21 research outputs found
Henri Temianka Correspondence; (boomkamp)
No full textThis collection contains material pertaining to the life, career, and activities of Henri Temianka, violin virtuoso, conductor, music teacher, and author. Materials include correspondence, concert programs and flyers, music scores, photographs, and books.https://digitalcommons.chapman.edu/temianka_correspondence/1349/thumbnail.jp
Role of sphingosine 1-phosphate receptors, sphingosine kinases and sphingosine in cancer and inflammation
No full textSphingosine kinase (there are two isoforms, SK1 and SK2) catalyses the formation of sphingosine 1-phosphate (S1P), a bioactive lipid that can be released from cells to activate a family of G protein-coupled receptors, termed S1P1-5. In addition, S1P can bind to intracellular target proteins, such as HDAC1/2, to induce cell responses. There is increasing evidence of a role for S1P receptors (e.g. S1P4) and SK1 in cancer, where high expression of these proteins in ER negative breast cancer patient tumours is linked with poor prognosis. Indeed, evidence will be presented here to demonstrate that S1P4 is functionally linked with SK1 and the oncogene HER2 (ErbB2) to regulate mitogen-activated protein kinase pathways and growth of breast cancer cells. Although much emphasis is placed on SK1 in terms of involvement in oncogenesis, evidence will also be presented for a role of SK2 in both T-cell and B-cell acute lymphoblastic leukemia. In patient T-ALL lymphoblasts and T-ALL cell lines, we have demonstrated that SK2 inhibitors promote T-ALL cell death via autophagy and induce suppression of c-myc and PI3K/AKT pathways. We will also present evidence demonstrating that certain SK inhibitors promote oxidative stress and protein turnover via proteasomal degradative pathways linked with induction of p53-and p21-induced growth arrest. In addition, the SK1 inhibitor, PF-543 exacerbates disease progression in an experimental autoimmune encephalomyelitis mouse model indicating that SK1 functions in an anti-inflammatory manner. Indeed, sphingosine, which accumulates upon inhibition of SK1 activity, and sphingosine-like compounds promote activation of the inflammasome, which is linked with multiple sclerosis, to stimulate formation of the pro-inflammatory mediator, IL-1β. Such compounds could be exploited to produce antagonists that diminish exaggerated inflammation in disease. The therapeutic potential of modifying the SK-S1P receptor pathway in cancer and inflammation will therefore, be reviewed
Lysosomal storage and pathologenesis in a novel in vitro cellular model of Sandhoff disease
No full textSandhoff disease is a devastating autosomal recessive GM2 gangliosidosis in which a deficiency of β-hexosaminidase results in lysosomal storage of the enzyme's substrates, including GM2 and GA2 glycolipid as well as glycoprotein-derived oligosaccharides (OS). The effect of individual storage products on the induction of neurodegeneration in the gangliosidoses has not been well defined. Currently there is no valid in vitro cellular model for studying this disease so the aim of this work was to chemically induce the disease phenotype using a potent, reversible β- hexosaminidase inhibitor, N-benzyl-2-acetamido-1,4-imino-1,2,4-trideoxy-L-arabinitol (NBnLABNAc, SRI). Multiple cell lines, both human and mouse-derived were studied, and following SRI treatment, murine RAW264.7 macrophage-like cells exhibited the Sandhoff phenotype, in agreement with glycoconjugate storage found in mouse models, and were used for further study. The structures of the glycosphingolipids (GSLs) and OS, stored due to β-hexosaminidase inhibition, as well as the cellular localization were determined by normal phase HPLC and mass spectrometry, and subcellular fractionation and chemical extraction of the cytosol and lysosome, respectively. These stored lysosomal β-hexosaminidase substrates resulted in a tightly regulated inflammatory response where caspase-dependent apoptosis was prevented. It remained unclear which of the glycoconjugates were responsible for triggering this cytokine-mediated state, so substrate (glycolipid) reduction therapeutics Nbutyldeoxynojirimycin (NB-DNJ) and N-butyldeoxygalactonojirimycin (NB-DGJ) were administered to SRI-induced storage cells. Reduced GSL storage levels were observed but OS accumulation, although changed in structural composition, did not decrease, as predicted from the mechanism of action of each of the imino sugar inhibitors used. Both imino sugars restored GM2 levels whereas the GA2 glycolipid and OS levels remained elevated but the inflammatory response was normalized, implicating the sole contributor to the pathogenesis of Sandhoff disease is GM2 ganglioside. However, NBDNJ treatment resulted in an inflammatory response at high concentrations, presumably due to α-glucosidase-mediated inhibition of protein folding, demonstrating the greater potential of NB-DGJ in treating Sandhoff disease and possibly other related disorders. Besides substrate reduction therapy, chaperone-mediated therapy (CMT) has promise in treating lysosomal storage disorders such as Sandhoff disease. Following administration of an inhibitor of the deficient enzyme to act as a molecular chaperone that stabilises the conformation of the mutant enzyme, ER associated degradation is avoided, improving traffic to the lysosome. The partial increase in enzyme activity using CMT may be sufficient to adjust the critical threshold enzyme activity to levels where GSL storage in the lysosome is reduced to non-pathological concentrations. Cells derived from human Sandhoff and Tay-Sachs patients were assayed for β-hexosaminidase activity, GSL and OS storage levels. However, despite the lack of β-hexosaminidase activity, GM2 and GA2 glycolipid levels were negligible, possibly due to the cellular origin. Following treatment with SRI, elevated activity of β-hexosaminidase did not result in significant amelioration of the GSL storage levels. In terms of OS storage and enzyme activity, SRI induced differential effects depending on the residual β-hexosaminidase activity present, demonstrating the limitations of this compound in enhancing the total activity of β-hexosaminidase in these cells exhibiting GM2 gangliosidosis
