Regulatory crosstalk between KLF5, miR-29a and Fbw7/CDC4 cooperatively promotes atherosclerotic development.

Atherogenesis is a chronic inflammatory process that involves complex interactions between endothelial dysfunction, lipid deposition and vascular smooth-muscle cell (VSMC) proliferation. However, the molecular mechanism is still unclear. We found that a pro-atherosclerotic factor (oxLDL) induced the expression of Krüppel-like factor 5 (KLF5), which in turn increased miR-29a expression levels. The increased miR-29a was retained within HASMCs and down-regulated Fbw7/CDC4 expression by targeting the 3´UTR of Fbw7/CDC4, subsequently increasing KLF5 stability by reducing the Fbw7/CDC4-dependent ubiquitination of KLF5, forming a positive feedback loop to enhance VSMC proliferation and promote atherogenesis. These results indicate a potentially important role for the oxLDL-activated feedback mechanism in VSMC proliferation and atherogenesis. Suppression of miR-29a may be an effective way to attenuate atherosclerosis. In conclusion, our data are the first to reveal that the regulatory crosstalk between KLF5, miR-29a, and Fbw7/CDC4 cooperatively promotes atherosclerotic development.

Exosome-Mediated miR-155 Transfer from Smooth Muscle Cells to Endothelial Cells Induces Endothelial Injury and Promotes Atherosclerosis.

The vascular response to pro-atherosclerotic factors is a multifactorial process involving endothelial cells (ECs), macrophages (MACs), and smooth muscle cells (SMCs), although the mechanism by which these cell types communicate with each other in response to environmental cues is yet to be understood. Here, we show that miR-155, which is significantly expressed and secreted in Krüppel-like factor 5 (KLF5)-overexpressing vascular smooth muscle cells (VSMCs), is a potent regulator of endothelium barrier function through regulating endothelial targeting tight junction protein expression. VSMCs-derived exosomes mediate the transfer of KLF5-induced miR-155 from SMCs to ECs, which, in turn, destroys tight junctions and the integrity of endothelial barriers, leading to an increased endothelial permeability and enhanced atherosclerotic progression. Moreover, overexpression of miR-155 in ECs inhibits endothelial cell proliferation/migration and re-endothelialization in vitro and in vivo and thus increases vascular endothelial permeability. Blockage of the exosome-mediated transfer of miR-155 between these two cells may serve as a therapeutic target for atherosclerosis.

miR-29a regulates vascular neointimal hyperplasia by targeting YY1.

OBJECTIVES: The formation of vascular neointima is mainly related to impairment of the vascular endothelial barrier and abnormal proliferation and migration of smooth muscle cells. The objective of this study was to investigate whether miR-29a exerts any promoting effect on the vascular neointimal hyperplasia and if so, its mechanism. MATERIALS AND METHODS: RT-qPCR was performed to determine expression of miR-29a in vascular smooth muscle cells (VSMC) and vascular neointimal hyperplasia. To further understand its role, we restored its expression in VSMCs by transfection with miR-29a mimics or inhibitors. Effects of miR-29a on cell proliferation were also determined. RESULTS: In this study, we used two kinds of model to observe the role of miR-29a in neointimal hyperplasia induced by carotid ligation or balloon injury. The major findings were that: (i) miR-29a overexpression promoted neointimal hyperplasia induced by carotid ligation; (ii) miR-29a increased proliferation of VSMCs, one aspect of which was by targeting expression of Ying and yang 1 protein (YY1), a negative regulator of Cyclin D1. A further aspect, was by increasing expression of Krüppel-like factor 5, a positive regulator of Cyclin D1, thereby allowing formation a synergistic effect. (iii) Tongxinluo (TXL), a traditional Chinese medicine reduced neointimal formation in ligated vessels by inhibiting VSMC proliferation and migration. CONCLUSIONS: These findings provide a new molecular mechanism of TXL in decreasing neointima hyperplasia.

1, 25(OH)2D3-induced interaction of vitamin D receptor with p50 subunit of NF-κB suppresses the interaction between KLF5 and p50, contributing to inhibition of LPS-induced macrophage proliferation.

