ZFP36L1 promotes monocyte/macrophage differentiation by repressing CDK6

1-L Transcription in Prion Diseases

Understanding the pathogenesis and mechanisms of prion diseases can significantly expand our knowledge in the field of neurodegenerative diseases. Prion biology is increasingly recognized as being relevant to the pathophysiology of Alzheimer's disease and Parkinson's disease, both of which affect millions of people each year. This bioinformatics study used a theoretical protein-RNA recognition code (1-L transcription) to reveal the post-transcriptional regulation of the prion protein (PrPC). The principle for this method is directly elucidated on PrPC, in which an octa-repeat can be 1-L transcribed into a GGA triplet repeat RNA aptamer known to reduce the misfolding of normal PrPC into abnormal PrPSc. The identified genes/proteins are associated with mitochondria, cancer, COVID-19 and ER-stress, and approximately half are directly or indirectly associated with prion diseases. For example, the octa-repeat supports CD44, and regions of the brain with astrocytic prion accumulation also display high levels of CD44.

CRISPR screen of venetoclax response-associated genes identifies transcription factor ZNF740 as a key functional regulator

BCL-2 inhibitors such as venetoclax offer therapeutic promise in acute myeloid leukemia (AML) and other cancers, but drug resistance poses a significant challenge. It is crucial to understand the mechanisms that regulate venetoclax response. While correlative studies have identified numerous genes linked to venetoclax sensitivity, their direct impact on the drug response remains unclear. In this study, we targeted around 1400 genes upregulated in venetoclax-sensitive primary AML samples and carried out a CRISPR knockout screen to evaluate their direct effects on venetoclax response. Our screen identified the transcription factor ZNF740 as a critical regulator, with its expression consistently predicting venetoclax sensitivity across subtypes of the FAB classification. ZNF740 depletion leads to increased resistance to ventoclax, while its overexpression enhances sensitivity to the drug. Mechanistically, our integrative transcriptomic and genomic analysis identifies NOXA as a direct target of ZNF740, which negatively regulates MCL-1 protein stability. Loss of ZNF740 downregulates NOXA and increases the steady state protein levels of MCL-1 in AML cells. Restoring NOXA expression in ZNF740-depleted cells re-sensitizes AML cells to venetoclax treatment. Furthermore, we demonstrated that dual targeting of MCL-1 and BCL-2 effectively treats ZNF740-deficient AML in vivo. Together, our work systematically elucidates the causal relationship between venetoclax response signature genes and establishes ZNF740 as a novel transcription factor regulating venetoclax sensitivity.

A Lacticaseibacillus rhamnosus secretome induces immunoregulatory transcriptional, functional and immunometabolic signatures in human THP-1 monocytes

Macrophage responses to activation are fluid and dynamic in their ability to respond appropriately to challenges, a role integral to host defence. While bacteria can influence macrophage differentiation and polarization into pro-inflammatory and alternatively activated phenotypes through direct interactions, many questions surround indirect communication mechanisms mediated through secretomes derived from gut bacteria, such as lactobacilli. We examined effects of secretome-mediated conditioning on THP-1 human monocytes, focusing on the ability of the Lacticaseibacillus rhamnosus R0011 secretome (LrS) to drive macrophage differentiation and polarization and prime immune responses to subsequent challenge with lipopolysaccharide (LPS). Genome-wide transcriptional profiling revealed increased M2-associated gene transcription in response to LrS conditioning in THP-1 cells. Cytokine and chemokine profiling confirmed these results, indicating increased M2-associated chemokine and cytokine production (IL-1Ra, IL-10). These cells had increased cell-surface marker expression of CD11b, CD86, and CX3CR1, coupled with reduced expression of the M1 macrophage-associated marker CD64. Mitochondrial substrate utilization assays indicated diminished reliance on glycolytic substrates, coupled with increased utilization of citric acid cycle intermediates, characteristics of functional M2 activity. LPS challenge of LrS-conditioned THP-1s revealed heightened responsiveness, indicative of innate immune priming. Resting stage THP-1 macrophages co-conditioned with LrS and retinoic acid also displayed an immunoregulatory phenotype with expression of CD83, CD11c and CD103 and production of regulatory cytokines. Secretome-mediated conditioning of macrophages into an immunoregulatory phenotype is an uncharacterized and potentially important route through which lactic acid bacteria and the gut microbiota may train and shape innate immunity at the gut-mucosal interface.

Systemic administration of STING agonist promotes myeloid cells maturation and antitumor immunity through regulating hematopoietic stem and progenitor cell fate

STING is a pivotal mediator of effective innate and adaptive anti-tumor immunity; however, intratumoral administration of STING agonists have shown limited therapeutic benefit in clinical trials. The systemic effect of the intravenous delivery of STING agonists in cancer is not well-defined. Here, we demonstrated that systemic administration of STING agonist inhibited melanoma growth, improved inflammatory effector cell infiltration, and induced bone marrow mobilization and extramedullary hematopoiesis, causing widespread changes in immune components in the peripheral blood. The systemically administered STING agonist promoted HSC expansion and influenced lineage fate commitment, which was manifested as the differentiation of HSPCs was skewed toward myeloid cells at the expense of B-cell lymphopoiesis and erythropoiesis. Transcriptome analysis revealed upregulation of myeloid lineage differentiation-related and type I interferon-related genes. This myeloid-biased differentiation promoted the production and maturation of myeloid cells toward an activated phenotype. Furthermore, depletion of Gr-1+ myeloid cells attenuated the anti-tumor immunity of STING agonist. Our findings reveal the anti-tumor mechanism of systemic administration of STING agonist that involves modulating HSPC differentiation and promoting myeloid cells maturation. Our study may help explain the limited clinical activity of STING agonists administered intratumorally.

RNA binding proteins in MLL-rearranged leukemia

RNA binding proteins (RBPs) have recently emerged as important post-transcriptional gene expression regulators in both normal development and disease. RBPs influence the fate of mRNAs through multiple mechanisms of action such as RNA modifications, alternative splicing, and miR-mediated regulation. This complex and, often, combinatorial regulation by RBPs critically impacts the expression of oncogenic transcripts and, thus, the activation of pathways that drive oncogenesis. Here, we focus on the major features of RBPs, their mechanisms of action, and discuss the current progress in investigating the function of important RBPs in MLL-rearranged leukemia.

