TARBP2-stablized SNHG7 regulates blood-brain barrier permeability by acting as a competing endogenous RNA to miR-17-5p/NFATC3 in Aβ-microenvironment

Exploring non-coding genetic variability in ACE2: Functional annotation and in vitro validation of regulatory variants

The surge in human whole-genome sequencing data has facilitated the study of non-coding region variations, yet understanding their biological significance remains a challenge. We used a computational workflow to assess the regulatory potential of non-coding variants, with a particular focus on the Angiotensin Converting Enzyme 2 (ACE2) gene. This gene is crucial in physiological processes and serves as the entry point for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 19 (COVID-19). In our analysis, using data from the gnomAD population database and functional annotation, we identified 17 significant Single Nucleotide Variants (SNVs) in ACE2, particularly in its enhancers, promoters, and 3' untranslated regions (UTRs). We found preliminary evidence supporting the regulatory impact of some of these variants on ACE2 expression. Our detailed examination of two SNVs, rs147718775 and rs140394675, in the ACE2 promoter revealed that these co-occurring SNVs, when mutated, significantly enhance promoter activity, suggesting a possible increase in specific ACE2 isoform expression. This method proves effective in identifying and interpreting impactful non-coding variants, aiding in further studies and enhancing understanding of molecular bases of monogenic and complex traits.

HNRNPA2B1 stabilizes NFATC3 levels to potentiate its combined actions with FOSL1 to mediate vasculogenic mimicry in GBM cells

BACKGROUND

Vasculogenic mimicry (VM) is an enigmatic physiological feature that influences blood supply within glioblastoma (GBM) tumors for their sustained growth. Previous studies identify NFATC3, FOSL1 and HNRNPA2B1 as significant mediators of VEGFR2, a key player in vasculogenesis, and their molecular relationships may be crucial for VM in GBM.

AIMS

The aim of this study was to understand how NFATC3, FOSL1 and HNRNPA2B1 collectively influence VM in GBM.

METHODS

We have investigated the underlying gene regulatory mechanisms for VM in GBM cell lines U251 and U373 in vitro and in vivo. In vitro cell-based assays were performed to explore the role of NFATC3, FOSL1 and HNRNPA2B1 in GBM cell proliferation, VM and migration, in the context of RNA interference (RNAi)-mediated knockdown alongside corresponding controls. Western blotting and qRT-PCR assays were used to examine VEGFR2 expression levels. CO-IP was employed to detect protein-protein interactions, ChIP was used to detect DNA-protein complexes, and RIP was used to detect RNA-protein complexes. Histochemical staining was used to detect VM tube formation in vivo.

RESULTS

Focusing on NFATC3, FOSL1 and HNRNPA2B1, we found each was significantly upregulated in GBM and positively correlated with VM-like cellular behaviors in U251 and U373 cell lines. Knockdown of NFATC3, FOSL1 or HNRNPA2B1 each resulted in decreased levels of VEGFR2, a key growth factor gene that drives VM, as well as the inhibition of proliferation, cell migration and extracorporeal VM activity. Chromatin immunoprecipitation (ChIP) studies and luciferase reporter gene assays revealed that NFATC3 binds to the promoter region of VEGFR2 to enhance VEGFR2 gene expression. Notably, FOSL1 interacts with NFATC3 as a co-factor to potentiate the DNA-binding capacity of NFATC3, resulting in enhanced VM-like cellular behaviors. Also, level of NFATC3 protein in cells was enhanced through HNRNPA2B1 binding of NFATC3 mRNA. Furthermore, RNAi-mediated silencing of NFATC3, FOSL1 and HNRNPA2B1 in GBM cells reduced their capacity for tumor formation and VM-like behaviors in vivo.

CONCLUSION

Taken together, our findings identify NFATC3 as an important mediator of GBM tumor growth through its molecular and epistatic interactions with HNRNPA2B1 and FOSL1 to influence VEGFR2 expression and VM-like cellular behaviors.

