Protein kinase C-δ interacts with and phosphorylates ARD1.

Protein kinase C-δ (PKCδ) is a diacylglycerol-dependent, calcium-independent novel PKC isoform that is engaged in various cell signaling pathways, such as cell proliferation, apoptosis, inflammation, and oxidative stress. In this study, we searched for proteins that bind PKCδ using a yeast two-hybrid assay and identified murine arrest-defective 1 (mARD1) as a binding partner. The interaction between PKCδ and mARD1 was confirmed by glutathione S-transferase pull-down and co-immunoprecipitation assays. Furthermore, recombinant PKCδ phosphorylated full-length mARD1 protein. The NetPhos online prediction tool suggested PKCδ phosphorylates Ser80 , Ser108 , and Ser114 residues of mARD1 with the highest probability. Based on these results, we synthesized peptides containing these sites and examined their phosphorylations using recombinant PKCδ. Autoradiography confirmed these sites were efficiently phosphorylated. Consequent mass spectrometry and peptide sequencing in combination with MALDI-TOF MS/MS confirmed that Ser80 and Ser108 were major phosphorylation sites. The alanine mutations of Ser80 and Ser108 abolished the phosphorylation of mARD1 by PKCδ in 293T cells supporting these observations. In addition, kinase assays using various PKC isotypes showed that Ser80 of ARD1 was phosphorylated by PKCßI and PKCζ isotypes with the highest selectivity, while Ser108 and/or Ser114 were phosphorylated by PKCγ with activities comparable to that of the PKCδ isoform. Overall, these results suggest the possibility that PKCδ transduces signals by regulating phosphorylation of ARD1.

A Low Frequency Vibration Energy Harvester Using ZnO Nanowires on Elastic Interdigitated Electrodes.

This paper presents a low frequency piezoelectric vibration energy harvester using ZnO nanowires on elastic interdigitated electrodes. The interdigitated electrodes are formed using electroplated Ni and have suspended parts at the edges that are elastic and deformable by applying external force. A spherical Ni ball is used as a proof mass, which transforms a low frequency mechanical vibration into the force applied to deform the elastic electrodes. The ZnO nanowires are grown selectively on the electrodes and can generate a piezoelectric potential when the elastic electrodes are deformed by the proof mass activated by the external mechanical vibration. The proposed operation concept is demonstrated using two different types of energy harvesters, which have simple suspended part and cantilever array structures added to the electrodes, respectively. The output voltage of the fabricated harvesters is measured using a vibration exciter at 6 Hz sinusoidal vibration with an acceleration of 0.5 g. Maximum output power of 12.8 pW and 18.8 pW was generated with a load resistance of 1 MΩ for the harvesters using the simple suspended structure and cantilever array, respectively.

Fabrication of Localized Surface Plasmon Resonance Sensor Based on Optical Fiber and Micro Fluidic Channel.

This paper proposes Fiber-Optic Localized Surface Plasmon Resonance (FO LSPR) sensor combined with a micro fluidic channel, which enables continuous supply of fluid for bio-reaction. The proposed method prevents degradation of the sensing performance due to changes in measurement conditions. The feasibility of the FO LSPR sensor with a micro fluidic channel was demonstrated by computational fluid dynamics (CFD) simulation. Also, the proposed method was assessed by measuring the output intensity of the FO LSPR sensor at various refractive index solutions. Finally, a prostate-specific antigen (PSA) immunoassay was performed to evaluate the possibility of the fabricated sensor system as a biosensor.

Novel microbial photobioelectrochemical cell using an invasive ultramicroelectrode array and a microfluidic chamber.

