TMED10对骨关节炎中TGF-β/Smads信号通路的影响

摘要 目的：探究跨膜P24转运蛋白10（TMED10）对骨关节炎中转化生长因子-β（TGF-β）/Smads信号通路的影响。方法：将大鼠软骨细胞分为Control组、IL-1β组、NC-sh+IL-1β组、TMED10-sh+IL-1β组、NC-OE+IL-1β组和TMED10-OE+IL-1β组。Control组和IL-1β组细胞不进行转染处理,NC-sh+IL-1β组、TMED10-sh+IL-1β组、NC-OE+IL-1β组和TMED10-OE+IL-1β组细胞分别转染NC-sh、TMED10-sh、NC-OE和TMED10-OE。转染后,除Control组之外,其他组软骨细胞均用白介素-1β（IL-1β）（10 ng/mL）处理24 h模拟OA软骨细胞的病理微环境。通过MTT法检测细胞增殖,通过TUNEL法检测细胞凋亡。采用前交叉韧带切断加内侧半月板部分切除法建立OA大鼠模型,将OA大鼠分为OA组、OA+NC-sh组和OA+TMED10-sh组（n=12）,Sham组（n=12）大鼠进行假手术操作。Sham组和OA组大鼠关节腔内注射40 μL生理盐水,OA+NC-sh组和OA+TMED10-sh组大鼠关节腔内分别注射40 μL的NC-sh和TMED10-sh（滴度为1×10⁹ TU/mL）,每周注射1次,共4周。采用番红O/固绿染色法评价膝关节软骨形态,采用TUNEL法检测软骨细胞凋亡。采用RT-qPCR检测软骨细胞和大鼠关节软骨中TMED10的mRNA水平,采用Western blot检测软骨细胞和大鼠关节软骨中TMED10、TGF-β1、Smad2、p-Smad2、Smad3、p-Smad3、Collagen II和MMP-13的蛋白表达水平。结果：与Control组比较,IL-1β组TUNEL阳性率、TMED10 mRNA和TMED10、MMP-13蛋白水平均升高（P<0.05）,相对细胞活力以及TGF-β1、p-Smad2/Smad2、p-Smad3/Smad3和Collagen II的蛋白水平均降低（P<0.05）。与IL-1β组和NC-sh+IL-1β组比较,TMED10-sh+IL-1β组TUNEL阳性率、TMED10 mRNA水平和TMED10、MMP-13的蛋白水平均降低（P<0.05）,相对细胞活力以及TGF-β1、p-Smad2/Smad2、p-Smad3/Smad3和Collagen II的蛋白水平均升高（P<0.05）。与IL-1β组和NC-OE+IL-1β组比较,TMED10-OE+IL-1β组TUNEL阳性率、TMED10 mRNA水平和TMED10、MMP-13的蛋白水平均升高（P<0.05）,相对细胞活力以及TGF-β1、p-Smad2/Smad2、p-Smad3/Smad3和Collagen II的蛋白水平均降低（P<0.05）。与Sham组比较,OA组大鼠的OARSI评分、TUNEL阳性率、TMED10 mRNA水平以及TMED10和MMP-13的蛋白水平均升高（P<0.05）,TGF-β1、p-Smad2/Smad2、p-Smad3/Smad3和Collagen II蛋白水平均降低（P<0.05）。与OA组和OA+NC-sh组比较,OA+TMED10-sh组大鼠的OARSI评分、TUNEL阳性率、TMED10 mRNA水平以及TMED10和MMP-13的蛋白水平均降低（P<0.05）,TGF-β1、p-Smad2/Smad2、p-Smad3/Smad3和Collagen II蛋白水平均升高（P<0.05）。结论：本研究表明TMED10可能通过抑制TGF-β/Smads信号通路导致软骨细胞丢失和软骨退变,TMED10/TGF-β/Smads信号通路可能是治疗OA的新靶标。     

炎性体与器官移植

炎性体是指存在于细胞质内能够激活半胱天冬酶-1（caspase-1）的大分子复合物,活化的caspase-1通过酶切白细胞介素-1β（IL-1β）和白细胞介素-18（IL-18）前体分子而生成具有生物学活性的IL-1β和IL-18.近来研究发现,炎性体分子NLRP1、NLRP2、NLRP5、CARD8、CASP5的基因型与移植的临床结果相关,心脏移植排斥反应时ASC和IL-1β的表达升高,缺血再灌注损伤中NLRP3炎性体激活增加IL-1β分泌,表明炎性体的激活与移植排斥反应和缺血再灌注损伤密切相关,但诱导炎性体活化的配体和参与的炎性体分子有待进一步研究.     

