Cardiac tumour necrosis factor receptor-associated factor 7 mediates the ubiquitination of apoptosis signal-regulating kinase 1 and aggravates cardiac hypertrophy.

AIMS: Cardiac remodelling is a common pathophysiological process in the development of various cardiovascular diseases, but there is still a lack of effective interventions. Tumour necrosis receptor-associated factor 7 (TRAF7) belongs to the tumour necrosis factor receptor-associated factor family and plays an important role in biological processes. Previous studies have shown that TRAF7 mutations lead to congenital defects and malformations of the heart. However, the molecular mechanisms of TRAF7 in the underlying pathogenesis of pathological cardiac hypertrophy remain unknown. We aim to study the molecular mechanisms and effects of TRAF7 in cardiac remodelling and whether it has the potential to become a therapeutic target for cardiac remodelling. METHODS AND RESULTS: The pressure overload-induced cardiac hypertrophy model in mice was established via transverse aortic constriction (TAC) surgery, and cardiomyocytes were treated with phenylephrine (PE) to induce hypertrophic phenotype. Levels of cardiac dysfunction and remodelling were measured with echocardiography and tissue or cell staining. RNA sequencing, western blot, qRT-PCR, co-immunoprecipitation, and in vivo ubiquitination assays were used to explore the molecular mechanisms. The results showed that the expression of TRAF7 increased gradually during the development of hypertrophy. Accordingly, TRAF7 significantly exacerbated the PE-induced enlargement of primary neonatal Sprague-Dawley rat cardiomyocytes, whereas TRAF7 knockdown alleviated the hypertrophic phenotype in primary cardiomyocytes. Cardiac-specific overexpression of TRAF7 accelerated hypertrophic phenotype in mice and cardiac-specific Traf7 conditional knockout mice improved hypertrophic phenotype induced by TAC. Mechanistically, TRAF7 directly interacted with apoptosis signal-regulating kinase-1 (ASK1) and promoted ASK1 phosphorylation by mediating the K63-linked ubiquitination of ASK1 in response to PE stimulation, which then promoted ASK1 activation and downstream signalling during cardiac hypertrophy. Notably, the pro-hypertrophic effect of TRAF7 was largely blocked by GS4997 in vitro and cardiac-specific Ask1 conditional knockout in vivo. CONCLUSION: In summary, we identified TRAF7 as an essential regulator during cardiac hypertrophy, and modulation of the regulatory axis between TRAF7 and ASK1 could be a novel therapeutic strategy to prevent this pathological process.

Forkhead box A2-mediated lncRNA SOX2OT up-regulation alleviates oxidative stress and apoptosis of renal tubular epithelial cells by promoting SIRT1 expression in diabetic nephropathy.

BACKGROUND: Renal tubular injury is the main feature of diabetic nephropathy (DN). We intend to investigate the function and related mechanisms of lncRNA SOX2 overlapping transcript (SOX2OT) in high glucose (HG)-induced oxidative stress and apoptosis of renal tubular epithelial cells (RTECs). METHODS: To construct diabetes models, the human kidney-2 (HK-2) cells were treated with HG (30 mM), and mice were injected with streptozotocin. The levels of intracellular and mitochondrial reactive oxygen species (ROS) were assessed by dihydroethidium staining and MitoSox staining. The cell apoptosis was assessed by flow cytometry and TUNEL staining. Levels of serum creatinine, blood urea nitrogen (BUN), Urinary ACR, and oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) were detected by relevant kits. In addition, fluorescence in situ hybridization staining, RNA-pull down, RNA immunoprecipitation (RIP), co-immunoprecipitation (co-IP), dual-luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) were also executed. RESULTS: Levels of SOX2OT and silent information regulator 1 (SIRT1) were down-regulated in HG-cultured HK-2 cells. Overexpressing SOX2OT reduced intracellular and mitochondrial ROS levels and cell apoptosis in vitro. Moreover, SOX2OT overexpression also reduced serum creatinine, BUN, urinary ACR, 8-OHdG, renal tubular injury markers KIM1 and NGAL, ROS levels, and cell apoptosis in vivo. In addition, SOX2OT promoted SIRT1 expression by suppressing its ubiquitination. Besides, interference with SIRT1 reversed the inhibitory effect of SOX2OT overexpression on HG-induced oxidative stress and apoptosis. Forkhead box A2 (Foxa2) levels were up-regulated in HG-cultured HK-2 cells. Foxa2 could bind to the SOX2OT promoter and suppress its expression. Furthermore, interfering with SOX2OT reversed the inhibitory effect of Foxa2 interference on HG-induced oxidative stress and apoptosis. CONCLUSION: Foxa2-mediated SOX2OT up-regulation reduced oxidative stress and apoptosis of RTECs by promoting SIRT1 expression, thus alleviating the progression of DN.

