Methionine sulfoxide reductase B2 protects against cardiac complications in diabetes mellitus.

Diabetes mellitus (DM) is a progressive, chronic metabolic disorder characterized by high oxidative stress, which can lead to cardiac damage. Methionine sulfoxylation (MetO) of proteins by excessive reactive oxygen species (ROS) can impair the basic functionality of essential cellular proteins, contributing to heart failure. Methionine sulfoxide reductase B2 (MsrB2) can reverse oxidation induced MetO in mitochondrial proteins, so we investigated its role in diabetic cardiomyopathy. We observed that DM-induced heart damage in diabetic mice model is characterized by increased ROS, increased protein MetO with mitochondria structural pathology, and cardiac fibrosis. In addition, MsrB2 was significantly increased in mouse DM cardiomyocytes, supporting the induction of a protective process. Further, MsrB2 directly induces Parkin and LC3 activation (mitophagy markers) in cardiomyocytes. In MsrB2, knockout mice displayed abnormal electrophysiological function, as determined by ECG analysis. Histological analysis confirmed increased cardiac fibrosis and disrupted cardiac tissue in MsrB2 knockout DM mice. We then corroborated our findings in human DM heart samples. Our study demonstrates that increased MsrB2 expression in the heart protects against diabetic cardiomyopathy.

Fabrication of Yolk-Shell Structure with Multifarious Nanoparticles via Double-Layered Encapsulation Strategy.

The post-encapsulation method (such as single-layered encapsulation) is a promising strategy to synthesize yolk-shell structures that protect functional nanoparticles by the molecular sieving effect. However, this method exhibited limited loading capacity and nonuniform encapsulation during the co-encapsulation of various nanoparticles owing to the insufficient surface area for nanoparticle attachment. To address these limitations, we proposed a double-layered encapsulation method comprising an increased number of silica template layers and separate attachment of multifarious nanoparticles to different layers. Compared with conventional methods, this strategy can precisely adjust the ratio of encapsulated nanoparticles and increase the loading amount, which improves the functionality of yolk-shell structures, such as the photothermal properties of gold nanoparticle-encapsulated yolk-shell structures (∼69%). We describe, for the first time, the precise control of the ratio of encapsulated nanoparticles and the loading of numerous nanoparticles. Consequently, this strategy has significant potential for various applications of yolk-shell structures.

Proteomic analysis reveals activation of platelet- and fibrosis-related pathways in hearts of ApoE-/- mice exposed to diesel exhaust particles.

Air pollution is an environmental risk factor linked to multiple human diseases including cardiovascular diseases (CVDs). While particulate matter (PM) emitted by diesel exhaust damages multiple organ systems, heart disease is one of the most severe pathologies affected by PM. However, the in vivo effects of diesel exhaust particles (DEP) on the heart and the molecular mechanisms of DEP-induced heart dysfunction have not been investigated. In the current study, we attempted to identify the proteomic signatures of heart fibrosis caused by diesel exhaust particles (DEP) in CVDs-prone apolipoprotein E knockout (ApoE-/-) mice model using tandem mass tag (TMT)-based quantitative proteomic analysis. DEP exposure induced mild heart fibrosis in ApoE-/- mice compared with severe heart fibrosis in ApoE-/- mice that were treated with CVDs-inducing peptide, angiotensin II. TMT-based quantitative proteomic analysis of heart tissues between PBS- and DEP-treated ApoE-/- mice revealed significant upregulation of proteins associated with platelet activation and TGFß-dependent pathways. Our data suggest that DEP exposure could induce heart fibrosis, potentially via platelet-related pathways and TGFß induction, causing cardiac fibrosis and dysfunction.

Clinical Usefulness of Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry Method for Low Serum Testosterone Measurement.

