YAP activity protects against endotoxemic acute lung injury by activating multiple mechanisms.

The roles of the Hippo­Yes­associated protein (YAP) pathway in lung injury and repair remain elusive. The present study examined the effects of systemic inhibition or stimulation of YAP activity on lung injury, repair and inflammation in a mouse model of lipopolysaccharide (LPS)­induced lung injury. Mice were treated with or without YAP inhibitor, verteporfin, or with or without YAP stimulator, XMU­MP­1, and intraperitoneally injected with LPS (7.5 mg/kg). Lung injury and repair were evaluated by histological analysis and by testing for markers of lung injury. Lung inflammation was assessed by measuring tissue levels of inflammatory mediators. Lung injury was associated with a decreased, whereas lung repair was associated with an increased YAP activity evidenced by nuclear translocation. Lung injury was associated with a high level of lung inflammation and epithelial adherens junction disassembly, but not with cell proliferation or epithelial cell regeneration. The injury phase was defined as 0­48 h post­LPS injection, and the 48­168 h time period was considered the repair phase. Inhibition of YAP activity at the injury phase, using verteporfin, exacerbated, whereas its stimulation, using XMU­MP­1, alleviated lung injury, lung inflammation and epithelial adherens junction disassembly. Inhibition or stimulation of YAP activity at the injury phase had no effects on cell proliferation or epithelial regeneration. By contrast, lung repair was associated with inflammation resolution, increased cell proliferation, epithelial regeneration and reassembly of epithelial adherens junctions. Inhibition of YAP activity at the repair phase delayed inflammation resolution, impeded lung recovery, inhibited cell proliferation and epithelial regeneration, and inhibited epithelial adherens junction reassembly. Stimulation of YAP activity at the repair phase reversed all these processes. The results of the current study demonstrated that the Hippo­YAP activity serves a protective role against endotoxemic lung injury. The Hippo­YAP activity alleviated lung inflammation and injury at the injury phase and promoted inflammation resolution and lung repair at the repair phase.

Hippo signaling pathway in cardiovascular development and diseases.

Cardiovascular diseases have become the leading cause of death in the world. Understanding the development of cardiovascular system and the pathogenesis of cardiovascular diseases will promote the generation of novel preventive and therapeutic strategy. The Hippo pathway is a recently identified signaling cascade that plays a critical role in organ size control, cell proliferation, apoptosis and fate determination of stem cells. Gene knockout and transgenic mouse models have revealed that the Hippo signaling pathway is involved in heart development, cardiomyocyte proliferation, apoptosis, hypertrophy and cardiac regeneration. The Hippo signaling pathway also regulates vascular development, differentiation and various functions of vascular cells. Dysregulation of the Hippo signaling pathway leads to different kinds of cardiovascular diseases, such as myocardial infarction, cardiac hypertrophy, neointima formation and atherosclerosis. In this review, we briefly summarize current research on the roles and regulation mechanisms of the Hippo signaling pathway in cardiovascular development and diseases.

[Effects of electroacupuncture on synovia free radicals in rabbits with knee osteoarthritis].

OBJECTIVE: To observe the effect of electroacupuncture( EA) on synovia superoxide dismutase (SOD) activity, malondialdehyde (MDA) and nitric oxide (NO) contents in rabbits with knee osteoarthritis (KOA). METHODS: A total of 40 New Zealand rabbits were randomly divided into control, model, massage and EA groups, with 10 cases in each. KOA model was established by gypusum fixing method. EA (1.6-2 Hz, 1-2 mA) was applied to left "Yanglingquan" (GB 34), "Xuehai" (SP 10), "Zusanli" (ST 36) and "Liangqiu" (ST 34) for 25 min, once daily for 21 days. For massage group, the affected knee joint was pressed, kneaded, stretched and rotated repeatedly for 15 min every time, followed by forced running about 100 m. The intra-joint synovia was collected (0.4-0.6 ml) for detecting contents of SOD with xanthine oxidase method, MDA with thiobarbituric acid method and NO with nitrate reductase method. RESULTS: Compared with control group, synovia SOD activity in model group decreased considerably (P<0.05), while MDA and NO contents increased significantly (P<0.05). After 3 weeks' treatment, compared with pre-treatment and model group, synovia SOD activity increased markedly (P<0.05), and MDA and NO contents lowered remarkably in both EA and massage groups (P<0.05). No significant differences were found between EA and massage groups in these 3 indexes (P>0.05). CONCLUSION: Both EA and massage can raise synovia SOD activity and lower MDA and NO content, which may contribute to their effect in relieving knee osteoarthritis in the rabbit.