Lacticaseibacillus rhamnosus R0011 secretome attenuates Salmonella enterica serovar Typhimurium secretome-induced intestinal epithelial cell monolayer damage and pro-inflammatory mediator production in intestinal epithelial cell and antigen-presenting cell co-cultures

Certain lactic acid bacteria (LAB) are associated with immune modulatory activities including down-regulation of pro-inflammatory gene transcription and expression. While host antigen-presenting cells (APCs) and intestinal epithelial cells (IEC) can interact directly with both pathogenic and commensal bacteria through innate immune pattern recognition receptors, recent evidence indicates indirect communication through secreted molecules is an important inter-domain communication mechanism. This communication route may be especially important in the context of IEC and APC interactions which shape host immune responses within the gut environment. We have previously shown that the Lacticaseibacillus rhamnosus R0011 secretome (LrS) dampens pro-inflammatory gene transcription and mediator production from Tumor Necrosis Factor-α and Salmonella enterica serovar Typhimurium secretome (STS)-challenged HT-29 IECs through the induction of negative regulators of innate immunity. However, many questions remain about interactions mediated through these bacterial-derived soluble components and the resulting host immune outcomes in the context of IEC and APC interactions. In the present study, we examined the ability of the LrS to down-regulate pro-inflammatory gene transcription and cytokine production from STS-challenged T84 human IEC and THP-1 human monocyte co-cultures. Cytokine and chemokine profiling revealed that apically delivered LrS induces apical secretion of macrophage inhibitory factor (MIF) and down-regulates STS-induced pro-inflammatory mediator secretion into the apical and basolateral chambers of the T84/THP-1 co-culture. Transcriptional profiling confirmed these results, as the LrS attenuated STS challenge-induced CXCL8 and NFκB1 expression in T84 IECs and THP-1 APCs. Interestingly, the LrS also reversed STS-induced damage to monolayer transepithelial resistance (TER) and permeability, results which were confirmed by ZO-1 gene expression and immunofluorescence visualization of ZO-1 expression in T84 IEC monolayers. The addition of a MIF-neutralizing antibody abrogated the ability of the LrS to reverse STS-induced damage to T84 IEC monolayer integrity, suggesting a novel role for MIF in maintaining IEC barrier function and integrity in response to soluble components derived from LAB. The results presented here provide mechanistic evidence for indirect communication mechanisms used by LAB to modulate immune responses to pathogen challenge, using in vitro approaches which allow for IEC and APC cell communication in a context which more closely mimics that which occurs in vivo.

Inhibitory and Stimulatory Effects of IL-32 on HIV-1 Infection

The proinflammatory cytokine IL-32 is elevated in the plasma and tissues of HIV-1–infected individuals. However, its significance in HIV-1 infection remains unclear because IL-32 inhibits and stimulates viral production in monocyte-derived macrophages (MDMs) and CD4+ T cells, respectively. In this study, we initially found that the inhibitory effect on human MDMs depends on SAMHD1, a dNTP triphosphohydrolase that inhibits viral reverse transcription. IL-32 increased the unphosphorylated active form of SAMHD1, which was consistent with the reduced expression of the upstream cyclin-dependent kinases. Indeed, IL-32 lost its anti–HIV-1 activity in MDMs when SAMHD1 was depleted. These results explain why IL-32 inhibits HIV-1 in MDMs but not CD4+ T cells, because SAMHD1 restricts HIV-1 in noncycling MDMs but not in cycling CD4+ T cells. Another unique feature of IL-32 is the induction of the immunosuppressive molecule IDO1, which is beneficial for HIV-1 infection. In this study, we found that IL-32 also upregulates other immunosuppressive molecules, including PD-L1, in MDMs. Moreover, IL-32 promoted the motility of MDMs, which potentially facilitates intercellular HIV-1 transmission. Our findings indicate that IL-32 has both the direct inhibitory effect on HIV-1 production in MDMs and the indirect stimulatory effects through phenotypic modulation of MDMs, and they suggest that the stimulatory effects may outweigh the inhibitory effect because the window for IL-32 to inhibit HIV-1 is relatively confined to SAMHD1-mediated reverse transcription suppression in the viral life cycle.

Conflicting Roles of ZFP36L1 in Regulating the Progression of Muscle Invasive Bladder Cancer

As the most common carcinoma of the human urinary system, bladder cancer (BC) is characterized by high recurrence, and poor prognosis after metastasis. In the past decade, genome-wide expression and sequencing studies had identified key genes and pathways related to BC, and pictured the comprehensive molecular features of the disease. Our previous study indicated that the coding gene of zinc finger protein 36 like 1 (ZFP36L1) mutated frequently in bladder tumor tissues and may be a potential suppressor for BC. The present study aimed to further investigate the role of ZFP36L1 in BC, and the survival analysis based on TCGA dataset revealed that high expressing level of ZFP36L1 associated with poorer prognosis of the patients with muscle invasive bladder cancer (MIBC). The associations of ZFP36L1 expression to the clinicopathological and molecular biological features also implicated the high level of ZFP36L1 may related to worse outcomes of patients. Also, GSEA indicated that high expression of ZFP36L1 significantly associated with enhanced activity of cancer metastasis related pathways. Functions of ZFP36L1 in MIBC were investigated further, and it was found that while ZFP36L1 suppressed the self-renewal of bladder cancer cells, it promoted the invasiveness of the cells markedly. Taken together, these results led to the conflicting roles of ZFP36L1 in regulating the progression of MIBC, and revealed further researches are needed to clarify the functions of the gene in tumor initiation and recurrence.

A comprehensive RNA editome reveals that edited Azin1 partners with DDX1 to enable hematopoietic stem cell differentiation

Adenosine-to-inosine RNA editing and the catalyzing enzyme adenosine deaminase are both essential for hematopoietic development and differentiation. However, the RNA editome during hematopoiesis and the underlying mechanisms are poorly defined. Here, we sorted 12 murine adult hematopoietic cell populations at different stages and identified 30 796 editing sites through RNA sequencing. The dynamic landscape of the RNA editome comprises stage- and group-specific and stable editing patterns, but undergoes significant changes during lineage commitment. Notably, we found that antizyme inhibitor 1 (Azin1) was highly edited in hematopoietic stem and progenitor cells (HSPCs). Azin1 editing results in an amino acid change to induce Azin1 protein (AZI) translocation to the nucleus, enhanced AZI binding affinity for DEAD box polypeptide 1 to alter the chromatin distribution of the latter, and altered expression of multiple hematopoietic regulators that ultimately promote HSPC differentiation. Our findings have delineated an essential role for Azin1 RNA editing in hematopoietic cells, and our data set is a valuable resource for studying RNA editing on a more general basis.

