TEL/ETV6 induces apoptosis in 32D cells through p53-dependent pathways

A novel role of ETV6 as a pro-viral factor in host response by inhibiting TBK1 phosphorylation

E26-transforming specific (ETS) variant 6 (ETV6) is a transcription factor regulating the expression of interferon stimulating genes (ISGs) and involved in the embryonic development and hematopoietic regulation, but the role of ETV6 in host response to virus infection is not clear. In this study, we show that ETV6 was upregulated in DF-1 cells with poly(I:C) stimulation or IBDV, AIV and ARV infection via engagement of dsRNA by MDA5. Overexpression of ETV6 in DF-1 cells markedly inhibited IBDV-induced type I interferon (IFN-I) and ISGs expressions. In contrast, knockdown, or knockout of ETV6 remarkably inhibited IBDV replication via promoting IFN-I response. Furthermore, our data show that ETV6 negatively regulated host antiviral response to IBDV infection by interaction with TANK binding kinase 1 (TBK1) and subsequently inhibited its phosphorylation. These results uncovered a novel role of ETV6 as a pro-viral factor in host response by inhibiting TBK1 phosphorylation, furthering our understandings of RNA virus immunosuppression and providing a valuable clue to the development of antiviral reagents for the control of avian RNA virus infection.

Regulation of phosphosignaling pathways involved in transcription of cell cycle target genes by TRH receptor activation in GH1 cells

Thyrotropin-releasing hormone (TRH) is known to activate several cellular signaling pathway, but the activation of the TRH receptor (TRH-R) has not been reported to regulate gene transcription. The aim of this study was to identify phosphosignaling pathways and phosphoprotein complexes associated with gene transcription in GH1 pituitary cells treated with TRH or its analog, taltirelin (TAL), using label-free bottom-up mass spectrometry-based proteomics. Our detailed analysis provided insight into the mechanism through which TRH-R activation may regulate the transcription of genes related to the cell cycle and proliferation. It involves control of the signaling pathways for β-catenin/Tcf, Notch/RBPJ, p53/p21/Rbl2/E2F, Myc, and YY1/Rb1/E2F through phosphorylation and dephosphorylation of their key components. In many instances, the phosphorylation patterns of differentially phosphorylated phosphoproteins in TRH- or TAL-treated cells were identical or displayed a similar trend in phosphorylation. However, some phosphoproteins, especially components of the Wnt/β-catenin/Tcf and YY1/Rb1/E2F pathways, exhibited different phosphorylation patterns in TRH- and TAL-treated cells. This supports the notion that TRH and TAL may act, at least in part, as biased agonists. Additionally, the deficiency of β-arrestin2 resulted in a reduced number of alterations in phosphorylation, highlighting the critical role of β-arrestin2 in the signal transduction from TRH-R in the plasma membrane to transcription factors in the nucleus.

Genome-wide analysis of RNA-binding proteins co-expression with alternative splicing events in mitral valve prolapse

Objectives

We investigated the role and molecular mechanisms of RNA-binding proteins (RBPs) and their regulated alternative splicing events (RASEs) in the pathogenesis of mitral valve prolapse (MVP).

Methods

For RNA extraction, we obtained peripheral blood mononuclear cells (PBMCs) from five patients with MVP, with or without chordae tendineae rupture, and five healthy individuals. High-throughput sequencing was used for RNA sequencing (RNA-seq). Differentially expressed genes (DEGs) analysis, alternative splicing (AS) analysis, functional enrichment analysis, co-expression of RBPs, and alternative splicing events (ASEs) analysis were conducted.

