Regulatory role of sphingosine kinase and sphingosine-1-phosphate receptor signaling in progenitor/stem cells

Balanced sphingolipid signaling is important for the maintenance of homeostasis. Sphingolipids were demonstrated to function as structural components, second messengers, and regulators of cell growth and survival in normal and disease-affected tissues. Particularly, sphingosine kinase 1 (SphK1) and its product sphingosine-1-phosphate (S1P) operate as mediators and facilitators of proliferation-linked signaling. Unlimited proliferation (selfrenewal) within the regulated environment is a hallmark of progenitor/stem cells that was recently associated with the S1P signaling network in vasculature, nervous,muscular, and immune systems. S1P was shown to regulate progenitor-related characteristics in normal and cancerstemcells(CSCs) viaG-protein coupled receptorsS1Pn(n=1 to 5). The SphK/S1P axis is crucially involved in the regulation of embryonic development of vasculature and the nervous system, hematopoietic stem cell migration, regeneration of skeletal muscle, and development of multiple sclerosis. The ratio of the S1P receptor expression, localization, and specific S1P receptoractivated downstream effectors influenced the rate of selfrenewal and should be further explored as regeneration related targets. Considering malignant transformation,it is essential to control the level of self-renewal capacity.Proliferation of the progenitor cell should be synchronized with differentiation to provide healthy lifelong function of blood, immune systems, and replacement of damaged ordead cells. The differentiation-related role of SphK/S1P remains poorly assessed. A few pioneering investigations exploredpharmacologicaltoolsthattargetsphingolipid signaling and can potentially confine and direct self-renewal towards normal differentiation. Further investigation is required to test the role of the SphK/S1P axis in regulation of self-renewal and differentiation.

Research progress of sphingosine 1-phosphate and its signal transduction in central nervous system diseases

Sphingosine 1-phosphate(S1P),as a sphingolipid metabolite,has become a key substance in regulating various physiological processes,involved in differentiation,proliferation,migration,morphogenesis,cytoskeleton formation,adhesion,apoptosis,etc.process.Sphingosine 1-phosphate can not only activate the S1P-S1PR signaling pathway by binding to the corresponding receptors on the cell membrane,but also play a role in the cell.In recent years,studies have found that there is a certain relationship between its level changes and the occurrence and development of central nervous system diseases.This article reviews the latest knowledge of sphingosine-1-phosphate in the occurrence and treatment of nervous system diseases,and further clarifies its molecular mechanism in the treatment and development of central nervous system diseases.

Sphingosine-1-Phosphate Protects Against the Development of Cardiac Remodeling via Sphingosine Kinase 2 and the S1PR2/ERK Pathway

Objective:Cardiac remodeling is a common pathological change in various cardiovascular diseases and can ultimately result in heart failure.Thus,there is an urgent need for more effective strategies to aid in cardiac protection.Our previous work found that sphingosine-1-phosphate(S1P)could ameliorate cardiac hypertrophy.In this study,we aimed to investigate whether S1P could prevent cardiac fibrosis and the associated mechanisms in cardiac remodeling.Methods:Eight-week-old male C57BL/6 mice were randomly divided into a sham,transverse aortic constriction(TAC)or a TAC+S1P treatment group.Results:We found that S1P treatment improved cardiac function in TAC mice and that the cardiac fibrosis ratio in the TAC+S1P group was significantly lower and was accompanied by a decrease inα-smooth muscle actin(α-SMA)and collagen type I(COL I)expression compared with the TAC group.We also found that one of the key S1P enzymes,sphingosine kinase 2(SphK2),which was mainly distributed in cytoblasts,was downregulated in the cardiac remodeling case and recovered after S1P treatment in vivo and in vitro.In addition,our in vitro results showed that S1P treatment activated extracellular regulated protein kinases(ERK)phosphorylation mainly through the S1P receptor 2(S1PR2)and spurred p-ERK transposition from the cytoplasm to cytoblast in H9c2 cells exposed to phenylephrine.Conclusion:These findings suggest that SphK2 and the S1PR2/ERK pathway may participate in the anti-remodeling effect of S1P on the heart.This work therefore uncovers a novel potential therapy for the prevention of cardiac remodeling.