A global screening identifies chromatin-enriched RNA-binding proteins and the transcriptional regulatory activity of QKI5 during monocytic differentiation

BACKGROUND

Cellular RNA-binding proteins (RBPs) have multiple roles in post-transcriptional control, and some are shown to bind DNA. However, the global localization and the general chromatin-binding ability of RBPs are not well-characterized and remain undefined in hematopoietic cells.

RESULTS

We first provide a full view of RBPs' distribution pattern in the nucleus and screen for chromatin-enriched RBPs (Che-RBPs) in different human cells. Subsequently, by generating ChIP-seq, CLIP-seq, and RNA-seq datasets and conducting combined analysis, the transcriptional regulatory potentials of certain hematopoietic Che-RBPs are predicted. From this analysis, quaking (QKI5) emerges as a potential transcriptional activator during monocytic differentiation. QKI5 is over-represented in gene promoter regions, independent of RNA or transcription factors. Furthermore, DNA-bound QKI5 activates the transcription of several critical monocytic differentiation-associated genes, including CXCL2, IL16, and PTPN6. Finally, we show that the differentiation-promoting activity of QKI5 is largely dependent on CXCL2, irrespective of its RNA-binding capacity.

CONCLUSIONS

Our study indicates that Che-RBPs are versatile factors that orchestrate gene expression in different cellular contexts, and identifies QKI5, a classic RBP regulating RNA processing, as a novel transcriptional activator during monocytic differentiation.

The oncogenic role of HIF-1α/miR-182-5p/ZFP36L1 signaling pathway in nasopharyngeal carcinoma

Background

Accumulating evidence indicates that dysregulation of miR-182-5p can serve as diagnostic and prognostic biomarkers for some cancers, whereas the role of miR-182-5p has not been explored in nasopharyngeal carcinoma (NPC). Our study aims to elucidate the biological function of miR-182-5p in NPC and the potential molecular mechanism involved.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine miR-182-5p expression in NPC primary tissues and cell lines. Immunohistochemistry (IHC) for ZFP36L1 was conducted in NPC samples. Western blot was used to evaluate protein expression in cell lines. A series of functional assays were carried out to evaluate the roles of miR-182-5p and ZFP36L1 in tumor development and progression of NPC. Bioinformatics tools and luciferase reporter assays were utilized to identify the potential mechanisms of action. Moreover, rescue experiments were applied to explore whether ZFP36L1 mediated the effects of miR-182-5p in NPC.

Results

Up-regulation of miR-182-5p was significantly associated with tumor development and poor prognosis in patients with NPC. Functional study demonstrated that miR-182-5p overexpression enhanced, whereas suppression of miR-182-5p impeded NPC cell proliferation, migration, tumorigenesis and metastasis. Mechanistically, miR-182-5p interacted with ZFP36L1 at two sites in its 3′ un-translated region (UTR) and repressed ZFP36L1 expression in NPC. Consistently, an inverse correlation was observed between the expression levels of miR-182-5p and ZFP36L1 using clinical NPC tissues, and down-regulation of ZFP36L1 in NPC predicts poor survival. Furthermore, overexpression of miR-182-5p in NPC was partly attributable to the transcriptional activation effect induced by hypoxia-inducible factor 1α (HIF-1α).

Conclusions

Our data suggests that miR-182-5p facilitates cell proliferation and migration in NPC through its ability to down-regulate ZFP36L1 expression, and that the HIF-1α/miR-182-5p/ZFP36L1 axis may serve as a novel therapeutic target in the management of NPC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02177-3.

Functional genomics atlas of synovial fibroblasts defining rheumatoid arthritis heritability

BACKGROUND

Genome-wide association studies have reported more than 100 risk loci for rheumatoid arthritis (RA). These loci are shown to be enriched in immune cell-specific enhancers, but the analysis so far has excluded stromal cells, such as synovial fibroblasts (FLS), despite their crucial involvement in the pathogenesis of RA. Here we integrate DNA architecture, 3D chromatin interactions, DNA accessibility, and gene expression in FLS, B cells, and T cells with genetic fine mapping of RA loci.

RESULTS

We identify putative causal variants, enhancers, genes, and cell types for 30-60% of RA loci and demonstrate that FLS account for up to 24% of RA heritability. TNF stimulation of FLS alters the organization of topologically associating domains, chromatin state, and the expression of putative causal genes such as TNFAIP3 and IFNAR1. Several putative causal genes constitute RA-relevant functional networks in FLS with roles in cellular proliferation and activation. Finally, we demonstrate that risk variants can have joint-specific effects on target gene expression in RA FLS, which may contribute to the development of the characteristic pattern of joint involvement in RA.

CONCLUSION

Overall, our research provides the first direct evidence for a causal role of FLS in the genetic susceptibility for RA accounting for up to a quarter of RA heritability.

miR-148a-3p suppresses the progression of acute myeloid leukemia via targeting cyclin-dependent kinase 6 (CDK6)

To study the regulation of miR-148a-3p on CDK6 and its mechanism in the progress of acute myeloid leukemia (AML), differential miRNAs were analyzed by bioinformatics, and the miR-148a-3p levels in AML cell lines were detected. Results showed that miR-148a-3p played a crucial role in AML, and the level was lower in AML cells, especially in J111 and KG-1a cells. In J111 and KG-1a cells, the up-regulation of miR-148a-3p mimics blocked the cell growth by arresting cell cycle at G2/M and enhancing cell apoptosis. Transwell and EMT markers detection indicated that miR-148a-3p reduced the cell migration and invasion. Afterward, through bioinformatics analysis, it showed that the CDK6 is one of the direct target genes of miR-148a-3p. DLR assay confirmed the target regulation. CDK6 overexpression reversed the effects of miR-148a-3p on AML cells. Collectively, miR-148a-3p inhibited the process of AML cells through disturbing the CDK-6 expression, implying that the trageting miR-148a-3p might be regarded as effective therapy of AML.

The AML-associated K313 mutation enhances C/EBPα activity by leading to C/EBPα overexpression

Mutations in the transcription factor C/EBPα are found in ~10% of all acute myeloid leukaemia (AML) cases but the contribution of these mutations to leukemogenesis is incompletely understood. We here use a mouse model of granulocyte progenitors expressing conditionally active HoxB8 to assess the cell biological and molecular activity of C/EBPα-mutations associated with human AML. Both N-terminal truncation and C-terminal AML-associated mutations of C/EBPα substantially altered differentiation of progenitors into mature neutrophils in cell culture. Closer analysis of the C/EBPα-K313-duplication showed expansion and prolonged survival of mutant C/EBPα-expressing granulocytes following adoptive transfer into mice. C/EBPα-protein containing the K313-mutation further showed strongly enhanced transcriptional activity compared with the wild-type protein at certain promoters. Analysis of differentially regulated genes in cells overexpressing C/EBPα-K313 indicates a strong correlation with genes regulated by C/EBPα. Analysis of transcription factor enrichment in the differentially regulated genes indicated a strong reliance of SPI1/PU.1, suggesting that despite reduced DNA binding, C/EBPα-K313 is active in regulating target gene expression and acts largely through a network of other transcription factors. Strikingly, the K313 mutation caused strongly elevated expression of C/EBPα-protein, which could also be seen in primary K313 mutated AML blasts, explaining the enhanced C/EBPα activity in K313-expressing cells.