Results

The MVP patients exhibited 306 up-regulated genes and 198 down-regulated genes. All down- and up-regulated genes were enriched in both Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Furthermore, MVP was closely associated with the top 10 enriched terms and pathways. In MVP patients, 2,288 RASEs were found to be significantly different, and four suitable RASEs (CARD11 A3ss, RBM5 ES, NCF1 A5SS, and DAXX A3ss) were tested. We identified 13 RNA-binding proteins (RBPs) from the DEGs and screened out four RBPs (ZFP36, HSPA1A, TRIM21, and P2RX7). We selected four RASEs based on the co-expression analyses of RBPs and RASEs, including exon skipping (ES) of DEDD2, alternative 3' splice site (A3SS) of ETV6, mutually exclusive 3'UTRs (3pMXE) of TNFAIP8L2, and A3SS of HLA-B. Furthermore, the selected four RBPs and four RASEs were validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and showed high consistency with RNA sequencing (RNA-seq).

Conclusion

Dysregulated RBPs and their associated RASEs may play regulatory roles in MVP development and may therefore be used as therapeutic targets in the future.

ETV6: A Candidate Gene for Predisposition to "Blend Pedigrees"? A Case Report from the NEXT-Famly Clinical Trial

Background

The identification of germline mutations in familial leukemia predisposition genes by next generation sequencing is of pivotal importance. Lately, some “blend pedigrees” characterized by both solid and hematologic malignancies have been described. Some genes were recognized as related to this double predisposition, while the involvement of others is still a matter of debate. ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known. Case Presentation. We present our recent experience in the identification of an ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known. ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known. ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known.

Conclusion

This evidence supports the involvement of ETV6 in the predisposition to both solid and hematologic neoplasia and the importance of the investigation of the noncoding regions of the genes as recently suggested by different expert groups.ETV6 was associated with hematologic malignancies, in particular myeloid malignancies, and recently described as mutated also in oncologic patients. No clear evidences in its involvement in blend pedigrees are known.

Combining CDKN1A gene expression and genome-wide SNPs in a twin cohort to gain insight into the heritability of individual radiosensitivity

Individual variability in response to radiation exposure is recognised and has often been reported as important in treatment planning. Despite many efforts to identify biomarkers allowing the identification of radiation sensitive patients, it is not yet possible to distinguish them with certainty before the beginning of the radiotherapy treatment. A comprehensive analysis of genome-wide single-nucleotide polymorphisms (SNPs) and a transcriptional response to ionising radiation exposure in twins have the potential to identify such an individual. In the present work, we investigated SNP profile and CDKN1A gene expression in blood T lymphocytes from 130 healthy Caucasians with a complex level of individual kinship (unrelated, mono- or dizygotic twins). It was found that genetic variation accounts for 66% (95% CI 37-82%) of CDKN1A transcriptional response to radiation exposure. We developed a novel integrative multi-kinship strategy allowing investigating the role of genome-wide polymorphisms in transcriptomic radiation response, and it revealed that rs205543 (ETV6 gene), rs2287505 and rs1263612 (KLF7 gene) are significantly associated with CDKN1A expression level. The functional analysis revealed that rs6974232 (RPA3 gene), involved in mismatch repair (p value = 9.68e-04) as well as in RNA repair (p value = 1.4e-03) might have an important role in that process. Two missense polymorphisms with possible deleterious effect in humans were identified: rs1133833 (AKIP1 gene) and rs17362588 (CCDC141 gene). In summary, the data presented here support the validity of this novel integrative data analysis strategy to provide insights into the identification of SNPs potentially influencing radiation sensitivity. Further investigations in radiation response research at the genomic level should be therefore continued to confirm these findings.

Acute myeloid leukemia carrying ETV6 mutations: biologic and clinical features

OBJECTIVES

E26 transformation-specific variant 6 gene (ETV6) is one of the most consistently rearranged genes in acute leukaemia. It encodes a principal hematopoietic transcription factor.

METHODS

We performed a systematic review focusing on the mechanisms responsible for etv6 acquisition, and its effect on the development of AML. We also review the Characteristics of ETV6 mutations and its fusion genes. Finally, for using ETV6 as a molecular target, we discuss future therapeutic approaches available to mitigate the associated disease.

RESULTS

ETV6 rearrangements often accompany other molecular mutations. Thirty-three distinct partner bands of ETV6 that contain various fusion genes were detected which plays a vital role in obtaining information about leukaemia genesis. RXDX-101 and PKC412 were reported to be inhibitors of ETV6-NTRK3.