Role of sphingosine kinase and sphingosine-1-phosphate in inflammatory arthritis

The importance of sphingosine kinase(SphK)and sphingosine-1-phosphate(S1P)in inflammation has been extensively demonstrated.As an intracellular second messenger,S1P plays an important role in calcium signaling and mobilization,and cell proliferation and survival.Activation of various plasma membrane receptors,such as the formyl methionyl leucyl phenylalanine receptor,C5a receptor,and tumor necrosis factor α receptor,leads to a rapid increase in intracellular S1P level via SphK stimulation.SphK and S1P are implicated in various chronic autoimmune conditions such as rheumatoid arthritis, primary Sjgren's syndrome,and inflammatory bowel disease.Recent studies have demonstrated the important role of SphK and S1P in the development of arthritis by regulating the pro-inflammatory responses.These novel pathways represent exciting potential therapeutic targets.

Role of sphingosine kinases and sphingosine 1-phosphate in mediating adipogenesis

Recent Background: Development of obesity involves promotion of preadipocyte differrentiation. This study investigated the role that sphingosine kinases (SPHK) and ceramide-derived sphingosine 1-phosphate (S1P) play in adipocyte terminal differentiation. Materials and Methods: The mouse 3T3-L1 cell line was used as a model for adipogenesis. Cells were harvested at specific time points after initation of differentiation, and SPHK activity was measured. 3T3-L1 cells were treated with S1P and expression of early adipogenesis transcription markers was measured by real time PCR. The expression of S1P-receptors (S1PRs) during differentiation was measured. Results: SPHK activity is induced when 3T3-L1 cells are treated with insulin, dexamethasone, and isobutylmethylxanthine to induce differentiation. SPHK1 is active in preadipocytes and early in the differentiation process. Both SPHK1 and SPHK2 isozymes contribute to activity in differentiated adipocytes. Inhibition of SPHK1 attenuates adipocyte differentiation;however, extracellular S1P does not rescue the effect of SPHK1 inhibition on adipogenesis. Although treatment of preadipocytes with S1P induced message expression of the early adipogenesis transcription factor CC AAT/ binding proteinalpha, continued treatment did not fully support the development of differentiated adipocytes. Sphingosine 1-phosphate receptors (S1PRs) are expressed in preadipocytes and message expression declines markedly during adipocyte differentiation. Conclusion: These results demonstrate that the contribution of SPHK and S1P to adipogenesis is mediated primarily through biphasic activation of SPHK1 and 2 with extracellular S1P and S1PRs playing little role during preadipocyte differentiation.

Expressions of Sphingosine-1-phosphate (S1P) Receptors, Sphingosine Kinases in Malignant Bone and Soft Tissue Tumors, and The role of Sphingosine Kinase-1 in Growth of MFH Cell Lines

Sphingolipids are ubiquitous components of cell membranes. Their metabolites ceramide, sphingosine, and sphingosine-1-phosphate (S1P) have important physiological functions, including regulation of cell growth and survival. S1P is generated by phosphorylation of sphingosine catalyzed by sphingosine kinase-1 (SPHK1). The purpose of this study is to explore the roles of S1P, S1P receptors, and sphingosine kinases in malignant musculoskeletal tumors. Twenty-one tumor samples (7 liposarcomas, 3 chondrosarcomas, 6 osteosarcomas, 5 MFH) obtained at open biopsy, and four human MFH cell lines (Nara H, Nara F, TNMY1, GBS-1) were used. We examined the mRNA expression of S1P receptors by RT-PCR, and the expression levels of SPHK by Real-time PCR. We used 4 MFH cell lines to analyze SPHK1 proteins by Western blotting. SPHK1 siRNA was transfected into MFH cell lines by lipofection method. Cell proliferation (control and transfected with siRNA) was assayed using WST-8 (Cell Counting Kit-8) assay. All high grade malignant tumors expressed S1P1, S1P2, S1P3 receptors, whereas the expression of S1P1 receptor was detected in 50% of low-grade malignant tumors, S1P2 receptor in 30%, and S1P3 in 50%. No statistically significant difference was found in the expression level of SPHK1 between high-grade and low-grade malignant tumors by Real-time PCR. By results of Western blotting, proteins of SPHK1 were expressed in all MFH cell lines. In MFH cell lines, transfection with SPHK1 siRNA oligonucleotides resulted in approximately 50 to 80% suppression of SPHK1 mRNA expression as determined by real-time PCR. Down-regulation of SPHK1 with small interfering RNA significantly reduced SPHK1 protein levels by Western blotting. Knock down of SPHK1 expression significantly decreased cell proliferation of all MFH cells. These results suggest that the expression of S1P receptors may play an important role for cell proliferation and may correlate with histologic grade in malignant bone and soft tissue tumors, and that SPHK1 may be one of essential molecules for cell proliferation in MFH cell lines.

