METTL3 protects METTL14 from STUB1-mediated degradation to maintain m6 A homeostasis.

N6 -Methyladenosine (m6 A) is an important RNA modification catalyzed by methyltransferase-like 3 (METTL3) and METTL14. m6 A homeostasis mediated by the methyltransferase (MTase) complex plays key roles in various biological processes. However, the mechanism underlying METTL14 protein stability and its role in m6 A homeostasis remain elusive. Here, we show that METTL14 stability is regulated by the competitive interaction of METTL3 with the E3 ligase STUB1. STUB1 directly interacts with METTL14 to mediate its ubiquitination at lysine residues K148, K156, and K162 for subsequent degradation, resulting in a significant decrease in total m6 A levels. The amino acid regions 450-454 and 464-480 of METTL3 are essential to promote METTL14 stabilization. Changes in STUB1 expression affect METTL14 protein levels, m6 A modification and tumorigenesis. Collectively, our findings uncover an ubiquitination mechanism controlling METTL14 protein levels to fine-tune m6 A homeostasis. Finally, we present evidence that modulating STUB1 expression to degrade METTL14 could represent a promising therapeutic strategy against cancer.

circMYBL2, a circRNA from MYBL2, regulates FLT3 translation by recruiting PTBP1 to promote FLT3-ITD AML progression.

Internal tandem duplication (ITD) mutations within FMS-like tyrosine kinase-3 (FLT3) occur in up to 30% of acute myeloid leukemia (AML) patients and confer a very poor prognosis. The oncogenic form of FLT3 is an important therapeutic target, and inhibitors specifically targeting FLT3 kinase can induce complete remission; however, relapse after remission has been observed due to acquired resistance with secondary mutations in FLT3, highlighting the need for new strategies to target FLT3-ITD mutations. Recent studies have reported that the aberrant formations of circular RNAs (circRNAs) are biological tumorigenesis-relevant mechanisms and potential therapeutic targets. Herein, we discovered a circRNA, circMYBL2, derived from the cell-cycle checkpoint gene MYBL2. circMYBL2 is more highly expressed in AML patients with FLT3-ITD mutations than in those without the FLT3-ITD mutation. We found that circMYBL2 knockdown specifically inhibits proliferation and promotes the differentiation of FLT3-ITD AML cells in vitro and in vivo. Interestingly, we found that circMYBL2 significantly influences the protein level of mutant FLT3 kinase, which contributes to the activation of FLT3-ITD-dependent signaling pathways. Mechanistically, circMYBL2 enhanced the translational efficiency of FLT3 kinase by increasing the binding of polypyrimidine tract-binding protein 1 (PTBP1) to FLT3 messenger RNA. Moreover, circMYBL2 knockdown impaired the cytoactivity of inhibitor-resistant FLT3-ITD+ cells, with a significant decrease in FLT3 kinase expression, followed by the inactivation of its downstream pathways. In summary, we are the first to reveal a circRNA that specifically influences FLT3-ITD AML and regulates FLT3 kinase levels through translational regulation, suggesting that circMYBL2 may be a potential therapeutic target for FLT3-ITD AML.

[Synthesis of fluorinated nitrogen-rich porous organic polymers and removal of perfluorooctanoic acid from water].