DISCUSSION

Future researches are needed to explain how ETV6 mutations act within the microenvironment of leukemic cells and how it affects the progression of leukaemia.

ETV6 and ETV7: Siblings in hematopoiesis and its disruption in disease

ETV6 (TEL1) and ETV7 (TEL2) are closely-related members of the ETS family of transcriptional regulators. Both ETV6 and ETV7 have been demonstrated to play key roles in hematopoiesis, particularly with regard to maintenance of hematopoietic stem cells and control of lineage-specific differentiation, with evidence of functional interactions between both proteins. ETV6 has been strongly implicated in the molecular etiology of a number of hematopoietic diseases, including as a tumor suppressor, an oncogenic fusion partner, and an important regulator of thrombopoiesis, but recent evidence has also identified ETV7 as a potential oncogene in certain malignancies. This review provides an overview of ETV6 and ETV7 and their contribution to both normal and disrupted hematopoiesis. It also highlights the key clinical implications of the growing knowledge base regarding ETV6 abnormalities with respect to prognosis and treatment.

Germline ETV6 mutations and predisposition to hematological malignancies

Patients with thrombocytopenia 5 have an autosomal dominant disorder of decreased platelet number with tendency to bleed, usually presenting in childhood, and have been found to have germline mutations in ETV6, which encodes a master hematopoietic transcription factor. Some patients who present similarly have inherited mutations in RUNX1 or ANKRD26. All three germline syndromes are also associated with a predisposition to myelodysplastic syndrome (MDS) and acute leukemia (AL). Since the first description of germline ETV6 mutations, 18 families have been reported. The common phenotype is mild to moderate thrombocytopenia with a variable predisposition to acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and MDS. This review will focus upon the role of ETV6 in hematopoiesis, especially in myeloid differentiation and maturation, and will describe the functional effects of mutant ETV6. The review will also provide an overview of common clinical features as well as recommendations for patient screening and follow-up and will debate whether additional clinical features should be included with the germline ETV6 syndrome.

Haploinsufficiency of ETV6 and CDKN1B in patients with acute myeloid leukemia and complex karyotype

BACKGROUND

Acute myeloid leukemia with complex karyotype (CK-AML) is a distinct biological entity associated with a very poor outcome. Since complex karyotypes frequently contain deletions of the chromosomal region 12p13 encompassing the tumor suppressor genes ETV6 and CDKN1B, we aimed to unravel their modes of inactivation in CK-AML.

RESULTS

To decipher deletions, mutations and methylation of ETV6 and CDKN1B, arrayCGH, SNP arrays, direct sequencing of all coding exons and pyrosequencing of the 5'UTR CpG islands of ETV6 and CDKN1B were performed. In total, 39 of 79 patients (49%) showed monoallelic deletions of 12p13 according to karyotypic data and 20 of 43 patients (47%) according to genomic profiling. Genomic profiling led to the minimal deleted region covering the 3'-UTR of ETV6 and CDKN1B. Direct sequencing revealed one novel monoallelic frameshift mutation in ETV6 while no mutations in CDKN1B were identified. Furthermore, methylation levels of ETV6 and CDKN1B did not indicate transcriptional silencing of any of these genes. ETV6 and CDKN1B had reduced expression levels in CK-AML patients with deletion in 12p13 as compared to CK-AML without deletion in 12p13, while the other genes (BCL2L14, LRP6, DUSP16 and GPRC5D) located within the minimal deleted region in 12p13 had very low or missing expression in CK-AML irrespective of their copy number status.

CONCLUSIONS

ETV6 and CDKN1B are mainly affected by small monoallelic deletions, whereas mutations and hypermethylation play a minor role in CK-AML. Reduced gene dosage led to reduced gene expression levels, pointing to haploinsufficiency as the relevant mechanism of inactivation of ETV6 and CDKN1B in CK-AML.

