Adiponectin upregulates prolyl-4-hydroxylase α1 expression in interleukin 6-stimulated human aortic smooth muscle cells by regulating ERK 1/2 and Sp1

Role of Sp1 in atherosclerosis

Specificity protein (Sp) is a famous family of transcription factors including Sp1, Sp2 and Sp3. Sp1 is the first one of Sp family proteins to be characterized and cloned in mammalian. It has been proposed that Sp1 acts as a modulator of the expression of target gene through interacting with a series of proteins, especially with transcriptional factors, and thereby contributes to the regulation of diverse biological processes. Notably, growing evidence indicates that Sp1 is involved in the main events in the development of atherosclerosis (AS), such as inflammation, lipid metabolism, plaque stability, vascular smooth muscle cells (VSMCs) proliferation and endothelial dysfunction. This review is designed to provide useful clues to further understanding roles of Sp1 in the pathogenesis of AS, and may be helpful for the design of novel efficacious therapeutics agents targeting Sp1.

Melatonin enhances atherosclerotic plaque stability by inducing prolyl-4-hydroxylase α1 expression

OBJECTIVE

Melatonin, an endogenous neurohormone secreted predominately by the pineal gland, has a variety of physiological functions. However, its protective role in atherosclerosis is not clear. In this study, we sought to investigate the potential effects of melatonin in modulating atherosclerotic plaque stability in apolipoprotein E knockout (ApoE) mice.

METHOD AND RESULTS

Smooth muscle cells were treated with melatonin, which significantly increased mRNA and protein levels of a key intracellular enzyme essential for collagen maturation and secretion, prolyl-4-hydroxylase α1 (P4Hα1). Mechanistically, melatonin increased Akt phosphorylation and transcriptional activation of specificity protein 1 (Sp1), which bound with the P4Hα1 promoter and then induced P4Hα1 expression. Pretreatment with either Akt inhibitor LY294002 or Sp1 inhibitor mithramycin A (MTM) could inhibit melatonin-induced P4Hα1 expression. Finally, atherosclerotic lesions were induced by placing a perivascular collar on the right common carotid artery of ApoE mice, which were received with or without different doses of melatonin or MTM. High-dose melatonin enhanced atherosclerotic plaque stability in ApoE mice in vivo by inducing the expression of P4Hα1, which was reversed by MTM.

CONCLUSION

We propose that melatonin supplementation may provide a novel and promising approach to atherosclerosis treatment.

Pro-inflammatory Cytokines in Acute Coronary Syndromes

BACKGROUND

Over the last decades, the role of inflammation and immune system activation in the initiation and progression of coronary artery disease (CAD) has been established.

OBJECTIVES

The study aimed to present the interplay between cytokines and their actions preceding and shortly after ACS.

METHODS

We searched in a systemic manner the most relevant articles to the topic of inflammation, cytokines, vulnerable plaque and myocardial infarction in MEDLINE, COCHRANE and EMBASE databases.

RESULTS

Different classes of cytokines (intereleukin [IL]-1 family, Tumor necrosis factor-alpha (TNF-α) family, chemokines, adipokines, interferons) are implicated in the entire process leading to destabilization of the atherosclerotic plaque, and consequently, to the incidence of myocardial infarction. Especially IL-1 and TNF-α family are involved in inflammatory cell accumulation, vulnerable plaque formation, platelet aggregation, cardiomyocyte apoptosis and adverse remodeling following the myocardial infarction. Several cytokines such as IL-6, adiponectin, interferon-γ, appear with significant prognostic value in ACS patients. Thus, research interest focuses on the modulation of inflammation in ACS to improve clinical outcomes.

CONCLUSION

Understanding the unique characteristics that accompany each cytokine-cytokine receptor interaction could illuminate the signaling pathways involved in plaque destabilization and indicate future treatment strategies to improve cardiovascular prognosis in ACS patients.