Background: Mass spectrometry methods exhibit higher accuracy and lower variability than immunoassays at low testosterone concentrations. We developed and validated an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay for quantifying serum total testosterone. Methods: We used an ExionLC UPLC (Sciex, Framingham, MA, USA) system and a Sciex Triple Quad 6500+ (Sciex) MS/MS system in electrospray ionization and positive ion modes with multiple reaction monitoring transitions to evaluate precision, accuracy, linearity, lower limit of quantitation (LLOQ), carryover, ion suppression, stability, and reference intervals. For method comparison, we measured serum testosterone concentrations using this method in 40 subjects whose testosterone concentrations ranged from 0.14 to 55.48 nmol/L as determined using the Architect i2000 immunoassay (Abbott Diagnostics, Abbott Park, IL, USA) and in an additional 160 sera with testosterone concentrations <1.67 nmol/L. Results: The intra- and inter-run precision CVs were <2.81%, and the accuracy bias values were <3.85%, which were all acceptable. The verified linear interval was 0.03-180.84 nmol/L; the LLOQ was 0.03 nmol/L. No significant carryover and ion suppression were observed. The testosterone in serum was stable at 4°C, at -20°C, and after three freeze-thaw cycles. The reference intervals were successfully verified. The correlation was good at testosterone concentrations of 0.14-55.48 nmol/L; however, the Architect assay showed positive percent bias at concentrations <1.67 nmol/L. Conclusions: The UPLC-MS/MS assay shows acceptable performance, with a lower LLOQ than the immunoassay. This method will enable the quantitation of low testosterone concentrations.

Diesel exhaust particles induce human umbilical vein endothelial cells apoptosis by accumulation of autophagosomes and caspase-8 activation.

Diesel exhaust particles (DEP) are risk factors for endothelial cells (ECs) dysfunction. However, the mechanism by which DEP induce ECs apoptosis remains unclear. Here, we investigated how DEP induce death of human umbilical vein ECs (HUVECs), with a focus on the autophagy-mediated apoptotic pathway. DEP induced dose-dependent HUVECs death and exposure to the IC50 concentration of DEP (70 µg/ml) led to apoptosis. DEP phosphorylated Beclin-1 (Ser93) and increased protein levels of p62 and LC3BII and the number of LC3B puncta, indicating autophagy initiation. DEP increased expression of pro- and mature forms of cathepsin D, which increases lysosomal activity. However, DEP suppressed expression of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins (STX17, VAMP8, SNAP29, YKT6, and STX7) to inhibit autolysosome formation, resulting in accumulation of autophagosomes. LC3B, p62, and caspase-8 form a tertiary complex in accumulated autophagosomes, which is known to serve as a platform for caspase-8 activation. Indeed, DEP activates caspase-8 and pretreatment with a caspase-8 inhibitor suppressed DEP-induced apoptosis. Furthermore, depletion of p62 decreased caspase-8 and caspase-3 activation and inhibited the DEP-induced apoptosis. Taken together, these findings demonstrated that DEP induced HUVECs apoptosis by inhibiting autophagosome maturation and identified caspase-8 as a novel mediator of DEP-induced ECs apoptosis.

The effect of tocolytics in women with preterm labor after 34 weeks of gestation: A propensity score-matched study.

OBJECTIVES: Since late preterm neonates are physiologically less mature than term neonates, the use of antenatal corticosteroids in the late preterm period has been recommended. The use of tocolytics can also be considered to gain valuable time for using antenatal corticosteroids in the late preterm period. In this study, we examined the efficacy of tocolytics on prolonging pregnancy in the late preterm period, by comparing women who received tocolytics with those who received none. STUDY DESIGN: This retrospective cohort study included women who were admitted due to preterm labor after 34 weeks of gestation and delivered in the late preterm period. Primary outcome was time from admission to delivery (days). Secondary outcomes were the proportion of preterm births within 2 days, and within 7 days, completed cycles of antenatal corticosteroids, and the neonatal outcomes. Primary and secondary outcomes were compared according to the use of tocolytics. Propensity score matching was performed to create comparable groups. The maternal age, pre-pregnancy body mass index, nulliparity, history of preterm birth, hypertensive disease during pregnancy, gestational diabetes mellitus, history of preterm labor, gestational age at admission, cervical length, and the number of contractions were the baseline characteristics included in the propensity score. RESULTS: Of 275 women, 44 women received tocolytics (tocolytics group) and 231 women did not (no tocolytics group). We matched 44 women who received tocolytics and 44 women who didn't. The tocolytics group was shown to exhibit a longer time from admission to delivery than the no tocolytics group, with a hazard ratio for tocolytics of 0.4 (95 % confidence interval, 0.2-0.6). In addition, the proportion of preterm births occurring within 2 days and 7 days were lower in those receiving tocolytics compared to those that didn't. CONCLUSION: In this propensity score matched-study, the use of tocolytics had a significant effect on pregnancy prolongation, which allows more time for use of corticosteroids in women with preterm labor after 34 weeks of gestation.

