HAX1 regulates E3 ubiquitin ligase activity of cIAPs by promoting their dimerization

HS-1-associated protein X-1 (HAX1) is a multi-functional protein which was first identified as a Hematopoietic cell specific Lyn Substrate 1 (HS1)-binding protein. Although the roles of HAX1 in apoptosis have been unraveled and HAX1 has been proposed to be involved in several diseases, additional roles of HAX1 are still being identified. Here, we demonstrated that HAX1 directly interacted with cellular Inhibitor of Apoptosis Proteins (cIAPs), ubiquitin E3 ligases which regulate the abundance of cellular proteins, via ubiquitin-dependent proteasomal degradation. We showed that HAX1 promotes auto-ubiquitination and degradation of cIAPs by facilitating the intermolecular homodimerization of RING finger domain. Moreover, HAX1 regulates the non-canonical Nuclear Factor-κB (NF-κB) signaling pathway by modulating the stability of NF-κB-Inducing Kinase (NIK), which is one of the substrates of cIAPs. Taken together, these results unveil a novel role of HAX1 in the non-canonical NF-κB pathway, and provide an important clue that HAX1 is a potential therapeutic target for the treatment of cancer.     

Mechanical Properties Enhancement of the Au-Cu-Al Alloys via Phase Constitution Manipulation

To enhance the mechanical properties (e.g., strength and elongation) of the face-centered cubic (fcc) α-phase in the Au-Cu-Al system, this study focused on the introduction of the martensite phase (doubled B19 (DB19) crystal structure of Au₂CuAl) via the manipulation of alloy compositions. Fundamental evaluations, such as microstructure observations, phase identifications, thermal analysis, tensile behavior examinations, and reflectance analysis, have been conducted. The presence of fcc annealing twins was observed in both the optical microscope (OM) and the scanning electron microscope (SEM) images. Both strength and elongation of the alloys were greatly promoted while the DB19 martensite phase was introduced into the alloys. Amongst all the prepared specimens, the 47Au41Cu12Al and the 44Au44Cu12Al alloys performed the optimized mechanical properties. The enhancement of strength and ductility in these two alloys was achieved while the stress plateau was observed during the tensile deformation. A plot of the ultimate tensile strength (UTS) against fracture strain was constructed to illustrate the effects of the introduction of the DB19 martensite phase on the mechanical properties of the alloys. Regardless of the manipulation of the alloy compositions and the introduction of the DB19 martensite phase, the reflectance stayed almost identical to pure Au.     

Vitamin C deficiency increases the binucleation of hepatocytes in SMP30 knock-out mice

Background and Aims: The binucleation of hepatocytes, which was known as an important feature of liver growth and physiology, has been reported to be increased during the chronic oxidative injury stage and has been regarded as an age‐related change of hepatic structures. Therefore, we investigated the binuclearity pattern in the livers of senescence marker proteins‐30 (SMP30) knock‐out (KO) mice compared with wild‐type (WT) mice and vitamin C‐treated KO (KO + VC) mice. Methods: The WT, KO and KO + VC mice were fed a vitamin C free diet and VC(+) group mice were given vitamin C water containing 1.5 g/L of vitamin C, whereas VC(?) group was given normal drinking water without vitamin C, for 16 weeks. Results: In microscopic examination, the livers of KO mice showed a significantly increased number of binuclear hepatocytes compared with that of WT mice and KO + VC mice. KO mice also showed the most increased expression level of CYP2E1 and PCNA determined by immunohistochemistry and immunoblot analysis. Moreover, KO mice indicated the highest level of serum alanine aminotransferase and aspartate aminotransferase level in serum biochemical analysis. Accordingly, significantly decreased levels of reactive oxygen species, MDA (malondialdehyde) and HAE (4‐hydroxyalkenals) were detected in KO + VC mice compared with KO mice. Conclusion: Therefore, it is concluded that vitamin C deficiency induces an increase of CYP2E1 expression and elevated ROS production, which causes oxidative liver injury and the elevation of hepatocyte binucleation in SMP30 KO mice.     

Calmodulin dynamically regulates the trafficking of the metabotropic glutamate receptor mGluR5

Metabotropic glutamate receptors (mGluRs) 1–8 are G protein-coupled receptors (GPCRs) that modulate excitatory neurotransmission, neurotransmitter release, and synaptic plasticity. PKC regulates many aspects of mGluR function, including protein–protein interactions, Ca²⁺ signaling, and receptor desensitization. However, the mechanisms by which PKC regulates mGluR function are poorly understood. We have now identified calmodulin (CaM) as a dynamic regulator of mGluR5 trafficking. We show that the major PKC phosphorylation site on the intracellular C terminus of mGluR5 is serine 901 (S901), and phosphorylation of this residue is up-regulated in response to both receptor and PKC activation. In addition, S901 phosphorylation inhibits mGluR5 binding to CaM, decreasing mGluR5 surface expression. Furthermore, blocking PKC phosphorylation of mGluR5 on S901 dramatically affects mGluR5 signaling by prolonging Ca²⁺ oscillations. Thus, our data demonstrate that mGluR5 activation triggers phosphorylation of S901, thereby directly linking PKC phosphorylation, CaM binding, receptor trafficking, and downstream signaling.     

