ALKBH1 promotes HIF-1α-mediated glycolysis by inhibiting N-glycosylation of LAMP2A.

ALKBH1 is a typical demethylase of nucleic acids, which is correlated with multiple types of biological processes and human diseases. Recent studies are focused on the demethylation of ALKBH1, but little is known about its non-demethylase function. Here, we demonstrate that ALKBH1 regulates the glycolysis process through HIF-1α signaling in a demethylase-independent manner. We observed that depletion of ALKBH1 inhibits glycolysis flux and extracellular acidification, which is attributable to reduced HIF-1α protein levels, and it can be rescued by reintroducing HIF-1α. Mechanistically, ALKBH1 knockdown enhances chaperone-mediated autophagy (CMA)-mediated HIF-1α degradation by facilitating the interaction between HIF-1α and LAMP2A. Furthermore, we identify that ALKBH1 competitively binds to the OST48, resulting in compromised structural integrity of oligosaccharyltransferase (OST) complex and subsequent defective N-glycosylation of LAMPs, particularly LAMP2A. Abnormal glycosylation of LAMP2A disrupts lysosomal homeostasis and hinders the efficient degradation of HIF-1α through CMA. Moreover, NGI-1, a small-molecule inhibitor that selectively targets the OST complex, could inhibit the glycosylation of LAMPs caused by ALKBH1 silencing, leading to impaired CMA activity and disruption of lysosomal homeostasis. In conclusion, we have revealed a non-demethylation role of ALKBH1 in regulating N-glycosylation of LAMPs by interacting with OST subunits and CMA-mediated degradation of HIF-1α.

Research progress of N1-methyladenosine RNA modification in cancer.

N1-methyladenosine (m1A) is a post-transcriptionally modified RNA molecule that plays a pivotal role in the regulation of various biological functions and activities. Especially in cancer cell invasion, proliferation and cell cycle regulation. Over recent years, there has been a burgeoning interest in investigating the m1A modification of RNA. Most studies have focused on the regulation of m1A in cancer enrichment areas and different regions. This review provides a comprehensive overview of the methodologies employed for the detection of m1A modification. Furthermore, this review delves into the key players in m1A modification, known as the "writers," "erasers," and "readers." m1A modification is modified by the m1A methyltransferases, or writers, such as TRMT6, TRMT61A, TRMT61B, TRMT10C, NML, and, removed by the demethylases, or erasers, including FTO and ALKBH1, ALKBH3. It is recognized by m1A-binding proteins YTHDF1, TYHDF2, TYHDF3, and TYHDC1, also known as "readers". Additionally, we explore the intricate relationship between m1A modification and its regulators and their implications for the development and progression of specific types of cancer, we discuss how m1A modification can potentially facilitate the discovery of novel approaches for cancer diagnosis, treatment, and prognosis. Our summary of m1A methylated adenosine modification detection methods and regulatory mechanisms in various cancers provides useful insights for cancer diagnosis, treatment, and prognosis. Video Abstract.

ALYREF (Aly/REF export factor): A potential biomarker for predicting cancer occurrence and therapeutic efficacy.

5-Methylcytosine (m5C) methylation is present in almost all types of RNA as an essential epigenetic modification. It is dynamically modulated by its associated enzymes, including m5C methyltransferases (NSUN, DNMT and TRDMT family members), demethylases (TET family and ALKBH1) and binding proteins (YTHDF2, ALYREF and YBX1). Among them, aberrant expression of the RNA-binding protein ALYREF can facilitate a variety of malignant phenotypes such as maintenance of proliferation, malignant heterogeneity, metastasis, and drug resistance to cell death through different regulatory mechanisms, including pre-mRNA processing, mRNA stability, and nuclear-cytoplasmic shuttling. The induction of these cellular processes by ALYREF results in treatment resistance and poor outcomes for patients. However, there are currently few reports of clinical applications or drug trials related to ALYREF. In addition, the looming observations on the role of ALYREF in the mechanisms of carcinogenesis and disease prognosis have triggered considerable interest, but critical evidence is not available. For example, animal experiments and ALYREF small molecule inhibitor trials. In this review, we, therefore, revisit the literature on ALYREF and highlight its importance as a prognostic biomarker for early prevention and as a therapeutic target.

