QKI shuttles internal m7G-modified transcripts into stress granules and modulates mRNA metabolism.

N7-methylguanosine (m7G) modification, routinely occurring at mRNA 5' cap or within tRNAs/rRNAs, also exists internally in messenger RNAs (mRNAs). Although m7G-cap is essential for pre-mRNA processing and protein synthesis, the exact role of mRNA internal m7G modification remains elusive. Here, we report that mRNA internal m7G is selectively recognized by Quaking proteins (QKIs). By transcriptome-wide profiling/mapping of internal m7G methylome and QKI-binding sites, we identified more than 1,000 high-confidence m7G-modified and QKI-bound mRNA targets with a conserved "GANGAN (N = A/C/U/G)" motif. Strikingly, QKI7 interacts (via C terminus) with the stress granule (SG) core protein G3BP1 and shuttles internal m7G-modified transcripts into SGs to regulate mRNA stability and translation under stress conditions. Specifically, QKI7 attenuates the translation efficiency of essential genes in Hippo signaling pathways to sensitize cancer cells to chemotherapy. Collectively, we characterized QKIs as mRNA internal m7G-binding proteins that modulate target mRNA metabolism and cellular drug resistance.

Suppression of YTHDF2 attenuates autoimmune hepatitis by expansion of myeloid-derived suppressor cells.

BACKGROUND & AIMS: The N6-methyladenosine (m6A) reader YTH domain-containing family protein 2 (YTHDF2) is critically involved in a multiplicity of biological processes by mediating the degradation of m6A modified mRNAs. Based on our current understanding of this process, we hypothesized that YTHDF2 will play a role in the natural history and function of myeloid-derived suppressor cells (MDSC) and in particular in AIH. APPROACH & RESULTS: We took advantage of YTHDF2 conditional knock-out mice to first address the phenotype and function of MDSCs by flow cytometry. Importantly, the loss of YTHDF2 resulted in a gradual elevation of MDSCs including PMN-MDSCs both in liver and ultimately in the BM. Notably, YTHDF2 deficiency in myeloid cells attenuated concanavalin (ConA)-induced liver injury, with enhanced expansion and chemotaxis to liver. Furthermore, MDSCs from Ythdf2CKO mice had a greater suppressive ability to inhibit the proliferation of T cells. Using multi-omic analysis of m6A RNA immunoprecipitation (RIP) and mRNA sequencing, we noted RXRα as potential target of YTHDF2. Indeed YTHDF2-RIP-qPCR confirmed that YTHDF2 directly binds RXRα mRNA thus promoting degradation and decreasing gene expression. Finally, by IHC and immunofluorescence, YTHDF2 expression was significantly upregulated in the liver of patients with AIH which correlated with the degree of inflammation. CONCLUSION: Suppression of YTHDF2 enhances the expansion, chemotaxis and suppressive function of MDSCs and our data reveals a unique therapeutical target in immune mediated hepatitis.

Habitat quality dynamics in China's first group of national parks in recent four decades: Evidence from land use and land cover changes.

As the most biodiversity-rich part of the protected areas system, habitats within the pilot national parks have long been threatened by drastic human-induced land use and land cover changes. The growing concern about habitat loss has spurred China's national park project to shift from pilot to construction phase with the official establishment of China's first group of national parks (CFGNPs) in October 2021. But far too little attention has been paid to the synergistic work concerning the habitat quality (HQ) dynamics of all five national parks. Here, the InVEST model, combined with a satellite-derived land use and land cover product and a hot spot analysis (HSA) method, was used to investigate the HQ dynamics at the park- and pixel-scale within the CFGNPs. Our results demonstrate that the past ecological conservation practices within national parks have been unpromising, especially in Giant Panda National Park, Northeast China Tiger and Leopard National Park (NCTL), and Wuyi Mountain National Park (WYM), where HQ as a whole showed a significant decline. Furthermore, more than half of Hainan Tropical Rainforest National Park (87.2%), WYM (77.4%), and NCTL (52.9%) showed significant HQ degradation from 1980 to 2019. Besides, increasing trends in the area shares of HQ degraded pixels were observed in all five national parks from 1980-1999 to 2000-2019. The HSA implied that the hot spots of high HQ degradation rates tend to occur in areas closer to urban settlements or on the edge of national parks, where human activities are intensive. Despite these disappointing findings, we highlighted from the observed local successes and the HQ plateau that the construction of CFGNPs is expected to reverse the deteriorating HQ trends. Thus, we concluded our paper by proposing an HSA-based regulatory zoning scheme that includes five subzones to guide the future construction of China's national park system.

