The physiological function of Sentrin/SUMO-specific proteases (SENPs) remains largely unexplored, and little is known about the regulation of SENPs themselves. Here, we show that a modest increase of reactive oxygen species (ROS) regulates SENP3 stability and localization. We found that SENP3 is continuously degraded through the ubiquitinproteasome pathway under basal condition and that ROS inhibit this degradation. Furthermore, ROS causes SENP3 to redistribute from the nucleoli to the nucleoplasm, allowing it to regulate nuclear events. The stabilization and redistribution of SENP3 correlate with an increase in the transcriptional activity of the hypoxia-inducing factor-1 (HIF-1) under mild oxidative stress. ROS-enhanced HIF-1 transactivation is blocked by SENP3 knockdown. The deSUMOylating activity of SENP3 is required for ROS-induced increase of HIF-1 transactivation, but the true substrate of SENP3 is the co-activator of HIF-1a, p300, rather than HIF-1a itself. Removing SUMO2/3 from p300 enhances its binding to HIF-1a. In vivo nude mouse xenografts overexpressing SENP3 are more angiogenic. Taken together, our results identify SENP3 as a redox sensor that regulates HIF-1 transcriptional activity under oxidative stress through the de-SUMOylation of p300.

Molecular dynamic (MD) simulations of preassembled sodium dodecyl sulfate (SDS) micelles are carried out using three versions of GROMOS, as well as CHARMM36, OPLS-AA, and OPLS-UA force fields at different aggregation numbers and box sizes. The differences among force fields have little effect on the overall micelle structure of small aggregates of size 60 or 100, but for micelles of an aggregation number of 300 or higher, bicelle structures with ordered tails, rather than the more realistic rodlike or cylindrical micelles with disordered tails, occur when using versions of GROMOS45A3 or the OPLS-AA force fields that are adapted to model the sulfate head group atoms using methods given in the literature. We find that the Lennard-Jones (L-J) parameters for the sodium ions and the ionic oxygens of the SDS head group, as well as the water model, control the transition to bicelles, regardless of other L-J parameters. A closer binding of the sodium ions to the head group ionic oxygens screens the electrostatic repulsions more strongly, resulting in condensation of SDS head groups, leading to unphysical bicelles for GROMOS45A3 or the OPLS-AA force fields, when the aggregation number is large. A telltale sign that the sodium-oxygen interaction is too strong shows up in high nearest neighbor peaks (height >8 and height >20 for micelles with 60 and 100 surfactants, respectively) in the radial distribution functions (RDFs) of sodium ions to ionic oxygens. In the 100-surfactant micelles, the high RDF peak is accompanied by "crystal-like" layering of sodium ions onto the surface of the micelle. The distance between the sodium ions and micelle also depends on the number of waters binding to sodium ions in the presence of surfactant head groups, which depends on both the sodium ion and water models, and for the same sodium model increases as the water model is changed in the order: TIP4P, SPC/E, SPC, and TIP3P.

Although arsenic trioxide (As 2 O 3 ) induces apoptosis in a relatively wide spectrum of tumors, the sensitivity of different cell types to this treatment varies to a great extent. Because reactive oxygen species (ROS) are critically involved in As 2 O 3 -induced apoptosis, we attempted to explore the possibility that elevating the cellular ROS level might be an approach to facilitate As 2 O 3 -induced apoptosis. Emodin, a natural anthraquinone derivative, was selected because its semiquinone structure is likely to increase the generation of intracellular ROS. Its independent and synergistic effects with As 2 O 3 in cytotoxicity were studied, and the plausible signaling mechanism was investigated in HeLa cells. Cell Proliferation Assay and flow cytometry were used to assess cell viability and apoptosis. Electrophoretic mobility shift assay, luciferase reporter assay, and Western blotting were performed to analyze signaling alteration. The results demonstrated that coadministration of emodin, at low doses of 0.5-10 M, with As 2 O 3 enhanced As 2 O 3 -rendered cytotoxicity on tumor cells, whereas these treatments caused no detectable proproliferative or proapoptotic effects on nontumor cells. ROS generation was increased, and activation of nuclear factor B and activator protein 1 was suppressed by coadministration. All enhancements by emodin could be abolished by the antioxidant N-acetyl-L-cysteine. Therefore, we concluded that emodin sensitized HeLa cells to As 2 O 3 via generation of ROS and ROS-mediated inhibition on two major prosurvival transcription factors, nuclear factor B and activator protein 1. This result allows us to propose a novel strategy in chemotherapy that uses mild ROS generators to facilitate apoptosisinducing drugs whose efficacy depends on ROS.

The reactivity of the various components of the Golgi apparatus of rat spermatids for three phosphatase activities (nicotinamide adenine dinucleotide phosphatase, NADPase; thiamine pyrophosphatase, TPPase; cytidine monophosphatase, CMPase) and the incorporation of 3H-fucose by the spermatids was analyzed at the 19 steps of spermiogenesis, i.e., during and after this organelle elaborated the glycoprotein-rich acrosomic system. During steps 1-3, the Golgi apparatus produced, in addition to the proacrosomic granules, multivesicular bodies that became associated with the chromatoid body. NADPase was located within the four of five intermediate saccules of Golgi stacks, and TPPase was found in the last one or two saccules on the trans aspect of the stacks from steps 1 to 17 of spermiogenesis. CMPase was located within the thick saccular GERL elements found in the trans region of the Golgi apparatus from steps 1 to 7 of spermiogenesis, but the CMPase-positive GERL disappeared from the Golgi apparatus after its detachment from the acrosomic system at step 8. Th acrosomic system itself was reactive from CMPase and TPPase but was negative for NADPase, while the multivesicular bodies were CMPase and NADPase positive but unreactive for TPPase. Tritiated-fucose was readily incorporated within the Golgi apparatus of steps 1-17 spermatids; in steps 1-7 it was subsequently incorporated within the acrosomic system and multivesicular bodies. These various data indicated (1) that the Golgi apparatus of spermatids, although it loses its CMPase-positive GERL element in step 8, retains evidence of functional capacity until it degenerates in step 17; (2) that in early spermatids the various saccular components of the Golgi are specialized with respect to enzymatic activities; and (3) that each Golgi region may contribute in a coordinated fashion to the formation of the acrosomic system and multivesicular bodies.