A DNA adenine demethylase impairs PRC2-mediated repression of genes marked by a specific chromatin signature.

BACKGROUND: The Fe (II)- and α-ketoglutarate-dependent AlkB family dioxygenases are implicated in nucleotide demethylation. AlkB homolog1 (ALKBH1) is shown to demethylate DNA adenine methylation (6mA) preferentially from single-stranded or unpaired DNA, while its demethylase activity and function in the chromatin context are unclear. RESULTS: Here, we find that loss-of-function of the rice ALKBH1 gene leads to increased 6mA in the R-loop regions of the genome but has a limited effect on the overall 6mA level. However, in the context of mixed tissues, rather than on individual loci, the ALKBH1 mutation or overexpression mainly affects the expression of genes with a specific combination of chromatin modifications in the body region marked with H3K4me3 and H3K27me3 but depleted of DNA CG methylation. In the similar context of mixed tissues, further analysis reveals that the ALKBH1 protein preferentially binds to genes marked by the chromatin signature and has a function to maintain a high H3K4me3/H3K27me3 ratio by impairing the binding of Polycomb repressive complex 2 (PRC2) to the targets, which is required for both the basal and stress-induced expression of the genes. CONCLUSION: Our findings unravel a function of ALKBH1 to control the balance between the antagonistic histone methylations for gene activity and provide insight into the regulatory mechanism of PRC2-mediated H3K27me3 deposition within the gene body region.

The N6-methyladenine DNA demethylase ALKBH1 promotes gastric carcinogenesis by disrupting NRF1 binding capacity.

DNA N6-methyladenine (6mA) is an epigenetic modification that regulates various biological processes. Here, we show that gastric cancer (GC) cells and tumors display a marked reduction in 6mA levels compared with normal gastric tissues and cells. 6mA is abundant in the surrounding transcription start sites and occurs at consensus motifs. Among the 6mA regulators, ALKBH1, a demethylase, is significantly overexpressed in GC tissues compared with adjacent normal tissues. Moreover, high ALKBH1 expression is associated with poor survival of patients with GC. ALKBH1 knockout in mice impairs chemically induced gastric carcinogenesis. Mechanistically, ALKBH1 mediates DNA 6mA demethylation to repress gene expression. In particular, the 6mA sites are enriched in NRF1 binding sequences and targeted for demethylation by ALKBH1. ALKBH1-induced 6mA demethylation inhibits NRF1-driven transcription of downstream targets, including multiple genes involved in the AMP-activated protein kinase (AMPK) signaling pathway. Accordingly, ALKBH1 suppresses AMPK signaling, causing a metabolic shift toward the Warburg effect, which facilitates tumorigenesis.

U-shaped association between serum IGF2BP3 and T2DM: A cross-sectional study in Chinese population.

OBJECTIVE: To clarify the expression of N6-methyladenosine (m6 A) modulators involved in the pathogenesis of type 2 diabetes mellitus (T2DM). We further explored the association of serum insulin-like growth factor 2 mRNA-binding proteins 3 (IGF2BP3) levels and odds of T2DM in a high-risk population. METHODS: The gene expression data set GSE25724 was obtained from the Gene Expression Omnibus, and a cluster heatmap was generated by using the R package ComplexHeatmap. Differential expression analysis for 13 m6 A RNA methylation regulators between nondiabetic controls and T2DM subjects was performed using an unpaired t test. A cross-sectional design, including 393 subjects (131 patients with newly diagnosed T2DM, 131 age- and sex-matched subjects with prediabetes, and 131 healthy controls), was carried out. The associations between serum IGF2BP3 concentrations and T2DM were modeled by restricted cubic spline and logistic regression models. RESULTS: Two upregulated (IGF2BP2 and IGF2BP3) and 5 downregulated (methyltransferase-like 3 [METTL3], alkylation repair homolog protein 1 [ALKBH1], YTH domain family 2 [YTHDF2], YTHDF3, and heterogeneous nuclear ribonucleoprotein [HNRNPC]) m6 A-related genes were found in islet samples of T2DM patients. A U-shaped association existed between serum IGF2BP3 levels and odds of T2DM according to cubic natural spline analysis models, after adjustment for body mass index, waist circumference, diastolic blood pressure, total cholesterol, and triglyeride. Multivariate logistic regression showed that progressively higher odds of T2DM were observed when serum IGF2BP3 levels were below 0.62 ng/mL (odds ratio 3.03 [95% confidence interval 1.23-7.47]) in model 4. CONCLUSION: Seven significantly altered m6 A RNA methylation genes were identified in T2DM. There was a U-shaped association between serum IGF2BP3 levels and odds of T2DM in the general Chinese adult population. This study provides important evidence for further examination of the role of m6 A RNA methylation, especially serum IGF2BP3 in T2DM risk assessment.

