Suppressed nuclear envelope proteins activate autophagy of vascular smooth muscle cells during cyclic stretch application.

Dysfunctions of vascular smooth muscle cells (VSMCs) play crucial roles in vascular remodeling in hypertension, which correlates with pathologically elevated cyclic stretch due to increased arterial pressure. Recent researches reported that autophagy, a life-sustaining process, was increased in hypertension. However, the mechanobiological mechanism of VSMC autophagy and its potential roles in vascular remodeling are still unclear. Using renal hypertensive rats in vivo and FX5000 stretch application Unit in vitro, the autophagy of VSMCs was detected. The results showed that LC3II remarkably enhanced in hypertensive rats and 15% cyclic stretch (mimic the pathologically increased mechanical stretch in hypertension), and the activity of mammalian target of rapamycin (mTOR) was suppressed in 15% cyclic stretch. Administration of autophagy inhibitors, bafilomycin A1 and chloroquine, repressed VSMC proliferation efficiently, but did not affect the degradation of two important nuclear envelope (NE) proteins, lamin A/C and emerin. Using RNA interference to decline the expression of lamin A/C and emerin, respectively, we discovered that autophagy was upregulated under both static and 5% cyclic stretch conditions, accompanying with the decreased mTOR activity. During 15% cyclic stretch application, mTOR inhibition was responsible for autophagy elevation. Chloroquine administration in vivo inhibited the expression of PCNA (marker of proliferation) of abdominal aorta in hypertensive rats. Altogether, these results demonstrated that pathological cyclic stretch suppresses the expression of lamin A/C and emerin which subsequently represses mTOR pathway so as to induce autophagy activation. Blocking autophagic flux may be a practicable way to relieve the pathological vascular remodeling in hypertensive.

Lamin A/C negatively regulated by miR-124-3p modulates apoptosis of vascular smooth muscle cells during cyclic stretch application in rats.

AIM: Apoptosis of vascular smooth muscle cells (VSMCs) influenced by abnormal cyclic stretch is crucial for vascular remodelling during hypertension. Lamin A/C, a nuclear envelope protein, is mechano-responsive, but the role of lamin A/C in VSMC apoptosis is still unclear. METHODS: FX-5000T Strain Unit provided cyclic stretch (CS) in vitro. AnnexinV/PI and cleaved Caspase 3 ELISA detected apoptosis. qPCR was used to investigate the expression of miR-124-3p and a luciferase reporter assay was used to evaluate the ability of miR-124-3p binding to the Lmna 3'UTR. Protein changes of lamin A/C and relevant molecules were detected using western blot. Ingenuity Pathway Analysis and Protein/DNA array detected the potential transcription factors. Renal hypertensive rats verified these changes. RESULTS: High cyclic stretch (15%-CS) induced VSMC apoptosis and repressed lamin A/C expressions compared with normal (5%-CS) control. Downregulation of lamin A/C enhanced VSMC apoptosis. In addition, 15%-CS had no significant effect on mRNA expression of Lmna, and lamin A/C degradation was not induced by autophagy. 15%-CS elevated miR-124-3p bound to the 3'UTR of Lmna and negatively regulated protein expression of lamin A/C. Similar changes occurred in renal hypertensive rats compared with sham controls. Lamin A/C repression affected activity of TP53, CREB1, MYC, STAT1/5/6 and JUN, which may in turn affect apoptosis. CONCLUSION: Our data suggested that the decreased expression of lamin A/C upon abnormal cyclic stretch and hypertension may induce VSMC apoptosis. These mechano-responsive factors play important roles in VSMC apoptosis and might be novel therapeutic targets for vascular remodelling in hypertension.

Single-cell analyses reveal functional classification of dendritic cells and their potential roles in inflammatory disease.

Dendritic cells (DCs) have crucial roles in immune-related diseases. However, it is difficult to explore DCs because of their rareness and heterogeneity. Although previous studies had been performed to detect the phenotypic characteristics of DC populations, the functional diversity has been ignored. Using a combination of flow cytometry, single-cell quantitative PCR, and bioinformatic analysis, we depicted the DC panorama with not only phenotypic but also functional markers. Functional classification of DCs in mouse lymphoid tissue (spleen) and nonlymphoid tissue (liver) was performed. The results revealed that expression of macrophage scavenger receptor 1 ( MSR1) and C-C motif chemokine receptors ( CCR) 1, CCR2, and CCR4 were elevated in liver DCs, suggesting increased lipid uptake and migration abilities. The enriched expression of costimulatory molecule CD80, TLR9, and TLR adaptor MYD88 in spleen DCs indicated a more-mature phenotype, enhanced pathogen recognition, and T-cell stimulation abilities. Furthermore, we compared DCs in the atherosclerotic mouse models with healthy controls. In addition to the quantitative increase in DCs in the liver and spleen of the apolipoprotein E-knockout ( ApoE-/-) mice, the functional expression patterns of the DCs also changed at the single-cell level. These results promote our understanding of the participation of DCs in inflammatory diseases and have potential applications in DC clinical assessment.-Shi, Q., Zhuang, F., Liu, J.-T., Li, N., Chen, Y.-X., Su, X.-B., Yao, A.-H., Yao, Q.-P., Han, Y., Li, S.-S., Qi, Y.-X., Jiang, Z.-L. Single-cell analyses reveal functional classification of dendritic cells and their potential roles in inflammatory disease.

