Deciphering RNA m6 A regulation in aging: Perspectives on current advances and future directions

Cellular senescence: from homeostasis to pathological implications and therapeutic strategies

Cellular aging is a multifactorial and intricately regulated physiological process with profound implications. The interaction between cellular senescence and cancer is complex and multifaceted, senescence can both promote and inhibit tumor progression through various mechanisms. M6A methylation modification regulates the aging process of cells and tissues by modulating senescence-related genes. In this review, we comprehensively discuss the characteristics of cellular senescence, the signaling pathways regulating senescence, the biomarkers of senescence, and the mechanisms of anti-senescence drugs. Notably, this review also delves into the complex interactions between senescence and cancer, emphasizing the dual role of the senescent microenvironment in tumor initiation, progression, and treatment. Finally, we thoroughly explore the function and mechanism of m6A methylation modification in cellular senescence, revealing its critical role in regulating gene expression and maintaining cellular homeostasis. In conclusion, this review provides a comprehensive perspective on the molecular mechanisms and biological significance of cellular senescence and offers new insights for the development of anti-senescence strategies.

Regulating translation in aging: from global to gene-specific mechanisms

Aging is characterized by a decline in various biological functions that is associated with changes in gene expression programs. Recent transcriptome-wide integrative studies in diverse organisms and tissues have revealed a gradual uncoupling between RNA and protein levels with aging, which highlights the importance of post-transcriptional regulatory processes. Here, we provide an overview of multi-omics analyses that show the progressive uncorrelation of transcriptomes and proteomes during the course of healthy aging. We then describe the molecular changes leading to global downregulation of protein synthesis with age and review recent work dissecting the mechanisms involved in gene-specific translational regulation in complementary model organisms. These mechanisms include the recognition of regulated mRNAs by trans-acting factors such as miRNA and RNA-binding proteins, the condensation of mRNAs into repressive cytoplasmic RNP granules, and the pausing of ribosomes at specific residues. Lastly, we mention future challenges of this emerging field, possible buffering functions as well as potential links with disease.

Characterization of N6-methyladenosine long non-coding RNAs in sporadic congenital cataract and age-related cataract

AIM

To characterize the N6-methyladenosine (m6A) modification patterns in long non-coding RNAs (lncRNAs) in sporadic congenital cataract (CC) and age-related cataract (ARC).

METHODS

Anterior capsule of the lens were collected from patients with CC and ARC. Methylated RNA immunoprecipitation with next-generation sequencing and RNA sequencing were performed to identify m6A-tagged lncRNAs and lncRNAs expression. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses and Gene Ontology annotation were used to predict potential functions of the m6A-lncRNAs.

RESULTS

Large amount of m6A peaks within lncRNA were identified for both CC and ARC, while the level was much higher in ARC (49 870 peaks) than that in CC (18 688 peaks), yet those difference between ARC in younger age group (ARC-1) and ARC in elder age group (ARC-2) was quite slight. A total of 1305 hypermethylated and 1178 hypomethylated lncRNAs, as well as 182 differential expressed lncRNAs were exhibited in ARC compared with CC. On the other hand, 5893 hypermethylated and 5213 hypomethylated lncRNAs, as well as 155 significantly altered lncRNA were identified in ARC-2 compared with ARC-1. Altered lncRNAs in ARC were mainly associated with the organization and biogenesis of intracellular organelles, as well as nucleotide excision repair.

CONCLUSION

Our results for the first time present an overview of the m6A methylomes of lncRNA in CC and ARC, providing a solid basis and uncovering a new insight to reveal the potential pathogenic mechanism of CC and ARC.

RNA modification in normal hematopoiesis and hematologic malignancies

N6-methyladenosine (m6A) is the most abundant RNA modification in eukaryotic cells. Previous studies have shown that m6A plays a critical role under both normal physiological and pathological conditions. Hematopoiesis and differentiation are highly regulated processes, and recent studies on m6A mRNA methylation have revealed how this modification controls cell fate in both normal and malignant hematopoietic states. However, despite these insights, a comprehensive understanding of its complex roles between normal hematopoietic development and malignant hematopoietic diseases remains elusive. This review first provides an overview of the components and biological functions of m6A modification regulators. Additionally, it highlights the origin, differentiation process, biological characteristics, and regulatory mechanisms of hematopoietic stem cells, as well as the features, immune properties, and self-renewal pathways of leukemia stem cells. Last, the article systematically reviews the latest research advancements on the roles and mechanisms of m6A regulatory factors in normal hematopoiesis and related malignant diseases. More importantly, this review explores how targeting m6A regulators and various signaling pathways could effectively intervene in the development of leukemia, providing new insights and potential therapeutic targets. Targeting m6A modification may hold promise for achieving more precise and effective leukemia treatments.