Perfluorooctanoic acid (PFOA) is a persistent contaminant with detrimental effects on the natural environment. This persistence leads to potential enrichment and osmotic transfer, which can affect normal circulation in the environment. PFOA poses significant threats to both the natural environment and human health. Therefore, the development of cost-effective, highly efficient, and environment-friendly PFOA adsorbents is a crucial endeavor. This paper presents the catalyst-free one-pot synthesis of fluorinated nitrogen-rich porous organic polymers (POP-3F) via a Schiff-base condensation reaction. The reaction between the nitrogen-rich compound 1,4-bis(2,4-diamino-1,3,5-triazine)benzene and p-trifluoromethylbenzaldehyde yielded POP-3F. The introduction of fluorine atoms into the nitrogen-rich porous organic polymer enhanced its hydrophobicity, thereby facilitating favorable fluoro-fluorine interactions with PFOA and, thus, improving the efficacy of the adsorbent. Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), solid-state nuclear magnetic resonance (ssNMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption analysis, and thermogravimetric analysis (TGA) were used to confirm the successful synthesis and characterization of POP-3F. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was conducted in negative electrospray ionization (ESI) mode coupled with multi-reaction monitoring mode (MRM). The instrument was equipped with an Atlantis T3 column (100 mm×2.1 mm, 3 µm), and analysis was conducted using an external standard method. The influences of various factors on PFOA adsorption by POP-3F, including pH, salt concentration, and humic acid presence, were investigated. The highest PFOA removal rate (98.6%) was achieved at a pH of 2, indicating the applicability of POP-3F for the effective removal of PFOA from acidic industrial wastewater. The removal rate of PFOA was unaffected by increases in NaCl concentration. This phenomenon can be attributed to electrostatic interactions between the protonated secondary amines in POP-3F and deprotonated PFOA. Upon the addition of NaCl, a double electric layer is formed on the POP-3F surface, with Cl- ions in the outer layer and Na+ ions in the inner layer, which weakened these interactions. Humic acid is competitively adsorbed with PFOA. However, POP-3F demonstrated good removal rates even in the presence of high humic acid concentrations in water. Adsorption isotherm and kinetics experiments were conducted at the optimal pH to explore the relevant adsorption mechanism. The results showed a rapid initial adsorption rate, with 95.4% PFOA removal within 5 min. Optimal adsorption equilibrium was achieved within 6 h, and the removal rate decreased by only 0.3% after 24 h. This finding indicates that POP-3F exhibits sustained efficacy for PFOA removal. Langmuir fitting analysis revealed a theoretical maximum adsorption capacity of 191 mg/g for POP-3F; this value surpasses those of activated carbon materials and most other adsorbents, highlighting the superior PFOA-adsorption performance of POP-3F. Additionally, matrix effects minimally affected the removal of PFOA by POP-3F, with only a slight reduction (0.1%) observed in simulated natural water. The recyclability of POP-3F was assessed over five adsorption-desorption cycles. The removal efficenecy exhibited a minor decrease of only 0.67% after five cycles. These results demonstrate the recyclability of the proposed adsorbent, which translates into cost reduction through reusability. This characteristic renders POP-3F a promising candidate for the economical and efficient removal of PFOA from wastewater in practical applications.

Regulating the activity of GABAergic neurons in the ventral pallidum alters the general anesthesia effect of propofol.

The full mechanism of action of propofol, a commonly administered intravenous anesthetic drug in clinical practice, remains elusive. The focus of this study was the role of GABAergic neurons which are the main neuron group in the ventral pallidum (VP) closely associated with anesthetic effects in propofol anesthesia. The activity of VP GABAergic neurons following propofol anesthesia in Vgat-Cre mice was observed via detecting c-Fos immunoreactivity by immunofluorescence and western blotting. Subsequently, chemogenetic techniques were employed in Vgat-Cre mice to regulate the activity of VP GABAergic neurons. The role of VP GABAergic neurons in generating the effects of general anesthesia induced by intravenous propofol was further explored through behavioral tests of the righting reflex. The results revealed that c-Fos expression in VP GABAergic neurons in Vgat-Cre mice dramatically decreased after propofol injection. Further studies demonstrated that chemogenetic activation of VP GABAergic neurons during propofol anesthesia shortened the duration of anesthesia and promoted wakefulness. Conversely, the inhibition of VP GABAergic neurons extended the duration of anesthesia and facilitated the effects of anesthesia. The results obtained in this study suggested that regulating the activity of GABAergic neurons in the ventral pallidum altered the effect of propofol on general anesthesia.

Blockade of the lncRNA-DOT1L-LAMP5 axis enhances autophagy and promotes degradation of MLL fusion proteins.

