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Berberine (BBR) has shown neuroprotective properties. The present study aims to investigate the effects of BBR on experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS), and SphK1/S1P signaling, which plays a key role in MS. EAE was induced in mice, followed by treatment with BBR at 50, 100, or 300 mg/kg/d. Neurophysiological function was evaluated daily; inflammation, cell infiltration, and the severity of demyelination were also examined. The SphK1, SphK2, and S1P levels in the animals and primary astrocyte culture were measured. We found that treatment with BBR reduced the loss of neurophysiological function and the degree of demyelination. Moreover, BBR was associated with a decrease in SphK1 and S1P levels both in the animals and in culture. These results indicated that BBR suppresses demyelination and loss of neurophysiological function by inhibiting the SphK1/S1P signaling pathway. The use of BBR as a treatment of MS warrant further exploration. [ABSTRACT FROM AUTHOR]

Abstract: Macrophage recruitment to sites of inflammation is an essential step in host defense. However, the signals regulating the mobilization of these cells are still not fully understood. Sphingosine-1-phosphate (S1P), a pleiotropic bioactive lipid mediator, is known to regulate an array of biological activities in various cell types. Here, we investigated the roles of S1P and S1P receptors (S1PRs) in macrophage migration in vitro. Furthermore, we explored the cross-talk between transforming growth factor-β1 (TGF-β1) and S1P signalling pathways in this process. We found that S1P exerted a powerful migratory action on RAW264.7 macrophages, as determined in Boyden chambers. Moreover, by employing RNA interference technology and pharmacological tools, we have demonstrated that S1PR1, but not S1PR2 and S1PR3, is required for S1P-induced macrophage migration. Importantly, we observed a pronounced increase in sphingosine kinase-1 (SphK1) mRNA expression and subsequently increase in S1P production, following transforming growth factor-β1 (TGF-β1) stimulation in RAW264.7 macrophages. The expression of S1PR1, but not S1PR2 and S1PR3, was also significantly up-regulated after TGF-β1 stimulation. Interestingly, exogenously added S1P-induced up-regulation of SphK1 and the synthesis of additional S1P, suggesting a self-amplifying loop of S1P to enhance macrophage migration. In conclusion, our results reveal that SphK1/S1PR1 signalling axis is induced by TGF-β1 and stimulates cell migration in RAW 264.7 macrophages. This study provides new clues for the molecular mechanisms of macrophage recruitment during inflammation. [Copyright &y& Elsevier]

Abstract: Spreds, a recently established class of negative regulators of the Ras–ERK (extracellular signal-regulated kinase) pathway, are involved in hematogenesises, allergic disorders and tumourigenesis. However, their role in hematologic neoplasms is largely unknown. Possible effects of Spreds on other signal pathways closely related to Ras–ERK have been poorly investigated. In this study, we investigated the in vitro effects of Spred2 on chronic myeloid leukemia (CML) cells. In addition to inhibiting the well-established Ras–ERK cascade, adenovirus-mediated Spred2 over-expression inhibits constitutive and stem cell factor (SCF)-stimulated sphingosine kinase-1 (SPHK1) and Mcl-1 expression, as well as inhibiting proliferation and inducing apoptosis in CML cells. In K562 cells and primary CML cells, imatinib induces endogenous Spred2 expression. Spred2 silencing by stable RNA interference partly protects K562 cells against imatinib-induced apoptosis. Together, these data implicate Spred2 in imatinib-induced cytotoxicity in CML cells, possibly by inhibiting the Ras–ERK cascade and the pro-survival signaling molecules SPHK1 and Mcl-1. These findings reveal potential targets for selective therapy of CML. [Copyright &y& Elsevier]

Abstract: Herein we report that the lipid kinase sphingosine kinase-1 (SphK1) is instrumental in mediating androgen-induced cell proliferation in osteoblasts. Dihydrotestosterone (DHT) triggered cell growth in steroid-deprived MC3T3 cells, which was associated with a rapid stimulation of SphK1 and activation of both Akt and ERK signaling pathways. This mechanism relied on functional androgen receptor/PI3K/Akt nongenotropic signaling as pharmacological antagonists could block SphK1 stimulation by DHT and its consequences. Finally, SphK1 inhibition not only abrogated DHT-induced ERK activation but also blocked cell proliferation, while ERK inhibition had no impact, suggesting that SphK1 was critical for DHT signaling yet independently of the ERK. [Copyright &y& Elsevier]

Abstract: Sphingosine kinases (SK) catalyze the production of sphingosine-1-phosphate which in turn regulates cell responses such as proliferation and migration. Here, we show that exposure of the human endothelial cell line EA.hy 926 to hypoxia stimulates a increased SK-1, but not SK-2, mRNA, protein expression, and activity. This effect was due to stimulated SK-1 promoter activity which contains two putative hypoxia-inducible factor-responsive-elements (HRE). By deletion of one of the two HREs, hypoxia-induced promoter activation was abrogated. Furthermore, hypoxia upregulated the expression of HIF-1α and HIF-2α, and both contributed to SK-1 gene transcription as shown by selective depletion of HIF-1α or HIF-2α by siRNA. The hypoxia-stimulated SK-1 upregulation was functionally coupled to increased migration since the selective depletion of SK-1, but not of SK-2, by siRNAs abolished the migratory response. In summary, these data show that hypoxia upregulates SK-1 activity and results in an accelerated migratory capacity of endothelial cells. SK-1 may thus serve as an attractive therapeutic target to treat diseases associated with increased endothelial migration and angiogenesis such as cancer growth and progression. [Copyright &y& Elsevier]