Integrative proteomics and immunochemistry analysis of the factors in the necrosis and repair in acetaminophen-induced acute liver injury in mice

Acetaminophen (APAP) overdose-induced acute liver injury (AILI) is a significant clinical problem worldwide, the hepatotoxicity mechanisms are well elucidated, but the factors involved in the necrosis and repair still remain to be investigated. APAP was injected intraperitoneally in male Institute of Cancer Research (ICR) mice. Quantitative proteome analysis of liver tissues was performed by 2-nitrobenzenesulfenyl tagging, two-dimensional-nano high-performance liquid chromatography separation, and matrix-assisted laser desorption/ionization-time of flight mass spectrometry analysis. Diffrenetial proteins were verified by the immunochemistry method. 36 and 44 differentially expressed proteins were identified, respectively, at 24 hr after APAP (200 or 300 mg·kg ^-1 ) administration. The decrease in the mitochondrial protective proteins Prdx6, Prdx3, and Aldh2 accounted for the accumulation of excessive reactive oxygen species (ROS) and aldehydes, impairing mitochondria structure and function. The Gzmf combined with Bax and Apaf-1 jointly contributed to the necrosis. The blockage of Stat3 activation led to the overexpression of unphosphorylated Stat3 and the overproduction of Bax. The overexpression of unphosphorylated Stat3 represented necrosis; the alternation from Stat3 to p-Stat3 in necrotic regions represented hepatocytes from death to renewal. The high expressions of P4hα1, Ncam, α-SMA, and Cygb were involved in the liver repair, they were not only the markers of activated HSC but also represented an intermediate stage of hepatocytes from damage or necrosis to renewal. Our data provided a comprehensive report on the profile and dynamic changes of the liver proteins in AILI; the involvement of Gzmf and the role of Stat3 in necrosis were revealed; and the role of hepatocyte in liver self-repair was well clarified.

Rosuvastatin Attenuates CD40L-Induced Downregulation of Extracellular Matrix Production in Human Aortic Smooth Muscle Cells via TRAF6-JNK-NF-κB Pathway

CD40L and statins exhibit pro-inflammatory and anti-inflammatory effects, respectively. They are both pleiotropic and can regulate extracellular matrix (ECM) degeneration in an atherosclerotic plaque. Statins can decrease both the CD40 expression and the resulting inflammation. However, the effects of CD40L and stains on atherosclerotic plaque ECM production and the underlying mechanisms are not well established. Moreover, prolyl-4-hydroxylase α1 (P4Hα1) is involved in collagen synthesis but its correlations with CD40L and statins are unknown. In the present study, CD40L suppressed P4Hα1 expression in human aortic smooth muscle cells (HASMCs) in a dose- and time-dependent manner, with insignificant changes in MMP2 expression and negative enzymatic activity of MMP9. CD40L increased TRAF6 expression, JNK phosphorylation, NF-κB nuclear translocation as well as DNA binding. Furthermore, silencing TRAF6, JNK or NF-κB genes abolished CD40L-induced suppression of P4Hα1. Lower NF-κB nuclear import rates were observed when JNK or TRAF6 silenced HASMCs were stimulated with CD40L compared to HASMCs with active JNK or TRAF6. Together, these results indicate that CD40L suppresses P4Hα1 expression in HASMCs by activating the TRAF6-JNK- NF-κB pathway. We also found that rosuvastatin inhibits CD40L-induced activation of the TRAF6-JNK- NF-κB pathway, thereby significantly rescuing the CD40L stimulated P4Hα1 inhibition. The results from this study will help find potential targets for stabilizing vulnerable atherosclerotic plaques.

Pathway-Based Genome-wide Association Studies Reveal That the Rac1 Pathway Is Associated with Plasma Adiponectin Levels

Pathway-based analysis as an alternative and effective approach to identify disease-related genes or loci has been verified. To decipher the genetic background of plasma adiponectin levels, we performed genome wide pathway-based association studies in extremely obese individuals and normal-weight controls. The modified Gene Set Enrichment Algorithm (GSEA) was used to perform the pathway-based analyses (the GenGen Program) in 746 European American females, which were collected from our previous GWAS in extremely obese (BMI > 35 kg/m(2)) and never-overweight (BMI<25 kg/m(2)) controls. Rac1 cell motility signaling pathway was associated with plasma adiponectin after false-discovery rate (FDR) correction (empirical P < 0.001, FDR = 0.008, family-wise error rate = 0.008). Other several Rac1-centered pathways, such as cdc42racPathway (empirical P < 0.001), hsa00603 (empirical P = 0.003) were among the top associations. The RAC1 pathway association was replicated by the ICSNPathway method, yielded a FDR = 0.002. Quantitative pathway analyses yielded similar results (empirical P = 0.001) for the Rac1 pathway, although it failed to pass the multiple test correction (FDR = 0.11). We further replicated our pathway associations in the ADIPOGen Consortium data by the GSA-SNP method. Our results suggest that Rac1 and related cell motility pathways might be associated with plasma adiponectin levels and biological functions of adiponectin.

