Programmed Release METTL3-14 Inhibitor Microneedle Protects Myocardial Function by Reducing Drp1 m6A Modification-Mediated Mitochondrial Fission

m6A control programmed cell death in cardiac fibrosis

N6-methyladenosine (m6A) modification is closely related to cardiac fibrosis. As the most common and abundant form of mRNA modification in eukaryotes, m6A is deposited by methylases ("writers"), recognized and effected by RNA-binding proteins ("readers"), and removed by demethylases ("erasers"), achieving highly dynamic reversibility. m6A modification is involved in regulating the entire biological process of target RNA, including transcription, processing and splicing, export from the nucleus to the cytoplasm, and enhancement or reduction of stability and translation. Programmed cell death (PCD) comprises many forms and pathways, with apoptosis and autophagy being the most common. Other forms include pyroptosis, ferroptosis, necroptosis, mitochondrial permeability transition (MPT)-dependent necrosis, and parthanatos. In recent years, increasing evidence suggests that m6A modification can mediate PCD, affecting cardiac fibrosis. Since the correlation between some PCD types and m6A modification is not yet clear, this article mainly introduces the relationship between four common PCD types (apoptosis, autophagy, pyroptosis, and ferroptosis) and m6A modification, as well as their role and influence in cardiac fibrosis.

Unravelling the impact of RNA methylation genetic and epigenetic machinery in the treatment of cardiomyopathy

Cardiomyopathy (CM) represents a heterogeneous group of diseases primarily affecting cardiac structure and function, with genetic and epigenetic dysregulation playing a pivotal role in its pathogenesis. Emerging evidence from the burgeoning field of epitranscriptomics has brought to light the significant impact of various RNA modifications, notably N6-methyladenosine (m6A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N1-methyladenosine (m1A), 2'-O-methylation (Nm), and 6,2'-O-dimethyladenosine (m6Am), on cardiomyocyte function and the broader processes of cardiac and vascular remodelling. These modifications have been shown to influence key pathological mechanisms including mitochondrial dysfunction, oxidative stress, cardiomyocyte apoptosis, inflammation, immune response, and myocardial fibrosis. Importantly, aberrations in the RNA methylation machinery have been observed in human CM cases and animal models, highlighting the critical role of RNA methylating enzymes and their potential as therapeutic targets or biomarkers for CM. This review underscores the necessity for a deeper understanding of RNA methylation processes in the context of CM, to illuminate novel therapeutic avenues and diagnostic tools, thereby addressing a significant gap in the current management strategies for this complex disease.

Nanoparticle-Patch System for Localized, Effective, and Sustained miRNA Administration into Infarcted Myocardium to Alleviate Myocardial Ischemia-Reperfusion Injury

Timely blood reperfusion after myocardial infarction (MI) paradoxically triggers ischemia-reperfusion injury (I/RI), which currently has not been conquered by clinical treatments. Among innovative repair strategies for myocardial I/RI, microRNAs (miRNAs) are expected as genetic tools to rescue damaged myocardium. Our previous study identified that miR-30d can provide protection against myocardial apoptosis and fibrosis to alleviate myocardial injury. Although common methods such as liposomes and viral vectors have been used for miRNA transfection, their therapeutic efficiencies have struggled with inefficient in vivo delivery, susceptible inactivation, and immunogenicity. Here, we establish a nanoparticle-patch system for miR-30d delivery in a murine myocardial I/RI model, which contains ZIF-8 nanoparticles and a conductive microneedle patch. Loaded with miR-30d, ZIF-8 nanoparticles leveraging the proton sponge effect enable miR-30d to escape the endocytic pathway, thus avoiding premature degradation in lysosomes. Meanwhile, the conductive microneedle patch offers a distinct advantage by intramyocardial administration for localized, effective, and sustained miR-30d delivery, and it simultaneously releases Au nanoparticles to reconstruct electrical impulses within the infarcted myocardium. Consequently, the nanoparticle-patch system supports the consistent and robust expression of miR-30d in cardiomyocytes. Results from echocardiography and electrocardiogram (ECG) revealed improved heart functions and standard ECG wave patterns in myocardial I/RI mice after implantation of a nanoparticle-patch system for 3 and 6 weeks. In summary, our work incorporated conductive microneedle patch and miR-30d nanodelivery systems to synergistically transcend the limitations of common RNA transfection methods, thus mitigating myocardial I/RI.