Role of sphingosine kinase localization in sphingolipid signaling

The sphingosine kinases, SK1 and SK2, produce the potent signaling lipid sphingosine-1-phosphate (S1P). These enzymes have garnered increasing interest for their roles in tumorigenesis, inflammation, vascular diseases, and immunity, as well as other functions. The sphingosine kinases are considered signaling enzymes by producing S1P, and their activity is acutely regulated by a variety of agonists. However, these enzymes are also key players in the control of sphingolipid metabolism. A variety of sphingolipids, such as sphingosine and the ceramides, are potent signaling molecules in their own right. The role of sphingosine kinases in regulating sphingolipid metabolism is potentially a critical aspect of their signaling function. A central aspect of signaling lipids is that their hydrophobic nature constrains them to membranes. Most enzymes of sphingolipid metabolism, including the enzymes that degrade S1P, are membrane enzymes. Therefore the localization of the sphingosine kinases and S1P is likely to be important in S1P signaling. Sphingosine kinase localization affects sphingolipid signaling in several ways. Translocation of SK1 to theplasma membrane promotes extracellular secretion of S1P. SK1 and SK2 localization to specific sites appears to direct S1P to intracellular protein effectors. SK localization also determines the access of these enzymes to their substrates. This may be an important mechanism for the regulation of ceramide biosynthesis by diverting dihydrosphingosine, a precursor in the ceramide biosynthetic pathway, from the de novo production of ceramide.

Sphingosine kinase 1 is upregulated with lysophosphatidic acid receptor 2 in human colorectal cancer

AIM: To examine the expression of SphK1, an oncogenic kinase that produces sphingosine 1-phosphate (S1P), and its correlation with the expression of LPAR2, a major lysophosphatidic acid (LPA) receptor overexpressed in various cancers, in human colorectal cancer.METHODS: Real-time reverse-transcription polymerase chain reaction was used to measure the mRNA expression of SphK1, LPAR2, and the three major S1P receptors in 27 colorectal cancer samples and corresponding normal tissue samples. We also examined the correlation between the expression of SphK1 and LPAR2.RESULTS: Colorectal cancer tissue in 22 of 27 patients had higher levels of SphK1 mRNA than in normal tissue. In two-thirds of the samples, SphK1 mRNA expression was more than two-fold higher than in normal tissue. Consistent with previous reports, LPAR2 mRNA expression in 20 of 27 colorectal cancer tissue samples was higher compared to normal tissue samples. Expression profiles of all three major S1P receptors, S1PR1, S1PR2, and S1PR3, varied without any trend, with no significant difference in expression between cancer and normal tissues. A highly significant positive correlation was found between SphK1 and LPAR2 expression [Pearson’s correlation coefficient (r) = 0.784 and P < 0.01]. The mRNA levels of SphK1 and LPAR2 did not correlate with TNM stage.CONCLUSION: Our findings suggest that S1P and LPA may play important roles in the development of colorectal cancer via the upregulation of SphK1 and LPAR2, both of which could serve as new therapeutic targets in the treatment of colorectal cancer.

Roles of sphingosine 1-phosphate on tumorigenesis

Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid with a variety of biological activities.It is generated from the conversion of ceramide to sphingosine by ceramidase and the subsequent conversion of sphingosine to S1P,which is catalyzed by sphingosine kinases.Through increasing its intracellular levels by sphingolipid metabolism and binding to its cell surface receptors,S1P regulates several physiological and pathological processes,including cell proliferation,migration,angiogenesis and autophagy.These processes are responsible for tumor growth,metastasis and invasion and promote tumor survival.Since ceramide and S1P have distinct functions in regulating in cell fate decision,the balance between the ceramide/sphingosine/S1P rheostat becomes a potent therapeutic target for cancer cells.Herein,we summarize our current understanding of S1P signaling on tumorigenesis and its potential as a target for cancer therapy.