OBJECTIVE: To fabricate a novel microbial photobioelectrochemical cell using silicon microfabrication techniques. RESULTS: High-density photosynthetic cells were immobilized in a microfluidic chamber, and ultra-microelectrodes in a microtip array were inserted into the cytosolic space of the cells to directly harvest photosynthetic electrons. In this way, the microbial photobioelectrochemical cell operated without the aid of electron mediators. Both short circuit current and open circuit voltage of the microbial photobioelectrochemical cell responded to light stimuli, and recorded as high as 250 pA and 45 mV, respectively. CONCLUSION: A microbial photobioelectrochemical cell was fabricated with potential use in next-generation photosynthesis-based solar cells and sensors.

Two nuclear export signals of Cdc6 are differentially associated with CDK-mediated phosphorylation residues for cytoplasmic translocation.

Cdc6 is cleaved at residues 442 and 290 by caspase-3 during apoptosis producing p49-tCdc6 and p32-tCdc6, respectively. While p32-tCdc6 is unable to translocate into the cytoplasm, p49-tCdc6 retains cytoplasmic translocation activity, but it has a lower efficiency than wild-type Cdc6. We hypothesized that a novel nuclear export signal (NES) sequence exists between amino acids 290 and 442. Cdc6 contains a novel NES in the region of amino acids 300-315 (NES2) that shares sequence similarity with NES1 at residues 462-476. In mutant versions of Cdc6, we replaced leucine with alanine in NES1 and NES2 and co-expressed the mutant constructs with cyclin A. We observed that the cytoplasmic translocation of these mutants was reduced in comparison to wild-type Cdc6. Moreover, the cytoplasmic translocation of a mutant in which all four leucine residues were mutated to alanine was significantly inhibited in comparison to the translocation of wild-type Cdc6. The Crm1 binding activities of Cdc6 NES mutants were consistent with the efficiency of its cytoplasmic translocation. Further studies have revealed that L468 and L470 of NES1 are required for cytoplasmic translocation of Cdc6 phosphorylated at S74, while L311 and L313 of NES2 accelerate the cytoplasmic translocation of Cdc6 phosphorylated at S54. These results suggest that the two NESs of Cdc6 work cooperatively and distinctly for the cytoplasmic translocation of Cdc6 phosphorylated at S74 and S54 by cyclin A/Cdk2.

Phosphorylation of Cdc6 at serine 74, but not at serine 106, drives translocation of Cdc6 to the cytoplasm.

Phosphorylation-dependent cytoplasmic translocation of human Cdc6 during S phase is sufficient to control its activity after origin firing. Export from the nucleus also serves as a mechanism for preventing re-replication in mammalian cells. Phosphorylation of the CDK consensus serine residues 54, 74, and 106 has been suggested to be involved in the cytoplasmic translocation of Cdc6. To determine the relative importance of the three phosphorylation sites, we have generated Cdc6 variants by substituting one or more of the three serine residues with alanine or aspartic acid and have assessed their cytoplasmic translocation behavior. Phosphorylation of serine 74 mainly contributes to the cytoplasmic translocation of Cdc6, while serine 54 phosphorylation provides a minor contribution. In contrast, phosphorylation at serine 106 does not affect the nuclear export of Cdc6. Comparative results were found in cells coexpressing the phosphorylation defective mutants of Cdc6 and cyclin A as well as in non-transfected cells synchronized by their release from a double thymidine block. We conclude that Cdk-mediated phosphorylation of Cdc6 at serine 74 is required for the cytoplasmic translocalization of Cdc6 during the cell cycle. Phosphorylation of Cdc6 at serine 54 plays a minor role and phosphorylation of serine 106 plays no role in the cytoplasmic localization of Cdc6. The phosphorylation of S74 in Cdc6 could be important for binding to the nuclear export protein for translocalization.

Bimetallic nanodisk-based fiber-optic plasmonic nanoprobe for gas detection.

