Project description:N6-methyladenosine (m6A) is the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes. Here we report ALKBH5 as a new mammalian demethylase that oxidatively removes the m6A modification in mRNA in vitro and inside cells. This demethylation activity of ALKBH5 significantly affects mRNA export and RNA metabolism as well as the assembly of mRNA processing factors in nuclear speckles. Alkbh5-deficient male mice are characterized by impaired fertility resulting from apoptosis that affects meiotic metaphase-stage spermatocytes. In accordance with this defect, we have identified in mouse testes 1552 differentially expressed genes which cover broad functional categories and include spermatogenesis-related mRNAs involved in the p53 functional interaction network. We show that Alkbh5-deficiency impacts the expression levels of some of these mRNAs, supporting the observed phenotype. The discovery of this new RNA demethylase strongly suggests that the reversible m6A modification plays fundamental and broad functions in mammalian cells. RNA-seq in two cell types
Project description:To investigate the function of ALKBH5 in the regulation of maternal RNA decay during mice oocyte meiosis, we established Alkbh5 knockout mice and analyzed the m6A level changes between control and Alkbh5 knockout oocyte at GV stage
Project description:Objectives: To investigate the role of ALKBH5 in fibroblasts during post-myocardial infarction (MI) repair. Background: N6-methyladenosine (m6A) mRNA modification has been shown to play an important role in cardiovascular diseases. The RNA demethylase, AlkB homolog 5 (ALKBH5), is an m6A "eraser" that is responsible for decreased m6A methylation. However, its role in cardiac fibroblasts during the post-MI healing process remains elusive. Methods: MI was mimicked by permanent left anterior descending artery ligation in global ALKBH5-knockout, ALKBH5-knockin, and fibroblast-specific ALKBH5-knockout mice to study the function of ALKBH5 during post-MI collagen repair. Methylated RNA immunoprecipitation sequencing was performed to explore potential ALKBH5 targets. Results: Dramatic alterations in ALKBH5 expression were observed during the early stage post-MI and in hypoxic fibroblasts. Global ALKBH5 knockin reduced infarct size and improved cardiac function after MI. The global and fibroblast-specific ALKBH5-knockout mice both exhibited low survival rates along with poor collagen repair, impaired cardiac function, and cardiac rupture. Both in vivo and in vitro ALKBH5 loss led to impaired fibroblast activation and decreased collagen deposition. Additionally, hypoxia, but not TGF-β1 or Ang II, upregulated ALKBH5 expression in myofibroblasts in a HIF-1α-dependent transcriptional manner. Mechanistically, ALKBH5 promoted the stability of ErbB4 mRNA and the degradation of ST14 mRNA via m6A demethylation. Fibroblast-specific ErbB4 overexpression ameliorated the impaired fibroblast-to-myofibroblast transformation and poor post-MI repair due to ALKBH5 knockout. Conclusions: Fibroblast ALKBH5 positively regulates post-MI healing via post-transcriptional modification and stabilization of ErbB4 mRNA in an m6A-dependent manner. Targeting ALKBH5/ERBB4 may be a potential therapeutic option for post-MI cardiac rupture.
Project description:To investigate the function of ALKBH5 in the regulation of maternal RNA decay during mice oocyte meiosis, we established Alkbh5 knockout mice and analyzed the transcriptome changes between control and Alkbh5 knockout oocyte at different meiotic maturation stages
Project description:Neutrophils are key immune components in rheumatoid arthritis (RA), but the role of ALKBH5 in neutrophil function and RA progression remains unclear. METTL3, METTL14, WTAP, ALKBH5, FTO, YTHDF2, autophagy related gene were investigated by RT-qPCR. Autophagy, LC3B were respectively detected by flow cytometry analysis, Western blotting. Correlation analyses between ALKBH5 levels and RA disease activity, autophagy were performed, and receiver operating characteristic (ROC) curves were constructed to evaluate its predictive value. Univariate analysis and multivariate regression analysis were used to analyze the risk factors and construct predictive model. Sh-ALKBH5 lentiviral vectors was constructed and used to infect HL-60 cell line. The role of ALKBH5 in autophagy regulation was explored using RNA immunoprecipitation with next generation sequencing (RIP-Seq), m6A RNA Methylation Analysis, m6A immunocoprecipitation-quantitative polymerase chain reaction (MeRIP-qPCR) and Actinomycin D treatment. Results showed significantly reduced ALKBH5 levels in RA neutrophils compared to healthy controls (HC) and ankylosing spondylitis (AS) patients, correlating with RA disease activity. A novel predictive model incorporating ALKBH5, hemoglobin (HGB), and lymphocyte percentage (L%) exhibited enhanced efficacy in distinguishing RA patients from HC (AUC = 0.937) and AS patients (AUC = 0.943), and could reflect RA severity and activity. Additionally, autophagy levels in neutrophils were highest in RA synovial fluid, followed by RA peripheral blood, and lowest in HC peripheral blood, with ALKBH5 expression showing the opposite trend. Moreover, ALKBH5 negatively correlated with neutrophil autophagy and the silencing of ALKBH5 in HL-60 enhanced the autophagy. Silencing ALKBH5 increased m6A level of ATG7 mRNA and ATG7 mRNA stability. Mechanistically, ALKBH5 inhibited neutrophil autophagy through mediating m6A modification of the ATG7 mRNA. In conclusion, these findings demonstrate that ALKBH5 regulates neutrophil autophagy in RA, and the ALKBH5-HGB-L% model holds potential as a diagnostic and disease activity indicator for RA.
Project description:To investigate the function of ALKBH5 in the regulation of keratinocyte cellular function, we established HaCAT cell lines in which ALKBH5 has been knocked down by siRNA. We then performed gene expression profiling analysis using data obtained from RNA-seq of 4 different cells from duplicate experiments.