Transcriptional analysis of gasoline engine exhaust particulate matter 2.5-exposed human umbilical vein endothelial cells reveals the different gene expression patterns related to the cardiovascular diseases.

Particulate matter (PM) causes several diseases, including cardiovascular diseases (CVDs). Previous studies compared the gene expression patterns in airway epithelial cells and keratinocytes exposed to PM. However, analysis of differentially expressed gene (DEGs) in endothelial cells exposed to PM2.5 (diameter less than 2.5 µm) from fossil fuel combustion has been limited. Here, we exposed human umbilical vein endothelial cells (HUVECs) to PM2.5 from combustion of gasoline, performed RNA-seq analysis, and identified DEGs. Exposure to the IC50 concentrations of gasoline engine exhaust PM2.5 (GPM) for 24 h yielded 1081 (up-regulation: 446, down-regulation: 635) DEGs. The most highly up-regulated gene is NGFR followed by ADM2 and NUPR1. The most highly down-regulated gene is TNFSF10 followed by GDF3 and EDN1. Gene Ontology enrichment analysis revealed that GPM regulated genes involved in cardiovascular system development, tube development and circulatory system development. Kyoto Encyclopedia of Genes and Genomes and Reactome pathway analyses showed that genes related to cytokine-cytokine receptor interactions and cytokine signaling in the immune system were significantly affected by GPM. We confirmed the RNA-seq data of some highly altered genes by qRT-PCR and showed the induction of NGFR, ADM2 and IL-11 at a protein level, indicating that the observed gene expression patterns were reliable. Given the adverse effects of PM2.5 on CVDs, our findings provide new insight into the importance of several DEGs and pathways in GPM-induced CVDs.

Ternary Logic with Stateful Neural Networks Using a Bilayered TaOX -Based Memristor Exhibiting Ternary States.

A memristive stateful neural network allowing complete Boolean in-memory computing attracts high interest in future electronics. Various Boolean logic gates and functions demonstrated so far confirm their practical potential as an emerging computing device. However, spatio-temporal efficiency of the stateful logic is still too limited to replace conventional computing technologies. This study proposes a ternary-state memristor device (simply a ternary memristor) for application to ternary stateful logic. The ternary-state implementable memristor device is developed with bilayered tantalum oxide by precisely controlling the oxygen content in each oxide layer. The device can operate 157 ternary logic gates in one operational clock, which allows an experimental demonstration of a functionally complete three-valued Lukasiewicz logic system. An optimized logic cascading strategy with possible ternary gates is ≈20% more efficient than conventional binary stateful logic, suggesting it can be beneficial for higher performance in-memory computing.

Coronin 1B regulates the TNFα-induced apoptosis of HUVECs by mediating the interaction between TRADD and FADD.