Fabrication of nanocrystal forms of ᴅ-cycloserine and their application for transdermal and enteric drug delivery systems

ᴅ-cycloserine (DCS), an FDA-approved medicine for the treatment of tuberculosis, is also a partial agonist at the glycine recognition site of N-methyl-ᴅ-aspartate (NMDA) receptor and has shown significant treatment efficacy for central nervous system (CNS) disorders including depression, schizophrenia, Alzheimer's disease, and post-traumatic stress disorder. The physicochemical properties of DCS, however, limit the options of formulation and medicinal applications of DCS, and warrants further investigation for the development of CNS therapeutics. Nanocrystals play an important role in pharmaceutic design and development. The properties of nanocrystals are remarkably different from their bulk material counterpart, attributed to the large surface-area-to-volume ratio which can improve the bioavailability. In this study, for the first time, DCS, a highly water-soluble compound, has formed nanocrystals and this was confirmed by scanning electronic microscopy and X-ray powder diffraction. Furthermore, DCS nanocrystals were applied to several formulations to test their stability and then to the in vitro Franz diffusion test with reservoir patch formulation as well as in vivo pharmacokinetics study with enteric capsules. We tested these formulations regarding their nanocrystal physical properties, size effect, and dissolution rate, respectively. We found that DCS nanocrystals showed good performance in the Franz diffusion test and rodent pharmacokinetic studies due to the nanoparticle size and faster dissolution as compared with the commercial DCS powder. These DCS nanocrystal formulations could offer a new approach for the development of an advanced drug delivery system for the treatment of CNS disorders.

ROS-Suppression Nanoplatform Combined Activation of STAT3/Bcl-2 Pathway for Preventing Myocardial Infarction in Mice

Myocardial infarction (MI) is the leading cause of death worldwide. The most effective way to treat myocardial infarction is to rescue ischemic cardiomyocytes. After an ischemic event, the overproduction of reactive oxygen species (ROS) is a key driver of myocardial injury. The produced ROS affects mitochondrial function and induces apoptosis in cardiomyocytes. This was accomplished by constructing platelet-membrane-encapsulated ROS-responsive drug-releasing nanoparticles (PMN@NIC-MalNPs) to deliver malonate and niclosamide (NIC). The results revealed that PMN@NIC-MalNPs degraded and released malonate and niclosamide in a high-level ROS microenvironment, effectively reducing the oxidative stress and apoptosis rate. By enhancing basal mitochondrial oxygen consumption rate (OCR), adenosine triphosphate (ATP) production, and spare respiratory capacity (SRC) in vitro, reduced the oxidative stress levels and restored mitochondrial function. In vivo studies revealed that the PMN@NIC-MalNPs improved cardiac dysfunction, inhibited succinate dehydrogenase (SDH) activity, increased ATP production, and reduced the myocardial infarct size in myocardial infarction model mice. Further, transcriptome analysis and Western blot revealed that PMN@NIC-MalNPs prevented apoptosis by activating the expressions of the signal transducer and activator of transcription 3 (STAT3) and Bcl-2, and inhibiting the expression of Bax. Thus, this study provides a novel therapeutic solution for treating myocardial infarction and predicting the viability of an antioxidant and antiapoptotic therapeutic solution in the treatment of myocardial injury.

METTL3-Mediated LINC00475 Alternative Splicing Promotes Glioma Progression by Inducing Mitochondrial Fission

Mitochondrial fission promotes glioma progression. The function and regulation mechanisms of lncRNAs in glioma mitochondrial fission are unclear. The expression of LINC00475 and its correlation with clinical parameters in glioma were analyzed using bioinformatics. Then, in vitro and in vivo assays were performed to explore the function of spliced variant LINC00475 (LINC00475-S) in gliomas. To explore the mechanisms, RNA-seq, MeRIP, RIP, pulldown-IP, dCas9-ALKBH5 editing system, LC/MS, and Western blotting were utilized. LINC00475 was confirmed to be overexpressed and with higher frequencies of AS events in gliomas compared to normal brain tissue and was associated with worse prognosis. In vitro and animal tumor formation experiments demonstrated that the effect of LINC00475-S on proliferation, metastasis, autophagy, and mitochondrial fission of glioma cells was significantly stronger than that of LINC00475. Mechanistically, METTL3 induced the generation of LINC00475-S by splicing LINC00475 through m6A modification and subsequently promotes mitochondrial fission in glioma cells by inhibiting the expression of MIF. Pull-down combined LC/MS and RIP assays identified that the m6A recognition protein HNRNPH1 bound to LINC00475 within GYR and GY domains and promoted LINC00475 splicing. METTL3 facilitated HNRNPH1 binding to LINC00475 in an m6A-dependent manner, thereby inducing generation of LINC00475-S. METTL3 facilitated HNRNPH1-mediated AS of LINC00475, which promoted glioma progression by inducing mitochondrial fission. Targeting AS of LINC00475 and m6A editing could serve as a therapeutic strategy against gliomas.