RBM3 enhances the stability of MEF2C mRNA and modulates blood-brain barrier permeability in AD microenvironment

Blood-brain barrier (BBB) changes are acknowledged as early indicators of Alzheimer's disease (AD). The permeability and integrity of the BBB rely significantly on the essential role played by the tight junction proteins (TJPs) connecting endothelial cells. This study found the reduced RNA binding motif protein 3 (RBM3) expression in brain microvascular endothelial cells (BMECs) incubated with Aβ1-42. This downregulation of RBM3 caused a decrease in the levels of ZO-1 and occludin and increased the permeability of BBB cell model in AD microenvironment. Myocyte enhancer factor 2C (MEF2C) expression was also inhibited in BMECs incubated with Aβ1-42. A decrease in MEF2C expression led to increased permeability of BBB cell model in AD microenvironment and reductions in the levels of ZO-1 and occludin. Further analysis of the underlying mechanism revealed that RBM3 binds to and stabilizes MEF2C mRNA. MEF2C binds to the promoters of ZO-1 and occludin, enhancing their transcriptional activities and modulating BBB permeability. RBM3 increases the stability of MEF2C mRNA and subsequently modulates BBB permeability through the paracellular pathway of TJPs. This may provide new insights for AD research.

ZNF787 and HDAC1 Mediate Blood-Brain Barrier Permeability in an In Vitro Model of Alzheimer's Disease Microenvironment

The permeability of the blood-brain barrier (BBB) is increased in Alzheimer's disease (AD). This plays a key role in the instigation and maintenance of chronic inflammation during AD. Experiments using AD models showed that the increased permeability of the BBB was mainly caused by the decreased expression of tight junction-related proteins occludin and claudin-5. In this study, we found that ZNF787 and HDAC1 were upregulated in β-amyloid (Aβ)1-42-incubated endothelial cells, resulting in increased BBB permeability. Conversely, the silencing of ZNF787 and HDAC1 by RNAi led to reduced BBB permeability. The silencing of ZNF787 and HDAC1 enhanced the expression of occludin and claudin-5. Mechanistically, ZNF787 binds to promoter regions for occludin and claudin-5 and functions as a transcriptional regulator. Furthermore, we demonstrate that ZNF787 interacts with HDAC1, and this resulted in the downregulation of the expression of genes encoding tight junction-related proteins to increase in BBB permeability. Taken together, our study identifies critical roles for the interaction between ZNF787 and HDAC1 in regulating BBB permeability and the pathogenesis of AD.

Long Non-coding RNA SNHG7 Suppresses Inflammation and Apoptosis of Chondrocytes Through Inactivating of p38 MAPK Signaling Pathway in Osteoarthritis

This study aims to explore the molecular mechanism of LncRNA SNHG7 in Osteoarthritis (OA). Cartilage tissues of OA patients or patients with trauma or amputation were collected. Compared to normal cartilage tissues, SNHG7 was downregulated while miR-324-3p was upregulated in cartilage tissues of OA patients. IL-1β was used to induce damage to chondrocytes and treatment with IL-1β reduced SNHG7 expression in OA chondrocytes. In IL-1β-treated OA chondrocytes, SNHG7 overexpression reduced the levels of TNF-α and IL-6, inhibited cell apoptosis, and increased cell viability. Additionally, the luciferase reporter assay proved that SNHG7 upregulated dual-specificity phosphatase 1 (DUSP1) by sponging miR-324-3p, thereby inactivating the p38 MAPK signaling pathway by regulating the miR-324-3p/DUSP1 axis. Anisomycin (a p38 MAPK activator) enhanced OA chondrocytes inflammation, promoted cell apoptosis, and reduced cell viability; however, this was reversed by SNHG7 overexpression. This study demonstrates that the SNHG7/miR-324-3p/DUSP1 axis suppresses OA chondrocytes inflammation and apoptosis by inhibiting the p38 MAPK signaling pathway. Thus, this study indicates that SNHG7 is a novel target for OA treatment.

MiR-17-5p Mediates the Effects of ACE2-Enriched Endothelial Progenitor Cell-Derived Exosomes on Ameliorating Cerebral Ischemic Injury in Aged Mice