Inhibitory Effect of Resveratrol on LPS-induced Glomerular Mesangial Cells Proliferation and TGF-β1 Expression via Sphingosine Kinase 1 Pathway

Objective To elucidate the renoprotective effect of resveratrol(RSV)on sphingosine kinase 1(SphK1)signaling pathway and expression of its downstream molecules including activator protein 1(AP-1)and transformation growth factor-β1(TGF-β1)in lipopolysaccharide(LPS)-induced glomerular mesangial cells(GMCs).Methods The rat GMCs line(HBZY-1)were cultured and randomly divided into 5 groups,including control,LPS(100 ng/mL),and 5,10,20µmol/L RSV-treated groups.In addition,SphK1 inhibitor(SK-II)was used as positive control.GMCs were pretreated with RSV for 2 h and treated with LPS for another 24 h.GMCs proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)assay.The proteins expression of SphK1,p-c-Jun and TGF-β1 in GMCs were detected by Western blot,and DNA-binding activity of AP-1 was performed by electrophoretic mobility shift assay(EMSA).The binding activity between RSV and SphK1 protein was detected by AutoDock Vina and visualized by Discovery Studio 2016.Results LPS could obviously stimulate GMCs proliferation,elevate SphK1,p-c-Jun and TGF-β1 expression levels and increase the DNA-binding activity of AP-1(P<0.05 or P<0.01),whereas these effects were significantly blocked by RSV pretreatment.It was also suggested that the effect of RSV was similar to SK-II(P>0.05).Moreover,RSV exhibited good binding affinity towards SphK1,with docking scores of−8.1 kcal/moL and formed hydrogen bonds with ASP-178 and LEU-268 in SphK1.Conclusion RSV inhibited LPS-induced GMCs proliferation and TGF-β1 expression,which may be independent of its hypoglycemic effect on preventing the development of mesangial cell fibrosis and closely related to the direct inhibition of SphK1 pathway.

阿芬太尼调节SphK1/S1P信号通路保护心肌缺血再灌注损伤大鼠

[目的]探究阿芬太尼对心肌缺血再灌注损伤(MIRI)大鼠的作用及在该过程中对鞘氨醇激酶1(SphK1)/鞘氨醇-1-磷酸(S1P)信号通路的调节机制。[方法]将SPF级SD雄性大鼠随机分为假手术组、模型组、阳性药物组(复方丹参组)和阿芬太尼低剂量组、阿芬太尼高剂量组、阿芬太尼高剂量+SphK1激动剂组(阿芬太尼+PMA组),每组20只。除假手术组,其余组均利用结扎左前降支冠状动脉后再灌注复制MIRI模型。全自动生物化学分析仪检测血清乳酸脱氢酶(LDH)、肌酸激酶(CK)和谷草转氨酶(AST)的活性;TTC检测大鼠心肌梗死面积;HE染色观察大鼠心肌组织形态学特征;TUNEL染色检测大鼠心肌细胞凋亡;ELISA检测血清肿瘤坏死因子α(TNF-α)、白细胞介素6(IL-6)、白细胞介素1β(IL-1β)及S1P的水平;试剂盒检测心肌组织中丙二醛(MDA)含量和超氧化物歧化酶(SOD)的活性;Western blot检测心肌组织SphK1蛋白表达。[结果]相较于假手术组,模型组大鼠心肌组织病理损伤严重,血清中心肌损伤标志物LDH、CK和AST的活性,心肌梗死面积和心肌细胞凋亡率,TNF-α、IL-6、IL-1β、MDA、S1P水平及SphK1蛋白表达均升高,SOD活性降低(P<0.05);相较于模型组,阳性药物组和阿芬太尼低、高剂量组大鼠心肌组织损伤减轻,血清中心肌损伤标志物LDH、CK和AST的活性,心肌梗死面积和心肌细胞凋亡率,TNF-α、IL-6、IL-1β、MDA、S1P水平及SphK1蛋白表达均降低,SOD活性升高(P<0.05)。SphK1激动剂可逆转高剂量阿芬太尼对上述指标的影响(P<0.05)。[结论]阿芬太尼对MIRI大鼠发挥保护作用,其机制可能与抑制SphK1/S1P信号通路有关。

