Microtubular stability affects pVHL-mediated regulation of HIF-1alpha via the p38/MAPK pathway in hypoxic cardiomyocytes

Genomic microsatellite characterization and development of polymorphic microsatellites in Eospalax baileyi

Microsatellite markers are cost-effective, rapid, efficient, and show great advantages in in large-sample kinship analysis and population structure studies. However, microsatellite loci are seriously underdeveloped in non-model organisms. The plateau zokor (Eospalax baileyi) is a key species living underground in the Tibetan Plateau, the effective management of which has long been challenging. In this study, we analyzed the distribution characteristics and functions of microsatellites in the genome of plateau zokors, and their polymorphic sites. The mononucleotide and dinucleotide types being the most abundant in the genome. The largest number of microsatellites and their abundance in the intergenic region whereas the smallest number of microsatellites and their abundance in the coding region. The coding sequences containing microsatellites were annotated to 52 major functional genes and assigned 19,358 Gene Ontology entries. The Kyoto Encyclopedia of Genes and Genomes pathway was the most enriched in the signal transduction pathway. Thirteen pairs of polymorphic loci were successfully amplified, with the number of alleles ranging from 3 to 8, observed heterozygosity ranging from 0.059 to 0.810, and expected heterozygosity ranging from 0.469 to 0.854. These microsatellite markers provide a cornerstone for studies on the identification of parentage and population genetics of plateau zokors.

Deciphering the effective combinatorial components from Si-Miao-Yong-An decoction regarding the intervention on myocardial hypertrophy

ETHNOPHARMACOLOGICAL RELEVANCE

Si-Miao-Yong-An decoction (SMYAD), a classical traditional Chinese medicine (TCM) formula, has been used to treat various cardiovascular diseases in clinics.

AIM OF THE STUDY

The aim of this study is to investigate the effective combinatorial components from SMYAD and its mechanism regarding the intervention on myocardial hypertrophy.

MATERIALS AND METHODS

SMYAD constituents absorbed in rat plasma and heart were identified using UHPLC Q-Exactive-Orbitrap MS/MS. The identified constituents in SMYAD were further analyzed using ADMET (absorption, distribution, metabolism, excretion and toxicity) prediction and molecular docking. The effective constituents were identified using isoproterenol (ISO)-induced H9c2 cardiomyocyte hypertrophy, and neochlorogenic acid (NCA), chlorogenic acid (CA), cryptochlorogenic acid (CCA), isochlorogenic acid C (ICAC), angoroside C (AGDC), isochlorogenic acid A (ICAA), sweroside (SRD), and harpagide (HPD) in SMYAD extract were quantified by HPLC for compatibility. Finally, anti-hypertrophic activities of candidate effective combinatorial components, which were prepared according to the determined molar concentration ratio of effective constituents using reference substance solution, were analyzed using immunofluorescence staining and Quantitative real-time PCR. The expression levels of PI3Kα, p-ERK, p-Akt, Akt, p-mTOR, mTOR and HIF-1α were measured using Western blot.

RESULTS

32 prototypes of SMYAD were identified from plasma and heart tissue of rat. Combining with ADMET prediction, 31 dominant constituents were focused. Based on HIF-1 pathway identified in preliminary result, 17 targets were focused, which were used to dock with 31 constituents. 27 constituents were therefore hit as the potential effective constituents of SMYAD in inhibiting myocardial hypertrophy. Bioactivity evaluation showed that NCA, CA, CCA, ICAC, AGDC, ICAA, SRD, and HPD significantly inhibited the increase of H9c2 cell surface area induced by ISO. Except for ICAA and AGDC, the remaining 6 effective constituents, showing a certain inhibitory effect on ISO-induced ANP mRNA overexpression at high and low concentrations, participated in compatibility based on the molar concentration ratio determined by HPLC. Effective combinatorial components composed of the 6 effective constituents (effective combinatorial components ABC) showed significant inhibitory effect on the increase of cell surface area, and the overexpression of ANP and β-MHC mRNA in H9c2 cells induced by ISO. Moreover, effective combinatorial components ABC significantly inhibited the protein overexpressions of p-Akt, p-mTOR and HIF-1α. Based on the results, we put forward the strategy of "Focusing constituents" and "Focusing targets" for the effective constituents research of TCM formula.