A framework for identifying bird conservation priority areas in croplands at national level.

Global biodiversity is declining at an unprecedented rate, and the Post-2020 Global Biodiversity Framework requires each country to fulfill the conservation targets in biodiversity-inclusive spatial planning. Croplands provide habitat and food for many species, making them crucial for biodiversity conservation in addition to food production. Assessing conservation priorities in cropland is a prerequisite to allocate conservation resources and plan actions for better conservation outcomes. Yet quantitative methods to assess cropland conservation priority for biodiversity conservation at a national scale are still lacking. We proposed a framework for identifying the conservation priority in cropland for bird species at a national scale and applied the framework in China. We calculated the suitable habitat for each species and used a complementarity-based approach to designate the irreplaceable conservation priority areas considering richness, threatened level, and conservation percentage targets. We identified cropland taking up 6.76% of China's land area as a bird conservation priority, partially covering the suitable habitat of all the study species. By analyzing the landscape pattern of the priority areas and species' foraging traits, we provided policy-making suggestions according to area-specific characteristics. This framework can be used to identify priority areas for large-scale biodiversity conservation for different countries.

Association of Hepatic Steatosis Index and Fatty Liver Index with Carotid Atherosclerosis in Type 2 Diabetes.

Background/aim: Previous studies have suggested that the hepatic steatosis index (HSI) and fatty liver index (FLI) can be used as a predictor of non-alcoholic fatty liver disease (NAFLD). The aim of our study was to determine whether non-invasive indices of hepatic steatosis (HSI and FLI) are associated with carotid atherosclerosis in type 2 diabetes mellitus (T2DM). Methods: This was a cross-sectional study conducted in the T2DM patients (n=768). Carotid intima-media thickness (CIMT) was measured by the Color Doppler ultrasound. The HSI was calculated based on gender, body mass index (BMI), and transaminases level. The FLI was based on BMI, waist circumference (WC), triacylglycerols (TG) and g-glutamyl transferase (GGT). Results: Raised HSI and FLI levels was associated with increased CIMT levels in T2DM patients. Patients with greater CIMT had higher HSI (39.10 ± 5.70 vs 36.10 ± 4.18, P < 0.001) and FLI (46.35 (29.96, 65.54) vs 36.93 (18.7, 57.93), P < 0.001) than those with lower CIMT. Subjects with existing carotid plaque had higher HSI (38.28 ± 5.63 vs 35.69 ± 3.45 P < 0.001) and FLI (47.41 (27.77, 66.62) vs 37.19 (17.71, 51.78), P < 0.001) accordingly. HSI (r = 0.343, P < 0.001) and FLI (r = 0.184, P < 0.001) were positively related with the CIMT. In the linear regression, after full adjustment metabolic risk factors, smoking, and measures of insulin resistance, HSI and FLI were independently associated with CIMT (HSI: ß = 0.011, FLI: ß = 0.001, all P < 0.01). Further, logistic regression analyses showed that higher HSI and FLI had an impact on the risk for carotid atherosclerosis [HSI: OR (95%CI): 1.174 (1.123-1.228), FLI: OR (95%CI): 1.011(1.004-1.019), all P < 0.01]. Overall, increasing values of HSI and FLI were associated with CIMT (P < 0.05) significantly across different categories of age and hypertension. Conclusion: Current data suggest HSI and FLI are independently correlated with carotid atherosclerosis in T2DM. They may be a simple and useful marker for assessing the progression of diabetic macrovascular complications.

One-third of lands face high conflict risk between biodiversity conservation and human activities in China.