Cyclic stretch induces VEGFA alternative splicing via Serine/Arginine-Rich Splicing Factor 1.

Abnormal proliferation of vascular smooth muscle cells (VSMCs) induced by high cyclic stretch is crucial in the vascular remodeling during hypertension. Vascular endothelial growth factor A (VEGFA) alternative splicing plays important roles in the pathological process of vascular diseases and remodeling. However, the roles of VEGFA isoforms in modulating VSMC functions in response to cyclic stretch remain unclear. We hypothesize that high cyclic stretch may induce VEGFA alternative splicing via Serine/arginine-rich splicing factor 1 (SRSF1) which subsequently induce VSMC proliferation. In the present research, hypertensive rat model was established using the abdominal aortic constriction method. In comparison with sham-operated group, immunohistology staining showed translocation of SRSF1 into nuclei in hypertensive rat thoracic aorta, and RT-PCR detected a shift of VEGFA expression pattern, including the increased expression of VEGFA120 and VEGFA164, but not VEGFA188.Then VSMCs were subjected to cyclic stretch in vitro using a Flexercell strain unit. VEGFA ELISA assay showed 15% cyclic stretch increased the secretion of VEGFA which significantly increased proliferation of VSMCs. Western blot and immunofluorescence detected accumulation of SRSF1 in nuclei after 15% cyclic stretch application. Furthermore, SRSF1-specific siRNA transfection reversed the VEGFA secretion induced by pathological high cyclic stretch. Our present results suggested that pathologically high cyclic stretch induces the shuttling of SRSF1 which results in the secretive pattern splicing of VEGFA and finally contributes to the proliferation of VSMCs.

Platelet-derived microparticles promote endothelial cell proliferation in hypertension via miR-142-3p.

Endothelial cells (ECs) are located at the interface between flowing blood and the vessel wall, and abnormal EC proliferation induced by pathologic environments plays an important role in vascular remodeling in hypertensive conditions. Exchanges of information between blood components and ECs are important for EC function. Hence, the present study sought to determine how platelets induce EC dysfunction under hypertensive conditions. EC proliferation was increased in renal hypertensive rats established by abdominal aortic coarctation compared with control rats and that elevated thrombin in plasma promoted platelet activation, which may induce the release of platelet-derived microparticles (PMPs). MicroRNA (MiR) array and qPCR revealed a higher level of miR-142-3p in platelets and PMPs. In vitro, PMPs delivered miR-142-3p into ECs and enhanced their proliferation via Bcl-2-associated transcription factor (BCLAF)1 and its downstream genes. These results indicate that PMPs deliver miR-142-3p from activated platelets into ECs and that miR-142-3p may play important roles in EC dysfunction in hypertensive conditions and may be a novel therapeutic target for maintaining EC homeostasis in hypertension.-Bao, H., Chen, Y.-X., Huang, K., Zhuang, F., Bao, M., Han, Y., Chen, X.-H., Shi, Q., Yao, Q.-P., Qi, Y.-X. Platelet-derived microparticles promote endothelial cell proliferation in hypertension via miR-142-3p.

Atrial fibrillation: rhythm control offers no advantage over rate control for some, but not all.

Atrial fibrillation (AF) is not a benign condition. Although AF is the most common sustained cardiac arrhythmia, the management of AF remains controversial. In recent years, several clinical trials comparing rhythm control with rate control for AF management found that rhythm control offers no advantage over rate control, but the findings may not apply equally to all patients. The main point is the high risk of AF recurrence in these trials and the toxic effects and poor efficacy of presently available antiarrhythmic drugs negate the benefit of rhythm control. Rhythm control should be considered as the preferred initial therapy if sinus rhythm had been maintained in a higher proportion of patients. For the moment, the optimal strategy to treat AF should be individualized, with a bias towards rate control if patients are at high risk for arrhythmias or can be kept asymptomatic. Rhythm control may still be justified in younger patients or patients who still have symptoms despite adequate rate control. In addition, patients with new or first-episode AF often warrant at least an initial trial of rhythm control.