Coronin 1B is an actin-binding protein that plays important roles in actin-dependent cellular processes. We previously reported that coronin 1B is involved in vascular endothelial cell growth factor-induced migration of human umbilical vein endothelial cells (HUVECs). However, the role of coronin 1B in tumor necrosis factor alpha (TNFα)-induced endothelial cell apoptosis remained unknown. In this study, we investigated whether coronin 1B affects TNFα-induced HUVEC apoptosis and sought to elucidate the mechanism by which coronin 1B regulates this cellular process. Depletion of coronin 1B by siRNA transfection decreased TNFα-induced apoptosis of HUVECs, as determined by MTT, terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase-3 activity assays. Coronin 1B depletion also decreased caspase-8 cleavage via a JNK-independent pathway. Coronin 1B interacted with Fas-associated death domain protein (FADD) in both a plasmid overexpression system in HEK293T cells and at the endogenous protein level in TNFα-stimulated HUVECs. Immunoprecipitation and in situ proximity ligation assays showed that coronin 1B depletion diminished the interaction between TNFα-induced TNF receptor-1-associated death domain protein (TRADD) and FADD, suggesting that coronin 1B is required for the TNFα-induced TRADD and FADD interaction and subsequent caspase-8/caspase-3 cascade activation, ultimately leading to apoptosis.

PAR-1 is a novel mechano-sensor transducing laminar flow-mediated endothelial signaling.

Recent studies have indicated that protease-activated receptor-1 (PAR-1) is involved in cytoprotective and anti-inflammatory responses in endothelial cells (ECs). However, the role of PAR-1 in laminar flow-mediated atheroprotective responses remains unknown. Herein, we investigated whether PAR-1 regulates laminar flow-mediated mechanotransduction in ECs. Confocal analysis showed that PAR-1 was internalized into early endosomes in response to laminar flow. In addition, flow cytometry analysis showed that cell surface expression of PAR-1 was reduced by laminar flow, suggesting that PAR-1 was activated in response to laminar flow. Depletion of PAR-1 using human PAR-1 siRNA inhibited unidirectional laminar flow-mediated actin stress fiber formation and cellular alignment as well as atheroprotective gene expressions in HUVECs. Moreover, PAR-1 knockdown inhibited laminar flow-stimulated eNOS phosphorylation, and inhibited the phosphorylations of Src, AMPK, ERK5 and HDAC5. Furthermore, PAR-1 depletion inhibited laminar flow-mediated anti-inflammatory responses as demonstrated by reduced TNFα-induced VCAM-1 expression and by monocyte adhesion to HUVECs, and prevented laminar flow-mediated anti-apoptotic response. An investigation of the role of PAR-1 in vasomotor modulation using mouse aortic rings revealed that acetylcholine-induced vasorelaxation was diminished in PAR-1 deficient mice compared to littermate controls. Taken together, these findings suggest that PAR-1 be viewed as a novel pharmacologic target for the treatment of vascular diseases, including atherosclerosis.

Zadoff-Chu sequence-based upstream ranging in OFDMA-PON mobile radio access networks.

Orthogonal frequency division multiple access (OFDMA) uplink in a passive optical network (PON) requires the delay alignment for OFDMA symbols from remotely distributed optical network units (ONUs). In this paper, we experimentally demonstrate and analyze the performance of a Zadoff-Chu (ZC) sequence-based upstream ranging scheme in an intensity modulation/direct detection (IM/DD)-based OFDMA-PON. The experimental results show that the proposed scheme can achieve upstream synchronization with only marginal inter-carrier interference (ICI) and requires no additional bandwidths in a typical OFDMA transmission with cyclic prefix (CP).

Lactoferrin Protects Human Mesenchymal Stem Cells from Oxidative Stress-Induced Senescence and Apoptosis.

Mesenchymal stem cells (MSCs) have been suggested as a primary candidate for cell therapy applications because they have self-renewal and differentiation capabilities. Although they can be expanded in ex vivo system, clinical application of these cells is still limited because they survive poorly and undergo senescence or apoptosis when transplanted and exposed to environmental factors such as oxidative stress. Thus, reducing oxidative stress is expected to improve the efficacy of MSC therapy. The milk protein lactoferrin is a multifunctional iron-binding glycoprotein that plays various roles, including reduction of oxidative stress. Thus, we explored the effect of lactoferrin on oxidative stress-induced senescence and apoptosis of human MSCs (hMSCs). Measurement of reactive oxygen species (ROS) revealed that lactoferrin inhibited the production of hydrogen peroxide-induced intracellular ROS, suggesting lactoferrin as a good candidate as an antioxidant in hMSCs. Pretreatment of lactoferrin suppressed hydrogen peroxide-induced senescence of hMSCs. In addition, lactoferrin reduced hydrogen peroxide-induced apoptosis via inhibition of caspase-3 and Akt activation. These results demonstrate that lactoferrin can be a promising factor to protect hMSCs from oxidative stress-induced senescence and apoptosis, thus increasing the efficacy of MSC therapy.