Biodiversity is declining at an unprecedented rate, and conservation is needed in many places including human-dominated landscapes. Evaluation of conflict risk between biodiversity conservation and human activities is a prerequisite for countries to develop strategies to achieve better conservation outcomes. However, quantitative methods to measure the conflict risk in large-scale areas are still lacking. Here we put forward a quantitative model in large-scale areas and produce the first continuum map of conflict risk in China. Our results show that conflict risk hotspots take up 32.86 % of China's terrestrial area, which may affect 42.98 % of China's population and more than 98 % of threaten vertebrates. Although species richness is high in these hotspot regions, only 10.69 % of them are covered by protected areas. Therefore, alternative conservation measures and proactive spatial planning are needed, especially in regions along the coastlines and around the Sichuan Basin. Especially, extraordinary attentions should be paid to urban agglomerations such as the Pearl River Delta and Yangtze River Delta. Compared to previous studies, our study quantifies the conflict risk of every gird cell, enabling the comparison among any locations. The analysis of 500 times generations shows a low sensitivity of the model as the maximum standard deviation is only 0.017. Furthermore, our model can be applied in other countries or at global scale to provide strategies for conflict governance and biodiversity conservation.

Correction to: YTHDF2 reduction fuels inflammation and vascular abnormalization in hepatocellular carcinoma.

An amendment to this paper has been published and can be accessed via the original article.

Epitranscriptomics in liver disease: Basic concepts and therapeutic potential.

The development of next-generation sequencing technology and the discovery of specific antibodies targeting chemically modified nucleotides have paved the way for a new era of epitranscriptomics. Cellular RNA is known to dynamically and reversibly undergo different chemical modifications after transcription, such as N6-methyladenosine (m6A), N1-methyladenosine, N6,2'-O-dimethyladenosine, 5-methylcytosine, and 5-hydroxymethylcytidine, whose identity and location comprise the field of epitranscriptomics. Dynamic post-transcriptional modifications determine the fate of target RNAs by regulating various aspects of their processing, including RNA export, transcript processing, splicing, and degradation. The most abundant internal mRNA modification in eukaryotic cells is m6A, which exhibits essential roles in physiological processes, such as embryogenesis, carcinogenesis, and neurogenesis. m6A is deposited by the m6A methyltransferase complex (composed of METTL3/14/16, WTAP, KIAA1429, and RBM15/15B), erased by demethylases (FTO and ALKBH5), and recognised by binding proteins (e.g., YTHDF1/2/3, YTHDC1/2, IGF2BP1/2/3). The liver is the largest digestive and metabolic organ, and m6A modifications play unique roles in critical physiological hepatic functions and various liver diseases. This review focuses on the biological roles of m6A RNA methylation in lipid metabolism, viral hepatitis, non-alcoholic fatty liver disease, liver cancer, and tumour metastasis. In addition, we summarise the existing inhibitors targeting m6A regulators and discuss the potential of modulating m6A modifications as a therapeutic strategy.

YTHDF2 reduction fuels inflammation and vascular abnormalization in hepatocellular carcinoma.

BACKGROUND: Dynamic N6-methyladenosine (m6A) modification was previously identified as a ubiquitous post-transcriptional regulation that affected mRNA homeostasis. However, the m6A-related epitranscriptomic alterations and functions remain elusive in human cancer. Here we aim to identify the profile and outcome of m6A-methylation in hepatocellular carcinoma (HCC). RESULTS: Using liquid chromatography-tandem mass spectrometry and m6A-immunoprecipitation in combination with high-throughput sequencing, we determined the m6A-mRNA levels in human HCC. Human HCC exhibited a characteristic gain of m6A modification in tandem with an increase of mRNA expression, owing to YTH domain family 2 (YTHDF2) reduction. The latter predicted poor classification and prognosis of HCC patients, and highly correlated with HCC m6A landscape. YTHDF2 silenced in human HCC cells or ablated in mouse hepatocytes provoked inflammation, vascular reconstruction and metastatic progression. Mechanistically, YTHDF2 processed the decay of m6A-containing interleukin 11 (IL11) and serpin family E member 2 (SERPINE2) mRNAs, which were responsible for the inflammation-mediated malignancy and disruption of vascular normalization. Reciprocally, YTHDF2 transcription succumbed to hypoxia-inducible factor-2α (HIF-2α). Administration of a HIF-2α antagonist (PT2385) restored YTHDF2-programed epigenetic machinery and repressed liver cancer. CONCLUSION: Our results have characterized the m6A-mRNA landscape in human HCC and revealed YTHDF2 as a molecular 'rheostat' in epitranscriptome and cancer progression.