In this study, gold-palladium bimetallic nanodisks were patterned on optical fibers via nanosphere lithography and chemical growth. The conditions related to the density of the structures, concentration of the growth solution, and growth time were modified. The structural features of nanodisks with a large surface area and enhancement of plasmonic efficiency owing to the palladium shell resulted in a high refractive index sensitivity. Additionally, based on palladium's sensitivity to hydrogen, hydrogen sensing was performed at various concentrations with a detection limit of 0.125 % and signal-to-noise ratio of 24.2 dB. The response time and hysteresis showed a good performance relative to those of other hydrogen sensors. The high throughput of the nanosphere lithography and simple seed-mediated growth make this system a cost-effective fiber-optic plasmonic nanoprobe. Based on these investigations, the optical fiber-based plasmonic nanoprobe can be actively applied to detect dangerous environments using remote sensing for safety management in the clean energy era.

Integrated Logic Circuits Based on Wafer-Scale 2D-MoS2 FETs Using Buried-Gate Structures.

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) materials, such as molybdenum disulfide (MoS2), stand out due to their atomically thin layered structure and exceptional electrical properties. Consequently, they could potentially become one of the main materials for future integrated high-performance logic circuits. However, the local back-gate-based MoS2 transistors on a silicon substrate can lead to the degradation of electrical characteristics. This degradation is caused by the abnormal effect of gate sidewalls, leading to non-uniform field controllability. Therefore, the buried-gate-based MoS2 transistors where the gate electrodes are embedded into the silicon substrate are fabricated. The several device parameters such as field-effect mobility, on/off current ratio, and breakdown voltage of gate dielectric are dramatically enhanced by field-effect mobility (from 0.166 to 1.08 cm2/V·s), on/off current ratio (from 4.90 × 105 to 1.52 × 107), and breakdown voltage (from 15.73 to 27.48 V) compared with a local back-gate-based MoS2 transistor, respectively. Integrated logic circuits, including inverters, NAND, NOR, AND, and OR gates, were successfully fabricated by 2-inch wafer-scale through the integration of a buried-gate MoS2 transistor array.

Skin-Whitening Effect of a Callus Extract of Nelumbo nucifera Isolate Haman.

The sacred lotus (Nelumbo nucifera Gaertn. Isolate Haman, in the family Nelumbonaceae) used in this study originated from the Haman region of Korea, and lotus seeds dating back to the Goryeo Dynasty (650-760 years ago) were accidentally discovered. Lotus is known to possess antioxidant, anti-inflammatory, and soothing properties. Instead of using the lotus alone, we obtained extracts using Haman region lotus-derived callus (HLC), which allowed for a controlled, quantitative, and infinite supply. Based on the reported effects of the lotus, we formulated a hypothesis to investigate the skin-whitening effect of the HLC extract (HLCE). The HLCE was first obtained by extraction with distilled water and using 5% propanediol as a solvent and subsequently verified for the whitening effect (melanin content tests) using mammalian cells in vitro. Its efficacy at the molecular level was confirmed through real-time polymerase chain reaction (PCR) using melanin-related genes. Furthermore, clinical trials with 21 volunteers confirmed the significant whitening effect of cosmetics containing the HLCE. In conclusion, we found that the HLCE not only has anti-inflammatory, antioxidant, and skin-soothing properties but also plays an essential role in skin whitening. Therefore, we propose that the HLCE has the potential to become a new raw material for the cosmetic industry.

Ibulocydine is a novel prodrug Cdk inhibitor that effectively induces apoptosis in hepatocellular carcinoma cells.