CONCLUSION

Effective combinatorial components ABC composed of NCA, CA, CCA, ICAC, SRD and HPD from SMYAD inhibited ISO-induced cardiomyocyte hypertrophy and down-regulated expression of ANP and β-MHC mRNA through the inactivation of Akt/mTOR/HIF-1α pathway.

Study on hypoxia-inducible factor and its roles in immune system

The Hypoxia-Inducible Factor-1 (HIF-1) is a dimeric protein complex that plays a significant role in responding to low oxygen or hypoxia concentrations. Chronic inflammation is one of the immune system responses and can increase HIF expression in involved tissues through lowering the oxygen and hypoxia. The HIF factor has many critical roles in immunity, and thus, we reviewed the crucial roles of this factor in the immune system. The results showed various key roles on the immune system, including physical defenses, innate immune (neutrophils apoptosis, macrophages) and inflammatory responses (pyrexia and local heat, iron access, etc.), upregulation in response to microbial infections, cytokines expression (IL-1, IL-2, IL-6, IL-8, IL-12, IL-18, TNF, etc.), drug targeting, etc. The HIF roles in the acquired immune system include: enhance the adaptation of cells (dendritic cells) to new conditions and triggering the signal pathways. The findings of the present review demonstrated that the HIF has important roles in the immune system, including physical defense, innate immune as well as acquired immunity; therefore, it may be considered as a potent drug targeting several diseases such as cancers, infectious diseases, etc.

H(+)/Cl(‑) exchange transporter 7 promotes lysosomal acidification‑mediated autophagy in mouse cardiomyocytes

Autophagy protects cardiomyocytes in various pathological and physiological conditions; however, the molecular mechanisms underlying its influence and the promotion of autophagic clearance are not completely understood. The present study aimed to explore the role of H(+)/Cl(−) exchange transporter 7 (CLC-7) in cardiomyocyte autophagy. In this study, rapamycin was used to induce autophagy in mouse cardiomyocytes, and the changes in CLC-7 were investigated. The expression levels of CLC-7 and autophagy-related proteins, such as microtubule associated protein 1 light chain 3, autophagy related 5 and Beclin 1, were detected using western blotting or immunofluorescence. Autolysosomes were observed and analyzed using transmission electron microscopy and immunofluorescence following CLC-7 silencing with small interfering RNAs. Cellular viability was assessed using Cell Counting Kit-8 and lactate dehydrogenase assays. Lysosomal acidification was measured using an acidification indicator. Increased CLC-7 co-localization with lysosomes was identified during autophagy. CLC-7 knockdown weakened the acidification of lysosomes, which are the terminal compartments of autophagy flux, and consequently impaired autophagy flux, ultimately resulting in cell injury. Collectively, the present study demonstrated that in cardiomyocytes, CLC-7 may contribute to autophagy via regulation of lysosomal acidification. These findings provide novel insights into the role of CLC-7 in autophagy and cytoprotection.

Toll-like Receptor 4-Induced Glycolytic Burst in Human Monocyte-Derived Dendritic Cells Results from p38-Dependent Stabilization of HIF-1α and Increased Hexokinase II Expression