ALKBH1 contributes to renal cell carcinoma progression by reducing N6-methyladenine of GPR137.

BACKGROUND: Renal cell carcinoma (RCC) accounts for approximately 4% of all adult malignancies with high mortality worldwide. Although conventional chemotherapy and radiotherapy treatment has been applied for RCC in clinic, the mortality rate of patients is increasing each year, and patients with metastatic RCC are still suffering from poor prognosis. Thus, further investigation of the molecular mechanisms responsible for the development and progression of RCC is of particular importance. METHODS: Total of 10 pairs of RCC tissues and adjacent nontumor tissues were collected for examination of ALKBH1 and GPR137 expression. The correlations between ALKBH1 and GPR137 expression in RCC patient were assessed by GEPIA online tool and were analyzed using auto best cutoff. The human RCC cell lines Caki-1, 786-O, ACHN, Osrc2, A498, and 769-P, were used for mechanistic investigation. RESULTS: Here, we report that the expression of AlkB homologue 1 (ALKBH1) is upregulated in RCC tissues, which is correlated with G-protein-coupled receptor 137 (GPR137) expression. The elevated expression of ALKBH1 is associated with RCC cell malignant characteristics, including cell proliferation and movement (migration and invasion). Mechanistic investigation further reveals that ALKBH1 reduces m6 A levels of GPR137 mRNA in RCC cells, which upregulates GPR137 mRNA levels, resulting in the increased GPR137 protein expression subsequently and the enhanced RCC cell biological actions consequently. In contrast, the suppression of GPR137 effectively alleviates the ALKBH1-induced malignancies of RCC cells. CONCLUSION: Our results indicate that ALKBH1-GPR137 axis might be used as a potential therapeutic target in RCC, contributing to finding new prognostic biomarkers for RCC at an early stage.

ALKBH1-mediated m1 A demethylation of METTL3 mRNA promotes the metastasis of colorectal cancer by downregulating SMAD7 expression.

Colorectal cancer (CRC) is one of the most common malignancies, and the main cause of death from CRC is tumor metastasis. m1 A RNA modification plays critical role in many biological processes. However, the role of m1 A modification in CRC remains unclear. Here, we find that the m1 A demethylase alkB homolog 1, histone H2A dioxygenase (ALKBH1) is overexpressed in CRC and is associated with metastasis and poor prognosis. Upregulation of ALKBH1 expression promotes CRC metastasis in vitro and in vivo. Mechanistically, knockdown of ALKBH1 results in a decrease in methyltransferase 3, N6-adenosine-methyltransferase complex catalytic subunit (METTL3) expression, probably due to m1 A modification of METTL3 mRNA, followed by m6 A demethylation of SMAD family member 7 (SMAD7) mRNA. In addition, downregulation of SMAD7 establishes an aggressive phenotype. More importantly, the cell migration and invasion defects caused by ALKBH1 depletion or METTL3 depletion are significantly reversed by SMAD7 silencing. Considering these results collectively, we propose that ALKBH1 promotes CRC metastasis by destabilizing SMAD7 through METTL3.

Tyrosyl-DNA phosphodiesterase 1 excises the 3'-DNA-ALKBH1 cross-link and its application for 3'-DNA-ALKBH1 cross-link characterization by LC-MS/MS.