Regulation of angiopoietin-like protein 8 expression under different nutritional and metabolic status.

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with increasing prevalence worldwide. Angiopoietin-like protein 8 (ANGPTL8), a member of the angiopoietin-like protein family, is involved in glucose metabolism, lipid metabolism, and energy homeostasis and believed to be associated with T2DM. Expression levels of ANGPTL8 are often significantly altered in metabolic diseases, such as non-alcoholic fatty liver disease (NAFLD) and diabetes mellitus. Studies have shown that ANGPTL8, together with other members of this protein family, such as angiopoietin-like protein 3 (ANGPTL3) and angiopoietin-like protein 4 (ANGPTL4), regulates the activity of lipoprotein lipase (LPL), thereby participating in the regulation of triglyceride related lipoproteins (TRLs). In addition, members of the angiopoietin-like protein family are varyingly expressed among different tissues and respond differently under diverse nutritional and metabolic status. These findings may provide new options for the diagnosis and treatment of diabetes, metabolic syndromes and other diseases. In this review, the interaction between ANGPTL8 and ANGPTL3 or ANGPTL4, and the differential expression of ANGPTL8 responding to different nutritional and metabolic status during the regulation of LPL activity were reviewed.

Roles of partitioning-defective protein 6 (Par6) and its complexes in the proliferation, migration and invasion of cancer cells.

A pivotal regulator of cell polarity and homeostasis, partitioning-defective protein 6 (Par6) forms multicomponent complexes that not only regulate cell polarity and stabilize cell morphology, but have also been demonstrated to participate in the proliferation, migration and invasion of cancer cells. The transforming growth factor (TGF)-ß and extracellular signal-regulated kinase (Erk) 1/2 pathways are the most thoroughly studied pathways involving Par6 in many cancers. Aurothiomalate has been used to disrupt the interaction between Par6 and atypical protein kinase C within the multicomponent complexes, and has been shown to effectively block transformed growth and metastasis in vitro and/or in vivo in a variety of cancers, including pancreatic, prostate and lung cancers, as well as alveolar rhabdomyosarcoma. It is likely that with further revelations regarding the critical roles of Par6 in cancer initiation, progression and metastasis, targeted therapies against Par6 will be discovered and prove effective preclinically, and hopefully clinically, in cancer treatment.

Over 1/4 of China's terrestrial area significantly contributed both to biodiversity conservation and carbon neutrality, requiring protection.

Protected areas (PAs) play a crucial role in halting biodiversity loss and mitigating climate change. However, research on the advantages of integrating biodiversity conservation and climate mitigation within PAs remains limited, and there is a deficiency in holistic, scientifically supported management strategies. To address these gaps, we conducted a case study in China, comparing the conservation effectiveness of designating conservation priorities considering either single or multiple objectives, including biodiversity conservation and carbon neutrality. The results showed that integrating multiple values could truly increase the effectiveness of PAs compared to a single value considered. Over 1/4 of China's terrestrial area had a significant contribution for both biodiversity conservation and carbon neutrality, yet remained unprotected. Expanding PAs in these areas holds tremendous win-win biodiversity conservation and carbon neutrality opportunity. We delineated different conservation priorities for comprehensive management and outlined strategies for different types of areas. The framework presented in this study can serve as a reference for other places with comparable scales or management objectives.

A cost-effective approach to identify conservation priority for 30 × 30 biodiversity target on the premise of food security.