Single-cell transcriptional changes associated with drug tolerance and response to combination therapies in cancer

Tyrosine kinase inhibitors were found to be clinically effective for treatment of patients with certain subsets of cancers carrying somatic mutations in receptor tyrosine kinases. However, the duration of clinical response is often limited, and patients ultimately develop drug resistance. Here, we use single-cell RNA sequencing to demonstrate the existence of multiple cancer cell subpopulations within cell lines, xenograft tumors and patient tumors. These subpopulations exhibit epigenetic changes and differential therapeutic sensitivity. Recurrently overrepresented ontologies in genes that are differentially expressed between drug tolerant cell populations and drug sensitive cells include epithelial-to-mesenchymal transition, epithelium development, vesicle mediated transport, drug metabolism and cholesterol homeostasis. We show analysis of identified markers using the LINCS database to predict and functionally validate small molecules that target selected drug tolerant cell populations. In combination with EGFR inhibitors, crizotinib inhibits the emergence of a defined subset of EGFR inhibitor-tolerant clones. In this study, we describe the spectrum of changes associated with drug tolerance and inhibition of specific tolerant cell subpopulations with combination agents.

HMGB1: an important regulator of myeloid differentiation and acute myeloid leukemia as well as a promising therapeutic target

Abstract

High mobility group box 1 (HMGB1) is a non-histone nuclear protein which has been intensively studied in various physiological and pathological processes including leukemia. Here in this study, we further demonstrated that HMGB1 presents higher expression in the bone marrow mononuclear cells of acute myeloid leukemia (AML) patients compared with the normal controls and contributes to the AML pathogenesis and progression by inhibiting apoptosis, facilitating proliferation, and inducing myeloid differentiation blockade of AML cells. Mechanistic investigation revealed that transforming growth factor beta-induced (TGFBI) acts as a potential downstream target of HMGB1 and lentivirus-mediated knockdown of TGFBI expression impaired phorbol-12-myristate-13-acetate (PMA) and all-trans retinoic acid (ATRA)–induced myeloid differentiation of AML cell lines. On the other hand, chidamide, an orally histone deacetylase inhibitor, decreases HMGB1 expression significantly in AML cells with concomitant upregulation of TGFBI expression, and confers therapeutic effect on AML by inducing cell differentiation, apoptosis and inhibiting cell proliferation. In conclusion, our findings provide additional insights that HMGB1 is a promising therapeutic target of AML, and also present experimental evidence for the clinical application of chidamide as a novel agent in AML therapy by downregulating HMGB1 expression.

Key messages

HMGB1 induces cell proliferation and myeloid differentiation blockade and inhibits apoptosis of AML cells.

TGFBI acts as a potential target of HMGB1.

Chidamide, a selective HDAC inhibitor, confers promising therapeutic effect for AML via downregulating HMGB1 expression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00109-020-01998-5.

The Transcriptional Network That Controls Growth Arrest and Macrophage Differentiation in the Human Myeloid Leukemia Cell Line THP-1

The response of the human acute myeloid leukemia cell line THP-1 to phorbol esters has been widely studied to test candidate leukemia therapies and as a model of cell cycle arrest and monocyte-macrophage differentiation. Here we have employed Cap Analysis of Gene Expression (CAGE) to analyze a dense time course of transcriptional regulation in THP-1 cells treated with phorbol myristate acetate (PMA) over 96 h. PMA treatment greatly reduced the numbers of cells entering S phase and also blocked cells exiting G2/M. The PMA-treated cells became adherent and expression of mature macrophage-specific genes increased progressively over the duration of the time course. Within 1–2 h PMA induced known targets of tumor protein p53 (TP53), notably CDKN1A, followed by gradual down-regulation of cell-cycle associated genes. Also within the first 2 h, PMA induced immediate early genes including transcription factor genes encoding proteins implicated in macrophage differentiation (EGR2, JUN, MAFB) and down-regulated genes for transcription factors involved in immature myeloid cell proliferation (MYB, IRF8, GFI1). The dense time course revealed that the response to PMA was not linear and progressive. Rather, network-based clustering of the time course data highlighted a sequential cascade of transient up- and down-regulated expression of genes encoding feedback regulators, as well as transcription factors associated with macrophage differentiation and their inferred target genes. CAGE also identified known and candidate novel enhancers expressed in THP-1 cells and many novel inducible genes that currently lack functional annotation and/or had no previously known function in macrophages. The time course is available on the ZENBU platform allowing comparison to FANTOM4 and FANTOM5 data.

The Tristetraprolin Family of RNA-Binding Proteins in Cancer: Progress and Future Prospects

Post-transcriptional regulation of gene expression plays a key role in cellular proliferation, differentiation, migration, and apoptosis. Increasing evidence suggests dysregulated post-transcriptional gene expression as an important mechanism in the pathogenesis of cancer. The tristetraprolin family of RNA-binding proteins (RBPs), which include Zinc Finger Protein 36 (ZFP36; commonly referred to as tristetraprolin (TTP)), Zinc Finger Protein 36 like 1 (ZFP36L1), and Zinc Finger Protein 36 like 2 (ZFP36L2), play key roles in the post-transcriptional regulation of gene expression. Mechanistically, these proteins function by binding to the AU-rich elements within the 3′-untranslated regions of their target mRNAs and, in turn, increasing mRNA turnover. The TTP family RBPs are emerging as key regulators of multiple biological processes relevant to cancer and are aberrantly expressed in numerous human cancers. The TTP family RBPs have tumor-suppressive properties and are also associated with cancer prognosis, metastasis, and resistance to chemotherapy. Herein, we summarize the various hallmark molecular traits of cancers that are reported to be regulated by the TTP family RBPs. We emphasize the role of the TTP family RBPs in the regulation of trait-associated mRNA targets in relevant cancer types/cell lines. Finally, we highlight the potential of the TTP family RBPs as prognostic indicators and discuss the possibility of targeting these TTP family RBPs for therapeutic benefits.