Sphingosine-1-phosphate signaling and the gut-liver axis in liver diseases

The liver is the central organ involved in lipid metabolism and the gastrointestinal(GI)tract is responsible for nutrient absorption and partitioning.Obesity,dyslipidemia and metabolic disorders are of increasing public health concern worldwide,and novel therapeutics that target both the liver and the GI tract(gut-liver axis)are much needed.In addition to aiding fat digestion,bile acids act as important signaling molecules that regulate lipid,glucose and energy metabolism via activating nuclear receptor,G protein-coupled receptors(GPCRs),Takeda G protein receptor 5(TGR5)and sphingosine-1-phosphate receptor 2(S1PR2).Sphingosine-1-phosphate(S1P)is synthesized by two sphingosine kinase isoforms and is a potent signaling molecule that plays a critical role in various diseases such as fatty liver,in-flammatory bowel disease(IBD)and colorectal cancer.In this review,we will focus on recent findings related to the role of S1P-mediated signaling pathways in the gut-liver axis.

松萝酸通过调节SphK1/S1P信号通路减轻缺氧/复氧诱导的心肌细胞损伤

目的 探讨松萝酸(UA)对缺氧/复氧(H/R)诱导的心肌细胞损伤的影响及其作用机制。方法 构建H9c2细胞H/R模型,使用0.5~64μmol/L UA分别预处理H9c2细胞,MTT法筛选UA浓度;H9c2细胞随机分为对照组、模型组、UA低剂量组(1μmol/L)、UA中剂量组(4μmol/L)、UA高剂量组(16μmol/L)和UA高剂量+Benzyl butyl phthalate(BBP)组(16μmol/L UA+100 nmol/L BBP),检测各组细胞增殖活力、细胞凋亡情况,白介素(IL)-1β、IL-6、丙二醛(MDA)、超氧化物歧化酶(SOD)、腺嘌呤核苷三磷酸(ATP)、鞘氨醇激酶1(SphK1)、鞘氨醇-1-磷酸受体1(S1PR1)、细胞外调节蛋白激酶1/2(ERK1/2)蛋白表达水平。结果 1μmol/L以上浓度UA可以显著提高H/R H9c2细胞增殖活力。与对照组相比,模型组细胞增殖能力和ATP、SOD含量下降,细胞凋亡率和IL-1β、IL-6、MDA、SphK1、S1PR1、ERK1/2表达增加(P<0.05);与模型组相比,UA低、中、高剂量组细胞增殖能力和ATP、SOD含量上升,细胞凋亡率和IL-1β、IL-6、MDA、SphK1、S1PR1、ERK1/2表达下降,干预效果呈浓度依赖性(P<0.05);BBP完全沉默UA对H/R诱导的心肌细胞的治疗作用。结论 UA减轻H/R H9c2细胞损伤与其抑制SphK1/S1P信号通路有关。