Binding of coronin 1B to TßRI negatively regulates the TGFß1 signaling pathway.

Coronin 1B is an actin-binding protein that regulates several actin-dependent cellular processes including migration and endocytosis. However, the role of coronin 1B in the tumor growth factor (TGF)ß signaling pathway is largely unknown. Here, we investigated whether coronin 1B affects the TGFß signaling cascade and found that coronin 1B negatively regulates the TGFß signaling pathway. Immunoprecipitation and glutathione-S-transferase-pulldown assays revealed that coronin 1B directly associated with TGFß receptor I (TßRI). Overexpression of coronin 1B inhibited the TGFß1-induced interaction between TßRI and Smad2/3 in plasmid-transfected HEK293T cells. Coronin 1B was basally bound to TßRI in vascular smooth muscle cells (VSMCs), but TGFß1 stimulation did not affect their association, suggesting constitutive binding between coronin 1B and TßRI. Overexpression of coronin 1B suppressed TGFß1-induced activation of a Smad-binding element-luciferase reporter construct and a plasminogen activator inhibitor (PAI)-1 promoter-luciferase reporter construct in HEK293T cells. By contrast, depletion of coronin 1B by siRNA transfection increased TGFß1-induced Smad2/3 phosphorylation and PAI-1 expression in VSMCs. These results suggest that coronin 1B regulates the TGFß1 signaling cascade by constitutively interacting with TßRI and inhibiting the binding of Smad2/3 to TßRI in response to TGFß1 stimulation.

Coronin 1B serine 2 phosphorylation by p38α is critical for vascular endothelial growth factor-induced migration of human umbilical vein endothelial cells.

Coronin 1B is an actin-binding protein that regulates various cellular processes including cell motility. However, the role of coronin 1B in vascular cell migration remains controversial. Here, we examined the function of coronin 1B in vascular endothelial growth factor (VEGF)-induced migration of human umbilical vein endothelial cells (HUVECs) and investigated the mechanism by which coronin 1B regulates this cellular process. We found that depletion of coronin 1B increased the VEGF-induced migration of HUVECs. VEGF phosphorylated coronin 1B at Ser2 and stimulated its translocation to the leading edge of stimulated cells. Lentivirus-mediated overexpression of wild-type coronin 1B or a phosphodeficient coronin 1B S2A mutant decreased VEGF-induced transwell migration of HUVECs. Treatment with the p38 inhibitor SB203580 or depletion of p38α by small interfering RNA transfection decreased VEGF-induced coronin 1B phosphorylation. In vitro binding and kinase assays revealed that active p38α directly binds to and phosphorylates coronin 1B at Ser2. In addition, VEGF induced active p38α binding to coronin 1B in HUVECs. VEGF disrupted the interaction between coronin 1B and the actin-related protein (Arp)2/3 complex and p38α depletion prevented this VEGF-induced dissociation. These findings suggest that coronin 1B plays an inhibitory role in VEGF-induced migration of HUVECs and that VEGF-activated p38α phosphorylates coronin 1B at Ser2 and activates the Arp2/3 complex by liberating it from coronin 1B.

Erratum to: Gecko proteins induce the apoptosis of bladder cancer 5637 cells by inhibiting Akt and activating the intrinsic caspase cascade.

