Nox4-SH3YL1 complex is involved in diabetic nephropathy.

Nox4-derived H2O2 generation plays an important role in the pathogenesis of chronic kidney diseases (CKDs) such as diabetic nephropathy (DN). Here, we showed that SH3 domain-containing Ysc84-like 1 (SH3YL1), a Nox4 cytosolic activator, regulated DN. Streptozotocin (STZ)-induced type Ⅰ diabetic models in SH3YL1 whole-body knockout (KO) mice and podocyte-specific SH3YL1 conditional KO (Nphs2-Cre/SH3YL1fl/fl) mice were established to investigate the function of SH3YL1 in DN. The expression of fibrosis markers and inflammatory cytokines, the generation of oxidative stress, and the loss of podocytes were suppressed in diabetic SH3YL1 KO and Nphs2-Cre/SH3YL1fl/fl mice, compared to diabetic control mice. To extrapolate the observations derived from diabetic mice to clinical implication, we measured the protein level of SH3YL1 in patients DN. In fact, the SH3YL1 level was increased in patients DN. Overall, the SH3YL1-Nox4 complex was identified to play an important role in renal inflammation and fibrosis, resulting in the development of DN.

LPS-Induced Acute Kidney Injury Is Mediated by Nox4-SH3YL1.

Cytosolic proteins are required for regulation of NADPH (nicotinamide adenine dinucleotide phosphate) oxidase (Nox) isozymes. Here we show that Src homology 3 (SH3) domain-containing YSC84-like 1 (SH3YL1), as a Nox4 cytosolic regulator, mediates lipopolysaccharide (LPS)-induced H2O2 generation, leading to acute kidney injury. The SH3YL1, Ysc84p/Lsb4p, Lsb3p, and plant FYVE proteins (SYLF) region and SH3 domain of SH3YL1 contribute to formation of a complex with Nox4-p22phox. Interaction of p22phox with SH3YL1 is triggered by LPS, and the complex induces H2O2 generation and pro-inflammatory cytokine expression in mouse tubular epithelial cells. After LPS injection, SH3YL1 knockout mice show lower levels of acute kidney injury biomarkers, decreased secretion of pro-inflammatory cytokines, decreased infiltration of macrophages, and reduced tubular damage compared with wild-type (WT) mice. The results strongly suggest that SH3YL1 is involved in renal failure in LPS-induced acute kidney injury (AKI) mice. We demonstrate that formation of a ternary complex of p22phox-SH3YL1-Nox4, leading to H2O2 generation, induces severe renal failure in the LPS-induced AKI model.

Function of NADPH Oxidases in Diabetic Nephropathy and Development of Nox Inhibitors.

Several recent studies have reported that reactive oxygen species (ROS), superoxide anion and hydrogen peroxide (H2O2), play important roles in various cellular signaling networks. NADPH oxidase (Nox) isozymes have been shown to mediate receptormediated ROS generation for physiological signaling processes involved in cell growth, differentiation, apoptosis, and fibrosis. Detectable intracellular levels of ROS can be induced by the electron leakage from mitochondrial respiratory chain as well as by activation of cytochrome p450, glucose oxidase and xanthine oxidase, leading to oxidative stress. The up-regulation and the hyper-activation of NADPH oxidases (Nox) also likely contribute to oxidative stress in pathophysiologic stages. Elevation of the renal ROS level through hyperglycemia-mediated Nox activation results in the oxidative stress which induces a damage to kidney tissues, causing to diabetic nephropathy (DN). Nox inhibitors are currently being developed as the therapeutics of DN. In this review, we summarize Nox-mediated ROS generation and development of Nox inhibitors for therapeutics of DN treatment.

Inhibition of Neuroinflammation by AIBP: Spinal Effects upon Facilitated Pain States.

Apolipoprotein A-I binding protein (AIBP) reduces lipid raft abundance by augmenting the removal of excess cholesterol from the plasma membrane. Here, we report that AIBP prevents and reverses processes associated with neuroinflammatory-mediated spinal nociceptive processing. The mechanism involves AIBP binding to Toll-like receptor-4 (TLR4) and increased binding of AIBP to activated microglia, which mediates selective regulation of lipid rafts in inflammatory cells. AIBP-mediated lipid raft reductions downregulate LPS-induced TLR4 dimerization, inflammatory signaling, and expression of cytokines in microglia. In mice, intrathecal injections of AIBP reduce spinal myeloid cell lipid rafts, TLR4 dimerization, neuroinflammation, and glial activation. Intrathecal AIBP reverses established allodynia in mice in which pain states were induced by the chemotherapeutic cisplatin, intraplantar formalin, or intrathecal LPS, all of which are pro-nociceptive interventions known to be regulated by TLR4 signaling. These findings demonstrate a mechanism by which AIBP regulates neuroinflammation and suggest the therapeutic potential of AIBP in treating preexisting pain states.

NADPH Oxidase 1 Activity and ROS Generation Are Regulated by Grb2/Cbl-Mediated Proteasomal Degradation of NoxO1 in Colon Cancer Cells.

