Lipid microdomains or caveolae, small invaginations of plasma membrane, have emerged as important elements for lipid uptake and glucose homeostasis. Sphingomyelin (SM) is one of the major phospholipids of the lipid microdomains. In this study, we investigated the physiological function of sphingomyelin synthase 2 (SMS2) using SMS2 knock-out mice, and we found that SMS2 deficiency prevents high fat diet-induced obesity and insulin resistance. Interestingly, in the liver of SMS2 knock-out mice, large and mature lipid droplets were scarcely observed. Treatment with siRNA for SMS2 also decreased the large lipid droplets in HepG2 cells. Additionally, the siRNA of SMS2 decreased the accumulation of triglyceride in liver of leptin-deficient (ob/ob) mice, strongly suggesting that SMS2 is involved in lipid droplet formation. Furthermore, we found that SMS2 exists in lipid microdomains and partially associates with the fatty acid transporter CD36/FAT and with caveolin 1, a scaffolding protein of caveolae. Because CD36/FAT and caveolin 1 exist in lipid microdomains and are coordinately involved in lipid droplet formation, SMS2 is implicated in the modulation of the SM in lipid microdomains, resulting in the regulation of CD36/FAT and caveolae. Here, we established new cell lines, in which we can completely distinguish SMS2 activity from SMS1 activity, and we demonstrated that SMS2 could convert ceramide produced in the outer leaflet of the plasma membrane into SM. Our findings demonstrate the novel and dynamic regulation of lipid microdomains via conformational changes in lipids on the plasma membrane by SMS2, which is responsible for obesity and type 2 diabetes.

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h i g h l i g h t sThe effects of recycled nylon fiber mixed in mortar on flexural behavior are focused. Improvement of flexural strength and toughness are observed by using recycled nylon fiber. Post peak behavior is directly affected by bond strength between fiber and matrix. a b s t r a c tThis paper discusses the utilization of recycle waste fishing nets in fiber reinforced mortar. Experimental test results compared the mechanical properties of such mortar made with recycled nylon fiber to those of such mortar made with recycled PET and PVA (polyvinyl alcohol) short fibers. The recycled nylon (RNylon) fibers were obtained by manually cutting of waste fishing nets to the lengths of 20 mm, 30 mm and 40 mm. Two types of R-Nylon fibers were investigated that are straight and knotted types. The addition of straight R-Nylon fiber improved the flexural strength up to 41% in comparison with that of the knotted R-Nylon, recycled PET, and PVA fibers. The compressive strength of the mortar with R-Nylon fiber decreased with increase in fiber fraction and length. The post peak load, toughness and residual strength depended on the properties of fiber such as Young's modulus, tensile strength, and geometry as well as the bond strength between fiber and matrix.

a b s t r a c tCeramide kinase (CERK) is an enzyme that phosphorylates ceramide to produce ceramide 1-phosphate. Recently, evidence has emerged that CERK has a role in inflammatory signaling of immune cells. Since obesity is accompanied by chronic, low-grade inflammation, we examined whether CERK might be involved using CERK-null mice. We determined that CERK deficiency suppresses dietinduced increases in body weight, and improves glucose intolerance. Furthermore, we demonstrated that CERK deficiency attenuates MCP-1/CCR2 signaling in macrophages infiltrating the adipose tissue, resulting in the suppression of inflammation in adipocytes, which might otherwise lead to obesity and diabetes.

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