羟基喜树碱脂质体调节SphK1/S1P信号通路对心力衰竭大鼠心肌纤维化的影响

【目的】探讨羟基喜树碱脂质体(LHCPT)调节鞘氨醇激酶1(SphK1)/1-磷酸鞘氨醇(S1P)信号通路对心力衰竭大鼠心肌纤维化的影响。【方法】SD大鼠分为对照组、模型组、羟基喜树碱(HCPT)组、LHCPT组、卡托普利组、LHCPT+K6PC-5(SphK1激活剂)组,每组12只。除对照组外,其他组大鼠均需通过腹腔注射阿霉素的方法构建心力衰竭大鼠模型,建模成功后,进行给药处理,给药一天一次,持续4周。彩色多普勒超声仪检测大鼠左室收缩末期内径(LVESD)、左室舒张末期内径(LVEDD)、左室射血分数(LVEF);HE、Masson染色分别检测大鼠心肌组织病理损伤、心肌纤维化;ELISA法检测大鼠心肌组织中肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)水平;qRT-PCR检测大鼠心肌组织中转化生长因子-β1(TGF-β1)、I型胶原蛋白(Collagen I)、Ⅲ型胶原蛋白(CollagenⅢ)表达;Western blot检测大鼠心肌组织中SphK1、S1P蛋白表达。【结果】与对照组比较,模型组大鼠心肌组织病理损伤及纤维化严重,LVESD、LVEDD、TNF-α、IL-6水平、TGF-β1、Collagen I、CollagenⅢmRNA表达及SphK1、S1P蛋白表达升高,LVEF降低(P<0.05);与模型组比较,HCPT组、LHCPT组、卡托普利组大鼠心肌组织病理损伤及纤维化减轻,LVESD、LVEDD、TNF-α、IL-6水平、TGF-β1、CollagenⅠ、CollagenⅢmRNA表达及SphK1、S1P蛋白表达降低,LVEF升高(P<0.05);与LHCPT组比较,LHCPT+K6PC-5组大鼠心肌组织病理损伤及纤维化加剧,LVESD、LVEDD、TNF-α、IL-6水平、TGF-β1、CollagenⅠ、CollagenⅢmRNA表达及SphK1、S1P蛋白表达升高,LVEF降低(P<0.05)。【结论】LHCPT可能通过抑制SphK1/S1P信号通路抑制心力衰竭大鼠心肌纤维化。

真武汤调节鞘氨醇激酶1-磷酸鞘氨醇信号通路抗阿霉素肾病大鼠肾损伤的作用研究

目的:研究真武汤对阿霉素肾病(Adriamycin Nephropathy,AN)模型大鼠鞘氨醇激酶1(Sphingosine Kinase 1,SphK1)-磷酸鞘氨醇(Sphingosine-1-phosphate,S1P)信号分子的影响,探讨真武汤治疗阿霉素肾病大鼠蛋白尿的机制。方法:常规检测各试验组动物血脂、血浆白蛋白、24小时尿蛋白含量;实时聚合酶链反应(Real-time Polymerase Chain Reaction,RTPCR)检测肾组织中SphK1基因表达;免疫印迹法(Western Blot)检测肾组织中SphK1蛋白表达;液相色谱-串联质谱法(Liquid Chromatography-tandem Mass Spectrometry,LC-MS/MS)检测SphK1、S1P活性。结果:模型组大鼠血脂水平、24小时尿蛋白含量显著升高,血浆白蛋白水平显著降低(P<0.05),肾脏SphK1酶活性、蛋白表达及S1P含量显著升高(P<0.05);与模型组相比,各给药组血脂水平、24小时尿蛋白含量明显降低,血浆白蛋白水平明显升高(P<0.05),肾脏SphK1酶活性、基因和蛋白表达及S1P含量明显下降(P<0.05),各治疗组之间差异无统计学意义。结论:真武汤可减少AN模型大鼠肾组织的SphK1酶活性、蛋白表达及S1P含量,改善其蛋白尿、血脂及血浆白蛋白水平。其作用可能与抑制SphK1、S1P信号分子的表达有关。

p38 mitogen-activated protein kinase regulates type-Ⅰ vs type-Ⅱ phenotyping of human vascular endothelial cells