KLF5 and nuclear factor κB (NF-κB) regulate cell proliferation and inflammation. Vitamin D signaling through vitamin D receptor (VDR) exerts anti-proliferative and anti-inflammatory actions. However, an actual relationship between KLF5, NF-κB and VDR in the inflammation and proliferation of macrophages is still unclear. Here, we showed that LPS and proinflammatory cytokines stimulate KLF5 gene expression in macrophages, and that 1, 25(OH)2D3 suppresses LPS-induced KLF5 expression and cell proliferation via upregulation of VDR expression. Mechanistic studies suggested that KLF5 interacts with p50 subunit of NF-κB to cooperatively induce the expressions of positive cell cycle regulators cyclin B1 and Cdk1/Cdc2 in LPS-treated macrophages. Further studies revealed that 1, 25(OH)2D3-induced interaction of VDR with p50 decreases LPS-induced interaction of KLF5 with p50. Collectively, we identify a novel regulatory pathway in which 1, 25(OH)2D3 induces VDR expression and promotes VDR interaction with p50 subunit of NF-κB, which in turn attenuates the association of KLF5 with p50 subunit of NF-κB and thus exerts anti-inflammatory and anti-proliferative effects on macrophages.

Interictal epileptiform discharges were associated with poorer cognitive performance in adult epileptic patients.

OBJECTIVE: Cognitive impairment is one of the major consequences of epilepsy and has been shown to reduce quality of life. Interictal epileptiform discharges (IEDs) were associated with poorer cognitive performance in children, and the aim of this study was to determine whether there was a similar association in adults. METHODS: A prospective cohort of 167 seizure-free adult patients underwent EEG recording and extensive cognitive evaluations. Global cognition was evaluated using Addenbrooke's Cognitive Examination-Revised (ACE-R), while sub-dimensions of cognition were evaluated using the Auditory Verbal Learning Test (AVLT), Trial Making Test (TMT)-A and -B, and the 5 constitutive subscales of ACE-R. RESULTS: Performance in ACER, but not AVLT or TMT, was significantly lower in patients with general IEDs. Furthermore, the five subscale scores of ACE-R were significantly lower in patients with general IEDs, and verbal fluency and language scores contributed in a major way to the low scores. Stratified analysis showed that sleep-phase IEDs were also associated with lower performance in ACE-R and its subscales. Finally, non-rapid eye movement (NREM)-IEDs were found to be associated with visuospatial and memory impairment, and IEDs while awake, with poorer performance in TMT-B. SIGNIFICANCE: The results of this study demonstrate that cognitive performance is associated with IEDs in adult epilepsy patients, and could serve as a springboard for further research into reducing IEDs to bring about better cognitive performance.

SUMOylation of KLF4 acts as a switch in transcriptional programs that control VSMC proliferation.

The regulation of vascular smooth muscle cell (VSMC) proliferation is an important issue due to its major implications for the prevention of pathological vascular conditions. The objective of this work was to assess the function of small ubiquitin-like modifier (SUMO)ylated Krϋppel-like transcription factor 4 (KLF4) in the regulation of VSMC proliferation in cultured cells and in animal models with balloon injury. We found that under basal conditions, binding of non-SUMOylated KLF4 to p300 activated p21 (p21(WAF1/CIP1))transcription, leading to VSMC growth arrest. PDGF-BB promoted the interaction between Ubc9 and KLF4 and the SUMOylation of KLF4, which in turn recruited transcriptional corepressors to the p21 promoter. The reduction in p21 enhanced VSMC proliferation. Additionally, the SUMOylated KLF4 did not affect the expression of KLF4, thereby forming a positive feedback loop enhancing cell proliferation. These results demonstrated that SUMOylated KLF4 plays an important role in cell proliferation by reversing the transactivation action of KLF4 on p21 induced with PDGF-BB.

Photo-Activatable Substrates for Site-Specific Differentiation of Stem Cells.