RNA-Binding Proteins in Acute Leukemias

Acute leukemias are genetic diseases caused by translocations or mutations, which dysregulate hematopoiesis towards malignant transformation. However, the molecular mode of action is highly versatile and ranges from direct transcriptional to post-transcriptional control, which includes RNA-binding proteins (RBPs) as crucial regulators of cell fate. RBPs coordinate RNA dynamics, including subcellular localization, translational efficiency and metabolism, by binding to their target messenger RNAs (mRNAs), thereby controlling the expression of the encoded proteins. In view of the growing interest in these regulators, this review summarizes recent research regarding the most influential RBPs relevant in acute leukemias in particular. The reported RBPs, either dysregulated or as components of fusion proteins, are described with respect to their functional domains, the pathways they affect, and clinical aspects associated with their dysregulation or altered functions.

Milk fermented with Lactobacillus rhamnosus R0011 induces a regulatory cytokine profile in LPS-challenged U937 and THP-1 macrophages

Fermented dairy products have become attractive functional foods for the delivery of probiotics and their biologically active metabolites. The aim of this study was to examine the immunomodulatory activity of milk fermented with the probiotic lactic acid bacterium Lactobacillus rhamnosus R0011 (LrF) on macrophages challenged with lipopolysaccharide (LPS), a potent pro-inflammatory stimulus. To this end, human THP-1 or U937 monocytes were differentiated into resting macrophages then stimulated with LPS and co-incubated with the LrF or with milk controls. Levels of pro-inflammatory and immunoregulatory cytokines were determined by enzyme-linked immunosorbent assays. Culturing of LPS-stimulated U937 macrophages with either the whole or filtered LrF resulted in an increase in Interleukin (IL)-1Ra production relative to the negative control. THP-1 macrophages cultured with the LrF demonstrated an increase in LPS-induced IL-10 and IL-1β production, while production of LPS-induced IL-6, sCD54, IL-8, IL-1β, TNF-α, IL-12p70 and Transforming Growth Factor-β (TGF-β) was unaffected. Further, the LrF induced the expression of DC-SIGN and CD206, markers of immunoregulatory M2 macrophage polarization, in LPS-challenged THP-1 macrophages. Taken together, milk fermented with L. rhamnosus R0011 increased regulatory cytokine production from LPS-challenged U937 and THP-1 macrophages, while simultaneously up-regulating the production of IL-1β and expression of DC-SIGN and CD206, a profile characteristic of polarization into the immunoregulatory M2 macrophage phenotype.

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Milk fermented with Lactobacillus rhamnosus R0011 (Lrf) induces a regulatory macrophage phenotype.

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Modulation of cytokine profiles induced by lipopolysaccharide challenge consistent with an alternatively activated (M2) macrophage phenotype.

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Fermented milk conditioning induced macrophage expression of genes characteristic of M2 macrophage polarization (DC-SIGN and CD206).

Phosphoproteomic profiling reveals a defined genetic program for osteoblastic lineage commitment of human bone marrow-derived stromal stem cells

Bone marrow-derived mesenchymal stem cells (MSCs) differentiate into osteoblasts upon stimulation by signals present in their niche. Because the global signaling cascades involved in the early phases of MSCs osteoblast (OB) differentiation are not well-defined, we used quantitative mass spectrometry to delineate changes in human MSCs proteome and phosphoproteome during the first 24 h of their OB lineage commitment. The temporal profiles of 6252 proteins and 15,059 phosphorylation sites suggested at least two distinct signaling waves: one peaking within 30 to 60 min after stimulation and a second upsurge after 24 h. In addition to providing a comprehensive view of the proteome and phosphoproteome dynamics during early MSCs differentiation, our analyses identified a key role of serine/threonine protein kinase D1 (PRKD1) in OB commitment. At the onset of OB differentiation, PRKD1 initiates activation of the pro-osteogenic transcription factor RUNX2 by triggering phosphorylation and nuclear exclusion of the histone deacetylase HDAC7.

RNA-Binding Protein ZFP36L1 Suppresses Hypoxia and Cell-Cycle Signaling

ZFP36L1 is a tandem zinc-finger RNA-binding protein that recognizes conserved adenylate-uridylate-rich elements (ARE) located in 3'untranslated regions (UTR) to mediate mRNA decay. We hypothesized that ZFP36L1 is a negative regulator of a posttranscriptional hub involved in mRNA half-life regulation of cancer-related transcripts. Analysis of in silico data revealed that ZFP36L1 was significantly mutated, epigenetically silenced, and downregulated in a variety of cancers. Forced expression of ZFP36L1 in cancer cells markedly reduced cell proliferation in vitro and in vivo, whereas silencing of ZFP36L1 enhanced tumor cell growth. To identify direct downstream targets of ZFP36L1, systematic screening using RNA pull-down of wild-type and mutant ZFP36L1 as well as whole transcriptome sequencing of bladder cancer cells {plus minus} tet-on ZFP36L1 was performed. A network of 1,410 genes was identified as potential direct targets of ZFP36L1. These targets included a number of key oncogenic transcripts such as HIF1A, CCND1, and E2F1. ZFP36L1 specifically bound to the 3'UTRs of these targets for mRNA degradation, thus suppressing their expression. Dual luciferase reporter assays and RNA electrophoretic mobility shift assays showed that wild-type, but not zinc-finger mutant ZFP36L1, bound to HIF1A 3'UTR and mediated HIF1A mRNA degradation, leading to reduced expression of HIF1A and its downstream targets. Collectively, our findings reveal an indispensable role of ZFP36L1 as a posttranscriptional safeguard against aberrant hypoxic signaling and abnormal cell-cycle progression. SIGNIFICANCE: RNA-binding protein ZFP36L1 functions as a tumor suppressor by regulating the mRNA stability of a number of mRNAs involved in hypoxia and cell-cycle signaling.