Early statin therapy within 48 hours decreased one-year major adverse cardiac events in patients with acute myocardial infarction

HMG-CoA reductase inhibitors (statins) reduce major adverse cardiac events (MACE) and mortality in patients with acute coronary syndrome. We investigated whether early statin therapy would be effective at reducing MACE in patients with acute myocardial infarction (AMI).A total of 1,159 patients were analyzed. They were grouped by initiation time of statin administration after admission as follows: group I; n = 945, ≤ 48 hours, group II; n = 214, > 48 hours.Cardiovascular risk factors and noncardiac comorbidities were not different between the two groups. ST-elevation MI as initial diagnosis was more prevalent in group I (68.4% versus 59.3%, P = 0.013). In-hospital mortality was not different in the two groups (0.8% versus 0.5%, P = 0.483). In one-year clinical follow-up, MACE and repercutaneous coronary intervention were lower in group I (17.8% versus 24.6%, P = 0.016, 10.2% versus 15.5%, P = 0.021, respectively). However, there was no difference in mortality (3.8% versus 4.7%, P = 0.319). In multivariate analysis, statin initiation within 48 hours after admission was an independent predictor of one-year MACE (OR 1.49, 95% CI = 1.00-2.21, P = 0.045).Consequently, early statin therapy within 48 hours after admission reduced MACE at one-year follow-up in patients with AMI.     

Risk factors and outcomes of bloodstream infections with metallo-beta-lactamase-producing Acinetobacter

The spread of Gram-negative bacilli with acquired metallo-beta-lactamase (MBL) threatens the successful treatment of major nosocomial infections. The objective of this study was to evaluate the differences in the clinical characteristics of bacteremia caused by MBL-producing Acinetobacter species and MBL non-producing isolates. Two retrospective case-control studies were conducted using data on patients with Acinetobacter bacteremia, who were admitted between January 2001 and December 2005 at a 1500-bed, tertiary-care teaching hospital. Case group 1 (n=27) included patients from whom imipenem-resistant Acinetobacter was isolated in blood culture, and case group 2 (n=7) consisted of those patients from group 1 who yielded MBL-producing isolates. The control group (n=41) included patients from whom carbapenem-susceptible Acinetobacter isolates were isolated in blood culture. Multivariate analysis revealed that the independent risk factors for imipenem-resistant Acinetobacter bacteremia were neutropenia and prolonged use of carbapenem. The independent risk factors for MBL-producing Acinetobacter bacteremia were neutropenia and prolonged use of cephalosporins. The results of this study suggest that a prolonged use of cephalosporins may be associated with MBL-producing Acinetobacter bacteremia.     

Accuracy of chest radiography for evaluating significantly abnormal pulmonary vascularity in children with congenital heart disease

This study aims to investigate the blood flow around the perivalvular area in a human superficial vein using high-frequency ultrasound (HFUS) speckle image velocimetry. HFUS B-mode images were captured from the superficial veins of human lower extremity with a 35-MHz transducer. To measure the instantaneous velocity fields of blood flow, a cross-correlation particle image velocimetry (PIV) algorithm was applied to two B-mode images that were captured consecutively. The echo speckles of red blood cells (RBCs) were used as flow tracers. In the vicinity of the venous valve, the opening and closing motions of valve cusps were simultaneously visualized with the phasic variation of velocity fields. Large-scale vortices were observed behind the sinus pockets while the main bloodstream was directed proximally. This measurement technique combining PIV algorithm and HFUS B-mode imaging was found to be unique and useful for investigating the hemodynamic characteristics of blood flow in the perivalvular area and for diagnosing venous insufficiency and valve abnormality in superficial blood vessels.     

