The role of cullin 5-containing ubiquitin ligases

The suppressor of cytokine signaling (SOCS) box consists of the BC box and the cullin 5 (Cul5) box, which interact with Elongin BC and Cul5, respectively. SOCS box-containing proteins have ubiquitin ligase activity mediated by the formation of a complex with the scaffold protein Cul5 and the RING domain protein Rbx2, and are thereby members of the cullin RING ligase superfamily. Cul5-type ubiquitin ligases have a variety of substrates that are targeted for polyubiquitination and proteasomal degradation. Here, we review the current knowledge on the identification of Cul5 and the regulation of its expression, as well as the signaling pathways regulated by Cul5 and how viruses highjack the Cul5 system to overcome antiviral responses.     

Constraining OCT with Knowledge of Device Design Enables High Accuracy Hemodynamic Assessment of Endovascular Implants

Background

Stacking cross-sectional intravascular images permits three-dimensional rendering of endovascular implants, yet introduces between-frame uncertainties that limit characterization of device placement and the hemodynamic microenvironment. In a porcine coronary stent model, we demonstrate enhanced OCT reconstruction with preservation of between-frame features through fusion with angiography and a priori knowledge of stent design.

Methods and Results

Strut positions were extracted from sequential OCT frames. Reconstruction with standard interpolation generated discontinuous stent structures. By computationally constraining interpolation to known stent skeletons fitted to 3D ‘clouds’ of OCT-Angio-derived struts, implant anatomy was resolved, accurately rendering features from implant diameter and curvature (n = 1 vessels, r² = 0.91, 0.90, respectively) to individual strut-wall configurations (average displacement error ~15 μm). This framework facilitated hemodynamic simulation (n = 1 vessel), showing the critical importance of accurate anatomic rendering in characterizing both quantitative and basic qualitative flow patterns. Discontinuities with standard approaches systematically introduced noise and bias, poorly capturing regional flow effects. In contrast, the enhanced method preserved multi-scale (local strut to regional stent) flow interactions, demonstrating the impact of regional contexts in defining the hemodynamic consequence of local deployment errors.

Conclusion

Fusion of planar angiography and knowledge of device design permits enhanced OCT image analysis of in situ tissue-device interactions. Given emerging interests in simulation-derived hemodynamic assessment as surrogate measures of biological risk, such fused modalities offer a new window into patient-specific implant environments.     

Valproate induces apoptosis by inducing accumulation of neutral lipids which was prevented by disruption of the SIR2 gene in Saccharomyces cerevisiae

We investigated the participation of HDACs in VPA induced apoptosis in Saccharomyces cerevisiae. VPA (20 mM) induced apoptosis in several HDAC mutants, including PRD3 and HDA1-disrupted cells and SIR2 over expressing cells, as well as in wild-type cells but not SIR2-disrupted cells. Intracellular reactive oxygen species and neutral lipid content increased markedly in all kinds of HDAC mutant cells tested except for SIR2-disrupted cells. Thus, these results suggest that 20 mM VPA induces neutral lipid accumulation and apoptosis-like features in S. cerevisiae, and that VPA-induced apoptosis was evaded by deletion of SIR2.     

Generation and maintenance of suspension cultures from cotyledons and their organogenic potential of two mangrove species, Sonneratia alba and S. caseolaris

Liquid cultures were successfully generated from cotyledons of two Sonneratia species, S. alba and S. caseolaris in Murashige and Skoog (MS) medium containing 0.1 μmol L⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D). Adventitious roots differentiated from cotyledons of S. alba. Proliferated cells were subcultured and a large volume of suspension cells was subsequently established in 100-mL flasks. All the cytokinins tested inhibited cell proliferation. After three years of culture, the potential to differentiate was tested as indicated by greening of the cells. Greening occurred when suspension cells were transferred to solid MS medium with and without 0.1 μmol L⁻¹ 2,4-D. Greening was stimulated by low concentrations of the weak auxins indolebutyric acid (IBA) and naphthaleneacetic acid (NAA) while 2,4-D stimulated late-stage greening. Abscisic acid (ABA) inhibited greening. Gibberellic acid (GA₃) at 1.0 μmol L⁻¹ stimulated callus greening and was not inhibitory even when tested at high concentrations. Cytokinins were inhibitory in combination with 0.1 μmol L⁻¹ of either IBA or NAA. The cause of different effects of plant hormones on growth and differentiation was discussed. Small-scale liquid media and 24-well culture plates of solid media methods developed in this paper are suitable for the optimization of hormonal conditions for cell proliferation and differentiation.     