The apurinic/apyrimidinic (abasic, AP) site is one of the most abundant DNA lesions. Previous studies by others demonstrated that human AlkB homologue 1 (ALKBH1) catalyzes the DNA strand incision at an AP site, resulting in suicidal cross-linking of the enzyme to the 3'-DNA end. Prior site-directed mutagenesis experiments had reported that Cys129 of ALKBH1 is the predominant nucleophile that conjugates to the C3' position of the incised AP site, 3'-phospho-α,ß-unsaturated aldehyde (3'-PUA), to form a 3'-PUA-ALKBH1 cross-link. However, direct evidence to support this mechanism was lacking. The 3'-PUA-ALKBH1 cross-link is so far the only adduct that has been found to form via a Michael addition reaction between a protein and 3'-PUA. It is unclear whether and how this type of cross-link is repaired. In this study, we first demonstrated that the 3'-PUA-ALKBH1 cross-link is fairly stable under physiological temperature and pH as only ~10% of the adduct decomposed after a 3-day incubation. Using a gel-based assay with an aldehyde-reacting probe, we demonstrated that the 3'-PUA-ALKBH1 cross-link has a free aldehyde group that is in line with the Michael addition mechanism. Moreover, we found that the 3'-PUA-ALKBH1 cross-link can be excised by human tyrosyl-DNA phosphodiesterase 1 (TDP1) and the removal efficiency is significantly enhanced if the adduct is pre-digested by trypsin. Notably, we employed TDP1 as a molecular tool to homogeneously release the cross-linked peptides from DNA to facilitate liquid chromatography tandem mass spectrometry analysis, and demonstrated that Cys129 and Cys371 of ALKBH1 cross-link to 3'-PUA.

The enhanced genomic 6 mA metabolism contributes to the proliferation and migration of TSCC cells.

In contrast to the well-established genomic 5-methylcytosine (5mC), the existence of N6-methyladenine (6 mA) in eukaryotic genomes was discovered only recently. Initial studies found that it was actively regulated in cancer cells, suggesting its involvement in the process of carcinogenesis. However, the contribution of 6 mA in tongue squamous cell carcinoma (TSCC) still remains uncharacterized. In this study, a pan-cancer type analysis was first performed, which revealed enhanced 6 mA metabolism in diverse cancer types. The study was then focused on the regulation of 6 mA metabolism, as well as its effects on TSCC cells. To these aspects, genome 6 mA level was found greatly increased in TSCC tissues and cultured cells. By knocking down 6 mA methylases N6AMT1 and METTL4, the level of genomic 6 mA was decreased in TSCC cells. This led to suppressed colony formation and cell migration. By contrast, knockdown of 6 mA demethylase ALKBH1 resulted in an increased 6 mA level, enhanced colony formation, and cell migration. Further study suggested that regulation of the NF-κB pathway might contribute to the enhanced migration of TSCC cells. Therefore, in the case of TSCC, we have shown that genomic 6 mA modification is involved in the proliferation and migration of cancer cells.

Characterization of the prognostic and diagnostic values of ALKBH family members in non-small cell lung cancer.

BACKGROUND: AlkB homolog (ALKBH) family genes have been known to play a crucial role in the development of several types of cancers. Nevertheless, the prognostic and diagnostic values of ALKBH family members have not been systematically investigated in non-small cell lung cancer (NSCLC). METHODS: The mRNA expression, genomic mutations, and biological functions of ALKBH family genes in NSCLC were evaluated using ONCOMINE, UALCAN, Kaplan-Meier Plotter, cBioPortal, Metascape, and SurvivalMeth. ALKBH2 expression and associated clinicopathological features were analyzed in LUAD tissues using immunohistochemistry (IHC). RESULTS: The mRNA levels of ALKBH1/2/4/6 were significantly upregulated in NSCLC patients, while those of ALKBH7 and FTO were downregulated. Also, a higher expression of ALKBH2/4/6 correlated with poor overall survival (OS), first-progression survival (FPS), and post-progression survival (PPS). ALKBH3/8 and FTO were upregulated and related to better OS, FPS, and PPS. ALKBH2/4/6 and FTO showed a higher diagnostic value in differentiating NSCLC patients from healthy individuals. Furthermore, the ALKBH family mutation rate was as high as 57% in lung adenocarcinoma (LUAD) patients and mutations in ALKBHs were related to poor OS. ALKBH family genes were also involved in universal DNA methylation in NSCLC. Finally, it was confirmed using tissues microarray that ALKBH2 shows a high expression and has a great diagnosis value in LUAD. CONCLUSIONS: Firstly, our results provided prognostic and diagnostic values of ALKBH family genes in NSCLC at both the DNA and RNA levels. Secondly, ALKBH2 is a potential novel diagnostic biomarker for LUAD.