Cell metabolism now appears as an essential regulator of immune cells activation. In particular, TLR stimulation triggers metabolic reprogramming of dendritic cells (DCs) with an increased glycolytic flux, whereas inhibition of glycolysis alters their functional activation. The molecular mechanisms involved in the control of glycolysis upon TLR stimulation are poorly understood for human DCs. TLR4 activation of human monocyte-derived DCs (MoDCs) stimulated glycolysis with an increased glucose consumption and lactate production. Global hexokinase (HK) activity, controlling the initial rate-limiting step of glycolysis, was also increased. TLR4-induced glycolytic burst correlated with a differential modulation of HK isoenzymes. LPS strongly enhanced the expression of HK2, whereas HK3 was reduced, HK1 remained unchanged, and HK4 was not expressed. Expression of the other rate-limiting glycolytic enzymes was not significantly increased. Exploring the signaling pathways involved in LPS-induced glycolysis with various specific inhibitors, we observed that only the inhibitors of p38-MAPK (SB203580) and of HIF-1α DNA binding (echinomycin) reduced both the glycolytic activity and production of cytokines triggered by TLR4 stimulation. In addition, LPS-induced HK2 expression required p38-MAPK-dependent HIF-1α accumulation and transcriptional activity. TLR1/2 and TLR2/6 stimulation increased glucose consumption by MoDCs through alternate mechanisms that are independent of p38-MAPK activation. TBK1 contributed to glycolysis regulation when DCs were stimulated via TLR2/6. Therefore, our results indicate that TLR4-dependent upregulation of glycolysis in human MoDCs involves a p38-MAPK-dependent HIF-1α accumulation, leading to an increased HK activity supported by enhanced HK2 expression.

The key role of microtubules in hypoxia preconditioning-induced nuclear translocation of HIF-1α in rat cardiomyocytes

Background

Hypoxia-inducible factor (HIF)-1 is involved in the regulation of hypoxic preconditioning in cardiomyocytes. Under hypoxic conditions, HIF-1α accumulates and is translocated to the nucleus, where it forms an active complex with HIF-1β and activates transcription of approximately 60 kinds of hypoxia-adaptive genes. Microtubules are hollow tubular structures in the cell that maintain cellular morphology and that transport substances. This study attempted to clarify the role of microtubule structure in the endonuclear aggregation of HIF-1α following hypoxic preconditioning of cardiomyocytes.

Methods

Primary rat cardiomyocytes were isolated and cultured. The cardiomyocyte culture system was used to establish a hypoxia model and a hypoxic preconditioning model. Interventions were performed on primary cardiomyocytes using a microtubule-depolymerizing agent and different concentrations of a microtubule stabilizer. The microtubule structure and the degree of HIF-1α nuclear aggregation were observed by confocal laser scanning microscopy. The expression of HIF-1α in the cytoplasm and nucleus was detected using Western blotting. Cardiomyocyte energy content, reflected by adenosine triphosphate/adenosine diphosphate (ATP/ADP), and key glycolytic enzymes were monitored by colorimetry and high-performance liquid chromatography (HPLC). Reactive oxygen species (ROS) production was also used to comprehensively assess whether microtubule stabilization can enhance the myocardial protective effect of hypoxic preconditioning.

Results

During prolonged hypoxia, it was found that the destruction of the microtubule network structure of cardiomyocytes was gradually aggravated. After this preconditioning, an abundance of HIF-1α was clustered in the nucleus. When the microtubules were depolymerized and hypoxia pretreatment was performed, HIF-1α clustering occurred around the nucleus, and HIF-1α nuclear expression was low. The levels of key glycolytic enzymes were significantly higher in the microtubule stabilizer group than in the hypoxia group. Additionally, the levels of lactate dehydrogenase and ROS were significantly lower in the microtubule stabilizer group than in the hypoxia group.

Conclusion

The microtubules of cardiomyocytes may be involved in the process of HIF-1α endonuclear aggregation, helping to enhance the anti-hypoxic ability of cardiomyocytes.

