• June 3, 2021

METTL3 reguluje angiogenezę poprzez modulowanie

METTL3 reguluje angiogenezę poprzez modulowanie ekspresji let-7e-5p i miRNA-18a-5p w komórkach śródbłonka 

Objective: Postnatal angiogenesis is critical in vascular homeostasis and repair. m6RNA methylation is emerging as a new layer for fine-tuning gene expression. Although the contribution of the m6A-catalyzing enzyme, METTL3 (methyltransferase-like 3), in cancer biology has been described, its role in endothelial cell (EC) function, particularly during angiogenesis, remains unclear. Approach and Results: To characterize the relevance of METTL3 in angiogenesis regulation, we performed gain- and loss-of-function studies in vitro. We demonstrated that depletion of METTL3 in ECs reduced the level of m6A and impaired EC function, whereas adenovirus-mediated METTL3 overexpression increased angiogenesis. Mechanistically, we showed that METTL3 depletion in ECs decreased mature angiogenic microRNAs let-7e-5p and the miR-17-92 cluster, and increased the expression of their common target, Tsp1 (thrombospondin 1).

Conversely, Ad.METTL3 increased the expression of let-7e-5p and miR-17-92 cluster and reduced protein levels of Tsp1 in ECs. Moreover, overexpression of let-7e-5p and miR-18a-5p restored the angiogenic potential of METTL3-depleted ECs. We corroborated our data in vivo employing 3 mouse models. When tested in an in vivo Matrigel plug assay, METTL3-depleted ECs had diminished ability to vascularize the plug, whereas overexpression of METTL3 promoted angiogenesis. Local Ad.METTL3 gene transfer increased postischemic neovascularization in mice with either unilateral limb ischemia or myocardial infarction.

Conclusions: METTL3 regulates m6RNA methylation in ECs. Endogenous METTL3 is essential for EC function and angiogenesis, potentially through influencing let-7e and miR-17-92 cluster processing. Thus, the therapeutic modulation of METTL3 should be considered as a new approach for controlling angiogenic responses in the clinical setting


Rola transkryptomicznych biomarkerów receptywności endometrium w spersonalizowanym transferze zarodków u pacjentek z powtarzającymi się niepowodzeniami implantacji 

Background: Window of implantation (WOI) displacement is one of the endometrial origins of embryo implantation failure, especially repeated implantation failure (RIF). An accurate prediction tool for endometrial receptivity (ER) is extraordinarily needed to precisely guide successful embryo implantation. We aimed to establish an RNA-Seq-based endometrial receptivity test (rsERT) tool using transcriptomic biomarkers and to evaluate the benefit of personalized embryo transfer (pET) guided by this tool in patients with RIF.

Methods: This was a two-phase strategy comprising tool establishment with retrospective data and benefit evaluation with a prospective, nonrandomized controlled trial. In the first phase, rsERT was established by sequencing and analyzing the RNA of endometrial tissues from 50 IVF patients with normal WOI timing. In the second phase, 142 patients with RIF were recruited and grouped by patient self-selection (experimental group, n = 56; control group, n = 86). pET guided by rsERT was performed in the experimental group and conventional ET in the control group.

Results: The rsERT, comprising 175 biomarker genes, showed an average accuracy of 98.4% by using tenfold cross-validation. The intrauterine pregnancy rate (IPR) of the experimental group (50.0%) was significantly improved compared to that (23.7%) of the control group (RR, 2.107; 95% CI 1.159 to 3.830; P = 0.017) when transferring day-3 embryos. Although not significantly different, the IPR of the experimental group (63.6%) was still 20 percentage points higher than that (40.7%) of the control group (RR, 1.562; 95% CI 0.898 to 2.718; P = 0.111) when transferring blastocysts.

Conclusions: The rsERT was developed to accurately predict the WOI period and significantly improve the pregnancy outcomes of patients with RIF, indicating the clinical potential of rsERT-guided pET.

Deregulacja mikroRNA w hipertrofii i kostnieniu Ligamentum Flavum: nowe postępy, wyzwania i potencjalne kierunki 

Pathological changes in the ligamentum flavum (LF) can be defined as a process of chronic progressive aberrations in the nature and structure of ligamentous tissues characterized by increased thickness, reduced elasticity, local calcification, or aggravated ossification, which may cause severe myelopathy, radiculopathy, or both. Hypertrophy of ligamentum flavum (HLF) and ossification of ligamentum flavum (OLF) are clinically common entities. Though accumulated evidence has indicated both genetic and environmental factors could contribute to the initiation and progression of HLF/OLF, the definite pathogenesis remains fully unclear. MicroRNAs (miRNAs), one of the important epigenetic modifications, are short single-stranded RNA molecules that regulate protein-coding gene expression at posttranscriptional level, which can disclose the mechanism underlying diseases, identify valuable biomarkers, and explore potential therapeutic targets. 

Considering that miRNAs play a central role in regulating gene expression, we summarized current studies from the point of view of miRNA-related molecular regulation networks in HLF/OLF. Exploratory studies revealed a variety of miRNA expression profiles and identified a battery of upregulated and downregulated miRNAs in OLF/HLF patients through microarray datasets or transcriptome sequencing. Experimental studies validated the roles of specific miRNAs (e.g., miR-132-3p, miR-199b-5p in OLF, miR-155, and miR-21 in HLF) in regulating fibrosis or osteogenesis differentiation of LF cells and related target genes or molecular signaling pathways. Finally, we discussed the perspectives and challenges of miRNA-based molecular mechanism, diagnostic biomarkers, and therapeutic targets of HLF/OLF.

Fenotypowe i epigenetyczne adaptacje limfocytów T CD4 + krwi pępowinowej do otyłości u matki 

Pregravid obesity has been shown to disrupt the development of the offspring’s immune system and increase susceptibility to infection. While the mechanisms underlying the impact of maternal obesity on fetal myeloid cells are emerging, the consequences for T cells remain poorly defined. In this study, we collected umbilical cord blood samples from infants born to lean mothers and mothers with obesity and profiled CD4 T cells using flow cytometry and single cell RNA sequencing at resting and following ex vivo polyclonal stimulation. We report that maternal obesity is associated with higher frequencies of memory CD4 T cells suggestive of in vivo activation. Moreover, single cell RNA sequencing revealed expansion of an activated subset of memory T cells with maternal obesity.

However, ex vivo stimulation of purified CD4 T cells resulted in poor cytokine responses, suggesting functional defects. These phenotypic and functional aberrations correlated with methylation and chromatin accessibility changes in loci associated with lymphocyte activation and T cell receptor signaling, suggesting a possible link between maternal obesogenic environment and fetal immune reprogramming. These observations offer a potential explanation for the increased susceptibility to microbial infection in babies born to mothers with obesity.

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