This study was conducted to investigate the possible involvement of protein kinase C (PKC) and serine/threonine phosphorylation of the insulin receptor in insulin resistance and/or obesity. Insulin receptor tyrosine kinase activity was depressed in muscle from obese insulin-resistant patients compared with lean insulinresponsive control subjects. Alkaline phosphatase treatment resulted in a significant 48% increase in in vitro insulin-stimulated receptor tyrosine kinase activity in obese but not lean muscle. To investigate the involvement of PKC in skeletal muscle insulin resistance and/or obesity, membrane-associated PKC activity and the protein content of various PKC isoforms were measured in human skeletal muscle from lean, insulinresponsive, and obese insulin-resistant patients. Membrane-associated PKC activity was not changed; however, PKC-␤ protein content, assayed by Western blot analysis, was significantly higher, whereas PKC-, -, and -µ were significantly lower in muscle from obese patients compared with muscle from lean control subjects. Incubation of muscle strips with insulin significantly increased membrane-associated PKC activity in muscle from obese but not lean subjects. PKC-␦, -␤, and -were translocated from the cytosol to the membrane fraction in response to insulin treatment. These results suggest that in skeletal muscle from insulin-resistant obese patients, insulin receptor tyrosine kinase activity was reduced because of hyperphosphorylation on serine/threonine residues. Membrane-associated PKC-␤ protein was elevated under basal conditions, and membraneassociated total PKC activity was increased under insulin-stimulated conditions in muscle from obese insulin-resistant patients. Thus, we postulate that the decreased tyrosine kinase activity of the insulin receptor may be caused by serine/threonine phosphorylation by PKC. Diabetes 49:1353-1358, 2000 W hereas insulin binding induces autophosphorylation of the insulin receptor on specific tyrosine residues, phosphorylation of the insulin receptor on serine/threonine residues reduces tyrosine kinase activity (1,2). In vitro purified protein kinase C (PKC) directly phosphorylated purified insulin receptors and decreased their tyrosine kinase activity (3). Furthermore, in tissue cultured cells overexpressing the insulin receptor, an increase in PKC activity was correlated to an increase in serine phosphorylation of the insulin receptor (4).Evidence that increased activity of PKC may be associated with insulin resistance comes from many cell culture experiments (4-8). In addition, it was observed that membranebound PKC activity was increased in insulin-resistant rat fat cells, and insulin resistance was reversed with the addition of specific PKC inhibitors (9). Evidence from our laboratory (10) also suggests the involvement of PKC in insulin resistance. When insulin-resistant muscle was incubated with a PKC inhibitor, insulin action was restored. Incubation of insulin-sensitive muscle with a PKC activator reduced insulin action. This result is stro...

Recognition of viral nucleic acids by pattern recognition receptors initiates type I IFN induction and innate antiviral immune response. Here we show that LSm14A, a member of the LSm family involved in RNA processing in the processing bodies, binds to synthetic or viral RNA and DNA and mediates IRF3 activation and IFN-β induction. Knockdown of LSm14A inhibits cytosolic RNA-and DNA-trigger type I IFN production and cellular antiviral response. Moreover, LSm14A is essential for early-phase induction of IFN-β after either RNA or DNA virus infection. We further found that LSm14A-mediated IFN-β induction requires RIG-I-VISA or MITA after RNA or DNA virus infection, respectively, and viral infection causes translocation of LSm14A to peroxisomes, where RIG-I, VISA, and MITA are located. These findings suggest that LSm14A is a sensor for both viral RNA and DNA and plays an important role in initiating IFN-β induction in the early phase of viral infection.

The MHC-related 1, MR1, molecule presents a new class of microbial antigens (derivatives of the riboflavin [Vitamin B2] biosynthesis pathway) to mucosal-associated invariant T (MAIT) cells. This raises many questions regarding antigens loading and intracellular trafficking of the MR1/ligand complexes. The MR1/MAIT field is also important because MAIT cells are very abundant in humans and their frequency is modified in many infectious and non-infectious diseases. Both MR1 and the invariant TCRα chain expressed by MAIT cells are strikingly conserved among species, indicating important functions. Riboflavin is synthesized by plants and most bacteria and yeasts but not animals, and its precursor derivatives activating MAIT cells are short-lived unless bound to MR1. The recognition of MR1 loaded with these compounds is therefore an exquisite manner to detect invasive bacteria. Herein, we provide an historical perspective of the field before describing the main characteristics of MR1, its ligands, and the few available data regarding its cellular biology. We then summarize the current knowledge of MAIT cell differentiation and discuss the definition of MAIT cells in comparison to related subsets. Finally, we describe the phenotype and effector activities of MAIT cells.