The generation of reactive oxygen species (ROS) is required for proper cell signaling, but must be tightly regulated to minimize deleterious oxidizing effects. Activation of the NADPH oxidases (Nox) triggers ROS production and, thus, regulatory mechanisms exist to properly control Nox activity. In this study, we report a novel mechanism in which Nox1 activity is regulated through the proteasomal degradation of Nox organizer 1 (NoxO1). We found that through the interaction between NoxO1 and growth receptor-bound protein 2 (Grb2), the Casitas B-lineage lymphoma (Cbl) E3 ligase was recruited, leading to decreased NoxO1 stability and a subsequent reduction in ROS generation upon epidermal growth factor (EGF) stimulation. Additionally, we show that EGF-mediated phosphorylation of NoxO1 induced its release from Grb2 and facilitated its association with Nox activator 1 (NoxA1) to stimulate ROS production. Consistently, overexpression of Grb2 resulted in decreased Nox1 activity, whereas knockdown of Grb2 led to increased Nox1 activity in response to EGF. CRISPR/Cas9-mediated NoxO1 knockout in human colon cancer cells abrogated anchorage-independent growth on soft agar and tumor-forming ability in athymic nude mice. Moreover, the expression and stability of NoxO1 were significantly increased in human colon cancer tissues compared with normal colon. Taken together, these results support a model whereby Nox1 activity and ROS generation are regulated by Grb2/Cbl-mediated proteolysis of NoxO1 in response to EGF, providing new insight into the processes by which excessive ROS production may promote oncogenic signaling to drive colorectal tumorigenesis.

Fabrication of pseudo-ceramide-based lipid microparticles for recovery of skin barrier function.

The recovery of skin barrier functions was investigated with pseudo-ceramide-based lipid microparticles. The microparticles were prepared by using a fluid bed technique where lipid components (a pseudo-ceramide, cholesterol and a fatty acid) were coated on a sugar seed, and a polymer was subsequently coated on the lipid microparticles. The microparticles contained large amount of pseudo-ceramide, and the pseudo-ceramide was in the form of lamellar structures mixed with other lipid components. In addition, the microparticles were stably dispersed in aqueous media or emulsion systems without any disruption of the microparticles' structures, thereby supplying sufficient amount of the pseudo-ceramide to skins for improving skin barrier functions such as preventing water loss. Such a role of the microparticles was proven by evaluating in vivo the efficacy of the lipid microparticles in reducing a trans-epidermal water loss (TEWL) of impaired murine skins. As a result, the novel pseudo-ceramide-based lipid microparticles for barrier recovery may potentially be applied in the field of dermatology, cosmetics and pharmaceuticals.

Fabrication and characterization of pseudo-ceramide-based liposomal membranes.

We present a facile and straightforward method to fabricate liposomal membranes with a significantly stable lamellar structure consisting of pseudo-ceramide, fatty acid, and cholesterol. Characterizing their membrane properties, in which we have used differential scanning calorimetry, X-ray diffraction, and FT-IR spectra, enables us to demonstrate that pseudo-ceramide with appropriate amounts of stearic acid and cholesterol can assemble to form a stable lamellar alpha-phase. Moreover, we show that cholesterol is indeed important and plays a role in controlling the melting entropy of lipid membranes, which is attributed to a disordered molecular packing, thus creating more flexible liposomal membranes. This approach to use pseudo-ceramide offers a useful means to fabricate a variety of biocompatible liposomes with controllable membrane properties, which enlarges their applicability in the field of drug delivery, dermatology, and cosmetics.

Polymer-associated liposomes as a novel delivery system for cyclodextrin-bound drugs.

It is known that cyclodextrins (CDs) extract lipid components from bilayer of liposomes. This could undermine the potential benefits of liposomes as drug carriers. In this study, we demonstrated that PC-Chol liposomes with various CDs or rhapontin (Rh)-hydroxypropyl betaCD (HPbetaCD) complexes could be stabilized by association with the amphiphilic polyelectrolyte, poly(methacrylic acid-co-stearyl methacrylate). Based on the results of differential scanning calorimetry, photocorrelation spectroscopy and transmission electron microscopy, the polymer-associated liposomes had the same vesicular form as liposome with clear boundaries and retained structural integrity for at least 1 month. In addition, the polymer-associated structure was unaffected by the type of CD, the composition and concentration of lipid components, and the concentration of the Rh-HPbetaCD complex. This contrasted with PC-Chol liposomes, whose structure was dependent on these factors. Using structurally different polymer-associated liposomes and PC-Chol liposomes containing the Rh-HPbetaCD complex, we also showed that the stability of vesicles could influence the skin permeability of CD-drug complexes.

Aqueous self-assembly of amphiphilic nanocrystallo-polymers and their surface-active properties.

The self-assembly of nanocrystals using a bottom-up approach is advantageous because it is possible to control their direct structure at a nanometre length scale and their collective optical and electronic properties. Here, we present the novel fabrication and aqueous self-assembly of amphiphilic nanocrystallo-polymers. Hydrophobic nanocrystals are used as the hydrophobic component of amphiphiles, and they can drive the hydrophobic interaction-mediated direct self-assembly to create various nanostructures, such as spherical aggregates, core-shell unimolecular micelles, and cylinders. The nanocrystals can be uniformly arranged in the core of the nanostructures. We further show that the amphiphilic nanocrystallo-polymers have dynamic self-assembling and surface-active properties.