markers, and caspase-mediated apoptosis. Consistent with the central role of p21 on cell senescence, the transcriptional effects induced by overexpression of Btg2 are attenuated by silencing p21. Our findings indicate that cell senescence and apoptosis are complementary processes in the regression of embryonic tissues and share common regulatory signals.

Immune cell-specific transcriptional profiling highlights distinct molecular pathways controlled by Tob1 upon experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system characterized by focal lymphocytic infiltration, demyelination and neurodegeneration. Despite the recent advances in understanding MS molecular basis, no reliable biomarkers have been identified yet to monitor disease progression. Our group has previously reported that low levels of TOB1 in CD4(+) T cells are strongly associated with a higher risk of MS conversion in individuals experiencing an initial demyelinating event. Consistently, Tob1 ablation in mice exacerbates the clinical phenotype of the MS model experimental autoimmune encephalomyelitis (EAE). To shed light on Tob1 molecular functions in the immune system, we have conducted the first cell-based transcriptomic analysis in Tob1(-/-) and wildtype mice upon EAE. Next-generation sequencing was employed to characterize the changes in gene expression in T and B cells at pre- and post-symptomatic EAE stages. Remarkably, we found only modest overlap among the different genetic signatures, suggesting that Tob1 may control distinct genetic programs in the different cytotypes. This hypothesis was corroborated by gene ontology and global interactome analyses, which highlighted specific cellular pathways in each cellular subset before and after EAE induction. In summary, our work pinpoints a multifaceted activity of Tob1 in both homeostasis and disease progression.

BTG1 ameliorates liver steatosis by decreasing stearoyl-CoA desaturase 1 (SCD1) abundance and altering hepatic lipid metabolism

Liver steatosis, a condition in which lipid accumulates in liver cells, is a leading cause of many liver diseases. The livers of patients with hepatocellular carcinoma, a cancer characterized by liver steatosis, have decreased abundance of the transcription cofactor BTG1 (B cell translocation gene 1). We showed that the livers of db/db mice, which are a genetic model of obesity, had decreased BTG1 mRNA and protein abundance. BTG1 overexpression ameliorated liver steatosis in db/db mice, whereas knockdown of BTG1 induced liver steatosis in wild-type mice. Consistent with these changes, we found that BTG1 decreased triglyceride accumulation in cultured hepatocytes. BTG1 overexpression inhibited the expression of the gene encoding stearoyl-CoA desaturase 1 (SCD1), an enzyme involved in the synthesis of fatty acids, by suppressing the activity of activating transcription factor 4 (ATF4). Knockdown of SCD1 prevented liver steatosis in wild-type mice induced by knockdown of BTG1. Conversely, the ability of BTG1 overexpression to ameliorate liver steatosis in db/db mice was negated by ATF4 overexpression. Moreover, BTG1 transgenic mice were resistant to liver steatosis induced by a high-carbohydrate diet. BTG1 abundance was decreased by this diet through a pathway that involved mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase 1 (S6K1), and cAMP response element-binding protein (CREB). Together, our study identifies a role of BTG1 in regulating hepatic lipid metabolism and specifically in preventing ATF4 and SCD1 from inducing liver steatosis.

BTG2 bridges PABPC1 RNA-binding domains and CAF1 deadenylase to control cell proliferation

While BTG2 plays an important role in cellular differentiation and cancer, its precise molecular function remains unclear. BTG2 interacts with CAF1 deadenylase through its APRO domain, a defining feature of BTG/Tob factors. Our previous experiments revealed that expression of BTG2 promoted mRNA poly(A) tail shortening through an undefined mechanism. Here we report that the APRO domain of BTG2 interacts directly with the first RRM domain of the poly(A)-binding protein PABPC1. Moreover, PABPC1 RRM and BTG2 APRO domains are sufficient to stimulate CAF1 deadenylase activity in vitro in the absence of other CCR4–NOT complex subunits. Our results unravel thus the mechanism by which BTG2 stimulates mRNA deadenylation, demonstrating its direct role in poly(A) tail length control. Importantly, we also show that the interaction of BTG2 with the first RRM domain of PABPC1 is required for BTG2 to control cell proliferation.

BTG2 promotes mRNA poly(A) tail shortening and regulates cellular differentiation. Here, Stupfler et al. show that the BTG2 APRO domain interacts with PABPC1 RRM1, allowing the former to recruit and stimulate the poly(A) tail shortening activity of CAF1 deadenylase and to control cell proliferation.

p53 deficiency linked to B cell translocation gene 2 (BTG2) loss enhances metastatic potential by promoting tumor growth in primary and metastatic sites in patient-derived xenograft (PDX) models of triple-negative breast cancer

Background

Despite advances in early diagnosis and treatment of cancer patients, metastasis remains the major cause of mortality. TP53 is one of the most frequently mutated genes in human cancer, and these alterations can occur during the early stages of oncogenesis or as later events as tumors progress to more aggressive forms. Previous studies have suggested that p53 plays a role in cellular pathways that govern metastasis. To investigate how p53 deficiency contributes to late-stage tumor growth and metastasis, we developed paired isogenic patient-derived xenograft (PDX) models of triple-negative breast cancer (TNBC) differing only in p53 status for longitudinal analysis.

Methods

Patient-derived isogenic human tumor lines differing only in p53 status were implanted into mouse mammary glands. Tumor growth and metastasis were monitored with bioluminescence imaging, and circulating tumor cells (CTCs) were quantified by flow cytometry. RNA-Seq was performed on p53-deficient and p53 wild-type tumors, and functional validation of a lead candidate gene was performed in vivo.

Results

Isogenic p53 wild-type and p53-deficient tumors metastasized out of mammary glands and colonized distant sites with similar frequency. However, p53-deficient tumors metastasized earlier than p53 wild-type tumors and grew faster in both primary and metastatic sites as a result of increased proliferation and decreased apoptosis. In addition, greater numbers of CTCs were detected in the blood of mice engrafted with p53-deficient tumors. However, when normalized to tumor mass, the number of CTCs isolated from mice bearing parental and p53-deficient tumors was not significantly different. Gene expression profiling followed by functional validation identified B cell translocation gene 2 (BTG2), a downstream effector of p53, as a negative regulator of tumor growth both at primary and metastatic sites. BTG2 expression status correlated with survival of TNBC patients.

Conclusions

Using paired isogenic PDX-derived metastatic TNBC cells, loss of p53 promoted tumor growth and consequently increased tumor cell shedding into the blood, thus enhancing metastasis. Loss of BTG2 expression in p53-deficient tumors contributed to this metastatic potential by enhancing tumor growth in primary and metastatic sites. Furthermore, clinical data support conclusions generated from PDX models and indicate that BTG2 expression is a candidate prognostic biomarker for TNBC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0673-9) contains supplementary material, which is available to authorized users.