In an effort to improve industrial production of 1,3-propanediol (1,3-PD), we engineered a novel polycistronic operon under the control of the temperature-sensitive lambda phage P L P R promoter regulated by the cIts857 repressor and expressed it in Escherichia coli K-12 ER2925. The genes for the production of 1,3-PD in Clostridium butyricum, dhaB1 and dhaB2, which encode the vitamin B 12 -independent glycerol dehydratase DhaB1 and its activating factor, DhaB2, respectively, were tandemly arrayed with the E. coli yqhD gene, which encodes the 1,3-propanediol oxidoreductase isoenzyme YqhD, an NADP-dependent dehydrogenase that can directly convert glycerol to 1,3-PD. The microbial conversion of 1,3-PD from glycerol by this recombinant E. coli strain was studied in a two-stage fermentation process. During the first stage, a novel high-cell-density fermentation step, there was significant cell growth and the majority of the metabolites produced were organic acids, mainly acetate. During the second stage, glycerol from the fresh medium was rapidly converted to 1,3-PD following a temperature shift from 30°C to 42°C. The by-products were mainly pyruvate and acetate. During this two-stage process, the overall 1,3-PD yield and productivity reached 104.4 g/liter and 2.61 g/liter/h, respectively, and the conversion rate of glycerol to 1,3-PD reached 90.2% (g/g). To our knowledge, this is the highest reported yield and productivity efficiency of 1,3-PD with glycerol as the sole source of carbon. Furthermore, the overall fermentation time was only 40 h, shorter than that of any other reports.

We link micellar structures to their rheological properties for two surfactant body-wash formulations at various concentrations of salts and perfume raw materials (PRMs) using molecular simulations and micellar-scale modeling, as well as traditional surfactant packing arguments. The two body washes, namely, BW-1EO and BW-3EO, are composed of sodium lauryl ethylene glycol ether sulfate (SLEnS, where n is the average number of ethylene glycol repeat units), cocamidopropyl betaine (CAPB), ACCORD (which is a mixture of six PRMs), and NaCl salt. BW-3EO is an SLE3S-based body wash, whereas BW-1EO is an SLE1S-based body wash. Additional PRMs are also added into the body washes. The effects of temperature, salt, and added PRMs on micellar lengths, breakage times, end-cap free energies, and other properties are obtained from fits of the rheological data to predictions of the "Pointer Algorithm" [ Zou , W. ; Larson , R.G. J. Rheol. 2014 , 58 , 1 - 41 ], which is a simulation method based on the Cates model of micellar dynamics. Changes in these micellar properties are interpreted using the Israelachvili surfactant packing argument. From coarse-grained molecular simulations, we infer how salt modifies the micellar properties by changing the packing between the surfactant head groups, with the micellar radius remaining nearly constant. PRMs do so by partitioning to different locations within the micelles according to their octanol/water partition coefficient P and chemical structures, adjusting the packing of the head and/or tail groups, and by changing the micelle radius, in the case of a large hydrophobic PRM. We find that relatively hydrophilic PRMs with log P < 2 partition primarily to the head group region and shrink micellar length, decreasing viscosity substantially, whereas more hydrophobic PRMs, with log P between 2 and 4, mix with the hydrophobic surfactant tails within the micellar core and slightly enhance the viscosity and micelle length, which is consistent with the packing argument. Large and very hydrophobic PRMs, with log P > 4, are isolated deep inside the micelle, separating from the tails and swelling the radius of the micelle, leading to shorter micelles and much lower viscosities, leading eventually to swollen-droplet micelles.

No abstract

During steps 1-7 of spermiogenesis the Golgi apparatus contributes to the formation of the acrosomic system which develops at the surface of the nucleus. Later, in step 8, the Golgi apparatus detaches from the acrosome and remains suspended in the elongated cytoplasm until it degenerates during step 16. Using 3H-fucose as a tracer and the radioautographic technique, we observed that the Golgi apparatus incorporates the tracer and delivers the labeled glycoproteins to the developing acrosomic system during steps 1-7 of spermiogenesis, to multivesicular bodies during steps 1-9, and to the remaining cytoplasm and plasma membrane during steps 1-15. Throughout these steps of spermiogenesis the Golgi apparatus does not show major changes in structure; it is composed of a cortex made up of connected stacks of saccules and a medulla showing a loose aggregate of vesicular profiles. Glycoprotein synthesis in this Golgi apparatus, before and after it contributes lysosomal glycoproteins to the growing acrosomic system, was quantitatively assessed in electron microscope EM radioautographs of tissue sections from animals sacrificed at 1, 4, 8, and 24 h of 3H-fucose injection. The incorporation of the labeled sugar was found to remain quantitatively similar during steps 1-15 of spermiogenesis, and therefore, no shift in glycoprotein synthesis took place following separation of the Golgi apparatus from the acrosomic system. Throughout these steps, fucose molecules are first incorporated in the cortex of the organelle and subsequently transported to the medulla, where they temporarily accumulate before being delivered, depending on the step of spermiogenesis, to the acrosomic system, to the multivesicular bodies, and also, presumably, to the plasma membrane.