Methodological accuracy and firm interpretation of enzymatic analysis: the usefulness of Bisswanger's "Practical Enzymology"
No full textNo abstract available
The development of a ε-polycaprolactone (PCL) scaffold for CNS repair
No full textPotential treatment strategies for the repair of spinal cord injury (SCI) currently favour a combinatorial approach incorporating several factors, including exogenous cell transplantation and biocompatible scaffolds. The use of scaffolds for bridging the gap at the injury site is very appealing although there has been little investigation into CNS neural cell interaction and survival on such scaffolds before implantation. Previously we demonstrated that aligned micro-grooves 12.5-25 µm wide on ε-polycaprolactone (PCL) promoted aligned neurite orientation and supported myelination. In this study we identify the appropriate substrate and its topographical features required for the design of a 3D scaffold intended for transplantation in SCI. Using an established myelinating culture system of dissociated spinal cord cells, recapitulating many of the features of the intact spinal cord, we demonstrate that astrocytes plated on the topography secrete soluble factors(s) that delay oligodendrocyte differentiation but do not prevent myelination. However, as myelination does occur after a further 10-12 days in culture this does not prevent the use of PCL as a scaffold material as part of a combined strategy for the repair of SCI
The extent and the nature of the cholinergic contribution to the hepatic encephalopathy-induced cognitive impairment
No full textNo abstract available
Erratum to: Lanthanum-induced neurotoxicity: solving the riddle of its involvement in cognitive impairment?
No full textDue to an unfortunate oversight, a mistake was made in the Fig. 1 legend (p. 2033). Readers should note that the elements in blue colour are reported to be up-regulated/activated/increased, while the elements highlighted in red colour are reported to be down-regulated/inhibited/decreased following in vivo exposure to La3+, not the other way round as falsely indicated
The development of a rat in vitro model of spinal cord injury demonstrating the additive effects of rho and ROCK inhibitors on neurite outgrowth and myelination
No full textIt is currently thought that treatment for spinal cord injury (SCI) will involve a combined pharmacological and biological approach; however, testing their efficacy in animal models of SCI is time-consuming and requires large animal cohorts. For this reason we have modified our myelinating cultures as an in vitro model of SCI and studied its potential as a prescreen for combined therapeutics. This culture comprises dissociated rat embryonic spinal cord cells plated onto a monolayer of astrocytes, which form myelinated axons interspaced with nodes of Ranvier. After cutting the culture, an initial cell-free area appears persistently devoid of neurites, accompanied over time by many features of SCI, including demyelination and reduced neurite density adjacent to the lesion, and infiltration of microglia and reactive astrocytes into the lesioned area. We tested a range of concentrations of the Rho inhibitor C3 transferase (C3) and ROCK inhibitor Y27632 that have been shown to promote SCI repair in vivo. C3 promoted neurite extension into the lesion and enhanced neurite density in surrounding areas but failed to induce remyelination. In contrast, while Y27632 did not induce significant neurite outgrowth, myelination adjacent to the lesion was dramatically enhanced. The effects of the inhibitors were concentration-dependent. Combined treatment with C3 and Y27632 had additive affects with an enhancement of neurite outgrowth and increased myelination adjacent to the lesion, demonstrating neither conflicting nor synergistic effects when coadministered. Overall, these results demonstrate that this culture serves as a useful tool to study combined strategies that promote CNS repair. 2011 Wiley Periodicals, In
Effect of sphingosine kinase modulators on interleukin-1β release, sphingosine 1-phosphate receptor 1 expression and experimental autoimmune encephalomyelitis
No full textBackground and Purpose:
The sphingosine analogue, FTY720 (GilenyaR), alleviates clinical disease progression in multiple sclerosis. Here, we variously assessed the effects of an azide analogue of (S)-FTY720 vinylphosphonate (compound 5; a sphingosine kinase 1 activator), (R)-FTY720 methyl ether (ROMe, a sphingosine kinase 2 inhibitor) and RB-020 (a sphingosine kinase 1 inhibitor and sphingosine kinase 2 substrate) on IL-1β formation, sphingosine 1-phosphate levels and expression of S1P1 receptors. We also assessed the effect of compound 5 and ROMe in an experimental autoimmune encephalomyelitis (EAE) model in mice.
Experimental Approach:
We measured IL-1β formation by macrophages, sphingosine 1-phosphate levels and expression levels of S1P1 receptors in vitro and clinical score in mice with EAE and the extent of inflammatory cell infiltration into the spinal cord in vivo.
Key Results:
Treatment of differentiated U937 macrophages with compound 5, RB-020 or sphingosine (but not ROMe) enhanced IL-1β release. These data suggest that these compounds might be pro-inflammatory in vitro. However, compound 5 or ROMe reduced disease progression and infiltration of inflammatory cells into the spinal cord in EAE, and ROMe induced a reduction in CD4+ and CD8+ T-cell levels in the blood (lymphopenia). Indeed, ROMe induced a marked decrease in expression of cell surface S1P1 receptors in vitro.
Conclusion and Implications:
This is the first demonstration that an activator of sphingosine kinase 1 (compound 5) and an inhibitor of sphingosine kinase 2 (ROMe, which also reduces cell surface S1P1 receptor expression) have an anti-inflammatory action in EAE