AIM: To identify kinases involved in phenotype regulation of vascular endothelial cells(VECs): Proproliferative G-protein signaling 5(RGS5)^(high)(typeⅠ) vs anti-proliferative RGS5^(low)(typeⅡ) VECs.METHODS: Proteomic kinase assays were performed to identify the crucial kinase involved in the phenotype regulation of human VECs using typeⅠ VECs, which promotes the proliferation of human vascular smooth muscle cells(VSMCs), and typeⅡ VECs, which suppress the proliferation of human VSMCs. The assays were performed using multiple pairs of typeⅠ and typeⅡ VECs to obtain the least number of candidates. The involvement of the candidate kinases was verified by evaluating the effects of their specific inhibitors on the phenotype regulation of human VECs as well as the expression levels of regulator of RGS5, which is the causative gene for the "typeⅡ to typeⅠ" phenotype conversion of human VECs. RESULTS: p38α mitogen-activated protein kinase(p38α MAPK) was the only kinase that showed distinctive activities between typeⅠ and typeⅡ VECs: p38α MAPK activities were low and high in type-Ⅰand typeⅡ VECs, respectively. We found that an enforced expression of RGS5 indeed lowered p38α MAPK activitiesin typeⅡ VECs. Furthermore, treatments with a p38α MAPK inhibitor nullified the anti-proliferative potential in typeⅡ VECs. Interestingly, MAPK inhibitor treatments enhanced the induction of RGS5 gene. Thus, there is a vicious cycle between "RGS5 induction" and "p38α MAPK inhibition", which can explain the unidirectional process in the stress-induced "typeⅡ to typeⅠ" conversions of human VECs. To understand the upstream signaling of RGS5, which is known as an inhibitory molecule against the G protein-coupled receptor(GPCR)-mediated signaling, we examined the effects of RGS5 overexpression on the signaling events from sphingosine-1-phosphate(S1P) to N-cadherin, because S1 P receptors belong to the GPCR family gene and N-cadherin, one of their downstream effectors, is reportedly involved in the regulation of VEC-VSMC interactions. We found that RGS5 specifically bound with S1P1. Moreover, N-cadherin localization at intercellular junctions in typeⅡ VECs was abolished by "RGS5 overexpression" and "p38α MAPK inhibition".CONCLUSION: p38α MAPK plays crucial roles in "type-Ⅰ vs type-Ⅱ" phenotype regulations of human VECs at the downstream of RGS5.

SphK1/S1P信号通路在肾脏疾病中的作用

鞘氨醇-1-磷酸(sphingosine 1-phosphate,S1P)具有很高的生物学活性,它参与细胞的增殖、凋亡、代谢等多个生理过程,是治疗多种疾病的一个潜在靶点。鞘氨醇激酶1(sphingosine kinase-1,SphK1)是一种广泛存在的脂类激酶,是维持体内S1P水平的关键调节酶,其在生物体内参与癌症、感染和炎症等诸多疾病的发生发展。目前已证实SphK1和S1P受体在肾脏中表达,并且多种肾脏疾病的发生发展与之相关,因此SphK1和S1P在肾脏疾病中作用受到人们越来越多的关注。本文就SphK1/S1P信号通路在肾脏疾病中的作用的研究现状进行综述,重点介绍SphK1/S1P信号通路及其在多种肾脏疾病进展中的作用。

亚砷酸钠对人脐静脉内皮细胞损伤及鞘氨醇激酶1/1-磷酸鞘氨醇信号轴的影响

背景:血管内皮细胞是砷毒作用的关键靶点,砷致内皮细胞损伤的分子机制有待进一步研究。目的:研究亚砷酸钠对人脐静脉内皮细胞的损伤及鞘氨醇激酶1/1-磷酸鞘氨醇(SPHK1/S1P)信号轴的影响。方法:分离培养并鉴定人脐静脉内皮细胞,将人脐静脉内皮细胞暴露于含0,5,10,15,20,25μmol/L亚砷酸钠的培养液24 h,CCK-8法检测细胞存活率;倒置显微镜观察细胞形态;荧光探针DCFH-DA染色检测细胞内活性氧含量;Annexin V-FITC/PI双标记结合流式细胞术及TUNEL法检测细胞凋亡;ELISA检测细胞内1-磷酸鞘氨醇含量;实时荧光定量PCR、Western blot分别检测血管细胞黏附分子1、鞘氨醇激酶1、1-磷酸鞘氨醇受体1的mRNA和蛋白表达。结果与结论:①与对照组(0μmol/L亚砷酸钠)相比,随着亚砷酸钠浓度的增加:细胞存活率逐渐降低,且呈剂量-效应关系;细胞融合率逐渐降低,细胞间隙逐渐增宽,脱落漂浮的细胞逐渐增多;细胞内活性氧含量逐渐升高;细胞凋亡率逐渐升高;细胞内1-磷酸鞘氨醇含量逐渐升高;血管细胞黏附分子1、鞘氨醇激酶1 mRNA和蛋白的相对表达量逐渐升高,1-磷酸鞘氨醇受体1 mRNA和蛋白相对表达量逐渐降低。②结果提示,亚砷酸钠诱导的人脐静脉内皮细胞损伤可能与SPHK1/S1P信号轴激活、1-磷酸鞘氨醇受体1下调有关。SPHK1/S1P信号轴可能成为砷致心血管损伤的新靶点。

