The melanization reaction induced by activated phenoloxidase in arthropods must be tightly controlled because of excessive formation of quinones and excessive systemic melanization damage to the hosts. However, the molecular mechanism by which phenoloxidase-induced melanin synthesis is regulated in vivo is largely unknown. It is known that the Spätzle-processing enzyme is a key enzyme in the production of cleaved Spätzle from pro-Spätzle in the Drosophila Toll pathway. Here, we provide biochemical evidence that the Tenebrio molitor Spätzle-processing enzyme converts both the 79-kDa Tenebrio prophenoloxidase and Tenebrio clip-domain SPH1 zymogen to an active melanization complex. This complex, consisting of the 76-kDa Tenebrio phenoloxidase and an active form of Tenebrio clip-domain SPH1, efficiently produces melanin on the surface of bacteria, and this activity has a strong bactericidal effect. Interestingly, we found the phenoloxidase-induced melanization reaction to be tightly regulated by Tenebrio prophenoloxidase, which functions as a competitive inhibitor of melanization complex formation. These results demonstrate that the Tenebrio Toll pathway and the melanization reaction share a common serine protease for the regulation of these two major innate immune responses.

The Drosophila Toll receptor does not interact directly with microbial determinants, but is instead activated by a cleaved form of the cytokine-like molecule Spä tzle. During the immune response, Spä tzle is processed by complex cascades of serine proteases, which are activated by secreted pattern-recognition receptors. Here, we demonstrate the essential role of ModSP, a modular serine protease, in the activation of the Toll pathway by Gram-positive bacteria and fungi. Our analysis shows that ModSP integrates signals originating from the circulating recognition molecules GNBP3 and PGRP-SA and connects them to the Grass-SPE-Spä tzle extracellular pathway upstream of the Toll receptor. It also reveals the conserved role of modular serine proteases in the activation of insect immune reactions.innate immunity ͉ proteolytic cascade ͉ insect immunity ͉ antifungal ͉ antimicrobial peptides

The recognition of lysine-type peptidoglycans (PG) by the PG recognition complex has been suggested to cause activation of the serine protease cascade leading to the processing of Spätzle and subsequent activation of the Toll signaling pathway. So far, two serine proteases involved in the lysine-type PG Toll signaling pathway have been identified. One is a modular serine protease functioning as an initial enzyme to be recruited into the lysine-type PG recognition complex. The other is the Drosophila Spätzle processing enzyme (SPE), a terminal enzyme that converts Spätzle proprotein to its processed form capable of binding to the Toll receptor. However, it remains unclear how the initial PG recognition signal is transferred to Spätzle resulting in Toll pathway activation. Also, the biochemical characteristics and mechanism of action of a serine protease linking the modular serine protease and SPE have not been investigated. Here, we purified and cloned a novel upstream serine protease of SPE that we named SAE, SPE-activating enzyme, from the hemolymph of a large beetle, Tenebrio molitor larvae. This enzyme was activated by Tenebrio modular serine protease and in turn activated the Tenebrio SPE. The biochemical ordered functions of these three serine proteases were determined in vitro, suggesting that the activation of a three-step proteolytic cascade is necessary and sufficient for lysine-type PG recognition signaling. The processed Spätzle by this cascade induced antibacterial activity in vivo. These results demonstrate that the three-step proteolytic cascade linking the PG recognition complex and Spätzle processing is essential for the PG-dependent Toll signaling pathway.

NAFLD was associated with risk for components of MetS, and the association was stronger in non-obese than in obese individuals, especially in women. Therefore, NAFLD should be considered a meaningful predictor of metabolic diseases in the non-obese population.

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The effect of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) area on metabolic syndrome (MS) has been debated. We aimed to evaluate the effects of VAT and SAT on the incidence of MS and its components in a large and apparently healthy Asian population. We performed a longitudinal cohort study of 1,964 subjects who received health screenings over a 5-year follow-up period; 317 incidents of MS (16.1%) were observed during a median follow-up of 4.5 years. The VAT area was significantly associated with a higher incidence of MS; the adjusted HR for incident MS per 1 SD of VAT was 1.50 (95% CI 1.29–1.74), and the adjusted HR of the 5th VAT quintile compared with the 1st quintile was 3.73 (95% CI 2.22–6.28). However, the SAT area was not associated with incident MS. Although the VAT area was longitudinally associated with the incidence of each component of MS, the SAT area was inversely associated with the risk of high blood pressure, fasting blood sugar, and triglycerides, with marginal significance. In conclusion, the VAT area is longitudinally associated with an increased risk of incident MS, while SAT may have a protective effect against the incidence of individual MS components.

BackgroundThe association between low serum testosterone levels, visceral adipose tissue (VAT), and metabolic syndrome is now well known. However, the relationship between hepatic steatosis and serum testosterone levels has not been extensively studied. Our aim was to investigate the association of serum total testosterone levels with nonalcoholic fatty liver disease (NAFLD), adjusting for the influence of VAT and insulin resistance.MethodsThis study is a retrospective observational cross-sectional one of healthy Korean men and was conducted at the Seoul National University Hospital Healthcare System Gangnam Center. We used data obtained from 495 men who were at least 20 years of age and who had undergone blood testing, abdominal computed tomography, and ultrasonography. Multiple logistic regression analysis was used to explore the association of serum total testosterone levels with NAFLD.ResultsMen in the low serum testosterone quintile were at a higher risk for NAFLD than men in the highest serum testosterone quintile. After adjusting for age, smoking, diabetes, exercise, BMI, triglycerides, and high-density-lipoprotein cholesterol, subjects with serum testosterone levels in the lowest quintile had an odds ratio (OR) (95% confidence interval (CI)) of 5.12 (2.43–10.77) for NAFLD (p value, 0.0004). The inverse association between serum testosterone and NAFLD was attenuated by further adjustment for variables including VAT; however, it remained statistically significant (OR (95% CI): 4.52 (2.09–9.80) in the lowest quintile; p value=0.004).ConclusionsA low serum total testosterone level was independently associated with NAFLD. This report is the first one suggesting the association remains unchanged even after controlling for VAT and insulin resistance.

The addition of financial incentives to Smartcare was effective in increasing physical activity and reducing obesity.