BACKGROUND: Mixed-lineage leukemia (MLL) fusion gene caused by chromosomal rearrangement is a dominant oncogenic driver in leukemia. Due to having diverse MLL rearrangements and complex characteristics, MLL leukemia treated by currently available strategies is frequently associated with a poor outcome. Therefore, there is an urgent need to identify novel therapeutic targets for hematological malignancies with MLL rearrangements. METHODS: qRT-PCR, western blot, and spearman correction analysis were used to validate the regulation of LAMP5-AS1 on LAMP5 expression. In vitro and in vivo experiments were conducted to assess the functional relevance of LAMP5-AS1 in MLL leukemia cell survival. We utilized chromatin isolation by RNA purification (ChIRP) assay, RNA pull-down assay, chromatin immunoprecipitation (ChIP), RNA fluorescence in situ hybridization (FISH), and immunofluorescence to elucidate the relationship among LAMP5-AS1, DOT1L, and the LAMP5 locus. Autophagy regulation by LAMP5-AS1 was evaluated through LC3B puncta, autolysosome observation via transmission electron microscopy (TEM), and mRFP-GFP-LC3 puncta in autophagic flux. RESULTS: The study shows the crucial role of LAMP5-AS1 in promoting MLL leukemia cell survival. LAMP5-AS1 acts as a novel autophagic suppressor, safeguarding MLL fusion proteins from autophagic degradation. Knocking down LAMP5-AS1 significantly induced apoptosis in MLL leukemia cell lines and primary cells and extended the survival of mice in vivo. Mechanistically, LAMP5-AS1 recruits the H3K79 histone methyltransferase DOT1L to LAMP5 locus, directly activating LAMP5 expression. Importantly, blockade of LAMP5-AS1-LAMP5 axis can represses MLL fusion proteins by enhancing their degradation. CONCLUSIONS: The findings underscore the significance of LAMP5-AS1 in MLL leukemia progression through the regulation of the autophagy pathway. Additionally, this study unveils the novel lncRNA-DOT1L-LAMP5 axis as promising therapeutic targets for degrading MLL fusion proteins.

Internet addiction-induced brain structure and function alterations: a systematic review and meta-analysis of voxel-based morphometry and resting-state functional connectivity studies.

Internet addiction (IA) is a growing social concern and has been intensively studied in recent years. Previous imaging studies have shown that IA may impair brain structure and function, but with no robust conclusions. We conducted a systematic review and meta-analysis of neuroimaging studies in IA. Two separate meta-analyses were conducted for voxel-based morphometry (VBM) studies and resting-state functional connectivity (rsFC) studies. All meta-analyses were performed using two analysis methods activation likelihood estimation (ALE) and seed-based d mapping with permutation of subject images (SDM-PSI). The ALE analysis of VBM studies revealed less gray matter volume (GMV) in the supplementary motor area (SMA) (1176 mm3), anterior cingulate cortex (ACC) (one cluster size is 744 mm3 and the other is 688 mm3), and orbitofrontal cortex (OFC) (624 mm3) in subjects with IA. The SDM-PSI analysis showed less GMV in the ACC (56 voxels). The ALE analysis of rsFC studies showed stronger rsFC from posterior cingulate cortex (PCC) (880 mm3) or insula (712 mm3) to the whole brain in subjects with IA; however, the SDM-PSI analysis revealed no obvious rsFC alteration. These changes may underlie the core symptoms of IA, which include emotional regulation disorder, distraction, and impaired executive control. Our results reflect the common features of neuroimaging studies related to IA in recent years and may potentially help inform the development of more effective diagnostic and treatment approaches.

Structural and Functional Neural Alterations in Internet Addiction: A Study Protocol for Systematic Review and Meta-Analysis.

A growing number of neuroimaging studies have revealed abnormal brain structural and functional alterations in subjects with internet addiction (IA), however, with conflicting conclusions. We plan to conduct a systematic review and meta-analysis on the studies of voxelbased morphometry (VBM) and resting-state functional connectivity (rsFC), to reach a consolidated conclusion and point out the future direction in this field. A comprehensive search of rsFC and VBM studies of IA will be conducted in the PubMed, Cochrane Library, and Web of Science databases to retrieve studies published from the inception dates to August 2021. If the extracted data are feasible, activation likelihood estimation and seed-based d mapping methods will be used to meta-analyze the brain structural and functional changes in IA patients. This study will hopefully reach a consolidated conclusion on the impact of IA on human brain or point out the future direction in this field.

Kinsenoside alleviates inflammation and fibrosis in experimental NASH mice by suppressing the NF-κB/NLRP3 signaling pathway.