Viral DNA sensing within the cytosol of infected cells activates type I interferon (IFN) expression. MITA/STING plays an essential role in this pathway by acting as both a sensor for the second messenger cGAMP and as an adaptor for downstream signaling components. In an expression screen for proteins that can activate the IFNB1 promoter, we identified the ER-associated protein ZDHHC1 as a positive regulator of virus-triggered, MITA/STING-dependent immune signaling. Zdhhc1(-/-) cells failed to effectively produce IFNs and other cytokines in response to infection with DNA but not RNA viruses. Zdhhc1(-/-) mice infected with the neurotropic DNA virus HSV-1 exhibited lower cytokine levels and higher virus titers in the brain, resulting in higher lethality. ZDHHC1 constitutively associated with MITA/STING and mediates dimerization/aggregation of MITA/STING and recruitment of the downstream signaling components TBK1 and IRF3. These findings support a role for ZDHHC1 in mediating MITA/STING-dependent innate immune response against DNA viruses.

Interferon-stimulated gene 56 (ISG56) family members play important roles in blocking viral replication and regulating cellular functions, however, their underlying molecular mechanisms are largely unclear. Here, we present the crystal structure of ISG54, an ISG56 family protein with a novel RNA-binding structure. The structure shows that ISG54 monomers have 9 tetratricopeptide repeat-like motifs and associate to form domain-swapped dimers. The Cterminal part folds into a super-helical structure and has an extensively positively-charged nucleotide-binding channel on its inner surface. EMSA results show that ISG54 binds specifically to some RNAs, such as adenylate uridylate (AU)-rich RNAs, with or without 5′ triphosphorylation. Mutagenesis and functional studies show that this RNAbinding ability is important to its antiviral activity. Our results suggest a new mechanism underlying the antiviral activity of this interferon-inducible gene 56 family member.

Quercetin, one of the most common natural flavonoids, has been reported to possess significant anti-tumor activities both in vitro and in vivo. The present study was to investigate the effects of quercetin on growth and apoptosis in human salivary adenoid cystic carcinoma (ACC). The result from MTT assay showed that quercetin decreased cell viability of both low metastatic cell line ACC-2 and high metastatic cell line ACC-M in a concentration- and time-dependent manner. Moreover, treatment with quercetin resulted in significantly increased apoptosis in ACC cells. Our data also revealed that the apoptosis induced by quercetin treatment was through a mitochondria-dependent pathway which showed close correlation with the down-regulation of the PI3K/Akt/IKK-alpha/NF-kappaB pathway. Most importantly, quercetin significantly prevented in vivo growth of ACC xenografts in nude mice, accompanied by induction of tumor cell apoptosis, suppression of NF-kappaB nuclear translocation, as well as down-regulation of Akt and IKK-alpha activation. In addition, we explored the clinical significance of the PI3K/Akt/IKK-alpha/NF-kappaB signaling axis in ACC by immunohistochemical analysis of tissue specimens followed by the clustering analyses. We determined that the PI3K/Akt/IKK-alpha/NF-kappaB pathway is ubiquitously activated in ACC and plays an essential role in the evasion of apoptosis. Taken together, the results from our study implicated that quercetin would be a promising chemotherapeutic agent against ACC through its function of down-regulating the PI3K/Akt/IKK-alpha/NF-kappaB signaling pathway.

A cilia array via a magnetic field was proposed as the dielectric layer for flexible capacitive sensors with high sensitivity and a broad detection range.

The trade‐off between sensitivity and linearity is critical for preserving the high pressure‐resolution over a broad range and simplifying the signal processing/conversion of flexible tactile sensors. Conventional dielectrics suffer from the difficulty of quantitatively controlling the interacted mechanical and dielectric properties, thus causing the restricted sensitivity and linearity of capacitive sensors. Herein, inspired by human skin, a novel hybrid dielectric composed of a low‐permittivity (low‐k) micro‐cilia array, a high‐permittivity (high‐k) rough surface, and micro‐dome array is developed. The pressure‐induced series‐parallel conversion between the low‐k and high‐k components of the hybrid dielectric enables the linear effective dielectric constant and controllable initial/resultant capacitance. The gradient compressibility of the hybrid dielectric enables the linear behavior of elastic modulus with pressures, which derives the capacitance variation determined by the effective dielectric constant. Therefore, an ultrawide linearity range up to 1000 kPa and a high sensitivity of 0.314 kPa–1 are simultaneously achieved by the optimized hybrid dielectric. The design is also applicable for triboelectric tactile sensors, which realizes the similar linear behavior of output voltage and enhanced sensitivity. With the high pressure‐resolution across a broad range, potential applications such as healthcare monitoring in diverse scenarios and control command conversion via a single sensor are demonstrated.