[Effect of Ferric-carbon Micro-electrolysis on Greenhouse Gas Emissions from Constructed Wetlands].

As the problem of global warming becomes increasingly serious, the greenhouse gas (GHG) emission reduction measures of constructed wetlands (CWs) have drawn significant attention. Ferric-carbon micro-electrolysis exhibits an excellent effect on wastewater purification as well as the potential to reduce GHG emissions. Therefore, to explore the impact of ferric-carbon micro-electrolysis on GHG emissions from intermittent aeration constructed wetlands, four kinds of different wetlands with different fillers were constructed. The four fillers were ferric-carbon micro-electrolysis filler+gravel (CW-Ⅰ), ferric-carbon micro-electrolysis filler+zeolite (CW-Ⅱ), zeolite (CW-Ⅲ), and gravel (CW-Ⅳ). Intermittent aeration technology was used to aerate the wetland systems. The results show that ferric-carbon micro-electrolysis significantly improved the nitrogen removal efficiency of the intermittent aeration constructed wetlands and reduced GHG emissions. Compared with CW-Ⅳ, the CH4 fluxes of CW-Ⅰ, CW-Ⅱ, and CW-Ⅲ decreased by 32.81% (P<0.05), 52.66% (P<0.05), and 54.50% (P<0.05), respectively. Among them, zeolite exhibited a stronger reduction effect on CH4 emissions in both the aeration and non-aeration sections. The ferric-carbon micro-electrolysis substantially reduced N2O emissions. In comparison with CW-Ⅳ, CW-, and CW-Ⅱ achieved N2O emission reduction by 30.29%-60.63% (P<0.05) and 43.10%-73.87% (P<0.05), respectively. During a typical hydraulic retention period, the comprehensive GWP caused by CH4 and N2O emitted by each group of wetland system are (85.21±6.48), (49.24±3.52), (127.97±11.44), and (137.13±11.45) g·m-2, respectively. The combined use of ferric-carbon micro-electrolysis and zeolite effectively reduces GHG emissions in constructed wetlands. Overall, ferric-carbon micro-electrolysis combined with zeolite (CW-Ⅱ) can be regarded as one of the valuable filler combination methods for constructed wetlands, which can ensure high removal efficiency of pollutants and effective GHG emission reduction in constructed wetlands.

Up-regulation of miR-135b expression induced by oxidative stress promotes the apoptosis of renal tubular epithelial cells under high glucose condition.

This study aimed to investigate the role and underlying mechanism of miR-135b in high glucose-induced oxidative stress of renal tubular epithelial cells. Here, in vivo experiments found that compared to the control group, miR-135b expression was significantly up-regulated in the diabetes group, whereas BMP7 mRNA and protein levels were down-regulated. In high glucose-treated renal tubular epithelial cells (HK-2) in vitro, oxidative stress was induced, which up-regulated miR-135b expression. In addition, the regulation of miR-135b on BMP7 expression was confirmed in HK-2 cells. Under high glucose conditions, oxidative stress promoted the apoptosis of HK-2 cells through the up-regulation of miR-135b expression. In vivo experiments indicated that interference with miR-135b improved renal function in mice with diabetic nephropathy. In conclusion, these results indicated that the up-regulation of miR-135b expression induced by oxidative stress promotes the apoptosis of HK-2 cells under high glucose conditions.