There is a growing consensus on expanding protected and conserved areas for biodiversity conservation. Nevertheless, it remains uncertain where to expand conserved areas as well as what appropriate management modalities to choose. Moreover, conserved areas expansion should be balanced with crop-related food security challenges. We developed a framework to identify cost-effective areas for expanding protected areas and other effective area-based conservation measures (OECMs), and applied it to China. By combining templates for biodiversity conservation priorities at global scale and the priority conservation areas based on 2413 vertebrates' extinction risk in China, we identified areas with high biodiversity conservation value. We then categorized the priority areas according to human impact, indicating the potential cost of management. As a result of combining the two aspects above, we identified the most cost-effective areas for expanding protected areas and OECMs while excluding both the current and predicted croplands that can be used for food security. The results show that China could expand its protected areas to 22.81 % of the country's land area and establish OECMs in areas accounting for 9.82 % and 17.37 % of the country's land area in a cost-effective approach in two scenarios. In the ambitious scenario, protected and conserved areas would account for a maximum of 40.18 % of terrestrial area, with an average 62.67 % coverage of the 2413 species' suitable habitat. To achieve the goals of protected and conserved areas in Kunming-Montreal Global Biodiversity Framework, countries could apply this framework to identify their protected areas and OECM expansion priorities.

RNA m6A reader YTHDF2 facilitates precursor miR-126 maturation to promote acute myeloid leukemia progression.

As the most common internal modification of mRNA, N6-methyladenosine (m6A) and its regulators modulate gene expression and play critical roles in various biological and pathological processes including tumorigenesis. It was reported previously that m6A methyltransferase (writer), methyltransferase-like 3 (METTL3) adds m6A in primary microRNAs (pri-miRNAs) and facilitates its processing into precursor miRNAs (pre-miRNAs). However, it is unknown whether m6A modification also plays a role in the maturation process of pre-miRNAs and (if so) whether such a function contributes to tumorigenesis. Here, we found that YTHDF2 is aberrantly overexpressed in acute myeloid leukemia (AML) patients, especially in relapsed patients, and plays an oncogenic role in AML. Moreover, YTHDF2 promotes expression of miR-126-3p (also known as miR-126, as it is the main product of precursor miR-126 (pre-miR-126)), a miRNA that was reported as an oncomiRNA in AML, through facilitating the processing of pre-miR-126 into mature miR-126. Mechanistically, YTHDF2 recognizes m6A modification in pre-miR-126 and recruits AGO2, a regulator of pre-miRNA processing, to promote the maturation of pre-miR-126. YTHDF2 positively and negatively correlates with miR-126 and miR-126's downstream target genes, respectively, in AML patients, and forced expression of miR-126 could largely rescue YTHDF2/Ythdf2 depletion-mediated suppression on AML cell growth/proliferation and leukemogenesis, indicating that miR-126 is a functionally important target of YTHDF2 in AML. Overall, our studies not only reveal a previously unappreciated YTHDF2/miR-126 axis in AML and highlight the therapeutic potential of targeting this axis for AML treatment, but also suggest that m6A plays a role in pre-miRNA processing that contributes to tumorigenesis.

METTL16 promotes liver cancer stem cell self-renewal via controlling ribosome biogenesis and mRNA translation.

