MicroRNA-4443 regulates monocyte activation by targeting tumor necrosis factor receptor associated factor 4 in stroke-induced immunosuppression

BACKGROUND AND PURPOSE

MicroRNAs (miRNAs) have been demonstrated to play crucial roles in the early stage of acute ischaemic stroke (AIS). The purpose of this study was to investigate the expression patterns of miRNAs in peripheral blood mononuclear cells (PBMCs) from AIS patients and further explore related molecular mechanisms in stroke-induced immunodeficiency syndrome (SIDS).

METHODS

The miRNA expression patterns of PBMCs were detected by miRNA microarray and validated by quantitative real-time polymerase chain reaction (qRT-PCR) in AIS patients and healthy controls. Bioinformatics methods and luciferase reporter assays were used to detect the downstream target genes. Following stimulation with lipopolysaccharide and interleukin-4, the expression of miR-4443, tumor necrosis factor receptor associated factor 4 (TRAF4) and the nuclear factor kappa B (NF-κB) pathway were evaluated. Furthermore, transfection with miR-4443 mimic or inhibitor in the monocytes was carried out to gain insight into the mechanisms in SIDS.

RESULTS

Interleukin-10 in AIS patients was significantly higher than that of healthy controls. The miRNA microarray analysis and qRTPCR validation showed that only miR-4443 was upregulated expressed in PBMCs from AIS patients, especially in monocytes. miR-4443 was shown to directly interact with the 3' untranslated regions of TRAF4, resulting in suppression of TRAF4 protein expression. Furthermore, the expression of miR-4443 and TRAF4 was regulated by stimulation with lipopolysaccharide or interleukin-4. Additionally, overexpression of miR-4443 suppressed the TRAF4/Iκα/NF-κB signaling pathway to activate the expression of anti-inflammatory cytokines in monocytes.

CONCLUSIONS

The increased expression of miR-4443 induced monocyte dysfunction by targeting TRAF4, which may function as a crucial mediator in SIDS.

Heat stress induces apoptosis through transcription-independent p53-mediated mitochondrial pathways in human umbilical vein endothelial cell

Cells apoptosis induced by intense heat stress is the prominent feature of heat-related illness. However, little is known about the biological effects of heat stress on cells apoptosis. Herein, we presented evidence that intense heat stress could induce early apoptosis of HUVEC cells through activating mitochondrial pathway with changes in mitochondrial membrane potential(ΔΨm), release of cytochrome c, and activation of caspase-9 and -3. We further revealed that p53 played a crucial role in heat stress-induced early apoptosis, with p53 protein rapidly translocated into mitochondria. Using pifithrin-α(PFT), a p53's mitochondrial translocation inhibitor, we found that pretreated with PFT, heat stress induced mitochondrial p53 translocation was significantly suppressed, accompanied by a significant alleviation in the loss of ΔΨm, cytochrome c release and caspase-9 activation. Furthermore, we also found that generation of reactive oxygen species (ROS) was a critical mediator in heat stress-induced apoptosis. In addition, the antioxidant MnTMPyP significantly decreased the heat stress-induced p53's mitochondrial translocation, followed by the loss of ΔΨm, cytochrome c release, caspase-9 activation and heat stress-mediated apoptosis. Conclusively, these findings indicate the contribution of the transcription-independent mitochondrial p53 pathway to early apoptosis in HUVEC cells induced by oxidative stress in response to intense heat stress.

Two- and three-dimensional 1H/13C PISEMA experiments and their application to backbone and side chain sites of amino acids and peptides

Two-dimensional 1H/13C polarization inversion spin exchange at the magic angle experiments were applied to single crystal samples of amino acids to demonstrate their potential utility on oriented samples of peptides and proteins. High resolution is achieved and structural information obtained on backbone and side chain sites from these spectra. A triple-resonance experiment that correlates the 1H-13Calpha dipolar coupling frequency with the chemical shift frequencies of the alpha-carbon, as well as the directly bonded amide 15N site, is also demonstrated. In this experiment the large 1H-13Calpha heteronuclear dipolar interaction provides an independent frequency dimension that significantly improves the resolution among overlapping 13C resonances of oriented polypeptides, while simultaneously providing measurements of the 13Calpha chemical shift, 1H-13C dipolar coupling, and 15N chemical shift frequencies and angular restraints for backbone structure determination.