BACKGROUND: Non-alcoholic steatohepatitis (NASH) has replaced viral hepatitis as the main driver of the rising morbidity and mortality associated with cirrhosis and liver cancer worldwide, while no FDA-approved therapies are currently known. Kinsenoside (KD), naturally isolated from Anoectochilus roxburghii, possesses multiple biological activities, including lipolysis, anti-inflammation, and hepatoprotection. However, the effects of KD on NASH remain unclear. PURPOSE: This study aimed to explore the roles of KD in NASH and its engaged mechanisms. METHODS: Two typical animal models of NASH, mice fed a methionine-choline-deficient (MCD) diet (representing non-obese NASH) and mice fed a high-fat and -fructose diet (HFFD) (representing obese NASH), were used to investigate the effect of KD on NASH in vivo. Transcriptome sequencing was performed to elucidate the underlying mechanisms of KD. Lipopolysaccharide (LPS)-stimulated THP-1 cells and transforming growth factor ß1 (TGF-ß1)-activated LX-2 cells were applied to further explore the effects and mechanisms of KD in vitro. RESULTS: The intragastric administration of KD remarkably alleviated MCD/HFFD-induced murine NASH almost in a dose-dependent manner. Specifically, KD reduced lipid accumulation, inflammation, and fibrosis in the liver of NASH mice. KD ameliorated alanine aminotransferase (ALT), aspartate aminotransferase (AST), superoxide dismutase (SOD), and malondialdehyde (MDA) abnormalities. In addition, it decreased the level of serum proinflammatory factors (IL-12p70, IL-6, TNF-α, MCP-1, IFN-γ) and the hepatic expression of typical fibrosis-related molecules (α-SMA, Col-I, TIMP-1). Mechanically, KD attenuated the MCD/HFFD-induced NASH through the inhibition of the NF-κB/NLRP3 signaling pathway. Consistently, KD reduced inflammation stimulated by LPS in THP-1 cells via suppressing the NF-κB/NLRP3 pathway. Furthermore, it prevented the activation of LX-2 cells directly, by inhibiting the proliferation stimulated by TGF-ß1, and indirectly, by inactivating the NLRP3 inflammasome in macrophages. CONCLUSION: For the first time, the practical improvement of NASH by KD was revealed. Our study found that KD exerted its alleviative effects on NASH through the inhibition of the NF-κB/NLRP3 signaling pathway. Given its hepatoprotective and nontoxic properties, KD has the potential to be a novel and effective drug to treat NASH.

Dynamic alterations of functional connectivity and amplitude of low-frequency fluctuations in patients with unilateral sudden sensorineural hearing loss.

Unilateral sudden sensorineural hearing loss (SSNHL) adversely affects the quality of life, leading to increased risk of depression and cognitive decline. Our previous studies have mainly focused on the static brain function abnormalities in SSNHL patients. However, the dynamic features of brain activity in SSNHL patients are not elucidated. To explore the dynamic brain functional alterations in SSNHL patients, age- and sex- matched SSNHL patients (n = 38) and healthy controls (HC, n = 44) were enrolled. The dynamic functional connectivity (dFC) and dynamic amplitude of low-frequency fluctuation (dALFF) methods were used to compare the temporal features and dynamic neural activity between the two groups. In dFC analyses, the multiple functional connectivities (FCs) were clustered into 2 different states; a greater proportion of FCs in SSNHL patients showed sparse state compared with HC. In dALFF analyses, SSNHL individuals exhibited decreased dALFF variability in bilateral inferior occipital gyrus, middle occipital gyrus, calcarine, right lingual gyrus, and right fusiform gyrus. dALFF variability showed a negative correlation with activated partial thromboplatin time. The dynamic characteristics of SSNHL patients were different from static functional connectivity and static amplitude of low-frequency fluctuation, especially within the visual cortices. These findings suggest that SSNHL patients experience cross-modal plasticity and visual compensation, which may be closely related to the pathophysiology of SSNHL.

Chromatin-associated orphan snoRNA regulates DNA damage-mediated differentiation via a non-canonical complex.

Small nucleolar RNAs (snoRNAs) are commonly acknowledged as a class of homogeneous non-coding RNAs that guide ribosomal RNA modifications. However, snoRNAs referred to as orphans have largely unknown functions. Here, we systematically profile chromatin-associated snoRNAs (casnoRNAs) in mammalian cells and identify a subgroup of orphan casnoRNAs responding to DNA damage stress, among which SNORA73 shows the most marked reduction in chromatin enrichment. Downregulated SNORA73 maintains cancer genome stability and differentiation block in hematopoietic malignancy. Mechanistically, casnoRNA the 5' end non-canonical structure of SNORA73 is critical for its function and binding to poly (ADP-ribose) polymerase 1 (PARP1). SNORA73 inhibits PARP1 auto-PARylation to affect cancer genome stability by forming a small nucleolar ribonucleoprotein (snoRNP) with PARP1 and canonical H/ACA proteins DKC1/NHP2. Our findings reveal the role of an orphan snoRNA serving as casnoRNA and highlights a link between non-canonical structure of snoRNA and their functional diversity.