Alkbh1-mediated DNA N6-methyladenine modification regulates bone marrow mesenchymal stem cell fate during skeletal aging.

OBJECTIVES: DNA N6-methyladenine (N6-mA) demethylase Alkbh1 participates in regulating osteogenic differentiation of mesenchymal stem cell (MSCs) and vascular calcification. However, the role of Alkbh1 in bone metabolism remains unclear. MATERIALS AND METHODS: Bone marrow mesenchymal stem cells (BMSCs)-specific Alkbh1 knockout mice were used to investigate the role of Alkbh1 in bone metabolism. Western blot, qRT-PCR, and immunofluorescent staining were used to evaluate the expression of Alkbh1 or optineurin (optn). Micro-CT, histomorphometric analysis, and calcein double-labeling assay were used to evaluate bone phenotypes. Cell staining and qRT-PCR were used to evaluate the osteogenic or adipogenic differentiation of BMSCs. Dot blotting was used to detect the level of N6-mA in genomic DNA. Chromatin immunoprecipitation (Chip) assays were used to identify critical targets of Alkbh1. Alkbh1 adeno-associated virus was used to overexpress Alkbh1 in aged mice. RESULTS: Alkbh1 expression in BMSCs declined during aging. Knockout of Alkbh1 promoted adipogenic differentiation of BMSCs while inhibited osteogenic differentiation. BMSC-specific Alkbh1 knockout mice exhibited reduced bone mass and increased marrow adiposity. Mechanistically, we identified optn as the downstream target through which Alkbh1-mediated DNA m6A modification regulated BMSCs fate. Overexpression of Alkbh1 attenuated bone loss and marrow fat accumulation in aged mice. CONCLUSIONS: Our findings demonstrated that Alkbh1 regulated BMSCs fate and bone-fat balance during skeletal aging and provided a potential target for the treatment of osteoporosis.

Single-Base Resolution Mapping Reveals Distinct 5-Formylcytidine in Saccharomyces cerevisiae mRNAs.

5-Formylcytidine (f5C) is one type of post-transcriptional RNA modification, which is known at the wobble position of tRNA in mitochondria and essential for mitochondrial protein synthesis. Here, we show a method to detect f5C modifications in RNA and a transcriptome-wide f5C mapping technique, named f5C-seq. It is developed based on the treatment of pyridine borane, which can reduce f5C to 5,6-dihydrouracil, thus inducing C-to-T transition in f5C sites during PCR to achieve single-base resolution detection. More than 1000 f5C sites were identified after mapping in Saccharomyces cerevisiae by f5C-seq. Moreover, codon composition demonstrated a preference for f5C within wobble sites in mRNA, suggesting the potential role in regulation of translation. These findings expand the scope of the understanding of cytosine modifications in mRNA.

Human HAND1 inhibits the conversion of cholesterol to steroids in trophoblasts.