[Effects of electroacupuncture on synovia IL-1beta and TNF-alpha contents in the rabbit with knee osteoarthritis].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on synovia IL-1beta and TNF-alpha contents in rabbits with knee osteoarthritis (KOA). METHODS: A total of 40 New Zealand rabbits were randomly divided into control, model, massage and EA groups. KOA model was established by gypsum fixing method. EA (2 Hz, 1-3 mA) was applied to left "Xiyan" (EX-LE 5), "Yanglingquan" (GB 34), "Xuehai" (SP 10), "Zusanli" (ST 36) and "Liangqiu" (ST 34) for 30 min, once daily and continuously for 21 days. For massage group, the affected knee joint was pressed, kneaded, stretched and rotated repeatedly for 15 min every time, followed by forced running about 100 m. The intra-joint synovia was collected (0.4-0.6 mL) for detecting the contents of IL-1beta and TNF-alpha with radioimmunoassay. RESULTS: No IL-1beta and TNF-alpha were detected in the synovia in control group, while in the other 3 groups, synovia IL-1beta and TNF-alpha levels increased significantly. Before treatment, no significant differences were found among model, EA and massage groups in the levels of IL-1beta and TNF-alpha (P > 0.05), while after the treatment the two indexes both decreased considerably (P < 0.05). Compared with model group, the two indexes were remarkably lower (P < 0.05), but no significant differences were found between EA and massage groups in synovia IL-1beta and TNF-alpha contents (P > 0.05). CONCLUSION: Both EA and massage can effectively suppress the release of synovia IL-1beta and TNF-alpha in KOA of rabbits, which may contribute to the effect of acupuncture in the treatment of osteoarthritis.

Noncanonical cAMP pathway and p38 MAPK mediate beta2-adrenergic receptor-induced IL-6 production in neonatal mouse cardiac fibroblasts.

We previously reported that cardiac fibroblasts, but not cardiomyocytes, are served as the predominant source of IL-6 after isoproterenol stimulation in mouse myocardium. The present study investigated the molecular mechanism of isoproterenol-mediated secretion of IL-6 in mouse cardiac fibroblasts. Treatment of cells with isoproterenol-induced a time-dependent accumulation of IL-6, which was mediated by beta(2)-adrenergic receptor (AR), the preponderant beta-AR subtype in cardiac fibroblasts. Isoproterenol-induced secretion of IL-6 was mainly mediated by Gs-AC-cAMP signaling cascade and could be negatively regulated by Gi and PI3K. Surprisingly, the effect of cAMP was independent of protein kinase A and the exchange protein directly activated by cAMP (Epac)-Rap1 pathway and suggests the existence of a novel cAMP-dependent mechanism. p38 MAPK inhibitor SB203580, but not extracellular regulated protein kinase inhibitor, abrogated isoproterenol-induced IL-6 release in cardiac fibroblasts and mouse myocardium. Interestingly, p38 MAPK could also be positively regulated by Gs-AC-cAMP but negatively regulated by Gi-PI3K pathway. Finally, multiple transcription factors (AP-1, C/EBP, NF-kappaB and CREB) regulating the IL-6 gene are activated in response to isoproterenol stimulation, which may provide essential linkage between upstream cAMP-p38 MAPK signaling cascade and downstream IL-6 gene transcription. The present results suggest that beta(2)-AR mediates IL-6 production through a noncanonical cAMP responsible pathway and p38 MAPK.

Interleukin-6 family of cytokines mediates isoproterenol-induced delayed STAT3 activation in mouse heart.

This study was aimed to determine whether beta-adrenergic receptor (beta-AR) stimulated by isoproterenol (ISO) activates signal transducers and activators of transcription (STAT) in mouse heart and, if so, to examine the underlying mechanism. We found that treatment of adult male mice by ISO (15 mg/kg body weight, intraperitoneal) caused a delayed STAT3 activation (at 60-120 min), which was fully abolished by beta-AR antagonist, propranolol. ISO-induced phosphorylation of STAT3 was markedly enhanced by phosphodiesterase inhibitor amrinone, indicating that cAMP is critically involved in beta-AR-mediated STAT3 activation. In addition, beta-AR stimulation significantly increased gene expression of interleukin-6 (IL-6) family of cytokines (IL-6, leukemia inhibitory factor, ciliary neurotrophic factor, and cardiotrophin-1). IL-6 protein levels in serum and mouse myocardium were also significantly increased in response to ISO treatment. In cultured cardiac fibroblasts, IL-6 level was enhanced significantly after ISO (10-6 mol/liter) stimulation for 2 h and then peaked at 12 h, whereas the response of IL-6 in cultured cardiomyocytes to ISO stimulation was not significant, suggesting that ISO-induced increase in IL-6 is primarily from cardiac fibroblasts rather than cardiomyocytes. Most importantly, IL-6 could activate STAT3 in a time-dependent manner in cultured cardiomyocytes, and inhibition of IL-6 level by anti-IL-6-neutralizing antibody clearly attenuated ISO-induced phosphorylation of STAT3 in myocardium. Taken together, these results indicate that beta-AR stimulation leads to a delayed STAT3 activation via an IL-6 family of cytokine-mediated pathway and that cardiac fibroblasts, but not cardiomyocytes, is probably the predominant source of IL-6 in response to ISO stimulation in mouse myocardium.