The snoRNA-like lncRNA LNC-SNO49AB drives leukemia by activating the RNA-editing enzyme ADAR1.

Long noncoding RNAs (lncRNAs) are usually 5' capped and 3' polyadenylated, similar to most typical mRNAs. However, recent studies revealed a type of snoRNA-related lncRNA with unique structures, leading to questions on how they are processed and how they work. Here, we identify a novel snoRNA-related lncRNA named LNC-SNO49AB containing two C/D box snoRNA sequences, SNORD49A and SNORD49B; and show that LNC-SNO49AB represents an unreported type of lncRNA with a 5'-end m7G and a 3'-end snoRNA structure. LNC-SNO49AB was found highly expressed in leukemia patient samples, and silencing LNC-SNO49AB dramatically suppressed leukemia progression in vitro and in vivo. Subcellular location indicated that the LNC-SNO49AB is mainly located in nucleolus and interacted with the nucleolar protein fibrillarin. However, we found that LNC-SNO49AB does not play a role in 2'-O-methylation regulation, a classical function of snoRNA; instead, its snoRNA structure affected the lncRNA stability. We further demonstrated that LNC-SNO49AB could directly bind to the adenosine deaminase acting on RNA 1(ADAR1) and promoted its homodimerization followed by a high RNA A-to-I editing activity. Transcriptome profiling shows that LNC-SNO49AB and ADAR1 knockdown respectively share very similar patterns of RNA modification change in downstream signaling pathways, especially in cell cycle pathways. These findings suggest a previously unknown class of snoRNA-related lncRNAs, which function via a manner in nucleolus independently on snoRNA-guide rRNA modification. This is the first report that a lncRNA regulates genome-wide RNA A-to-I editing by enhancing ADAR1 dimerization to facilitate hematopoietic malignancy, suggesting that LNC-SNO49AB may be a novel target in therapy directed to leukemia.

N6-methyladenosine methyltransferases: functions, regulation, and clinical potential.

N6-methyladenosine (m6A) has emerged as an abundant modification throughout the transcriptome with widespread functions in protein-coding and noncoding RNAs. It affects the fates of modified RNAs, including their stability, splicing, and/or translation, and thus plays important roles in posttranscriptional regulation. To date, m6A methyltransferases have been reported to execute m6A deposition on distinct RNAs by their own or forming different complexes with additional partner proteins. In this review, we summarize the function of these m6A methyltransferases or complexes in regulating the key genes and pathways of cancer biology. We also highlight the progress in the use of m6A methyltransferases in mediating therapy resistance, including chemotherapy, targeted therapy, immunotherapy and radiotherapy. Finally, we discuss the current approaches and clinical potential of m6A methyltransferase-targeting strategies.

Nuclear export of chimeric mRNAs depends on an lncRNA-triggered autoregulatory loop in blood malignancies.

Aberrant chromosomal translocations leading to tumorigenesis have been ascribed to the heterogeneously oncogenic functions. However, how fusion transcripts exporting remains to be declared. Here, we showed that the nuclear speckle-specific long noncoding RNA MALAT1 controls chimeric mRNA export processes and regulates myeloid progenitor cell differentiation in malignant hematopoiesis. We demonstrated that MALAT1 regulates chimeric mRNAs export in an m6A-dependent manner and thus controls hematopoietic cell differentiation. Specifically, reducing MALAT1 or m6A methyltransferases and the 'reader' YTHDC1 result in the universal retention of distinct oncogenic gene mRNAs in nucleus. Mechanically, MALAT1 hijacks both the chimeric mRNAs and fusion proteins in nuclear speckles during chromosomal translocations and mediates the colocalization of oncogenic fusion proteins with METTL14. MALAT1 and fusion protein complexes serve as a functional loading bridge for the interaction of chimeric mRNA and METTL14. This study demonstrated a universal mechanism of chimeric mRNA transport that involves lncRNA-fusion protein-m6A autoregulatory loop for controlling myeloid cell differentiation. Targeting the lncRNA-triggered autoregulatory loop to disrupt chimeric mRNA transport might represent a new common paradigm for treating blood malignancies.