In this report, a UV sensitive, PEGylated PFSSTKTC (Pro-Phe-Ser-Ser-Thr-Lys-Thr-Cys) peptide was modified on quartz substrate to investigate the spatial controlled differentiation of stem cells. This substrate could restrict the cell adhesion due to the steric hindrance of PEG shell. With UV irradiation, PFSSTKTC became exposed owing to the breakage of o-nitrobenzyl group with the detachment of PEG shell. The irradiation boundary on substrate was stable in the long term. The in vitro osteogenic differentiation results revealed that under the site-specific irradiation, the mesenchymal stem cells (MSCs) could specifically differentiate into osteoblast under the induction of PFSSTKTC peptide. This photoactivatable biomaterial shows great potential for region controllable and precise MSCs differentiation.

A novel function of BMHP1 and cBMHP1 peptides to induce the osteogenic differentiation of mesenchymal stem cells.

Bone marrow homing peptide 1 (BMHP1), which was derived from a phage display peptide library (PDPL), is known to be home to bone marrow and bind to stem cells. For the first time, the effect of BMHP1 on the differentiation behavior of mesenchymal stem cells (MSCs) was evaluated. BMHP1 was tethered to modified quartz substrates, and MSCs were seeded on the substrates. It was found that BMHP1 could enhance cell adhesion and proliferation. More importantly, we found that BMHP1 could induce osteogenic differentiation either with a maintenance medium (DMEM) or osteogenic differentiation medium (ODM). Cyclic BMHP1 (cBMHP1) was further synthesized and it was found that cBMHP1 also exhibit a similar, but slightly worse effect on the osteogenic differentiation of MSCs as compared to BMHP1. This work enlightens us on the fact that BMHP1 and cBMHP1 may be used as osteogenic stimulators for MSCs based therapy.

Evaluating the effects of charged oligopeptide motifs coupled with RGD on osteogenic differentiation of mesenchymal stem cells.

Mesenchymal stem cells, due to their multilineage differentiation potential, have emerged as a promising cell candidate for cell-based therapy. In recent years, biomaterials were artificially synthesized to control the differentiation of mesenchymal stem cells. In this study, a series of charged or neutral oligopeptide motifs coupled with RGD were synthesized and used for surface modification using quartz substrates as model. Cell behaviors on the modified surfaces with different charged oligopeptide motifs were studied. It was found that these different charged oligopeptide motifs coupled with RGD were biocompatible for cell proliferation and adhesion. Moreover, it was demonstrated that the positively charged oligopeptide motif could inhibit osteogenic differentiation, while the negatively charged and neutral oligopeptide motifs could enhance osteogenic differentiation in the presence of RGD. This work may bring us enlightenment that different charged oligopeptide motifs coupled with RGD may be used for biomaterial surface modification for different stem cell-based therapies.

Virus-Surface-Mimicking Surface Clustering of AuNPs onto DNA-Entrapped Polymeric Nanoparticle for Enhanced Cellular Internalization and Nanocluster-Induced NIR Photothermal Therapy.

Virus-surface-mimicking decoration of deoxyribonucleic acid (DNA)-entrapped polymeric nanoparticle with AuNPs is demonstrated to lead to enhanced cellular uptake, improved gene transfection, and particularly efficient near-infrared photothermal therapy that cannot be achieved by both of them separately. This hybrid nanosystem represents a novel paradigm of multipurpose organic-inorganic nanoplatform, especially for cancer treatments.

The synergistic effect of a BMP-7 derived peptide and cyclic RGD in regulating differentiation behaviours of mesenchymal stem cells.

Precisely controlling the behaviours of stem cells has far-reaching application potential in clinical trials. In this study, we have developed a self-assembled monolayer (SAM) of a cyclic RGD peptide (cycRGD) and bone forming peptide-1 (BFP-1) on a quartz substrate to regulate the behaviours of mesenchymal stem cells (MSCs). The results demonstrated that cycRGD can accelerate the cell adhesion on the substrate, thereby enhancing the ability of BFP-1 in mediating the osteogenic activity. And the synergistic effect between these two functional peptides in osteogenic differentiation of MSCs was confirmed in terms of immunofluorescent staining, Alizarin Red S staining for mineralization and alkaline phosphatase (ALP) activity assay. This finding might give a new insight into designing functional substrates to regulate desired differentiation of stem cells.