Mechanical stretch promotes matrix metalloproteinase-2 and prolyl-4-hydroxylase α1 production in human aortic smooth muscle cells via Akt-p38 MAPK-JNK signaling

Hypertension can increase mechanical stretch on the vessel wall, an important stimulus that induces collagen remodeling. Prolyl-4-hydroxylaseα1 (P4Hα1) and matrix metalloproteinases (MMPs) are essential for collagen synthesis and degradation. However, the effect of mechanical strain and collagen synthesis remains largely unknown. This study aimed to identify the effect of stretch on MMPs and P4Hα1 and the involved signaling pathways. Human aortic smooth muscle cells (HASMCs) were stimulated with mechanical stretch (0, 10% and 18% strain), and production of P4Hα1 as well as production and gelatinolytic activity of MMP-2 was force-dependently increased. Mechanical stretch at 18% also increased the expression of type I and III collagen and the phosphorylation of Akt, p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK). MMP-2 production and activity enhanced by 18% stretch were inhibited by the PI3K/Akt inhibitor LY294002. Blockade of p38 MAPK or JNK inhibited the promoting effect of stretch on P4Hα1. The in vivo model of aortic banding showed increased protein levels of MMP-2, P4Hα1 and collagen I and III in the aorta. Thus, mechanical stretch increased MMP-2 and P4Hα1 expression in HASMCs via AKT-P38 MAPK-JNK signaling, thereby inducing vascular remodeling.

Simvastatin increases Prolyl-4-Hydroxylase α1 expression in atherosclerotic plaque and ox-LDL-stimulated human aortic smooth muscle cells via p38 MAPK and ERK1/2 signaling

Prolyl-4-Hydroxylase α1 (P4Hα1) is essential for collagen synthesis but the effect of statin on P4Hα1 is unknown. We hypothesize that simvastatin may increase the expression of P4Hα1 in atherosclerotic plaques and ox-LDL-stimulated human aortic smooth muscle cells (HASMCs). In HASMCs, ox-LDL suppressed P4Hα1 expression significantly with peak value occurring at 50 ug/ml treated for 8h. Ox-LDL also inhibited the expression of type I and III collagen and increased the phosphorylation level of p38 MAPK and ERK1/2, but blockade or silencing of p38 and ERK1/2 inhibited the suppressive effect of ox-LDL on P4Hα1. Then HASMCs were stimulated with or without ox-LDL (50 ug/ml) for 8h after simvastatin pretreatment for 1h. Simvastatin significantly attenuated the suppressive effect of ox-LDL on P4Hα1 and collagen production by inhibiting ox-LDL uptake and the activation of p38 MAPK and ERK1/2. In apolipoprotein E-deficient mice, simvastatin and the inhibitors of p38 and ERK1/2 significantly increased the stability of the carotid plaques. We also found that simvastatin significantly increased the expression of P4Hα1 and collagen possibly due to decreased ox-LDL content and phosphorylation of p38 and ERK1/2 in plaques. Thus, simvastatin increases P4Hα1 and collagen expression in ox-LDL-stimulated HASMCs and atherosclerotic plaques via p38 MAPK and ERK1/2, thereby exerting a plaque stabilizing effect.

Lactoferricin enhances BMP7-stimulated anabolic pathways in intervertebral disc cells