Hepatocellular carcinoma (HCC) is frequently associated with abnormalities in cell cycle regulation, leading to increased activity of cyclin-dependent kinases (Cdks) due to the loss, or low expression of, Cdk inhibitors. In this study, we showed that ibulocydine (an isobutyrate prodrug of the specific Cdk inhibitor, BMK-Y101) is a candidate anti-cancer drug for HCC. Ibulocydine has high activity against Cdk7/cyclin H/Mat1 and Cdk9/cyclin T. Ibulocydine inhibited the growth of HCC cells more effectively than other Cdk inhibitors, including olomoucine and roscovitine, whereas ibulocydine as well as the other Cdk inhibitors and BMK-Y101 minimally influenced the growth of normal hepatocyte cells. Ibulocydine induced apoptosis in HCC cells, most likely by inhibiting Cdk7 and Cdk9. In vitro treatment of HCC cells with ibulocydine rapidly blocked phosphorylation of the carboxyl-terminal domain (CTD) of the large subunit of RNA polymerase II, a process mediated by Cdk7/9. Anti-apoptotic gene products such as Mcl-1, survivin, and X-linked IAP (XIAP) are crucial for the survival of many cell types, including HCC. Following the inhibition of RNA polymerase II phosphorylation, ibulocydine caused rapid down-regulation of Mcl-1, survivin, and XIAP, thus inducing apoptosis. Furthermore, ibulocydine effectively induced apoptosis in HCC xenografts with no toxic side effects. These results suggest that ibulocydine is a strong candidate anti-cancer drug for the treatment of HCC.

PKCδ promotes etoposide-induced cell death by phosphorylating Hsp27 in HeLa cells.

We investigated the regulation of Hsp27 phosphorylation by protein kinase C δ (PKCδ) during etoposide-induced apoptosis. The phosphorylation of Hsp27 at Ser78 was temporally correlated with the proteolytic activation of PKCδ during apoptosis. Hsp27 phosphorylation was dependent on the activity of PKCδ since treatment with rottlerin, a chemical inhibitor of PKCδ, or overexpression of a PKCδ dominant negative mutant abolished the phosphorylation. In addition, recombinant PKCδ phosphorylated Hsp27 at Ser78 in vitro. Moreover, caspase-3 was specifically activated following Hsp27 phosphorylation at Ser78. Pull-down assays using a phosphomimetic Hsp27 mutant revealed that binding between Hsp27 and cytochrome c was abolished by the phosphorylation. These results suggest that Hsp27 dissociates from cytochrome c following PKCδ-mediated phosphorylation at Ser78, which allows formation of the apoptosome and stimulates apoptotic progression.

Analysis of fiber-optic localized surface plasmon resonance sensor by controlling formation of gold nanoparticles and its bio-application.

Localized surface plasmon resonance (LSPR) occurs when nanoparticles are bound to the surface of a sensor which is sensitive to the refractive index of the surrounding medium. The sensitivity of the sensor is highly dependent on the type of nanoparticles and their size, density and shape. Using an optical fiber as a sensor has various advantages, such as guided signal delivery and low energy loss. In this study, a Fiber-optic localized surface plasmon resonance (FO-LSPR) sensor was developed and the sizes of the gold nanoparticles (Au NPs) used therein were controlled by reduction with chloroauric acid. The extinction cross-section was calculated by the Mie theory to examine the dependence of the resonance intensity and sensitivity of the fabricated FO-LSPR sensor on the size and density of the Au NPs situated on its end-face. In order to use it as a biosensor, the fabricated FO-LSPR sensor was used to detect the biotin-streptavidin interaction.

Ginsenoside Rh2 induces human hepatoma cell apoptosisvia bax/bak triggered cytochrome C release and caspase-9/caspase-8 activation.

Ginsenoside Rh2 (G-Rh2) has been shown to induce apoptotic cell death in a variety of cancer cells. However, the details of the signal transduction cascade involved in G-Rh2-induced cell death is unclear. In this manuscript we elucidate the molecular mechanism of G-Rh2-induced apoptosis in human hepatoma SK-HEP-1 cells by demonstrating that G-Rh2 causes rapid and dramatic translocation of both Bak and Bax, which subsequently triggers mitochondrial cytochrome c release and consequent caspase activation. Interestingly, siRNA-based gene inactivation of caspase-8 effectively delays caspase-9 activation and apoptosis induced by G-Rh2, indicating that caspase-8 also plays an important role in the G-Rh2-induced apoptosis program. Taken together, our results indicate that G-Rh2 employs a multi pro-apoptotic pathway to execute cancer cell death, suggesting a potential role for G-Rh2 as a powerful chemotherapeutic agent.