The BMB Reports would like to correct in the reference of BMB Rep. 48(9), 531-536 titled "Gecko proteins induce the apoptosis of bladder cancer 5637 cells by inhibiting Akt and activating the intrinsic caspase cascade". The ACKNOWLEDGEMENTS should be corrected as follows, "This work was supported by the National Research Foundation of Korea (NRF-2010-0009086, NRF-2012R1A1A2039992, and 2012M3A9C7050184) and the Brain Busan 21 Project." and not "This work was partially supported by the National Research Foundation of Korea (NRF-2010-0009086, NRF-2003-003-C00110, and 2012M3A9C7050184) and the Brain Busan 21 Project." The online version reflects this change.

Gecko proteins induce the apoptosis of bladder cancer 5637 cells by inhibiting Akt and activating the intrinsic caspase cascade.

Gecko proteins have long been used as anti-tumor agents in oriental medicine, without any scientific background. Although anti-tumor effects of Gecko proteins on several cancers were recently reported, their effect on bladder cancer has not been investigated. Thus, we explored the anti-tumor effect of Gecko proteins and its cellular mechanisms in human bladder cancer 5637 cells. Gecko proteins significantly reduced the viability of 5637 cells without any cytotoxic effect on normal cells. These proteins increased the Annexin-V staining and the amount of condensed chromatin, demonstrating that the Gecko proteinsinduced cell death was caused by apoptosis. Gecko proteins suppressed Akt activation, and the overexpression of constitutively active form of myristoylated Akt prevented Gecko proteins-induced death of 5637 cells. Furthermore, Gecko proteins activated caspase 9 and caspase 3/7. Taken together, our data demonstrated that Gecko proteins suppressed the Akt pathway and activated the intrinsic caspase pathway, leading to the apoptosis of bladder cancer cells. [BMB Reports 2015; 48(9): 531-536].

CHOP deficiency prevents methylglyoxal-induced myocyte apoptosis and cardiac dysfunction.

Epidemiological studies indicate that methylglyoxal (MGO) plasma levels are closely linked to diabetes and the exacerbation of diabetic cardiovascular complications. Recently, it was established that endoplasmic reticulum (ER) stress importantly contributes to the pathogenesis of diabetes and its cardiovascular complications. The objective of this study was to explore the mechanism by which diabetes instigates cardiomyocyte apoptosis and cardiac dysfunction via MGO-mediated myocyte apoptosis. Intriguingly, the MGO activated unfolded protein response pathway accompanying apoptotic events, such as cleavages of PARP-1 and caspase-3. In addition, Western blot analysis revealed that MGO-induced myocyte apoptosis was inhibited by depletion of CHOP with siRNA against Ddit3, the gene name for rat CHOP. To investigate the physiologic roles of CHOP in vivo, glucose tolerance and cardiac dysfunction were assessed in CHOP-deficient mice. No significant difference was observed between CHOP KO and littermate naïve controls in terms of the MGO-induced impairment of glucose tolerance. In contrast, myocyte apoptosis, inflammation, and cardiac dysfunction were significantly diminished in CHOP KO compared with littermate naïve controls. These results showed that CHOP is the key signal for myocyte apoptosis and cardiac dysfunction induced by MGO. These findings suggest a therapeutic potential of CHOP inhibition in the management of diabetic cardiovascular complications including diabetic cardiomyopathy.

Coronin 1A depletion protects endothelial cells from TNFα-induced apoptosis by modulating p38ß expression and activation.