Aging is one of the key mechanisms of vascular dysfunction and contributes to the initiation and progression of ischemic stroke (IS). Our previous study demonstrated that ACE2 priming enhanced the protective effects of exosomes derived from endothelial progenitor cells (EPC-EXs) on hypoxia-induced injury in aging endothelial cells (ECs). Here, we aimed to investigate whether ACE2-enriched EPC-EXs (ACE2-EPC-EXs) could attenuate brain ischemic injury by inhibiting cerebral EC damage through their carried miR-17-5p and the underlying molecular mechanisms. The enriched miRs in ACE2-EPC-EXs were screened using the miR sequencing method. EPC-EXs, ACE2-EPC-EXs, and ACE2-EPC-EXs with miR-17-5p deficiency (ACE2-EPC-EXs^{antagomiR-17-5p}) were administered to transient middle cerebral artery occlusion (tMCAO)-operated aged mice or coincubated with hypoxia/reoxygenation (H/R)-treated aging ECs. The results showed that (1) the level of brain EPC-EXs and their carried ACE2 were significantly decreased in aged mice compared to in young mice, and (2) after tMCAO, aged mice displayed increases in brain cell senescence, infarct volume, and neurological deficit score (NDS) and a decrease in cerebral blood flow (CBF). (3) Compared with EPC-EXs, ACE2-EPC-EXs were enriched with miR-17-5p and more effective in increasing ACE2 and miR-17-5p expression in cerebral microvessels, accompanied by obvious increases in cerebral microvascular density (cMVD) and cerebral blood flow (CBF) and decreases in brain cell senescence, infarct volume, neurological deficit score (NDS), cerebral EC ROS production, and apoptosis in tMCAO-operated aged mice. Moreover, silencing of miR-17-5p partially abolished the beneficial effects of ACE2-EPC-EXs. (4) In H/R-treated aging ECs, ACE2-EPC-EXs were more effective than EPC-EXs in decreasing cell senescence, ROS production, and apoptosis and increasing cell viability and tube formation. In a mechanistic study, ACE2-EPC-EXs more effectively inhibited PTEN protein expression and increased the phosphorylation of PI3K and Akt, which were partially abolished by miR-17-5p knockdown. Altogether, our data suggest that ACE-EPC-EXs have better protective effects on ameliorating aged IS mouse brain neurovascular injury by inhibiting cell senescence, EC oxidative stress, apoptosis, and dysfunction by activating the miR-17-5p/PTEN/PI3K/Akt signaling pathway.

New Insights into lncRNAs in Aβ Cascade Hypothesis of Alzheimer's Disease

Alzheimer's disease (AD) is the most common type of dementia, but its pathogenesis is not fully understood, and effective drugs to treat or reverse the progression of the disease are lacking. Long noncoding RNAs (lncRNAs) are abnormally expressed and deregulated in AD and are closely related to the occurrence and development of AD. In addition, the high tissue specificity and spatiotemporal specificity make lncRNAs particularly attractive as diagnostic biomarkers and specific therapeutic targets. Therefore, an in-depth understanding of the regulatory mechanisms of lncRNAs in AD is essential for developing new treatment strategies. In this review, we discuss the unique regulatory functions of lncRNAs in AD, ranging from Aβ production to clearance, with a focus on their interaction with critical molecules. Additionally, we highlight the advantages and challenges of using lncRNAs as biomarkers for diagnosis or therapeutic targets in AD and present future perspectives in clinical practice.

Transcription factor ZNF22 regulates blood-tumor barrier permeability by interacting with HDAC3 protein

OBJECTIVE

The primary goals of this study were to investigate the potential roles of ZNF22 and HDAC3 as a histone deacetylase in regulating an increases in blood-tumor barrier (BTB) permeability and some of the possible molecular mechanisms associated with this effect.

METHODS

The expression of ZNF22 and HDAC3 in glioma-exposed endothelial cells (GECs) of BTB were detected transcription real-time PCR or western blot. The interaction of ZNF22 and HDAC3 in GECs associated with transcript effect was analyzed by means of Co-Immunoprecipitation and luciferase reporter assay.

RESULTS

In the present investigation, GECs expressed higher levels of ZNF22 as a zinc finger transcription factor and HDAC3 than endothelial cells. We then affirmed that silencing HDAC3 or ZNF22 led to a reduction in BTB permeability. By bioinformatics analysis, chromatin immunoprecipitation (ChIP) assays and luciferase assay, we found that ZNF22 had a target binding relationship with the promoter regions of ZO-1, Occludin, and Claudin-5 and negatively regulated the expression of ZO-1, Occludin, and Claudin-5. Furthermore, we revealed that HDAC3, as a co-transcript repressor with histone deacetylase activity, could interact with ZNF22 to hinder the expression of TJ-associated proteins, thereby further facilitating the permeability of BTB.

CONCLUSION

ZNF22 acted as a transcription factor in conjunction with HDAC3 to modulate the expression of TJ-associated proteins, which was correlated with an increase in BTB permeability. These results may provide new strategies and targets for the chemotherapy of gliomas as well as intracranial infections.