Diminished AHR Signaling Drives Human Acute Myeloid Leukemia Stem Cell Maintenance

Eliminating leukemic stem cells (LSC) is a sought after therapeutic paradigm for the treatment of acute myeloid leukemia (AML). While repression of aryl hydrocarbon receptor (AHR) signaling has been shown to promote short-term maintenance of primitive AML cells in culture, no work to date has examined whether altered AHR signaling plays a pathologic role in human AML or whether it contributes at all to endogenous LSC function. Here, we show AHR signaling is repressed in human AML blasts and preferentially downregulated in LSC-enriched populations within leukemias. A core set of AHR targets are uniquely repressed in LSCs across diverse genetic AML subtypes. In vitro and in vivo administration of the specific AHR agonist FICZ significantly impaired leukemic growth, promoted differentiation, and repressed self-renewal. Furthermore, LSCs suppressed a set of FICZ-responsive AHR target genes that function as tumor suppressors and promoters of differentiation. FICZ stimulation did not impair normal hematopoietic stem and progenitor (HSPC) function, and failed to upregulate a prominent LSC-specific AHR target in HSPCs, suggesting that differential mechanisms govern FICZ-induced AHR signaling manifestations in HSCs versus LSCs. Altogether, this work highlights AHR signaling suppression as a key LSC-regulating control mechanism and provides proof of concept in a preclinical model that FICZ-mediated AHR pathway activation enacts unique transcriptional programs in AML that identify it as a novel chemotherapeutic approach to selectively target human LSCs. SIGNIFICANCE: The AHR pathway is suppressed in leukemic stem cells (LSC), therefore activating AHR signaling is a potential therapeutic option to target LSCs and to treat acute myeloid leukemia.

Transcriptomic Analysis Identifies RNA Binding Proteins as Putative Regulators of Myelopoiesis and Leukemia

Acute myeloid leukemia (AML) is a common and aggressive hematological malignancy. Acquisition of heterogeneous genetic aberrations and epigenetic dysregulation lead to the transformation of hematopoietic stem cells (HSC) into leukemic stem cells (LSC), which subsequently gives rise to immature blast cells and a leukemic phenotype. LSCs are responsible for disease relapse as current chemotherapeutic regimens are not able to completely eradicate these cellular sub-populations. Therefore, it is critical to improve upon the existing knowledge of LSC specific markers, which would allow for specific targeting of these cells more effectively allowing for their sustained eradication from the cellular milieu. Although significant milestones in decoding the aberrant transcriptional network of various cancers, including leukemia, have been achieved, studies on the involvement of post-transcriptional gene regulation (PTGR) in disease progression are beginning to unfold. RNA binding proteins (RBPs) are key players in mediating PTGR and they regulate the intracellular fate of individual transcripts, from their biogenesis to RNA metabolism, via interactions with RNA binding domains (RBDs). In this study, we have used an integrative approach to systematically profile RBP expression and identify key regulatory RBPs involved in normal myeloid development and AML. We have analyzed RNA-seq datasets (GSE74246) of HSCs, common myeloid progenitors (CMPs), granulocyte-macrophage progenitors (GMPs), monocytes, LSCs, and blasts. We observed that normal and leukemic cells can be distinguished on the basis of RBP expression, which is indicative of their ability to define cellular identity, similar to transcription factors. We identified that distinctly co-expressing modules of RBPs and their subclasses were enriched in hematopoietic stem/progenitor (HSPCs) and differentiated monocytes. We detected expression of DZIP3, an E3 ubiquitin ligase, in HSPCs, knockdown of which promotes monocytic differentiation in cell line model. We identified co-expression modules of RBP genes in LSCs and among these, distinct modules of RBP genes with high and low expression. The expression of several AML-specific RBPs were also validated by quantitative polymerase chain reaction. Network analysis identified densely connected hubs of ribosomal RBP genes (rRBPs) with low expression in LSCs, suggesting the dependency of LSCs on altered ribosome dynamics. In conclusion, our systematic analysis elucidates the RBP transcriptomic landscape in normal and malignant myelopoiesis, and highlights the functional consequences that may result from perturbation of RBP gene expression in these cellular landscapes.

Emerging Evidence of Translational Control by AU-Rich Element-Binding Proteins

RNA-binding proteins (RBPs) are key regulators of posttranscriptional gene expression and control many important biological processes including cell proliferation, development, and differentiation. RBPs bind specific motifs in their target mRNAs and regulate mRNA fate at many steps. The AU-rich element (ARE) is one of the major cis-regulatory elements in the 3′ untranslated region (UTR) of labile mRNAs. Many of these encode factors requiring very tight regulation, such as inflammatory cytokines and growth factors. Disruption in the control of these factors’ expression can cause autoimmune diseases, developmental disorders, or cancers. Therefore, these mRNAs are strictly regulated by various RBPs, particularly ARE-binding proteins (ARE-BPs). To regulate mRNA metabolism, ARE-BPs bind target mRNAs and affect some factors on mRNAs directly, or recruit effectors, such as mRNA decay machinery and protein kinases to target mRNAs. Importantly, some ARE-BPs have stabilizing roles, whereas others are destabilizing, and ARE-BPs appear to compete with each other when binding to target mRNAs. The function of specific ARE-BPs is modulated by posttranslational modifications (PTMs) including methylation and phosphorylation, thereby providing a means for cellular signaling pathways to regulate stability of specific target mRNAs. In this review, we summarize recent studies which have revealed detailed molecular mechanisms of ARE-BP-mediated regulation of gene expression and also report on the importance of ARE-BP function in specific physiological contexts and how this relates to disease. We also propose an mRNP regulatory network based on competition between stabilizing ARE-BPs and destabilizing ARE-BPs.

Epigenomic profiling of myelofibrosis reveals widespread DNA methylation changes in enhancer elements and ZFP36L1 as a potential tumor suppressor gene that is epigenetically regulated

In this study we interrogated the DNA methylome of myelofibrosis patients using high-density DNA methylation arrays. We detected 35,215 differentially methylated CpG, corresponding to 10,253 genes, between myelofibrosis patients and healthy controls. These changes were present both in primary and secondary myelofibrosis, which showed no differences between them. Remarkably, most differentially methylated CpG were located outside gene promoter regions and showed significant association with enhancer regions. This aberrant enhancer hypermethylation was negatively correlated with the expression of 27 genes in the myelofibrosis cohort. Of these, we focused on the ZFP36L1 gene and validated its decreased expression and enhancer DNA hypermethylation in an independent cohort of patients and myeloid cell-lines. In vitro reporter assay and 5’-azacitidine treatment confirmed the functional relevance of hyper-methylation of ZFP36L1 enhancer. Furthermore, in vitro rescue of ZFP36L1 expression had an impact on cell proliferation and induced apoptosis in SET-2 cell line indicating a possible role of ZFP36L1 as a tumor suppressor gene in myelofibrosis. Collectively, we describe the DNA methylation profile of myelofibrosis, identifying extensive changes in enhancer elements and revealing ZFP36L1 as a novel candidate tumor suppressor gene.