Steroidogenesis from cholesterol in placental trophoblasts is fundamentally involved in the establishment and maintenance of pregnancy. The transcription factor gene heart and neural crest derivatives expressed 1 (Hand1) promotes differentiation of mouse trophoblast giant cells. However, the role of HAND1 in human trophoblasts remains unknown. Here, we report that HAND1 inhibits human trophoblastic progesterone (P4) and estradiol (E2) from cholesterol through downregulation of the expression of steroidogenic enzymes, including aromatase, P450 cholesterol side-chain cleavage enzyme (P450scc), and 3ß-hydroxysteroid dehydrogenase type 1 (3ß-HSD1). Mechanically, although HAND1 inhibits transcription of aromatase by directly binding to aromatase gene promoter, it restrains transcription of P450scc by upregulation of the methylation status of P450scc gene promoter through its binding to ALKBH1, a demethylase. Unlike aromatase and P450scc, HAND1 decreases 3ß-HSD1 mRNA levels by the reduction of its RNA stability through binding to and subsequent destabilizing protein HuR. Finally, HAND1 suppresses circulating P4 and E2 levels derived from JEG-3 xenograft and attenuates uterine response to P4 and E2. Thus, our results uncover a hitherto uncharacterized role of HAND1 in the regulation of cholesterol metabolism in human trophoblasts, which may help pinpoint the underlying mechanisms involved in supporting the development and physiological function of the human placenta.

DNA demethylase ALKBH1 promotes adipogenic differentiation via regulation of HIF-1 signaling.

DNA N6-adenine methylation (6mA), as a novel adenine modification existing in eukaryotes, shows essential functions in embryogenesis and mitochondrial transcriptions. ALKBH1 is a demethylase of 6mA and plays critical roles in osteogenesis, tumorigenesis, and adaptation to stress. However, the integrated biological functions of ALKBH1 still require further exploration. Here, we demonstrate that knockdown of ALKBH1 inhibits adipogenic differentiation in both human mesenchymal stem cells (hMSCs) and 3T3-L1 preadipocytes, while overexpression of ALKBH1 leads to increased adipogenesis. Using a combination of RNA-seq and N6-mA-DNA-IP-seq analyses, we identify hypoxia-inducible factor-1 (HIF-1) signaling as a crucial downstream target of ALKBH1 activity. Depletion of ALKBH1 leads to hypermethylation of both HIF-1α and its downstream target GYS1. Simultaneous overexpression of HIF-1α and GYS1 restores the adipogenic commitment of ALKBH1-deficient cells. Taken together, our data indicate that ALKBH1 is indispensable for adipogenic differentiation, revealing a novel epigenetic mechanism that regulates adipogenesis.

The enhanced genomic 6 mA metabolism contributes to the proliferation and migration of TSCC cells / 国际口腔科学杂志·英文版

In contrast to the well-established genomic 5-methylcytosine (5mC), the existence of N6-methyladenine (6 mA) in eukaryotic genomes was discovered only recently. Initial studies found that it was actively regulated in cancer cells, suggesting its involvement in the process of carcinogenesis. However, the contribution of 6 mA in tongue squamous cell carcinoma (TSCC) still remains uncharacterized. In this study, a pan-cancer type analysis was first performed, which revealed enhanced 6 mA metabolism in diverse cancer types. The study was then focused on the regulation of 6 mA metabolism, as well as its effects on TSCC cells. To these aspects, genome 6 mA level was found greatly increased in TSCC tissues and cultured cells. By knocking down 6 mA methylases N6AMT1 and METTL4, the level of genomic 6 mA was decreased in TSCC cells. This led to suppressed colony formation and cell migration. By contrast, knockdown of 6 mA demethylase ALKBH1 resulted in an increased 6 mA level, enhanced colony formation, and cell migration. Further study suggested that regulation of the NF-κB pathway might contribute to the enhanced migration of TSCC cells. Therefore, in the case of TSCC, we have shown that genomic 6 mA modification is involved in the proliferation and migration of cancer cells.

ALKBH1-demethylated DNA N6-methyladenine modification triggers vascular calcification via osteogenic reprogramming in chronic kidney disease.

Vascular calcification (VC) predicts cardiovascular morbidity and mortality in chronic kidney disease (CKD). To date, the underlying mechanisms remain unclear. We detected leukocyte DNA N6-methyladenine (6mA) levels in patients with CKD with or without aortic arch calcification. We used arteries from CKD mice infected with vascular smooth muscle cell-targeted (VSMC-targeted) adeno-associated virus encoding alkB homolog 1 (Alkbh1) gene or Alkbh1 shRNA to evaluate features of calcification. We identified that leukocyte 6mA levels were significantly reduced as the severity of VC increased in patients with CKD. Decreased 6mA demethylation resulted from the upregulation of ALKBH1. Here, ALKBH1 overexpression aggravated whereas its depletion blunted VC progression and osteogenic reprogramming in vivo and in vitro. Mechanistically, ALKBH1-demethylated DNA 6mA modification could facilitate the binding of octamer-binding transcription factor 4 (Oct4) to bone morphogenetic protein 2 (BMP2) promoter and activate BMP2 transcription. This resulted in osteogenic reprogramming of VSMCs and subsequent VC progression. Either BMP2 or Oct4 depletion alleviated the procalcifying effects of ALKBH1. This suggests that targeting ALKBH1 might be a therapeutic method to reduce the burden of VC in CKD.