The resveratrol analogue, 3,4,5,4'‑trans-tetramethoxystilbene, inhibits the growth of A375 melanoma cells through multiple anticancer modes of action

Resveratrol is a natural dietary product that has demonstrated multifaceted anticancer activity. Several analogues of resveratrol have been synthesized in an effort to enhance the pharmacological potency and improve the pharmacokinetic properties of the compound. 3,4,5,4'‑trans‑tetramethoxystilbene (3,4,5,4'‑TMS) is a methoxylated analogue of resveratrol that has demonstrated anti-proliferative activity in vitro (in cancer cell lines) and in vivo (in xenograft models). In the present study, the anticancer effects of 3,4,5,4'‑TMS in A375 human melanoma cells were examined. 3,4,5,4'‑TMS markedly inhibited the proliferation of A375 cells (IC50=0.7 µM), via a mechanism involving mitotic arrest at the prometaphase stage of cell division. This effect was accompanied by the upregulation of the expression of the mitogen activated protein kinases, JNK and p38, and the concomitant activation of p38, that was verified by the nuclear translocation of the phoshorylated form of the protein. The pharmacological inhibition of p38 by SB203580 (4 µM) attenuated the effects of 3,4,5,4'‑TMS, as demonstrated by decreased cell cycle progression at the mitotic phase. Furthermore, 3,4,5,4'‑TMS increased the total levels of Aurora A, while it inhibited the localization of the protein to the spindle poles. Finally, 3,4,5,4'‑TMS exhibited anti-metastatic activity, inhibiting A375 cell migration and the attachment of the cells to a collagen type IV-coated surface. Collectively, the data suggest that 3,4,5,4'‑TMS is an effective chemotherapeutic drug for the treatment of human melanoma and that it exerts its effects through multiple anticancer modes of action.

Propofol administration to the fetal-maternal unit reduces cardiac oxidative stress in preterm lambs subjected to prenatal asphyxia and cardiac arrest

BACKGROUND

Little is known about the effects of propofol on oxidative stress and its effect on key structures of the contractile apparatus as the myosin light chain 2 (MLC2) and the p38MAPK survival pathway in the preterm heart. We hypothesized that propofol administration could attenuate the hypoxic myocardial injury after birth asphyxia.

METHODS

Pregnant ewes were randomized to receive either propofol or isoflurane anesthesia. A total of 44 late-preterm lambs were subjected to in utero umbilical cord occlusion (UCO), resulting in asphyxia and cardiac arrest, or sham treatment. After emergency cesarean delivery, each fetus was resuscitated, mechanically ventilated, and supported under anesthesia for 8 h using the same anesthetic as the one received by its mother.

RESULTS

At 8 h after UCO, occurrence of reactive oxygen species and activation of inducible nitric oxide synthase in the heart were lower in association with propofol anesthesia than with isoflurane. This was accompanied by less degradation of MLC2 but higher p38MAPK level and in echocardiography with a trend toward a higher median left ventricular fractional shortening.

CONCLUSION

The use of propofol resulted in less oxidative stress and was associated with less cytoskeletal damage of the contractile apparatus than the use of isoflurane anesthesia.

β-Catenin is central to DUX4-driven network rewiring in facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is an incurable disease, characterized by skeletal muscle weakness and wasting. Genetically, FSHD is characterized by contraction or hypomethylation of repeat D4Z4 units on chromosome 4, which causes aberrant expression of the transcription factor DUX4 from the last repeat. Many genes have been implicated in FSHD pathophysiology, but an integrated molecular model is currently lacking. We developed a novel differential network methodology, Interactome Sparsification and Rewiring (InSpiRe), which detects network rewiring between phenotypes by integrating gene expression data with known protein interactions. Using InSpiRe, we performed a meta-analysis of multiple microarray datasets from FSHD muscle biopsies, then removed secondary rewiring using non-FSHD datasets, to construct a unified network of rewired interactions. Our analysis identified β-catenin as the main coordinator of FSHD-associated protein interaction signalling, with pathways including canonical Wnt, HIF1-α and TNF-α clearly perturbed. To detect transcriptional changes directly elicited by DUX4, gene expression profiling was performed using microarrays on murine myoblasts. This revealed that DUX4 significantly modified expression of the genes in our FSHD network. Furthermore, we experimentally confirmed that Wnt/β-catenin signalling is affected by DUX4 in murine myoblasts. Thus, we provide the first unified molecular map of FSHD signalling, capable of uncovering pathomechanisms and guiding therapeutic development.