Bone-morphogenetic protein-7 (BMP7) is a well-known anabolic and anti-catabolic growth factor on intervertebral disc (IVD) matrix and cell homeostasis. Similarly, Lactoferricin B (LfcinB) has recently been shown to have pro-anabolic, anti-catabolic, anti-oxidative and/or anti-inflammatory effects in bovine disc cells in vitro. In this study, we investigated the potential benefits of using combined peptide therapy with LfcinB and BMP7 for intervertebral disc matrix repair and to understand cellular and signaling mechanisms controlled by these factors. We studied the effects of BMP7 and LfcinB as individual treatments and combined therapy on bovine nucleus pulposus (NP) cells by assessing proteoglycan (PG) accumulation and synthesis, and the gene expression of matrix protein aggrecan and transcription factor SOX-9. We also analyzed the role of Noggin, a BMP antagonist, in IVD tissue and examined its effect after stimulation with LfcinB. To understand the molecular mechanisms by which LfcinB synergizes with BMP7, we investigated the ERK-SP1 axis as a downstream intracellular signaling regulator involved in BMP7 and LfcinB-mediated activities. Treatment of bovine NP cells cultured in alginate with LfcinB plus BMP7 synergistically stimulates PG synthesis and accumulation in part by upregulation of aggrecan gene expression. The synergism results from LfcinB-mediated activation of Sp1 and SMAD signaling pathways by (i) phosphorylation of SMAD 1/5/8; (ii) downregulation of SMAD inhibitory factors [i.e., noggin and SMAD6 (inhibitory SMAD)]; and (iii) upregulation of SMAD4 (universal co-SMAD). These data indicate that LfcinB-suppression of Noggin may eliminate the negative feedback of BMP7, thereby maximizing biological activity of BMP7 and ultimately shifting homeostasis to a pro-anabolic state in disc cells. We propose that combination growth factor therapy using BMP7 and LfcinB may be beneficial for treatment of disc degeneration.

miR-122 regulates collagen production via targeting hepatic stellate cells and suppressing P4HA1 expression

BACKGROUND & AIMS

MicroRNAs (miRNAs) have been shown to be involved in many biological processes by affecting their target gene expression. miR-122 has been extensively studied in hepatocarcinogenesis. However, the role of miR-122 in liver fibrosis remains unknown.

METHODS

The mRNA expression levels of miR-122, prolyl 4-hydroxylase subunit alpha-1 (P4HA1), and CCAAT/enhancer binding protein alpha (C/EBPα) were assessed by real-time PCR. The protein expression levels of P4HA1, C/EBPα and collagen, type I, alpha 1 (COL1A1) were analyzed by Western blot and immunofluorescence. MTT assay was used to assess cell proliferation. Chromatin immunoprecipitation (ChIP) assay was used to examine the binding activity of C/EBPα to miR-122 promoter.

RESULTS

miR-122 expression was significantly reduced in transactivated HSCs and in the livers of mice treated with CCl(4). Overexpression of miR-122 inhibited the proliferation of LX2 cells. We also demonstrated that P4HA1 was a target gene of miR-122. The mRNA expression level of PAHA1 inversely correlated with that of miR-122 in HSCs and in the mouse liver. Overexpression of miR-122 markedly attenuated the expression of P4HA1 via targeting a binding site located at 3'-UTR of P4HA1 mRNA. We further showed that miR-122 overexpression led to decreased collagen maturation and ECM production. Finally, the binding activity of C/EBPα to miR-122 promoter was significantly decreased in activated HSCs.

CONCLUSIONS

Our study suggests that miR-122 may play an important role in negatively regulating collagen production in HSCs and that targeted expression of miR-122 in HSCs may represent a new strategy for the treatment of liver fibrosis.

miR-122 regulates collagen production via targeting hepatic stellate cells and suppressing P4HA1 expression

BACKGROUND & AIMS

MicroRNAs (miRNAs) have been shown to be involved in many biological processes by affecting their target gene expression. miR-122 has been extensively studied in hepatocarcinogenesis. However, the role of miR-122 in liver fibrosis remains unknown.

METHODS

The mRNA expression levels of miR-122, prolyl 4-hydroxylase subunit alpha-1 (P4HA1), and CCAAT/enhancer binding protein alpha (C/EBPα) were assessed by real-time PCR. The protein expression levels of P4HA1, C/EBPα and collagen, type I, alpha 1 (COL1A1) were analyzed by Western blot and immunofluorescence. MTT assay was used to assess cell proliferation. Chromatin immunoprecipitation (ChIP) assay was used to examine the binding activity of C/EBPα to miR-122 promoter.

RESULTS

miR-122 expression was significantly reduced in transactivated HSCs and in the livers of mice treated with CCl(4). Overexpression of miR-122 inhibited the proliferation of LX2 cells. We also demonstrated that P4HA1 was a target gene of miR-122. The mRNA expression level of PAHA1 inversely correlated with that of miR-122 in HSCs and in the mouse liver. Overexpression of miR-122 markedly attenuated the expression of P4HA1 via targeting a binding site located at 3'-UTR of P4HA1 mRNA. We further showed that miR-122 overexpression led to decreased collagen maturation and ECM production. Finally, the binding activity of C/EBPα to miR-122 promoter was significantly decreased in activated HSCs.