Telencephalon-specific Alkbh1 conditional knockout mice display hippocampal atrophy and impaired learning.

AlkB homolog 1 (ALKBH1) is responsible for the biogenesis of 5-formylcytidine (f5 C) on mitochondrial tRNAMet and essential for mitochondrial protein synthesis. The brain, especially the hippocampus, is highly susceptible to mitochondrial dysfunction; hence, the maintenance of mitochondrial activity is strongly required to prevent disorders associated with hippocampal malfunction. To study the role of ALKBH1 in the hippocampus, we generated dorsal telencephalon-specific Alkbh1 conditional knockout (cKO) mice in inbred C57BL/6 background. These mice showed reduced activity of the respiratory chain complex, hippocampal atrophy, and CA1 pyramidal neuron abnormalities. Furthermore, performances in the fear-conditioning and Morris water maze tests in cKO mice indicated that the hippocampal abnormalities led to impaired hippocampus-dependent learning. These findings indicate critical roles of ALKBH1 in the hippocampus.

Genetic characteristics and prognostic implications of m1A regulators in pancreatic cancer.

Studies have identified the methylation of N1 adenosine (m1A), an RNA modification, playing an important role in the progression of the tumorigenesis. The present study aimed to analyze the genetic characteristics and prognostic value of m1A regulators in pancreatic cancer. In the present study, data on gene mutations, single-nucleotide variants (SNVs), and copy number variation (CNV) were obtained from 363 patients with pancreatic cancer in the Cancer Genome Atlas (TCGA) database, and survival analysis was performed using the logarithmic rank test and Cox regression model. The chi-squared test was used to examine the relationship between the changes in m1A regulatory factors and clinicopathological characteristics. And we used ICGC database to verify the reliability of prognostic markers. The results show that changes in m1A-regulating genes are related to clinical stage and that the expression of some m1A-regulating genes is positively correlated with CNV. In addition, the low expression of the 'eraser' gene ALKBH1 is related to the poor prognosis of patients with pancreatic cancer, and its expression level has important clinical significance for patients with pancreatic adenocarcinoma (PAAD). Mechanistically, ALKBH1 may participate in the occurrence and development of pancreatic cancer through mTOR and ErbB signaling pathway. The expression of m1A-regulating genes can be used as a prognostic marker for pancreatic cancer. These findings provide valuable clues for us to understand the epigenetics of m1A in pancreatic cancer.

N6-methyladenine demethylase ALKBH1 inhibits the differentiation of skeletal muscle.

DNA N6-methyladenine (N6-mA) was recently recognized as a new epigenetic modification in mammalian genome, and ALKBH1 was discovered as its demethylase. Knock-out mice studies revealed that ALKBH1 was indispensable for normal embryonic development. However, the function of ALKBH1 in myogenesis is largely unknown. In this study, we found that N6-mA showed a steady increase, going along with a strong decrease of ALKBH1 during skeletal muscle development. Our results also showed that ALKBH1 enhanced proliferation and inhibited differentiation of C2C12 cells. Genome-wide transcriptome analysis and reporter assays further revealed that ALKBH1 accomplished the differentiation inhibiting function by regulating a core set of genes and multiple signaling pathways, including increasing chemokine (C-X-C motif) ligand 14 (CXCL14) and activating ERK signaling. Taken together, our results demonstrated that ALKBH1 is critical for the myogenic differentiation of C2C12 cells, and suggested that N6-mA might be a new epigenetic mechanism for the regulation of myogenesis.