Wnt信号途径与常见皮肤肿瘤

Wnt信号途径的传导和调控在胚胎发育和细胞恶性转变中起着重要作用,对其深入的研究,会对肿瘤的发生发展机制产生新的理解和认识。根据近几年国内外相关文献,对Wnt信号途径在常见皮肤肿瘤的发病机制进行评价,对最新研究进展进行综述,可以为肿瘤的早期诊断以及治疗提供良好的分子标记。     

GSK-3β suppresses the proliferation of rat hepatic oval cells through modulating Wnt/β-catenin signaling pathway

Aim:

Glycogen synthase kinase 3β (GSK-3β) plays a crucial role in hepatic biology, including liver development, regeneration, proliferation and carcinogenesis. In this study we investigated the role of GSK-3β in regulation of growth of hepatic oval cells in vitro and in liver regeneration in partially hepatectomized rats.

Methods:

WB-F344 cells, the rat hepatic stem-like epithelial cells, were used as representative of oval cells. Cell viability was examined using a WST-8 assay. The cells were transfected with a recombinant lentivirus expressing siRNA against GSK-3β (GSK-3βRNAiLV) or a lentivirus that overexpressed GSK-3β (GC-GSK-3βLV). Adult rats underwent partial (70%) hepatectomy, and liver weight and femur length were measured at d 7 after the surgery. The expression of GSK-3β, phospho-Ser⁹-GSK-3β, β-catenin and cyclin D1 was examined with immunoblotting assays or immunohistochemistry.

Results:

Treatment of WB-F344 cells with the GSK-3β inhibitor SB216763 (5 and 10 μmol/L) dose-dependently increased the levels of phospho-Ser⁹-GSK-3β, but not the levels of total GSK-3β, and promoted the cell proliferation. Knockout of GSK-3β with GSK-3βRNAiLV increased the cell proliferation, whereas overexpression of GSK-3β with GC-GSK-3βLV decreased the proliferation. Both SB216763 and GSK-3βRNAiLV significantly increased the levels of β-catenin and cyclin D1 in the cells, whereas GSK-3β overexpression decreased their levels. In rats with a partial hepatectomy, administration of SB216763 (2 mg/kg, ip) significantly increased the number of oval cells, the levels of phospho-Ser⁹-GSK-3β, β-catenin and cyclin D1 in liver, as well as the ratio of liver weight to femur length at d 7 after the surgery.

Conclusion:

GSK-3β suppresses the proliferation of hepatic oval cells by modulating the Wnt/β-catenin signaling pathway.     

帕立骨化醇抑制糖尿病肾病大鼠肾小管间质纤维化

目的:探讨帕立骨化醇(paricalcitol,P)对糖尿病肾病(DN)肾小管间质纤维化的干预作用及可能机制。方法:大鼠禁食后,采用单次无菌腹腔注射链脲佐菌素建立DN模型。将DN大鼠随机分为:(1)帕立骨化醇干预组(P组):帕立骨化醇溶于丙二醇中,于造模成功后第2天以0.4μg/kg的剂量腹腔注射,每周3次;(2)糖尿病肾病组(D组):给予等体积的丙二醇腹腔注射。设置正常对照组(C组)。帕立骨化醇连续干预12周后,测血、尿生化指标;进行肾脏病理学检查;利用免疫组化及Western blotting检测肾组织TGF-β1、Wnt-4、β-catenin及Klotho蛋白的表达;并进行指标间的相关分析。结果:(1)与C组比较,D组大鼠SCr、BUN及24 h尿蛋白水平均升高,而P组均较D组降低(P0.05)。(2)与C组比较,D组大鼠肾小管间质纤维化面积增加,而P组较D组减小(P0.05)。(3)D组大鼠肾组织Klotho蛋白表达低于C组,而P组高于D组(P0.05);与C组比较,D组大鼠肾组织TGF-β1、Wnt-4及β-catenin蛋白表达增加,而P组表达均较D组减少(P0.05)。(4)Klotho与纤维化面积、TGF-β1、Wnt-4及β-catenin均呈负相关(P0.05)。结论:帕立骨化醇可抑制DN大鼠肾小管间质纤维化,其作用可能与增加肾组织Klotho表达,抑制Wnt/β-catenin信号通路激活,同时减少TGF-β1合成相关。     

阻断经典Wnt通路对棕色脂肪干细胞向起搏样细胞分化的作用

目的:研究阻断经典Wnt通路对棕色脂肪干细胞向起搏样细胞分化的影响。方法:在诱导棕色脂肪干细胞向起搏特性诱导的过程中,培养基中加入经典Wnt通路阻断剂Dkk-1培养10 d。相差显微镜观察诱导组细胞的形态学变化、应用real-time PCR检测其中起搏细胞发育相关结构基因的表达情况,免疫荧光显色普通光镜和激光共聚焦显微镜观察起搏特征分子的蛋白表达。结果:分化后的棕色脂肪干细胞具有起搏细胞特性,经Dkk-1诱导后,棕色脂肪干细胞向起搏样细胞的转化率明显提高,起搏细胞发育相关基因和蛋白表达明显上调。结论:阻断经典Wnt通路可促进棕色脂肪干细胞向起搏样细胞的分化。     