RNA-binding protein ZFP36L1 regulates osteoarthritis by modulating members of the heat shock protein 70 family

Osteoarthritis (OA) is a whole-joint disease characterized by cartilage destruction and other whole-joint pathological changes. There is currently no effective disease-modifying therapy. Here we investigate the post-transcriptional mRNA regulation of OA-modulating proteins in chondrocytes and show that the ZFP36 family member, ZFP36L1, is specifically upregulated in OA chondrocytes and OA cartilage of humans and mice. Adenovirus-mediated overexpression of ZFP36L1 alone in mouse knee-joint tissue does not modulate OA pathogenesis. However, genetic ablation or silencing of Zfp36l1 significantly abrogates experimental OA in mice. Knockdown of Zfp36l1 increases the mRNA expression of two heat shock protein 70 (HSP70) family members, which act as its direct targets. Furthermore, overexpression of HSPA1A in joint tissues protects mice against experimental OA by inhibiting chondrocyte apoptosis. Our results indicate that the RNA-binding protein, ZFP36L1, regulates HSP70 family members that appear to protect against OA pathogenesis by inhibiting chondrocyte apoptosis.

Osteoarthritis is characterised by degeneration of joint cartilage. Here the authors show that the RNA-binding protein ZFP36L1 is upregulated in chondrocytes of humans and mice with osteoarthritis, and that its knockdown in mouse joints protects chondrocytes against apoptosis by modulating the function of heat shock proteins.

Levamisole suppresses adipogenesis of aplastic anaemia-derived bone marrow mesenchymal stem cells through ZFP36L1-PPARGC1B axis

Aplastic anaemia (AA) is a life‐threatening hematopoietic disorder characterized by hypoplasia and pancytopenia with increasing fat cells in the bone marrow (BM). The BM‐derived mesenchymal stem cells (MSCs) from AA are more susceptible to be induced into adipogenic differentiation compared with that from control, which may be causatively associated with the fatty BM and defective hematopoiesis of AA. Here in this study, we first demonstrated that levamisole displayed a significant suppressive effect on the in vitro adipogenic differentiation of AA BM‐MSCs. Mechanistic investigation revealed that levamisole could increase the expression of ZFP36L1 which was subsequently demonstrated to function as a negative regulator of adipogenic differentiation of AA BM‐MSCs through lentivirus‐mediated ZFP36L1 knock‐down and overexpression assay. Peroxisome proliferator‐activated receptor gamma coactivator 1 beta (PPARGC1B) whose 3′‐untranslated region bears adenine‐uridine‐rich elements was verified as a direct downstream target of ZFP36L1, and knock‐down of PPARGC1B impaired the adipogenesis of AA BM‐MSCs. Collectively, our work demonstrated that ZFP36L1‐mediated post‐transcriptional control of PPARGC1B expression underlies the suppressive effect of levamisole on the adipogenic differentiation of AA BM‐MSCs, which not only provides novel therapeutic targets for alleviating the BM fatty phenomenon of AA patients, but also lays the theoretical and experimental foundation for the clinical application of levamisole in AA therapy.

ZFP36L1 and ZFP36L2 inhibit cell proliferation in a cyclin D-dependent and p53-independent manner

ZFP36 family members include ZFP36, ZFP36L1, and ZFP36L2, which belong to CCCH-type zinc finger proteins with two tandem zinc finger (TZF) regions. Whether ZFP36L1 and ZFP36L2 have antiproliferative activities similar to that of ZFP36 is unclear. In this study, when ZFP36L1 or ZFP36L2 was overexpressed in T-REx-293 cells, cell proliferation was dramatically inhibited and the cell cycle was arrested at the G1 phase. The levels of cell-cycle-related proteins, including cyclin B, cyclin D, cyclin A, and p21, decreased; however, p53 increased in ZFP36L1-or ZFP36L2-overexpressing T-REx-293 cells. Forced expression of ZFP36L1 or ZFP36L2 also inhibited cell proliferation and cyclin D gene expression in three human colorectal cancer cell lines: HCT116 p53^+/+, HCT116 p53^−/−, and SW620 (mutated p53) cells. However, it increased p53 and p21 expression only in HCT116 p53^+/+ cells. Knockdown of ZFP36L1 or ZFP36L2 increased cell proliferation and cyclin D expression; furthermore, the mutation of the TZF of ZFP36L1 or ZFP36L2 caused them to lose their antiproliferative ability, to the extent that they could not inhibit cyclin D expression in these three cell lines. The results indicated that ZFP36L1 and ZFP36L2 play a negative role in cell proliferation; the underlying mechanisms might be mediated through a cyclin D-dependent and p53-independent pathway.

Maternal Pregravid Obesity Remodels the DNA Methylation Landscape of Cord Blood Monocytes Disrupting Their Inflammatory Program

Prepregnancy maternal obesity is associated with adverse outcomes for the offspring, including increased incidence of neonatal bacterial sepsis and necrotizing enterocolitis. We recently reported that umbilical cord blood (UCB) monocytes from babies born to obese mothers generate a reduced IL-6/TNF-α response to TLR 1/2 and 4 ligands compared to those collected from lean mothers. These observations suggest altered development of the offspring's immune system, which in turn results in dysregulated function. We therefore investigated transcriptional and epigenetic differences within UCB monocytes stratified by prepregnancy maternal body mass index. We show that UCB monocytes from babies born to obese mothers generate a dampened response to LPS stimulation compared with those born to lean mothers, at the level of secreted immune mediators and transcription. Because gene expression profiles of resting UCB monocytes from both groups were comparable, we next investigated the role of epigenetic differences. Indeed, we detected stark differences in methylation levels within promoters and regulatory regions of genes involved in TLR signaling in resting UCB monocytes. Interestingly, the DNA methylation status of resting cells was highly predictive of transcriptional changes post-LPS stimulation, suggesting that cytosine methylation is one of the dominant mechanisms driving functional inadequacy in UCB monocytes obtained from babies born to obese mothers. These data highlight a potentially critical role of maternal pregravid obesity-associated epigenetic changes in influencing the function of an offspring's monocytes at birth. These findings further our understanding of mechanisms that explain the increased risk of infection in neonates born to mothers with high prepregnancy body mass index.