Coronins are conserved actin-binding proteins that regulate various cellular processes such as migration and endocytosis. Among coronin family members, coronin 1A is highly expressed in hematopoietic lineage cells where it regulates cell homeostasis. However, the expression and function of coronin 1A in endothelial cells have not yet been elucidated. We found that coronin 1A is expressed in the human umbilical vein endothelial cell (HUVEC) and human brain microvascular endothelial cell (HBMVEC). In HUVEC depleted of coronin 1A by siRNA transfection, tumor necrosis factor α (TNFα)+cyclohexamide (CHX) treatment resulted in a decrease in the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive apoptotic cells. Coronin 1A depletion also resulted in the suppression of caspase 3 and poly(ADP-ribose) polymerase cleavage and a reduction in caspase 3 activity. Next, we examined TNFα-induced activation of several pro- and anti-apoptotic signaling molecules to find the target molecule of coronin 1A and found that p38 phosphorylation was enhanced by TNFα stimulation in coronin 1A-depleted HUVEC. Among the p38 isoforms, the expression of p38ß was significantly upregulated after coronin 1A depletion, suggesting that the expression and phosphorylation of anti-apoptotic p38ß were significantly induced in coronin 1A-depleted HUVEC. Inhibition of p38ß upregulation in coronin 1A-depleted HUVEC restored the cleavage of caspase 8 and caspase 3 and induced more apoptosis than in coronin 1A-depleted HUVEC in response to TNFα+CHX. These findings suggest that coronin 1A modulates endothelial cell apoptosis by regulating p38ß expression and activation.

Itch E3 ubiquitin ligase positively regulates TGF-ß signaling to EMT via Smad7 ubiquitination.

TGF-ß regulates pleiotropic cellular responses including cell growth, differentiation, migration, apoptosis, extracellular matrix production, and many other biological processes. Although non-Smad signaling pathways are being increasingly reported to play many roles in TGF-ß-mediated biological processes, Smads, especially receptor-regulated Smads (R-Smads), still play a central mediatory role in TGF-ß signaling for epithelial-mesenchymal transition. Thus, the biological activities of R-Smads are tightly regulated at multiple points. Inhibitory Smad (I-Smad also called Smad7) acts as a critical endogenous negative feedback regulator of Smad-signaling pathways by inhibiting R-Smad phosphorylation and by inducing activated type I TGF-ß receptor degradation. Roles played by Smad7 in health and disease are being increasingly reported, but the molecular mechanisms that regulate Smad7 are not well understood. In this study, we show that E3 ubiquitin ligase Itch acts as a positive regulator of TGF-ß signaling and of subsequent EMT-related gene expression. Interestingly, the Itch-mediated positive regulation of TGF-ß signaling was found to be dependent on Smad7 ubiquitination and its subsequent degradation. Further study revealed Itch acts as an E3 ubiquitin ligase for Smad7 polyubiquitination, and thus, that Itch is an important regulator of Smad7 activity and a positive regulator of TGF-ß signaling and of TGF-ß-mediated biological processes. Accordingly, the study uncovers a novel regulatory mechanism whereby Smad7 is controlled by Itch.

p62 binding to protein kinase C ζ regulates tumor necrosis factor α-induced apoptotic pathway in endothelial cells.

OBJECTIVE: Protein kinase C (PKC) ζ is a key pathological mediator of endothelial cell apoptosis. p62 is a scaffold protein that regulates several cell signaling pathways by binding to target proteins. Because PKCζ and p62 contain Phox/Bem1p (PB1) modules that mediate protein-protein interactions, we hypothesized that an interaction between p62 and PKCζ is required for tumor necrosis factor α-induced PKCζ signaling in endothelial cells. METHODS AND RESULTS: In human umbilical vein endothelial cell, tumor necrosis factor α (10 ng/mL) enhanced the interaction between p62 and PKCζ. Transfection with p62 small interfering RNA reduced the activation of both PKCζ and its downstream targets JNK and caspase 3, suggesting that p62 is necessary for PKCζ signaling. Overexpression of only the PB1 domain of p62 inhibited p62-PKCζ interaction, showing that binding of these 2 proteins is mediated by their PB1 domains. Furthermore, overexpression of the p62 PB1 domain suppressed tumor necrosis factor α-induced PKCζ activation and subsequent activation of JNK and caspase 3. Finally, transfection of either p62 small interfering RNA or the PB1 domain of p62 inhibited human umbilical vein endothelial cell apoptosis. CONCLUSIONS: Our results suggest a novel function of p62 that regulates the activity of PKCζ by binding to PKCζ, thereby activating the PKCζ-JNK-caspase 3 apoptotic pathway in endothelial cells.