Palmitoyl­RGD promotes the expression of dermal­epidermal junction components in HaCaT cells.

With age, the dermal­epidermal junction (DEJ) becomes thinner and production of its protein components decreases; this may be associated with increased fragility and wrinkling of skin. Topical treatment with palmitoyl­Arg­Gly­Asp (PAL­RGD) improves facial wrinkles, skin elasticity and dermal density in humans. In the present study, the effect of PAL­RGD on expression of DEJ components, such as laminin and collagen, was assessed. Human HaCaT keratinocytes were treated with PAL­RGD. The protein expression levels of laminin­332, collagen IV and collagen XVII were examined by western blotting. Reverse transcription-quantitative PCR was used to analyze laminin subunit (LAM)A3, LAMB3, LAMC2, collagen type IV α 1 chain (COL4A1) and COL17A1 mRNA expression levels. Western blot analysis showed that the expression levels of proteins comprising the DEJ, including laminin α3, ß3 and γ2 and collagen IV and XVII demonstrated a significant dose­dependent increase following PAL­RGD treatment. Furthermore, PAL­RGD treatment significantly enhanced LAMA3, LAMB3, LAMC2, COL4A1 and COL17A1 mRNA expression levels. PAL­RGD may enhance the DEJ by inducing the expression of laminin­332, collagen IV and collagen XVII.

Fiber Optic Plasmonic Sensors Based on Nanodome Arrays with Nanogaps.

In this study, a high-performance fiber optic surface plasmon resonance (FO-SPR) sensor using a dome array with nanogaps (DANG) is proposed for label-free real-time detection of biomolecules. A novel and simple method using polymer beads enables high sensitivity by allowing hotspots with nanometer spacing between the Au dome and the surrounding film. The nanodome structure, which comprises a polymer core and a Au shell, induces a localized surface plasmon, expands the sensing area, and extensively enhances the electromagnetic field. The refractive index sensitivity of the FO-SPR sensor with nanostructures, i.e., with nanogaps and nanodomes, was found to be 7.8 times higher than that of the FO-SPR sensor without nanostructures. The proposed sensor achieved a low detection limit of 38 fg/mL while quantifying thyroglobulin antibody-antigen interactions and exhibited excellent selectivity. In addition, it helped detect serum samples with a 103% recovery rate.

High-performance biosensor using a sandwich assay via antibody-conjugated gold nanoparticles and fiber-optic localized surface plasmon resonance.

For real-time and high-sensitivity analysis of low-concentration targets, a sandwich immunoassay using second antibody-second gold nanoparticle (2nd Ab-2nd AuNP) conjugates was combined with fiber-optic localized surface plasmon resonance (FO LSPR). An FO LSPR format was constructed by immobilizing AuNPs on a fiber-optic cross-section for compactness, portability, and ease of handling. In addition, it was combined with a microfluidic system to ensure reproducibility and reliability of measurements. A detection limit of 97.6 fg/mL (148 aM) was obtained for thyroglobulin (Tg) without a sandwich assay. The detection limit was enhanced by approximately 15 times (6.6 fg/mL, 10 aM) when a sandwich strategy was performed with a 2nd Ab-2nd AuNP signal amplifier to further improve the responsivity. Additionally, the good selectivity of the proposed method was confirmed against the unpaired antigen. To evaluate its practical applicability in the field, an FO LSPR biosensor boosted with a sandwich assay using antibody-functionalized AuNPs was applied to detect Tg contained in patient serum, and the results were compared and verified with those of a commercial radioimmunoassay kit. Based on the above results, the signal-enhancing immunoassay with FO LSPR will contribute to the development of optical biosensors for early diagnosis and preventive applications.

Cleavage of Cdc6 by caspase-3 promotes ATM/ATR kinase-mediated apoptosis of HeLa cells.

