METTL3-deficiency Suppresses Neural Apoptosis to Induce Protective Effects in Cerebral I/R Injury via Inhibiting RNA m6A Modifications: A Pre-clinical and Pilot Study

Role of m6A RNA Methylation in Ischemic Stroke

Ischemic stroke is a prominent contributor to global morbidity and mortality rates. The intricate and diverse mechanisms underlying ischemia-reperfusion injury remain poorly comprehended. RNA methylation, an emerging epigenetic modification, plays a crucial role in regulating numerous biological processes, including immunity, DNA damage response, tumorigenesis, metastasis, stem cell renewal, adipocyte differentiation, circadian rhythms, cellular development and differentiation, and cell division. Among the various RNA modifications, N6-methyladenosine (m6A) modification stands as the most prevalent in mammalian mRNA. Recent studies have demonstrated the crucial involvement of m6A modification in the pathophysiological progression of ischemic stroke. This review aims to elucidate the advancements in ischemic stroke-specific investigations pertaining to m6A modification, consolidate the underlying mechanisms implicated in the participation of m6A modification during the onset of ischemic stroke, and deliberate on the potential of m6A modification as a viable therapeutic target for ischemic stroke.

N6-methyladenosine demethylase ALKBH5 homologous protein protects against cerebral I/R injury though suppressing SNHG3-mediated neural PANoptosis: Involvement of m6A-related macromolecules in the diseases of nervous system

In order to address this gap in knowledge, the present study utilized both in vivo and in vitro models to investigate the role of the m6A demethylase ALKBH5 in protecting against cerebral I/R injury by inhibiting PANoptosis (Pytoptosis, Ppoptosis, and Necroptosis) in an m6A-dependent manner. They observed that ALKBH5, the predominant m6A demethylase, was downregulated in these models, while SNHG3 and PANoptosis-related proteins (ZBP1, AIM2, Cappase-3, Caspase-8, cleaved Caspase-1, GSDMD-N, and p-MLKL) were elevated. Additionally, both ALKBH5 overexpression and SNHG3-deficiency were found to ameliorate PANoptosis and injury induced by OGD/reperfusion and OGD/RX in both mice tissues and astrocyte cells. Further experiments demonstrated that ALKBH5 induced m6A-demethylation in SNHG3, leading to its degradation. Low expression of SNHG3, on the other hand, prevented the formation of the SNHG3-ELAVL1-ZBP1/AIM2 complex, which in turn destabilized ZBP1 and AIM2 mRNA, resulting in the downregulation of these PANoptosis-related genes. Ultimately, the rescue experiments provided evidence that ALKBH5 protected against PANoptosis in cerebral I/R injury models through the inhibition of SNHG3.This study sheds light on the intricate molecular mechanisms involved in the pathogenesis of cerebral I/R injury and highlights the potential of m6A-related genes as therapeutic targets in this condition.

N6-Methyladenosine Methylation of mRNA in Cell Apoptosis

Apoptosis, a highly controlled homeostatic mechanism that eliminates single cells without destroying tissue function, occurs during growing development and senescence. N6-methyladenosine (m6A), as the most common internal modification of eukaryotic mRNA, fine-tunes gene expression by regulating many aspects of mRNA metabolism, such as splicing, nucleation, stability, translation, and degradation. Remarkably, recent reports have indicated that aberrant methylation of m6A-related RNA may directly or indirectly influence the expression of apoptosis-related genes, thus regulating the process of cell apoptosis. In this review, we summarized the relationship between m6A modification and cell apoptosis, especially its role in the nervous system, and analyzed the limitations of the current research.

M2 macrophage-derived exosomes induce angiogenesis and increase skin flap survival through HIF1AN/HIF-1α/VEGFA control

BACKGROUND

Skin flap transplantation is a routine strategy in plastic and reconstructive surgery for skin-soft tissue defects. Recent research has shown that M2 macrophages have the potential for pro-angiogenesis during tissue healing.

METHODS

In our research, we extracted the exosomes from M2 macrophages(M2-exo) and applied the exosomes in the model of skin flap transplantation. The flap survival area was measured, and the choke vessels were assessed by morphological observation. Hematoxylin and eosin (H&E) staining and Immunohistochemistry were applied to assess the neovascularization. The effect of M2-exo on the function of Human umbilical vein endothelial cells (HUVECs) was also investigated. We also administrated 2-methoxyestradiol (2-ME2, an inhibitor of HIF-1α) to explore the underlying mechanism. We tested the effects of M2-Exo on the proliferation of HUVECs through CCK8 assay and EdU staining assay.

RESULTS

The survival area and number of micro-vessels in the skin flaps were increased in the M2-exo group. Besides, the dilation rate of choke vessels was also enhanced in the M2-exo group. Additionally, compared with the control group, M2-exo could accelerate the proliferation, migration and tube formation of HUVECs in vitro. Furthermore, the expression of the pro-angiogenesis factors, HIF-1α and VEGFA, were overexpressed with the treatment of the M2-exo. The expression of HIF1AN protein level was decreased in the M2-exo group. Finally, treatment with HIF-1α inhibitor reverses the pro-survival effect of M2-exo on skin flaps by interfering with the HIF1AN/HIF-1α/VEGFA signaling pathway.

CONCLUSION

This study showed that M2-exosomes promote skin flap survival by enhancing angiogenesis, with HIF1AN/HIF-1α/VEGFA playing a crucial role in this process.