Cis-acting lnc-eRNA SEELA directly binds histone H4 to promote histone recognition and leukemia progression.

BACKGROUND: Long noncoding enhancer RNAs (lnc-eRNAs) are a subset of stable eRNAs identified from annotated lncRNAs. They might act as enhancer activity-related therapeutic targets in cancer. However, the underlying mechanism of epigenetic activation and their function in cancer initiation and progression remain largely unknown. RESULTS: We identify a set of lncRNAs as lnc-eRNAs according to the epigenetic signatures of enhancers. We show that these lnc-eRNAs are broadly activated in MLL-rearranged leukemia (MLL leukemia), an aggressive leukemia caused by a chromosomal translocation, through a mechanism by which the HOXA cluster initiates enhancer activity, and the epigenetic reader BRD4 cooperates with the coregulator MLL fusion oncoprotein to induce transcriptional activation. To demonstrate the functional roles of lnc-eRNAs, two newly identified lnc-eRNAs transcribed from the SEELA eRNA cluster (SEELA), SEELA1 and SEELA2, are chosen for further studies. The results show that SEELA mediated cis-activated transcription of the nearby oncogene Serine incorporate 2 (SERINC2) by directly binding to the K31 amino acid (aa) of histone H4. Chromatin-bound SEELA strengthens the interaction between chromatin and histone modifiers to promote histone recognition and oncogene transcription. Further studies show that the SEELA-SERINC2 axis regulated aspects of cancer metabolism, such as sphingolipid synthesis, to affect leukemia progression. CONCLUSIONS: This study shows that lnc-eRNAs are epigenetically activated by cancer-initiating oncoproteins and uncovers a cis-activating mechanism of oncogene transcription control based on lnc-eRNA-mediated epigenetic regulation of enhancer activity, providing insights into the critical roles of lnc-eRNAs in cancer initiation and progression.

The lncRNA LAMP5-AS1 drives leukemia cell stemness by directly modulating DOT1L methyltransferase activity in MLL leukemia.

BACKGROUND: Mixed-lineage leukemia (MLL) gene rearrangements trigger aberrant epigenetic modification and gene expression in hematopoietic stem and progenitor cells, which generates one of the most aggressive subtypes of leukemia with an apex self-renewal. It remains a challenge to directly inhibit rearranged MLL itself because of its multiple fusion partners and the poorly annotated downstream genes of MLL fusion proteins; therefore, novel therapeutic targets are urgently needed. METHODS: qRT-PCR, receiver operating characteristic (ROC), and leukemia-free survival analysis were used to validate LAMP5-AS1 (LAMP5 antisense 1) expression and evaluate its clinical value. We performed in vitro and in vivo experiments to investigate the functional relevance of LAMP5-AS1 in MLL leukemia progression and leukemia cell stemness. RNA electrophoretic mobility shift assays (EMSA), histone methyltransferase assay, RNA pull-down assay, and RNA fluorescence in situ hybridization (FISH) were used to validate the relationship between LAMP5-AS1 and the methyltransferase activity of DOT1L. The downstream ectopic target genes of LAMP5-AS1/DOT1L were validated by the chromatin immunoprecipitation (ChIP) and western blot. RESULTS: We discovered that a long noncoding RNA (lncRNA) LAMP5-AS1 can promote higher degrees of H3K79 methylation, followed by upregulated expression of the self-renewal genes in the HOXA cluster, which are responsible for leukemia stemness in context of MLL rearrangements. We found that LAMP5-AS1 is specifically overexpressed in MLL leukemia patients (n = 58) than that in the MLL-wt leukemia (n = 163) (p < 0.001), and the patients with a higher expression level of LAMP5-AS1 exhibited a reduced 5-year leukemia-free survival (p < 0.01). LAMP5-AS1 suppression significantly reduced colony formation and increased differentiation of primary MLL leukemia CD34+ cells. Mechanistically, LAMP5-AS1 facilitated the methyltransferase activity of DOT1L by directly binding its Lys-rich region of catalytic domain, thus promoting the global patterns of H3K79 dimethylation and trimethylation in cells. These observations supported that LAMP5-AS1 upregulated H3K79me2/me3 and the transcription of DOT1L ectopic target genes. CONCLUSIONS: This is the first study that a lncRNA regulates the self-renewal program and differentiation block in MLL leukemia cells by facilitating the methyltransferase activity of DOT1L and global H3K79 methylation, showing its potential as a therapeutic target for MLL leukemia.