Inhibition of Mettl3 ameliorates osteoblastic senescence by mitigating m6A modifications on Slc1a5 via Igf2bp2-dependent mechanisms

Age-related osteoporosis is characterized by a marked decrease in the number of osteoblasts, which has been partly attributed to the senescence of cells of the osteoblastic lineage. Epigenetic studies have provided new insights into the mechanisms of current osteoporosis treatments and bone repair pathophysiology. N6-methyladenosine (m6A) is a novel transcript modification that plays a major role in cellular senescence and is essential for skeletal development and internal environmental stability. Bioinformatics analysis revealed that the expression of the m6A reading protein Igf2bp2 was significantly higher in osteoporosis patients. However, the role of Igf2bp2 in osteoblast senescence has not been elucidated. In this study, we found that Igf2bp2 levels are increased in ageing osteoblasts induced by multiple repetition and H2O2. Increasing Igf2bp2 expression promotes osteoblast senescence by increasing the stability of Slc1a5 mRNA and inhibiting cell cycle progression. Additionally, Mettl3 was identified as Slc1a5 m6A-methylated protein with increased m6A modification. The knockdown of Mettl3 in osteoblasts inhibits the reduction of senescence, whereas the overexpression of Mettl3 promotes the senescence of osteoblasts. We found that administering Cpd-564, a specific inhibitor of Mettl3, induced increased bone mass and decreased bone marrow fat accumulation in aged rats. Notably, in an OVX rat model, Igf2bp2 small interfering RNA delivery also induced an increase in bone mass and decreased fat accumulation in the bone marrow. In conclusion, our study demonstrated that the Mettl3/Igf2bp2-Slc1a5 axis plays a key role in the promotion of osteoblast senescence and age-related bone loss.

HIF-1α-induced expression of the m6A reader YTHDF1 inhibits the ferroptosis of nucleus pulposus cells by promoting SLC7A11 translation

The nucleus pulposus is in a hypoxic environment in the human body, and when intervertebral disc degeneration (IVDD) occurs, the hypoxic environment is disrupted. Nucleus pulposus cell (NPC) ferroptosis is one of the causes of IVDD. N6-methyladenosine (m6A) and its reader protein YTHDF1 regulate cellular activities by affecting RNA metabolism. However, the regulation of ferroptosis in NPCs by m6A-modified RNAs under hypoxic conditions has not been as well studied. In this study, through in vitro and in vivo experiments, we explored the underlying mechanism of HIF-1α and YTHDF1 in regulating ferroptosis in NPCs. The results indicated that the overexpression of HIF-1α or YTHDF1 suppressed NPC ferroptosis; conversely, the knockdown of HIF-1α or YTHDF1 increased ferroptosis levels in NPCs. Luciferase reporter assays and chromatin immunoprecipitation demonstrated that HIF-1α regulated YTHDF1 transcription by directly binding to its promoter region. Polysome profiling results showed that YTHDF1 promoted the translation of SLC7A11 and consequently the expression of the anti-ferroptosis protein GPX4 by binding to m6A-modified SLC7A11 mRNA. In conclusion, HIF-1α-induced YTHDF1 expression reduces NPC ferroptosis and delays IVDD by promoting SLC7A11 translation in a m6A-dependent manner.

Emerging epigenetic insights into aging mechanisms and interventions

Epigenetic dysregulation emerges as a critical hallmark and driving force of aging. Although still an evolving field with much to explore, it has rapidly gained significance by providing valuable insights into the mechanisms of aging and potential therapeutic opportunities for age-related diseases. Recent years have witnessed remarkable strides in our understanding of the epigenetic landscape of aging, encompassing pivotal elements, such as DNA methylation, histone modifications, RNA modifications, and noncoding (nc) RNAs. Here, we review the latest discoveries that shed light on new epigenetic mechanisms and critical targets for predicting and intervening in aging and related disorders. Furthermore, we explore burgeoning interventions and exemplary clinical trials explicitly designed to foster healthy aging, while contemplating the potential ramifications of epigenetic influences.