Wnt/β-catenin信号通路对孤独症模型大鼠重复呆板样行为的影响

目的　探讨Wnt/β-catenin信号通路对孤独症发生过程中重复呆板样行为的影响。 方法　利用丙戊酸（valproic acid,VPA）孤独症动物模型,检测了经典Wnt信号通路关键信号分子β-catenin及其负性调节因子GSK-3β在孤独症模型大鼠小脑脑区的表达变化;同时检测孤独症模型大鼠重复呆板样行为变化。Western blotting法检测GSK-3β、β-catenin总蛋白及磷酸化蛋白表达,运用旷场实验检测重复呆板样行为持续的时间、次数。 结果　与对照组相比,在小脑脑区模型组GSK-3β磷酸化蛋白表达增加,β-catenin磷酸化蛋白表达减少;重复呆板样行为持续的时间、次数均增加。 结论　孤独症大鼠小脑脑区经典wnt信号通路活性增加,运动亢进,提示经典Wnt信号通路活性增加可能导致重复呆板样行为变化,进而导致对孤独症的易感性增加。     

Wnt signaling in rheumatoid synoviocyte activation

Rheumatoid arthritis (RA) is a joint-specific disease with complex pathogenesis. It is characterized by synovial inflammation, cartilage loss, and joint destruction. The reasons why joint damage recurs when therapy is discontinued are not clearly understood. Several lines of evidence suggest that cartilage damage is promoted by the transformed and invasive fibroblast-like synoviocytes (FLS) of the rheumatoid joint. It has been demonstrated in several systems that aberrant wnt-mediated signaling causes blockade of cartilage differentiation and malformation of joints. In this review, we have discussed the importance of wnt–frizzled-mediated signaling in the autonomous activation of FLS in patients with RA. Anti-wnt/anti-frizzled antibodies, frizzled receptor antagonists, or small molecule inhibitors of wnt–frizzled signaling might be useful for therapeutic interventions in RA. Received: May 15, 2001/Accepted: September 28, 2001     

Wnt8a and Wnt3a cooperate in the axial stem cell niche to promote mammalian body axis extension

Background: Vertebrate body axis extension occurs in a head‐to‐tail direction from a caudal progenitor zone that responds to interacting signals. Wnt/β‐catenin signaling is critical for generation of paraxial mesoderm, somite formation, and maintenance of the axial stem cell pool. Body axis extension requires Wnt8a in lower vertebrates, but in mammals Wnt3a is required, although the anterior trunk develops in the absence of Wnt3a. Results: We examined mouse Wnt8a^–/– and Wnt3a^–/– single and double mutants to explore whether mammalian Wnt8a contributes to body axis extension and to determine whether a posterior growth function for Wnt8a is conserved throughout the vertebrate lineage. We find that caudal Wnt8a is expressed only during early somite stages and is required for normal development of the anterior trunk in the absence of Wnt3a. During this time, we show that Wnt8a and Wnt3a cooperate to maintain Fgf8 expression and prevent premature Sox2 up‐regulation in the axial stem cell niche, critical for posterior growth. Similar to Fgf8, Wnt8a requires retinoic acid (RA) signaling to restrict its caudal expression boundary and possesses an upstream RA response element that binds RA receptors. Conclusions: These findings provide new insight into interaction of caudal Wnt‐FGF‐RA signals required for body axis extension. Developmental Dynamics 244:797–807, 2015. © 2015 Wiley Periodicals, Inc.     

Rare LRP6 Variants Identified in Spina Bifida Patients

Several single‐nucleotide variants (SNVs) in low‐density lipoprotein receptor‐related protein 6 (Lrp6) cause neural tube defects (NTDs) in mice. We therefore examined LRP6 in 192 unrelated infants from California with the NTD, spina bifida, and found four heterozygous missense SNVs, three of which were predicted to be deleterious, among NTD cases and not in 190 ethnically matched nonmalformed controls. Parents and siblings could not be tested because of the study design. Like Crooked tail and Ringleschwanz mouse variants, the p.Tyr544Cys Lrp6 protein failed to bind the chaperone protein mesoderm development and impaired Lrp6 subcellular localization to the plasma membrane of MDCK II cells. Only the p.Tyr544Cys Lrp6 variant downregulated canonical Wnt signaling in a TopFlash luciferase reporter in vitro assay. In contrast, three Lrp6 mutants (p.Ala3Val, p.Tyr544Cys, and p.Arg1574Leu) increased noncanonical Wnt/planar cell polarity (PCP) signaling in an Ap1‐luciferase assay. Thus, LRP6 variants outside of YWTD repeats could potentially predispose embryos to NTDs, whereas Lrp6 modulation of Wnt/PCP signaling would be more essential than its canonical pathway role in neural tube closure.     

Silicone rubber membrane with specific pore size enhances wound regeneration

A porous structure is critically important for wound dressing or tissue engineering scaffolds. However, the influence of the pore sizes on cell proliferation, tissue regeneration and the underlying mechanism remains unclear. In this study, silicone rubber membranes with different pore sizes were prepared using certain constituents of liquid silicone rubber precursor/liquid paraffin/hexane based on our previous studies. It was found that pore size had a significant impact on cell proliferation and wound healing. The CCK8 analysis revealed that the membrane with a certain pore size (110.47 μm, middle pore membrane, MPM) was suitable for cell proliferation compared with the membranes with other pore sizes (218.03 μm, large pore membrane, LPM; 5.27 μm, small pore membrane, SPM; non‐porous membrane, NPM). Further studies demonstrated that the MPM promoted cell proliferation via activating the Wnt/β‐catenin signalling pathway. More importantly, wound healing experiments showed that 7 days post‐wounding, the rate of wound healing was 89.25% with the MPM, which was significantly higher than with LPM, SPM or NPM. The in vivo data indicated that wound healing was accelerated by treatment with a silicone rubber membrane with a pore size of 110.47 μm. Our results strongly suggest that different pore structures might affect cell proliferation and wound healing and that a silicone rubber membrane with a specific pore size could potentially be used as a promising wound dressing. Copyright © 2017 John Wiley & Sons, Ltd.