Tenc1-deficient mice develop glomerular disease in a strain-specific manner.

BACKGROUND/AIMS: Tenc1 (also known as tensin2) is an integrin-associated focal adhesion molecule that is broadly expressed in mouse tissues including the liver, muscle, heart and kidney. A mouse strain carrying mutated Tenc1, the ICR-derived glomerulonephritis (ICGN) strain, develops severe nephrotic syndrome. METHODS: To elucidate the function of Tenc1 in the kidney, Tenc1(ICGN) was introduced into 2 genetic backgrounds, i.e. DBA/2J (D2) and C57BL/6J (B6), strains that are respectively susceptible and resistant to chronic kidney disease. RESULTS: Biochemical and histological analysis revealed that homozygous Tenc1(ICGN) mice develop nephrotic syndrome on the D2 background (D2GN) but not on the B6 background (B6GN). Initially, abnormal assembly and maturation of glomerular basement membrane (GBM) were observed, and subsequently effacement of podocyte foot processes was noted in the kidneys of D2GN but not B6GN mice. These defects are likely to be involved in the integrin signaling pathway. CONCLUSION: This study suggests that Tenc1 contributes to the maintenance of GBM structures and that the genetic background influences the severity of nephrotic syndrome.

Solid-state NMR analysis of the ß-strand orientation of the protofibrils of amyloid ß-protein.

Alzheimer's disease (AD) is caused by abnormal deposition (fibrillation) of a 42-residue amyloid ß-protein (Aß42) in the brain. During the process of fibrillation, the Aß42 takes the form of protofibrils with strong neurotoxicity, and is thus believed to play a crucial role in the pathogenesis of AD. To elucidate the supramolecular structure of the Aß42 protofibrils, the intermolecular proximity of the Ala-21 residues in the Aß42 protofibrils was analyzed by (13)C-(13)C rotational resonance experiments in the solid state. Unlike the Aß42 fibrils, an intermolecular (13)C-(13)C correlation was not found in the Aß42 protofibrils. This result suggests that the ß-strands of the Aß42 protofibrils are not in an in-register parallel orientation. Aß42 monomers would assemble to form protofibrils with the ß-strand conformation, then transform into fibrils by forming intermolecular parallel ß-sheets.

Suppression of nanosilica particle-induced inflammation by surface modification of the particles.

It has gradually become evident that nanomaterials, which are widely used in cosmetics, foods, and medicinal products, could induce substantial inflammation. However, the roles played by the physical characteristics of nanomaterials in inflammatory responses have not been elucidated. Here, we examined how particle size and surface modification influenced the inflammatory effects of nanosilica particles, and we investigated the mechanisms by which the particles induced inflammation. We compared the inflammatory effects of silica particles with diameters of 30-1,000 nm in vitro and in vivo. In macrophages in vitro, 30- and 70-nm nanosilica particles (nSP30 and nSP70) induced higher production of tumor necrosis factor-α (TNFα) than did larger particles. In addition, intraperitoneal injection of nSP30 and nSP70 induced stronger inflammatory responses involving cytokine production than did larger particles in mice. nSP70-induced TNFα production in macrophage depended on the production of reactive oxygen species and the activation of mitogen-activated protein kinases (MAPKs). Furthermore, nSP70-induced inflammatory responses were dramatically suppressed by surface modification of the particles with carboxyl groups in vitro and in vivo; the mechanism of the suppression involved reduction in MAPK activation. These results provide basic information that will be useful for the development of safe nanomaterials.

Solid-state NMR analysis of interaction sites of curcumin and 42-residue amyloid ß-protein fibrils.

Aggregation of 42-residue amyloid ß-protein (Aß42) plays a pivotal role in the etiology of Alzheimer's disease (AD). Curcumin, the yellow pigment in the rhizome of turmeric, attracts considerable attention as a food component potentially preventing the pathogenesis of AD. This is because curcumin not only inhibits the aggregation of Aß42 but also binds to its aggregates (fibrils), resulting in disaggregation. However, the mechanism of interaction between curcumin and the Aß42 fibrils remains unclear. In this study, we analyzed the binding mode of curcumin to the Aß42 fibrils by solid-state NMR using dipolar-assisted rotational resonance (DARR). To improve the quality of 2D spectra, 2D DARR data were processed with the covariance NMR method, which enabled us to detect weak cross peaks between carbons of curcumin and those of the Aß42 fibrils. The observed (13)C-(13)C cross peaks indicated that curcumin interacts with the 12th and 17-21st residues included in the ß-sheet structure in the Aß42 fibrils. Interestingly, aromatic carbons adjacent to the methoxy and/or hydroxy groups of curcumin showed clear cross peaks with the Aß42 fibrils. This suggested that these functional groups of curcumin play an important role in its interaction with the Aß42 fibrils.

Silica and titanium dioxide nanoparticles cause pregnancy complications in mice.

The increasing use of nanomaterials has raised concerns about their potential risks to human health. Recent studies have shown that nanoparticles can cross the placenta barrier in pregnant mice and cause neurotoxicity in their offspring, but a more detailed understanding of the effects of nanoparticles on pregnant animals remains elusive. Here, we show that silica and titanium dioxide nanoparticles with diameters of 70 nm and 35 nm, respectively, can cause pregnancy complications when injected intravenously into pregnant mice. The silica and titanium dioxide nanoparticles were found in the placenta, fetal liver and fetal brain. Mice treated with these nanoparticles had smaller uteri and smaller fetuses than untreated controls. Fullerene molecules and larger (300 and 1,000 nm) silica particles did not induce these complications. These detrimental effects are linked to structural and functional abnormalities in the placenta on the maternal side, and are abolished when the surfaces of the silica nanoparticles are modified with carboxyl and amine groups.

The effect of surface modification of amorphous silica particles on NLRP3 inflammasome mediated IL-1beta production, ROS production and endosomal rupture.

Although amorphous silica particles (SPs) are widely used in cosmetics, foods and medicinal products, it has gradually become evident that SPs can induce substantial inflammation accompanied by interleukin-1beta (IL-1beta) production. Here, to develop safe forms of SPs, we examined the mechanisms of SP-induced inflammation and the relationship between particle characteristics and biological responses. We compared IL-1beta production levels in THP-1 human macrophage like cells in response to unmodified SP of various diameters (30- to 1000-nm) and demonstrated that unmodified microsized 1000-nm SP (mSP1000) induced higher levels of IL-1beta production than did smaller unmodified SPs. Furthermore, we found that unmodified mSP1000-induced IL-1beta production was depended on the sequence of reactive oxygen species (ROS) production, endosomal rupture, and subsequent activation of pro-inflammatory complex NLRP3 inflammasome. In addition, we compared IL-1beta production levels in THP-1 cells treated with mSP1000s modified with a functional group (-COOH, -NH(2), -SO(3)H, -CHO). Although unmodified and surface-modified mSP1000s were taken up with similar frequencies equally into the THP-1 cells, surface modification of mSP1000 dramatically suppressed IL-1beta production by reducing ROS production. Our results reveal a part of NLRP3 activation pathway and provide basic information that should help to create safe and effective forms of SPs.