棕矢车菊素对胃癌细胞增殖、凋亡和血管生成拟态的影响及作用机制实验研究

目的:探讨棕矢车菊素对胃癌细胞增殖、凋亡和血管生成拟态(VM)的影响及作用机制。方法:采用不同浓度棕矢车菊素(0、10、20、40、80、160μmol/L)作用于人胃癌细胞HGC-27,检测细胞存活率,根据半抑制浓度(IC 50)值选择10、20、40μmol/L棕矢车菊素进行后续实验。将HGC-27细胞随机分为Control组(无干预)、棕矢车菊素-L(加入10μmol/L棕矢车菊素培养)组、棕矢车菊素-M(加入20μmol/L棕矢车菊素培养)组、棕矢车菊素-H(加入40μmol/L棕矢车菊素培养)组和棕矢车菊素-H+K6PC-5(加入40μmol/L棕矢车菊素+10μmol/L SphK1激动剂K6PC-5培养)组。采用平板克隆形成实验检测细胞克隆形成能力,流式细胞术检测细胞凋亡情况,血管形成实验检测各组细胞管状结构形成情况,Western blot检测细胞SphK1和S1P蛋白表达。结果:相较于Control组,棕矢车菊素-L组、棕矢车菊素-M组、棕矢车菊素-H组细胞克隆形成数量、管状结构形成数目及细胞中SphK1和S1P蛋白表达水平逐渐降低,而细胞中管状结构损坏程度增加,细胞凋亡率逐渐升高(均P<0.05)。在高浓度棕矢车菊素的基础上加入K6PC-5逆转了以上指标的变化趋势(均P<0.05)。结论:棕矢车菊素能够抑制胃癌细胞增殖和VM发生,并促进其凋亡,其作用机制可能与下调SphK1/S1P信号通路有关。

胡黄连苷Ⅱ对非小细胞肺癌恶性进展的影响

目的探讨胡黄连苷Ⅱ对非小细胞肺癌(NSCLC)恶性进展的影响及机制。方法将A549细胞分组为对照组,胡黄连苷Ⅱ低、中、高浓度组,K6PC-5[鞘氨醇激酶1(SPHK1)激活剂]组,胡黄连苷Ⅱ高剂量+K6PC-5组,检测细胞增殖、迁移、侵袭情况,以及细胞中增殖细胞核抗原(PCNA)、基质金属蛋白酶2(MMP-2)、MMP-9、SPHK1、1-磷酸鞘氨醇受体3(S1PR3)及胞外信号调节激酶1/2(ERK1/2)蛋白的表达情况。以BALB/c裸鼠为对象,通过皮下接种A549细胞悬液建立NSCLC裸鼠移植瘤模型,并将其分为裸鼠-对照组,裸鼠-胡黄连苷Ⅱ低、中、高剂量组,裸鼠-K6PC-5组,裸鼠-胡黄连苷Ⅱ高剂量+K6PC-5组(每组5只),考察胡黄连苷Ⅱ对其瘤体质量及体积的影响。结果与对照组比较,胡黄连苷Ⅱ低、中、高浓度组的细胞OD450值、EdU阳性细胞率、划痕愈合率、细胞侵袭数及PCNA、MMP-2、MMP-9、SPHK1、S1PR3、ERK1/2蛋白的相对表达量均显著降低;与裸鼠-对照组比较,裸鼠-胡黄连苷Ⅱ低、中、高剂量组裸鼠体内的瘤体质量及体积均显著降低或缩小,上述指标均呈浓度/剂量依赖性变化(P<0.05);K6PC-5组细胞和裸鼠-K6PC-5组裸鼠对应指标的变化趋势则相反(P<0.05)。与胡黄连苷Ⅱ高浓度组或裸鼠-胡黄连苷Ⅱ高剂量组比较,胡黄连苷Ⅱ高浓度+K6PC-5组细胞和裸鼠-胡黄连苷Ⅱ高剂量+K6PC-5组裸鼠的上述定量指标均显著升高或增大(P<0.05)。结论胡黄连苷Ⅱ可能通过抑制SPHK1/1-磷酸鞘氨醇/S1PR3信号通路来抑制NSCLC的恶性进展。