A complex rearrangement involving cryptic deletion of ETV6 and CDKN1B genes in a case of childhood acute lymphoblastic leukemia

We report on a case of childhood B-cell lineage acute lymphoblastic leukemia (ALL). Conventional cytogenetic analysis at diagnosis showed the karyotype: 47,XY,add(3)(q?),-12,+2mar[4]/46,XY[18]. Fluorescence in situ hybridization (FISH) revealed a complex rearrangement: 47,XY,der(3)(3pter->3q29::12q13->12q24.33::12p13.31->12p13.2::12q24.33->12qter),der(12)(12pter->12p13.31::12p12.3->12q12::3q29->3qter),+del(21)(q?). The derivative chromosome 3 arose likely from multiple events due to clonal evolution. After insertion of the segment of the short arm of the chromosome 12 to the distal part of the long arm of chromosome 12 [ins(12)(q24.33p13.31p13.2)], a translocation occurred between chromosome 3 and derivative chromosome 12. Additional FISH results disclosed two heterozygous deletions flanking the translocated region on both 12p13.2 approximately p12.3 and 12q12 approximately q13.13. The deleted segment on 12p contains several genes, among the tumor suppressor genes ETV6 and CDKN1B, which are frequently involved in 12p abnormalities in childhood ALL. Thus, the present study documents the loss of both ETV6 and CDKN1B genes accompanying the occurrence of a complex rearrangement involving chromosomes 3 and 12 in a case of childhood ALL.

p53-mediated apoptosis of CLL cells: evidence for a transcription-independent mechanism

The p53 protein plays a key role in securing the apoptotic response of chronic lymphocytic leukemia (CLL) cells to genotoxic agents. Transcriptional induction of proapoptotic proteins including Puma are thought to mediate p53-dependent apoptosis. In contrast, recent studies have identified a novel nontranscriptional mechanism, involving direct binding of p53 to antiapoptotic proteins including Bcl-2 at the mitochondrial surface. Here we show that the major fraction of p53 induced in CLL cells by chlorambucil, fludarabine, or nutlin 3a was stably associated with mitochondria, where it binds to Bcl-2. The Puma protein, which was constitutively expressed in a p53-independent manner, was modestly up-regulated following p53 induction. Pifithrin α, an inhibitor of p53-mediated transcription, blocked the up-regulation of Puma and also of p21CIP1. Surprisingly, pifithrin α dramatically augmented apoptosis induction by p53-elevating agents and also accelerated the proapoptotic conformation change of the Bax protein. These data suggest that direct interaction of p53 with mitochondrial antiapoptotic proteins including Bcl-2 is the major route for apoptosis induction in CLL cells and that p53's transcriptional targets include proteins that impede this nontranscriptional pathway. Therefore, strategies that block up-regulation of p53-mediated transcription may be of value in enhancing apoptosis induction of CLL cells by p53-elevating drugs.

Identification of transcripts modulated by ETV6 expression

Deletions at chromosome 12p12-13 are observed in 26-47% of childhood pre-B acute lymphoblastic leukaemia (ALL) cases, suggesting the presence of a tumour suppressor gene (TSG). Accumulating genetic and functional evidence points to ETV6 as being the most probable TSG targeted by the deletions. ETV6 is a ubiquitously expressed transcription factor of the ETS family with very few known targets. To understand its function and to elucidate the impact of its absence in leukaemia, we conducted a study to identify targeted genes. Following the induction of ETV6 expression, global expression was evaluated at different time points. We identified 87 modulated genes, of which 10 (AKR1C1, AKR1C3, IL18, LUM, PHLDA1, PTGER4, PTGS2, SPHK1, TP53 and VEGF) were validated by real-time quantitative reverse transcription-polymerase chain reaction. To assess the significance of the validated candidate genes in leukaemia, their expression patterns were determined, as well as that of ETV6, in pre-B ALL patients. The expression of IL18, LUM, PTGER4, SPHK1 and TP53 was significantly correlated with that of ETV6, further suggesting that ETV6 could regulate the expression of these genes in leukaemia. This work constitutes another step towards the understanding of the functions of ETV6 and the impact of its inactivation in childhood leukaemia.