We show that caspase-3 cleaves Cdc6 at D(290)/S and D(442)/G sites, producing p32-tCdc6 (truncated Cdc6) and p49-tCdc6, respectively, during etoposide- or tumor necrosis factor (TNF)-alpha-induced apoptosis. The expression of these tCdc6 proteins, p32- and p49-tCdc6, promotes etoposide-induced apoptosis. The expression of tCdc6 perturbs the loading of Mcm2 but not Orc2 onto chromatin and activates ataxia telangiectasia mutated (ATM) and ATM and Rad-3 related (ATR) kinase activities with kinetics similar to that of the phosphorylation of Chk1/2. The activation kinetics are consistent with elevated cellular levels of p53 and mitochondrial levels of Bax. The tCdc6-induced effects are all suppressed to control levels by expressing a Cdc6 mutant that cannot be cleaved by caspase-3 (Cdc6-UM). Cdc6-UM expression attenuates the TNF-alpha-induced activation of ATM and caspase-3 activities. When ATM or ATR is down-expressed by using the small interfering RNA technique, the TNF-alpha- or tCdc6-induced activation of caspase-3 activities is suppressed in the cells. These results suggest that tCdc6 proteins act as dominant-negative inhibitors of replication initiation and that they disrupt chromatin structure and/or induce DNA damage, leading to the activation of ATM/ATR kinase activation and p53-Bax-mediated apoptosis.

Fabrication and measurement of fiber optic localized surface plasmon resonance sensor based on gold nanoparticle dimer.

Fiber optic localized surface plasmon resonance (FO LSPR) sensors capable of portable, real-time, and remote sensing are emerging with the progress of lab-on-fiber technology. However, the small area of the substrate by the optical fiber often restricts the sensitivity of the FO LSPR sensors. To improve the performance of the FO LSPR sensors, it is necessary to enhance the interactions between incident light and plasmonic nanostructures within a defined region. Dimer in which two nanoparticles are arranged with nanometer spacing can effectively increase the light-nanostructure interactions. It is well known that the nanogap made in the assembled nanoparticles significantly enhances the intensity of the electromagnetic field in the confined area by the hot spot effect. We fabricate the dimers of gold nanoparticles on the optical fiber with benzenethiol using a method that reduces the repulsive force between the nanoparticles. In the dimers, the strong plasmonic interaction between the two nanoparticles produces a longitudinal plasmon coupling band, which is compared to the transverse plasmon band by the monomer-based FO LSPR sensor with a similar density of gold nanoparticles. In the proposed sensor, the longitudinal band displays approximately 9.1 times improved sensitivity. When two types of sensors are applied to the biosensor application, the dimer-based FO LSPR sensor also proves an improved limit of detection of about 2.6 times. This method is expected to become a milestone in the field of measurement for small molecules and low concentration through the advancement of the yield and density of dimers.

Design and validation of fiber optic localized surface plasmon resonance sensor for thyroglobulin immunoassay with high sensitivity and rapid detection.

A simple optical fiber sensor based on localized surface plasmon resonance was constructed for direct and rapid measurement of thyroglobulin (Tg). Specific tests for Tg in patients that have undergone thyroidectomy are limited because of insufficient sensitivity, complicated procedures, and in some cases, a long time to yield a result. A sensitive, fast, and simple method is necessary to relieve the psychological and physical burden of the patient. Various concentrations of Tg were measured in a microfluidic channel using an optical fiber sensor with gold nanoparticles. The sensor chip has a detection limit of 93.11 fg/mL with no specificity for other antigens. The potential applicability of the Tg sensing system was evaluated using arbitrary samples containing specific concentrations of Tg. Finally, the sensor can be employed to detect Tg in the patient's serum, with a good correlation when compared with the commercial kit.

Quantitative two-photon microscopy imaging analysis of human skin to evaluate enhanced transdermal delivery by hybrid-type multi-lamellar nanostructure: retraction.

[This retracts the article on p. 3974 in vol. 9, PMID: 30338168.].