Monensin-mediated growth inhibition in human lymphoma cells through cell cycle arrest and apoptosis

Monensin, a Na+ ionophore, regulates many cellular functions, including apoptosis. We investigated the in vitro antiproliferative effect of monensin on nine human lymphoma cell lines. Monensin significantly inhibited the proliferation of all the lymphoma cell lines examined with a 50% inhibition concentration of about 0.5 micromol/l, and induced a G1 and/or a G2-M phase arrest in these cell lines. To address the antiproliferative mechanism of monensin, we examined the effect of this drug on cell-cycle-related proteins in CA46 cells (both G1 and G2 arrest) and Molt-4 cells (G2 arrest). Treatment with monensin for 72 h decreased CDK4 and cyclin A levels in CA46 cells, and cdc2 levels in Molt-4 cells. In monensin-treated CA46 cells, increased p21-CDK2, p27-CDK2 and p27-CDK4 complex forms were observed. And, in monensin-treated Molt-4 cells, increased p21-cdc2 complex form was detected. Furthermore, the activities of CDK2- and CDK4-associated kinases were reduced in association with Rb hypophosphorylation in monensin-treated CA46 cells. The activity of cdc2-associated kinase was decreased in both cell lines, which was accompanied by induction of Wee1. Also, monensin induced apoptosis in these cell lines, as evidenced by annexin V binding assay and flow cytometric detection of sub-G1 DNA content. This apoptotic process was associated with loss of mitochondria transmembrane potential (Delta(psi)m). Taken together, these results demonstrated for the first time that monensin potently inhibits the proliferation of human lymphoma cell lines via cell cycle arrest and apoptosis.     

Active intestinal calcium transport in the absence of transient receptor potential vanilloid type 6 and calbindin-D9k

To study the role of the epithelial calcium channel transient receptor potential vanilloid type 6 (TRPV6) and the calcium-binding protein calbindin-D9k in intestinal calcium absorption, TRPV6 knockout (KO), calbindin-D9k KO, and TRPV6/calbindin-D(9k) double-KO (DKO) mice were generated. TRPV6 KO, calbindin-D9k KO, and TRPV6/calbindin-D9k DKO mice have serum calcium levels similar to those of wild-type (WT) mice ( approximately 10 mg Ca2+/dl). In the TRPV6 KO and the DKO mice, however, there is a 1.8-fold increase in serum PTH levels (P < 0.05 compared with WT). Active intestinal calcium transport was measured using the everted gut sac method. Under low dietary calcium conditions there was a 4.1-, 2.9-, and 3.9-fold increase in calcium transport in the duodenum of WT, TRPV6 KO, and calbindin-D9k KO mice, respectively (n = 8-22 per group; P > 0.1, WT vs. calbindin-D9k KO, and P < 0.05, WT vs. TRPV6 KO on the low-calcium diet). Duodenal calcium transport was increased 2.1-fold in the TRPV6/calbindin-D9k DKO mice fed the low-calcium diet (P < 0.05, WT vs. DKO). Active calcium transport was not stimulated by low dietary calcium in the ileum of the WT or KO mice. 1,25-Dihydroxyvitamin D3 administration to vitamin D-deficient null mutant and WT mice also resulted in a significant increase in duodenal calcium transport (1.4- to 2.0-fold, P < 0.05 compared with vitamin D-deficient mice). This study provides evidence for the first time using null mutant mice that significant active intestinal calcium transport occurs in the absence of TRPV6 and calbindin-D9k, thus challenging the dogma that TRPV6 and calbindin-D9k are essential for vitamin D-induced active intestinal calcium transport.     

A family of variably expressed outer-membrane proteins (Vomp) mediates adhesion and autoaggregation in Bartonella quintana

Bartonella species are fastidious, Gram-negative human pathogens that can persist in the host bloodstream for years and bind to and invade several types of host cells. For many pathogens, adhesion to host cells and extracellular matrix (ECM) components is a critical virulence determinant. Bacteria often vary expression of surface adhesins by phase or antigenic variation to subvert the host immune response and permit adaptive interaction with different host structures. We developed a macaque animal model for Bartonella quintana infection to detect changes in bacterial outer-membrane proteins (OMP) during prolonged bloodstream infection. We identified a gene family encoding four highly conserved, 100-kDa, variably expressed OMP (Vomp), two of which function as adhesins. The variable expression of Vomp family members appears to be mediated by deletion of one or more vomp genes during chronic bloodstream infection. vomp deletion was observed also in isolates from humans with chronic B. quintana infection. The Vomp are closely related to the afimbrial adhesin, YadA, a virulence factor of Yersinia enterocolitica. The surface-expressed Vomp contain conserved structural features of YadA, including collagen-binding motifs. We demonstrate that the B. quintana Vomp are multifunctional OMP involved in binding to collagen and autoaggregation: VompC confers the ability to bind collagen IV, and VompA is necessary and sufficient for autoaggregation. The B. quintana Vomp are members of the newly recognized family of YadA-like trimeric autotransporters; the Vomp constitute a multigene family, they are variably expressed, and different virulence properties are attributable to individual Vomp family members.