Human renal carcinoma cells respond to Newcastle disease virus infection through activation of the p38 MAPK/NF-κB/IκBα pathway

PURPOSE

Newcastle disease virus (NDV) is an oncolytic virus that is known to have a higher preference to cancer cells than to normal cells. It has been proposed that this higher preference may be due to defects in the interferon (IFN) responses of cancer cells. The exact mechanism underlying this process, however, remains to be resolved. In the present study, we examined the antiviral response towards NDV infection of clear cell renal cell carcinoma (ccRCC) cells. ccRCC is associated with mutations of the von Hippel-Lindau tumor suppressor gene VHL, whose protein product is important for eliciting cellular responses to changes in oxygen levels. The most common first line treatment strategy of ccRCC includes IFN. Unfortunately, most ccRCC cases are diagnosed at a late stage and often are resistant to IFN-based therapies. Alternative treatment approaches, including virotherapy using oncolytic viruses, are currently being investigated. The present study was designed to investigate the mechanistic pathways underlying the response of ccRCC cells to oncolytic NDV infection.

METHODS AND RESULTS

We found that NDV induces activation of NF-κB in ccRCC cells by inducing phosphorylation and subsequent degradation of IκBα. IκBα was found to be phosphorylated as early as 1 hour post-infection and to result in rapid NF-κB nuclear translocation and activation. Importantly, p38 MAPK phosphorylation was found to occur upstream of the NDV-induced NF-κB activation. Restoration of VHL in ccRCC cells did not result in a reduction of this phosphorylation. A similar phenomenon was also observed in several other cancer-derived cell lines.

CONCLUSION

Our data provide evidence for involvement of the p38 MAPK/NF-κB/IκBα pathway in NDV infection and subsequent induction of apoptosis in ccRCC cells.

Analysis of grayscale characteristics in images of labeled microtubules from cultured cardiac myocytes

Microtubules of cardiac myocytes depolymerize after a hypoxic insult or treatment with colchicine. However, little attention has been paid to quantifying changes in microtubule distribution when using fluorescent images. We converted fluorescence images of labeled microtubules in H9C2 cardiac myocytes to grayscale images, then filtered the images to remove any noise, and used grayscale histograms to quantify features of the images. The results show that parameters such as the mean, variance, skewness, kurtosis, energy, and entropy can be used to quantitatively describe the distribution of microtubules in cells. Quantitative characteristics of microtubule distribution were similar after culturing cells under hypoxic conditions or after treatment with colchicine. These results parallel those described for neonatal rat cardiac myocytes following ischemia and hypoxia. In addition, we provide a method for internal segmentation of the cells, which revealed that microtubular depolymerization was more evident near the cell membrane following hypoxia or colchicine treatment.

Role of Ran-regulated nuclear-cytoplasmic trafficking of pVHL in the regulation of microtubular stability-mediated HIF-1α in hypoxic cardiomyocytes

Our previous study suggested that microtubule network alteration affects the process of glycolysis in cardiomyocytes (CMs) via the regulation of hypoxia-inducible factor (HIF)-1α during the early stages of hypoxia. However, little is known regarding the underlying mechanisms of microtubule network alteration-induced changes of HIF-1α. The von Hippel–Lindau tumor suppressor protein (pVHL) has been shown to mediate the ubiquitination of HIF-1α in the nuclear compartment prior to HIF-1α exportation to the cytoplasm, and pVHL dynamic nuclear-cytoplasmic trafficking is indicated to be involved in the process of HIF-1α degradation. In this study, by administering different microtubule-stabilizing and -depolymerizing interventions, we demonstrated that microtubule stabilization promoted pVHL nuclear export and drove the translocation of pVHL to the cytoplasm, while microtubule disruption prevented pVHL nuclear export in hypoxic CMs. Moreover, the ratio between nuclear and cytoplasmic pVHL was associated with HIF-1α regulation. Importantly, microtubule network alteration also affected the subcellular localization of Ran, which was involved in the regulation of pVHL nuclear-cytoplasmic trafficking. The above results suggest that the subcellular translocation of pVHL plays an important role in microtubular structure alteration-induced HIF-1α regulation. Interestingly, Ran is involved in the process of pVHL nuclear-cytoplasmic trafficking following microtubule network alteration in hypoxic CMs.