BACKGROUND: While liver cancer stem cells (CSCs) play a crucial role in hepatocellular carcinoma (HCC) initiation, progression, recurrence, and treatment resistance, the mechanism underlying liver CSC self-renewal remains elusive. We aim to characterize the role of Methyltransferase 16 (METTL16), a recently identified RNA N6-methyladenosine (m6A) methyltransferase, in HCC development/maintenance, CSC stemness, as well as normal hepatogenesis. METHODS: Liver-specific Mettl16 conditional KO (cKO) mice were generated to assess its role in HCC pathogenesis and normal hepatogenesis. Hydrodynamic tail-vein injection (HDTVi)-induced de novo hepatocarcinogenesis and xenograft models were utilized to determine the role of METTL16 in HCC initiation and progression. A limiting dilution assay was utilized to evaluate CSC frequency. Functionally essential targets were revealed via integrative analysis of multi-omics data, including RNA-seq, RNA immunoprecipitation (RIP)-seq, and ribosome profiling. RESULTS: METTL16 is highly expressed in liver CSCs and its depletion dramatically decreased CSC frequency in vitro and in vivo. Mettl16 KO significantly attenuated HCC initiation and progression, yet only slightly influenced normal hepatogenesis. Mechanistic studies, including high-throughput sequencing, unveiled METTL16 as a key regulator of ribosomal RNA (rRNA) maturation and mRNA translation and identified eukaryotic translation initiation factor 3 subunit a (eIF3a) transcript as a bona-fide target of METTL16 in HCC. In addition, the functionally essential regions of METTL16 were revealed by CRISPR gene tiling scan, which will pave the way for the development of potential inhibitor(s). CONCLUSIONS: Our findings highlight the crucial oncogenic role of METTL16 in promoting HCC pathogenesis and enhancing liver CSC self-renewal through augmenting mRNA translation efficiency.

Association of serum Tsukushi level with metabolic syndrome and its components.

PURPOSE: Tsukushi (TSK), a novel hepatokine, has recently been pointed out to play an important role in energy homeostasis and glycolipid metabolism. However, there are no clinical studies on the association of TSK with metabolic syndrome (MetS), the typical constellation of metabolic disorders. This study was conducted to explore the relationship between TSK and MetS as well as each of its metabolic component clinically. METHODS: We analyzed in this cross-sectional study serum TSK levels by ELISA in 392 participants, including 90 non-MetS and 302 MetS, to compare TSK in two groups and in different numbers of metabolic components. The odds ratios (OR) of TSK quartile in MetS and each metabolic component were computed by multivariate logistic regression analysis. RESULTS: TSK was substantially higher in MetS than in non-MetS subjects (P < 0.001). TSK increased with the concomitant increase of the number of metabolic components (P for <0.001). Logistic regression analyses demonstrated that the OR of MetS was 2.74 for the highest versus the lowest quartile of TSK (P < 0.001) after adjusting for age, gender, smoking status, alcohol consumption and medication use. Additionally, TSK was associated with the OR of poor HDL-C and elevated fasting glucose (P < 0.05). CONCLUSION: Circulating TSK was higher in MetS patients and linked with MetS risk, suggesting that TSK may play a role in the genesis of MetS and be a potential therapeutic target for MetS. Future study should investigate the connection between TSK levels and MetS pathogenesis.

Association between Circulating Ectodysplasin A and Diabetic Kidney Disease.

Background: Ectodysplasin A (EDA), a member of the TNF family, plays important roles in ectodermal development, while recent studies expanded its regulatory effects on insulin resistance and lipid metabolism. This study was the first time to investigate the correlation between circulating EDA and albuminuria in patients with T2DM. Methods: A total of 189 T2DM and 59 healthy subjects were enrolled in the study. We analyzed the concentrations of EDA by ELISA. Plasma glucose, insulin, HbA1c, lipids, creatinine, BUN, and UACR were also measured. Insulin resistance and pancreatic cell function were assessed by HOMA. Results: Circulating EDA concentration was significantly increased in T2DM patients and increased with the degree of albuminuria. EDA was positively correlated with age, FIns, HOMA-IR, HOMA-ß, Scr, and UACR, and negatively correlated with eGFR. Linear stepwise regression showed that FIns, HOMA-ß, and UACR were independent influencing factors of EDA. Logistic regression analysis showed that EDA was independently associated with the occurrence of albuminuria in T2DM. ROC curve showed that EDA had an area under the receiver operating curve of 0.701 [95%CI = (0.625 - 0.777), P < 0.001]. Conclusion: EDA is positively correlated with the degree of albuminuria in patients with T2DM and may be involved in the occurrence and progression of diabetic kidney disease (DKD).

METTL16 drives leukemogenesis and leukemia stem cell self-renewal by reprogramming BCAA metabolism.