Noncoding RNAs in cancer therapy resistance and targeted drug development.

Noncoding RNAs (ncRNAs) represent a large segment of the human transcriptome and have been shown to play important roles in cellular physiology and disease pathogenesis. Increasing evidence on the functional roles of ncRNAs in cancer progression emphasizes the potential of ncRNAs for cancer treatment. Here, we summarize the roles of ncRNAs in disease relapse and resistance to current standard chemotherapy and radiotherapy; the current research progress on ncRNAs for clinical and/or potential translational applications, including the identification of ncRNAs as therapeutic targets; therapeutic approaches for ncRNA targeting; and ncRNA delivery strategies in potential clinical translation. Several ongoing clinical trials of novel RNA-based therapeutics were also emphasized. Finally, we discussed the perspectives and obstacles to different target combinations, delivery strategies, and system designs for ncRNA application. The next approved nucleic acid drug to treat cancer patients may realistically be on the horizon.

Early-generated interneurons regulate neuronal circuit formation during early postnatal development.

A small subset of interneurons that are generated earliest as pioneer neurons are the first cohort of neurons that enter the neocortex. However, it remains largely unclear whether these early-generated interneurons (EGIns) predominantly regulate neocortical circuit formation. Using inducible genetic fate mapping to selectively label EGIns and pseudo-random interneurons (pRIns), we found that EGIns exhibited more mature electrophysiological and morphological properties and higher synaptic connectivity than pRIns in the somatosensory cortex at early postnatal stages. In addition, when stimulating one cell, the proportion of EGIns that influence spontaneous network synchronization is significantly higher than that of pRIns. Importantly, toxin-mediated ablation of EGIns after birth significantly reduce spontaneous network synchronization and decrease inhibitory synaptic formation during the first postnatal week. These results suggest that EGIns can shape developing networks and may contribute to the refinement of neuronal connectivity before the establishment of the adult neuronal circuit.

circRNA circAF4 functions as an oncogene to regulate MLL-AF4 fusion protein expression and inhibit MLL leukemia progression.

BACKGROUND: Circular RNAs (circRNAs) represent a type of endogenous noncoding RNAs that are generated by back-splicing events and favor repetitive sequences. Recent studies have reported that cancer-associated chromosomal translocations could juxtapose distant complementary repetitive intronic sequences, resulting in the aberrant formation of circRNAs. However, among the reported fusion genes, only a small number of circRNAs were found to originate from fusion regions during gene translocation. We question if circRNAs could also originate from fusion partners during gene translocation. METHODS: Firstly, we designed divergent primers for qRT-PCR to identify a circRNA circAF4 in AF4 gene and investigated the expression pattern in different types of leukemia samples. Secondly, we designed two small interfering RNAs specially targeting the back-spliced junction point of circAF4 for functional studies. CCK8 cell proliferation and cell cycle assay were performed, and a NOD-SCID mouse model was used to investigate the contribution of circAF4 in leukemogenesis. Finally, luciferase reporter assay, AGO2 RNA immunoprecipitation (RIP), and RNA Fluorescent in Situ Hybridization (FISH) were performed to confirm the relationship of miR-128-3p, circAF4, and MLL-AF4 expression. RESULTS: We discovered a circRNA, named circAF4, originating from the AF4 gene, a partner of the MLL fusion gene in MLL-AF4 leukemia. We showed that circAF4 plays an oncogenic role in MLL-AF4 leukemia and promotes leukemogenesis in vitro and in vivo. More importantly, knockdown of circAF4 increases the leukemic cell apoptosis rate in MLL-AF4 leukemia cells, while no effect was observed in leukemia cells that do not carry the MLL-AF4 translocation. Mechanically, circAF4 can act as a miR-128-3p sponge, thereby releasing its inhibition on MLL-AF4 expression. We finally analyzed most of the MLL fusion genes loci and found that a number of circRNAs could originate from these partners, suggesting the potential roles of fusion gene partner-originating circRNAs (named as FP-circRNAs) in leukemia with chromosomal translocations. CONCLUSION: Our findings demonstrate that the abnormal elevated expression of circAF4 regulates the cell growth via the circAF4/miR-128-3p/MLL-AF4 axis, which could contribute to leukemogenesis, suggesting that circAF4 may be a novel therapeutic target of MLL-AF4 leukemia.