Ultrasound-mediated destruction of paclitaxel and oxygen loaded lipid microbubbles for combination therapy in ovarian cancer xenografts

We have synthesized multifunctional oxygen and paclitaxel loaded microbubbles (OPLMBs) for ultrasound mediated delivery of combination therapy in an ovarian cancer xenograft model. In comparison with other therapeutic options, intravenous injection of OPLMBs followed by ultrasound mediation yielded a superior therapeutic outcome. Immunohistochemical analyses of the dissected tumor tissue confirmed the increased tumor apoptosis and the reduced VEGF expression after treatment. Western Blot tests further confirmed the decreased expressions of HIF-1α and P-gp. Our experiment suggests that ultrasound mediation of OPLMBs may provide a promising drug delivery strategy for the combination treatment of ovarian cancer.

Phosphorylation-dependent mitochondrial translocation of MAP4 is an early step in hypoxia-induced apoptosis in cardiomyocytes

Hypoxic or ischemic apoptosis is often tightly associated with the opening of mitochondrial permeability transition pore (mPTP); however, the molecular mechanisms regulating mPTP and thus mitochondrial-dependent apoptosis remain elusive. Emerging evidence indicates that the movement of key proteins in or out of mitochondria play a critical regulatory role in apoptosis. Here, we reported that, unexpectedly, the microtubule-associated protein 4 (MAP4) translocated from cytosol to mitochondria upon phosphorylation after hypoxia treatment in neonatal cardiomyocytes. When targeted to mitochondria, MAP4 was found to lead to mPTP opening and induce apoptosis. Mitochondrial accumulation and pro-apoptotic function of MAP4 could be reversed through the genetic inhibition of MAP4 phosphorylation. The MAP4(Ala) mutant, which mimicked the dephosphorylated form, suppressed mitochondrial translocation and apoptosis. Our data reveal a novel role of MAP4 in cardiac apoptosis and suggest a potential therapeutic strategy targeting mitochondrial translocation of MAP4 against apoptotic heart diseases.

Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming

Ocean acidification represents a threat to marine species worldwide, and forecasting the ecological impacts of acidification is a high priority for science, management, and policy. As research on the topic expands at an exponential rate, a comprehensive understanding of the variability in organisms' responses and corresponding levels of certainty is necessary to forecast the ecological effects. Here, we perform the most comprehensive meta-analysis to date by synthesizing the results of 228 studies examining biological responses to ocean acidification. The results reveal decreased survival, calcification, growth, development and abundance in response to acidification when the broad range of marine organisms is pooled together. However, the magnitude of these responses varies among taxonomic groups, suggesting there is some predictable trait-based variation in sensitivity, despite the investigation of approximately 100 new species in recent research. The results also reveal an enhanced sensitivity of mollusk larvae, but suggest that an enhanced sensitivity of early life history stages is not universal across all taxonomic groups. In addition, the variability in species' responses is enhanced when they are exposed to acidification in multi-species assemblages, suggesting that it is important to consider indirect effects and exercise caution when forecasting abundance patterns from single-species laboratory experiments. Furthermore, the results suggest that other factors, such as nutritional status or source population, could cause substantial variation in organisms' responses. Last, the results highlight a trend towards enhanced sensitivity to acidification when taxa are concurrently exposed to elevated seawater temperature.