N6-methyladenosine (m6A), the most prevalent internal modification in mammalian mRNAs, is involved in many pathological processes. METTL16 is a recently identified m6A methyltransferase. However, its role in leukemia has yet to be investigated. Here, we show that METTL16 is a highly essential gene for the survival of acute myeloid leukemia (AML) cells via CRISPR-Cas9 screening and experimental validation. METTL16 is aberrantly overexpressed in human AML cells, especially in leukemia stem cells (LSCs) and leukemia-initiating cells (LICs). Genetic depletion of METTL16 dramatically suppresses AML initiation/development and maintenance and significantly attenuates LSC/LIC self-renewal, while moderately influencing normal hematopoiesis in mice. Mechanistically, METTL16 exerts its oncogenic role by promoting expression of branched-chain amino acid (BCAA) transaminase 1 (BCAT1) and BCAT2 in an m6A-dependent manner and reprogramming BCAA metabolism in AML. Collectively, our results characterize the METTL16/m6A/BCAT1-2/BCAA axis in leukemogenesis and highlight the essential role of METTL16-mediated m6A epitranscriptome and BCAA metabolism reprograming in leukemogenesis and LSC/LIC maintenance.

TET2-mediated mRNA demethylation regulates leukemia stem cell homing and self-renewal.

TET2 is recurrently mutated in acute myeloid leukemia (AML) and its deficiency promotes leukemogenesis (driven by aggressive oncogenic mutations) and enhances leukemia stem cell (LSC) self-renewal. However, the underlying cellular/molecular mechanisms have yet to be fully understood. Here, we show that Tet2 deficiency significantly facilitates leukemogenesis in various AML models (mediated by aggressive or less aggressive mutations) through promoting homing of LSCs into bone marrow (BM) niche to increase their self-renewal/proliferation. TET2 deficiency in AML blast cells increases expression of Tetraspanin 13 (TSPAN13) and thereby activates the CXCR4/CXCL12 signaling, leading to increased homing/migration of LSCs into BM niche. Mechanistically, TET2 deficiency results in the accumulation of methyl-5-cytosine (m5C) modification in TSPAN13 mRNA; YBX1 specifically recognizes the m5C modification and increases the stability and expression of TSPAN13 transcripts. Collectively, our studies reveal the functional importance of TET2 in leukemogenesis, leukemic blast cell migration/homing, and LSC self-renewal as an mRNA m5C demethylase.

Phosphorylation stabilized TET1 acts as an oncoprotein and therapeutic target in B cell acute lymphoblastic leukemia.

Although the overall survival rate of B cell acute lymphoblastic leukemia (B-ALL) in childhood is more than 80%, it is merely 30% in refractory/relapsed and adult patients with B-ALL. This demonstrates a need for improved therapy targeting this subgroup of B-ALL. Here, we show that the ten-eleven translocation 1 (TET1) protein, a dioxygenase involved in DNA demethylation, is overexpressed and plays a crucial oncogenic role independent of its catalytic activity in B-ALL. Consistent with its oncogenic role in B-ALL, overexpression of TET1 alone in normal precursor B cells is sufficient to transform the cells and cause B-ALL in mice within 3 to 4 months. We found that TET1 protein is stabilized and overexpressed because of its phosphorylation mediated by protein kinase C epsilon (PRKCE) and ATM serine/threonine kinase (ATM), which are also overexpressed in B-ALL. Mechanistically, TET1 recruits STAT5B to the promoters of CD72 and JCHAIN and promotes their transcription, which in turn promotes B-ALL development. Destabilization of TET1 protein by treatment with PKC or ATM inhibitors (staurosporine or AZD0156; both tested in clinical trials), or by pharmacological targeting of STAT5B, greatly decreases B-ALL cell viability and inhibits B-ALL progression in vitro and in vivo. The combination of AZD0156 with staurosporine or vincristine exhibits a synergistic effect on inhibition of refractory/relapsed B-ALL cell survival and leukemia progression in PDX models. Collectively, our study reveals an oncogenic role of the phosphorylated TET1 protein in B-ALL independent of its catalytic activity and highlights the therapeutic potential of targeting TET1 signaling for the treatment of refractory/relapsed B-ALL.