Involvement of tyrosines at fucose-binding sites of Aleuria aurantia lectin: non-equal response to site-directed mutagenesis among five sites

Since the involvement of Tyr residues in the fucose-binding of Aleuria aurantia lectin (AAL) was proved by chemical modification using the Tyr-specific reagent tetranitromethane, site-directed mutagenesis was attempted. Since the tertiary structure of AAL was determined recently to be a six-bladed beta-propeller fold, and five fucose-binding sites per subunit were found, based on positions of Tyr residues in the tertiary structure, three classes of mutants were constructed: 1) Tyr on the 2nd beta-strand of each blade (beta-2 mutants), 2) Tyr or Trp on the 3rd beta-strand (beta-3 mutants), and 3) Tyr outside of binding sites (other-Y mutants). The mutagenized cDNA was expressed in Escherichia coli as His-tag-AAL, and the hemagglutinating activity was assayed. Among 14 mutants, three beta-2 mutants (Y26A, Y79A, and Y181A), and three beta-3 mutants (Y92A, W149A, and Y241A) showed decreased activity. These mutated residues resided at Sites 1, 2, and 4, at the same locations relatively in the binding sites. Mutagenesis of Tyr or Trp at the corresponding locations in Sites 3 and 5 did not lead to a reduction in activity. Results indicate that the properties of Sites 1, 2, and 4 are different from those of Sites 3 and 5, and that the contribution of these two sites to the hemagglutination reaction was minor.     

A specific receptor site for glycerol, a new sweet tastant for Drosophila: structure-taste relationship of glycerol in the labellar sugar receptor cell

Glycerol, a linear triol, is a sweet tastant for mammals but it has not previously been recognized to stimulate the sense of taste in insects. Here we show by electrophysiological experimentation that it effectively stimulates the labellar sugar receptor cell of Drosophila. We also show that in accord with the electrophysiological observations, the behavioral feeding response to glycerol is dose dependent. 3-Amino-1,2-propanediol inhibited the response of the sugar receptor cell to glycerol, specifically and competitively, while it had almost no effect on responses to sucrose, D-glucose, D-fructose and trehalose. In the null Drosophila mutant for the trehalose receptor (DeltaEP19), the response to glycerol showed no change, in sharp contrast with a characteristic drastic decrease in the response to trehalose. The glycerol concentration-response curves for I-type and L-type labellar hairs were statistically indistinguishable, while those for sucrose, D-glucose, D-fructose and trehalose were clearly different. These all indicate the presence of a specific receptor site for glycerol. The glycerol site was characterized by comparing the effectiveness of various derivatives of glycerol. Based on this structure-taste relationship of glycerol, a model is proposed for the glycerol site including three subsites and two steric barriers, which cannot accommodate carbon-ring containing sugars such as D-glucose.     

The hypothalamus is involved in the anorexic effect of glucagon-like peptide-1 in chicks

The present study was carried out to investigate whether the hypothalamus is involved in the anorexic effect of glucagon-like peptide-1 (GLP-1) in chicks. To examine this, Fos expression in the chick hypothalamus were immunohistochemically detected after intracerebroventricular (ICV) injection of 30-pmol GLP-1. ICV injection of GLP-1 stimulated the expression of Fos-like immunoreactive (FLI) cells in the ventromedial hypothalamic nucleus (VMN). When 15-pmol GLP-1 was directly injected into the chick VMN, the chick's food intake was significantly decreased compared with the control treatment. Microinjection of GLP-1 into the (LHA) also inhibited feeding in chicks, although ICV injection of GLP-1 did not stimulate FLI expression in the brain area. These results suggest that VMN and some brain regions are involved in the anorexic effect of GLP-1 in chicks.     

Cyclic ADP-ribose, a putative Ca2+-mobilizing second messenger, operates in submucosal gland acinar cells

Cyclic ADP-ribose (cADPR), a putative Ca(2+)-mobilizing second messenger, has been reported to operate in several mammalian cells. To investigate whether cADPR is involved in electrolyte secretion from airway glands, we used a patch-clamp technique, the measurement of microsomal Ca(2+) release, quantification of cellular cADPR, and RT-PCR for CD38 mRNA in human and feline tracheal glands. cADPR (>6 microM), infused into the cell via the patch pipette, caused ionic currents dependent on cellular Ca(2+). Infusions of lower concentrations (2-4 microM) of cADPR or inositol 1,4,5-trisphosphate (IP(3)) alone were without effect on the baseline current, but a combined application of cADPR and IP(3) mimicked the cellular response to low concentrations of acetylcholine (ACh). Microsomes derived from the isolated glands released Ca(2+) in response to both IP(3) and cADPR. cADPR released Ca(2+) from microsomes desensitized to IP(3) or those treated with heparin. The mRNA for CD38, an enzyme protein involved in cADPR metabolism, was detected in human tissues, including tracheal glands, and the cellular content of cADPR was increased with physiologically relevant concentrations of ACh. We conclude that cADPR, in concert with IP(3), operates in airway gland acinar cells to mobilize Ca(2+), resulting in Cl(-) secretion.