Genome-wide miRNA response to anacardic acid in breast cancer cells

MicroRNAs are biomarkers and potential therapeutic targets for breast cancer. Anacardic acid (AnAc) is a dietary phenolic lipid that inhibits both MCF-7 estrogen receptor α (ERα) positive and MDA-MB-231 triple negative breast cancer (TNBC) cell proliferation with IC50s of 13.5 and 35 μM, respectively. To identify potential mediators of AnAc action in breast cancer, we profiled the genome-wide microRNA transcriptome (microRNAome) in these two cell lines altered by the AnAc 24:1n5 congener. Whole genome expression profiling (RNA-seq) and subsequent network analysis in MetaCore Gene Ontology (GO) algorithm was used to characterize the biological pathways altered by AnAc. In MCF-7 cells, 69 AnAc-responsive miRNAs were identified, e.g., increased let-7a and reduced miR-584. Fewer, i.e., 37 AnAc-responsive miRNAs were identified in MDA-MB-231 cells, e.g., decreased miR-23b and increased miR-1257. Only two miRNAs were increased by AnAc in both cell lines: miR-612 and miR-20b; however, opposite miRNA arm preference was noted: miR-20b-3p and miR-20b-5p were upregulated in MCF-7 and MDA-MB-231, respectively. miR-20b-5p target EFNB2 transcript levels were reduced by AnAc in MDA-MB-231 cells. AnAc reduced miR-378g that targets VIM (vimentin) and VIM mRNA transcript expression was increased in AnAc-treated MCF-7 cells, suggesting a reciprocal relationship. The top three enriched GO terms for AnAc-treated MCF-7 cells were B cell receptor signaling pathway and ribosomal large subunit biogenesis and S-adenosylmethionine metabolic process for AnAc-treated MDA-MB-231 cells. The pathways modulated by these AnAc-regulated miRNAs suggest that key nodal molecules, e.g., Cyclin D1, MYC, c-FOS, PPARγ, and SIN3, are targets of AnAc activity.

Knockdown of miR-128a induces Lin28a expression and reverts myeloid differentiation blockage in acute myeloid leukemia

Lin28A is a highly conserved RNA-binding protein that concurs to control the balance between stemness and differentiation in several tissue lineages. Here, we report the role of miR-128a/Lin28A axis in blocking cell differentiation in acute myeloid leukemia (AML), a genetically heterogeneous disease characterized by abnormally controlled proliferation of myeloid progenitor cells accompanied by partial or total inability to undergo terminal differentiation. First, we found Lin28A underexpressed in blast cells from AML patients and AML cell lines as compared with CD34+ normal precursors. In vitro transfection of Lin28A in NPM1-mutated OCI-AML3 cell line significantly triggered cell-cycle arrest and myeloid differentiation, with increased expression of macrophage associate genes (EGR2, ZFP36 and ANXA1). Furthermore, miR-128a, a negative regulator of Lin28A, was found overexpressed in AML cells compared with normal precursors, especially in acute promyelocytic leukemia (APL) and in ‘AML with maturation’ (according to 2016 WHO classification of myeloid neoplasms and acute leukemia). Its forced overexpression by lentiviral infection in OCI-AML3 downregulated Lin28A with ensuing repression of macrophage-oriented differentiation. Finally, knockdown of miR-128a in OCI-AML3 and in APL/AML leukemic cells (by transfection and lentiviral infection, respectively) induced myeloid cell differentiation and increased expression of Lin28A, EGR2, ZFP36 and ANXA1, reverting myeloid differentiation blockage. In conclusion, our findings revealed a new mechanism for AML differentiation blockage, suggesting new strategies for AML therapy based upon miR-128a inhibition.

Cell cycle RNA regulons coordinating early lymphocyte development

Lymphocytes undergo dynamic changes in gene expression as they develop from progenitor cells lacking antigen receptors, to mature cells that are prepared to mount immune responses. While transcription factors have established roles in lymphocyte development, they act in concert with post-transcriptional and post-translational regulators to determine the proteome. Furthermore, the post-transcriptional regulation of RNA regulons consisting of mRNAs whose protein products act cooperatively allows RNA binding proteins to exert their effects at multiple points in a pathway. Here, we review recent evidence demonstrating the importance of RNA binding proteins that control the cell cycle in lymphocyte development and discuss the implications for tumorigenesis. WIREs RNA 2017, 8:e1419. doi: 10.1002/wrna.1419 For further resources related to this article, please visit the WIREs website.

High expression of MAP7 predicts adverse prognosis in young patients with cytogenetically normal acute myeloid leukemia

Microtubule-associated protein 7 (MAP7) plays an important role in cancer cells. In this study, we identified the prognostic significance of MAP7 expression in cytogenetically normal acute myeloid leukemia (CN-AML) patients (aged <60 years) based on several microarray datasets. In the first group (n = 129), high MAP7 expression (MAP7^high) was associated with adverse overall survival (OS; P = 0.0441) and event-free survival (EFS; P = 0.0114) compared with low MAP7 expression (MAP7^low). In addition, the prognostic significance of MAP7 was confirmed by European Leukemia Net (ELN) intermediate-I genetic categories and multivariable analysis. In the second independent group of CN-AML patients (aged <60 years), MAP7^high was also associated with adverse OS (n = 88, OS; P = 0.00811). To understand the inherent mechanisms of MAP7's prognosis, we investigated genome-wide gene/microRNA expression signatures associated with MAP7 expression. Several known oncogenic genes/microRNAs and anti-oncogenic genes/microRNAs were disordered in MAP7^high CN-AML patients. In conclusion, MAP7^high is an adverse prognostic biomarker for CN-AML, which may be attributed to the distinctive genome-wide gene/microRNA expression and related cell signaling pathways.

RNA-binding protein IGF2BP3 targeting of oncogenic transcripts promotes hematopoietic progenitor proliferation

Posttranscriptional control of gene expression is important for defining both normal and pathological cellular phenotypes. In vitro, RNA-binding proteins (RBPs) have recently been shown to play important roles in posttranscriptional regulation; however, the contribution of RBPs to cell specification is not well understood. Here, we determined that the RBP insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) is specifically overexpressed in mixed lineage leukemia-rearranged (MLL-rearranged) B-acute lymphoblastic leukemia (B-ALL), which constitutes a subtype of this malignancy associated with poor prognosis and high risk of relapse. IGF2BP3 was required for the survival of B-ALL cell lines, as knockdown led to decreased proliferation and increased apoptosis. Enforced expression of IGF2BP3 provided murine BM cells with a strong survival advantage, led to proliferation of hematopoietic stem and progenitor cells, and skewed hematopoietic development to the B cell/myeloid lineage. Cross-link immunoprecipitation and high throughput sequencing uncovered the IGF2BP3-regulated transcriptome, which includes oncogenes MYC and CDK6 as direct targets. IGF2BP3 regulated transcripts via targeting elements within 3' untranslated regions (3'UTR), and enforced IGF2BP3 expression in mice resulted in enhanced expression of Myc and Cdk6 in BM. Together, our data suggest that IGF2BP3-mediated targeting of oncogenic transcripts may represent a critical pathogenetic mechanism in MLL-rearranged B-ALL and support IGF2BP3 and its cognate RNA-binding partners as potential therapeutic targets in this disease.