Vagal Nerve Stimulation Attenuates Ischemia-Reperfusion Induced Retina Dysfunction in Acute Ocular Hypertension.

Purpose: The present study aimed to investigate whether cervical vagal nerve stimulation (VNS) could prevent retinal ganglion cell (RGC) loss and retinal dysfunction after ischemia/reperfusion (I/R) injury. Methods: First, rats were randomly divided into sham group (n = 4) and VNS group (n = 12). Activation of the nodose ganglia (NOG), nucleus of the solitary tract (NTS), superior salivatory nucleus (SSN), and pterygopalatine ganglion (PPG) neural circuit were evaluated by c-fos expression at 0 h after sham VNS and at 0 h (n = 4), 6 h (n = 4), 72 h (n = 4) after VNS. Secondly, rats were randomly assigned to I/R group (pressure-induced retinal ischemia for 1 h and reperfusion for 1 h in the right eye, n = 16) and I/R+VNS group (right cervical VNS for 2 h during the I/R period, n = 16). The left eye of each rat served as a control. Electroretinogram (ERG), RGC numbers, tumor necrosis factor-α (TNF-α) and vasoactive intestinal polypeptide (VIP) levels in retina were determined. Additionally, the level of VIP in PPG was evaluated. Results: In the first part of the study, compared with the sham group, the VNS group exhibited significantly increased expression of c-fos in NOG, NTS, SSN, and PPG tissues at 0, 6, and 72 h. In the second part of the study, compared with left eyes, retinal function in right eyes (as assessed by the a-wave, b-wave and the oscillatory potential amplitudes of ERG and RGC data) was significantly decreased by I/R. The decreased retinal function was attenuated by VNS. In addition, I/R induced an increase in inflammation, which was reflected by elevated TNF-α expression in the retina. VNS significantly attenuated the increase in I/R-induced inflammation. Moreover, VIP expression in the retina and PPG, which may contribute to the inhibition of the inflammatory response, was significantly increased after VNS. Conclusion: VNS could protect against retinal I/R injury by downregulating TNF-α. Upregulation of VIP expression due to activation of the NOG-NTS-SSN-PPG neural circuit may underlie to the protective effects of VNS.

Expression pattern of type 3 adenylyl cyclase in rodent dorsal root ganglion and its primary afferent terminals.

cAMP (Cyclic Adenosine monophosphate), one of the most highly studied second messengers, is regulated by a family of adenylyl cyclase (AC) enzymes. Type 3 adenylyl cyclase (abbreviated as AC3), a subtype of adenylyl cyclase, is reported to be expressed in cilia in the olfactory and central nervous system and plays an important role in many physiological functions such as olfaction, development. However, expression of AC3 in the dorsal root ganglion (DRG) is not reported. In the present study, using immunohistochemical method, we discovered that AC3 immunoreactivity (IR) is predominantly expressed in the cytoplasm of small to medium sized DRG neurons. Double labelling revealed that the majority of AC3 IR are colocalized with CGRP (a peptidergic nociceptor marker), rarely with NF200 (a myelinated neuronal marker) or IB4 (a nonpeptidergic nociceptor marker). Furthermore, dense AC3 IR exists in the superficial dorsal horn, especially in laminaⅠand dorsal part of lamina II, where CGRP-positive DRG neurons terminate. The expression pattern of AC3 is similar between C57/BL6 J mouse and Sprague Dawley rat. For instance, AC3 is primarily expressed in the cell bodies of small to medium sized DRG neurons and the majority of AC3 IR is also in CGRP-containing neurons in rat. Taken together, our data suggest that AC3 is primarily expressed in the small to medium sized cell bodies and central terminals of CGRP-positive DRG neurons, implying AC3 enzyme might potentially function in nociception.