CONCLUSIONS

Our study suggests that miR-122 may play an important role in negatively regulating collagen production in HSCs and that targeted expression of miR-122 in HSCs may represent a new strategy for the treatment of liver fibrosis.

Globular adiponectin protects H9c2 cells from palmitate-induced apoptosis via Akt and ERK1/2 signaling pathways

Background

Cardiomyocytes apoptosis is an important contributor to myocardial dysfunction and heart failure. Adiponectin has cardioprotective effects, potential mechanisms behind it are not clear in cardiomyocytes. The purpose of the study was to investigate whether adiponectin can block palmitate-induced apoptosis and the underlying biochemical mechanism in H9c2 cells.

Methods

H9c2 cells were treated with palmitate presence or absence of 2.5 μg/mL globular adiponectin. The effect on the cell viability of H9c2 cells was evaluated using MTT assay, and cell apoptosis was determined by Hoechst 33342 staining. Protein expression was measured using the western blot method.

Results

Our results showed that the palmitate treatment induced apoptosis in H9c2 cells, which was associated with increasing the level of cleaved caspase-3 and cleaved PARP. Meanwhile, palmitate-induced apoptosis increased the protein level of p-ERK1/2, and decreased the protein level of p-Akt significantly. However, levels of both of these proteins were restored to the normal when pretreated with adiponectin, and followed with the decrease of cleaved caspase-3 and cleaved PARP. In line with these results, the protective effect of adiponectin can be blocked by PI3K/Akt inhibitor LY294002, and palmitate-induced apoptosis can be attenuated by ERK1/2 inhibitor U0126.

Conclusions

Taken together, the present study demonstrated that adiponectin protects H9c2 cells from palmitate-induced apoptosis via PI3K/Akt and ERK1/2 signaling pathways. Our results reveal a link between adiponectin and cardiomyocytes apoptosis, suggesting that adioponectin may be a promising therapeutic for the treatment of lipotoxicity cardiomyopathy.

Proteomic analysis of the nuclear phosphorylated proteins in dairy cow mammary epithelial cells treated with estrogen

Estrogen regulates a variety of physiological processes, including mammary gland growth, morphogenesis of the mammary gland, proliferation and differentiation, and elevating the expression of milk proteins. Many nuclear phosphorylated proteins such as pStat5 and mTOR regulate milk protein synthesis. But the detail of milk protein synthesis controlled at the transcript level and posttranslational level is not well-known. To contribute to the understanding of the molecular mechanism underlying estrogen action on the dairy cow mammary epithelial cells (DCMECs), nuclear phosphorylated proteins regulated by estrogen in DCMECs were identified. Two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization/time of flight mass spectrometry were used to identify the changes of nuclear phosphorylated proteins in DCMECs treated with estrogen. Seven proteins were identified differentially up-expressed in DCMECs after 24-h estrogen exposure: including glycyl-tRNA synthetase, previously reported in milk protein synthesis of DCMECs, belonging to the class-II aminoacyl-tRNA synthetase family; proteins involved in other cellular functions, such as translation initiation factors, GTP-binding nuclear proteins, heat-shock proteins, and proteins belonging to ubiquitin-proteasome system. This screening reveals that estrogen influences the levels of nuclear phosphorylated proteins of DCMECs which opens new avenue for the study of the molecular mechanism linking to milk synthesis.

Adiponectin and interleukin-6 in inflammation-associated disease

Numerous lines of evidence implicate a role for adipose tissue in the development of a systemic inflammatory state that contributes to metabolic, cardiovascular, and autoimmune disorders. Serum levels of adiponectin, a cytokine that is mainly produced by adipocytes, are paradoxically decreased in individuals with obesity, type 2 diabetes, and cardiovascular disease compared with healthy individuals. Mounting experimental data have revealed that adiponectin exhibits beneficial effects on energy homeostasis and cardiovascular functions that are attributed to its direct modulation of a proinflammatory factor, interleukin-6. However, some recent studies indicate that adiponectin appears to function as an inducer of proinflammatory factors and the elevated adiponectin level aggravates inflammation response in autoimmune disease. In this review, we focus on the action of adiponectin in chronic inflammation-associated metabolic, cardiovascular, and autoimmune disorders. In particular, we discuss the interaction between adiponectin and interleukin-6 in adipocytes and cardiovascular cells.