维生素C对创伤性脑损伤后神经细胞焦亡及NLRP3通路的影响

摘要 目的：考察创伤性脑损伤（TBI）中维生素C（Vit C）预处理抗神经细胞焦亡的作用和分子机制。方法：培养HT22细胞系,随机分为空白组（Sham组）、DMSO组（Con组）和Vit C预处理组（Vit C组）,Vit C组分为低剂量和高剂量2组。Vit C组和Con组进行预处理72 h后划伤12 h,制成神经细胞创伤性脑损伤模型。利用荧光免疫组化法和Western-blot检测NLRP3的表达变化;标准ELISA试剂盒检测IL-1β和 IL-18表达变化。结果：相较于Sham组,Con组和Vit C组中HT22细胞中NLRP3的染色阳性率高;与Con组比较,Vit C组的NLRP3表达明显减少(P<0.05),且IL-1β和 IL-18表达也显著降低(P<0.05),各组间差异有统计学意义(P<0.05)。结论：TBI后利用不同剂量Vit C均可有效降低神经细胞焦亡,可能是通过下调NLRP3表达水平,减少IL-1β和 IL-18等释放,发挥神经保护作用。     

副猪嗜血杆菌外膜囊泡激活caspase-11和NLRP3炎性体诱导炎性细胞因子IL-1β和IL-18分泌

【背景】副猪嗜血杆菌可引起多种炎性反应和较高死亡率,其致炎机制目前尚不清楚。【目的】探究副猪嗜血杆菌外膜囊泡(outer membrane vesicles,OMVs)诱导RAW264.7细胞caspase-11及NLRP3炎性体活化的功能,以及caspase-11在OMVs活化炎性体诱导炎性因子表达过程中的关键作用。【方法】副猪嗜血杆菌OMVs感染RAW264.7细胞,收集6、12和24h细胞,RT-PCR检测caspase-11、NLRP3、ASC和caspase-1 mRNA的表达;收集感染后48 h细胞,Western blotting检测caspase-11、NLRP3、ASC和caspase-1蛋白表达。收集感染后6、12、24、48和72h细胞上清,ELISA检测interleukin(IL)-1β和IL-18表达水平;不同浓度OMVs(0、2.5、10、25、50和100μg/mL)感染RAW264.7细胞24h,ELISA检测上清中IL-1β和IL-18水平。构建caspase-11沉默RAW264.7细胞株,收集OMVs感染后12、24和48h细胞培养上清检测IL-1β和IL-18水平。【结果】Caspase-11 mRNA转录水平在OMVs感染6、12和24h均极显著高于对照组(P<0.01);NLRP3 mRNA转录水平在感染后6、24h极显著高于对照组(P<0.01);ASC mRNA转录水平在感染后12、24h显著低于对照组(P<0.05);caspase-1 mRNA转录水平在感染后6、12和24h显著高于对照组(P<0.05)。Western blotting结果显示,与空白对照组相比,OMVs组caspase-11、NLRP3、ASC和caspase-1蛋白表达均明显升高。OMVs感染RAW264.7细胞后12、24、48和72h,IL-1β表达量极显著高于对照组(P<0.01),而且呈现时间依赖性升高,IL-18表达水平在感染后6、12、24、48和72h显著高于对照组(P<0.05);不同浓度OMVs感染细胞时,OMVs对细胞的致炎作用呈现剂量依赖性增强。Caspase-11沉默后,IL-1β水平在感染后12、24和48h显著低于未沉默组;Caspase-11沉默组IL-18表达量在感染后24、48h均显著低于未沉默组(P<0.05)。【结论】副猪嗜血杆菌OMVs在副猪嗜血杆菌诱导的炎症反应中发挥重要作用,OMVs可诱导RAW264.7细胞caspase-11介导的非经典NLRP3炎性体信号通路活化。     

牙龈卟啉单胞菌脂多糖通过TXNIP/Nlrp3炎性通路对小鼠牙周膜成纤维细胞迁移的影响

摘要 目的：研究牙龈卟啉单胞菌脂多糖（Porphyromonas lipopolysaccharide,LPS-PG）对牙周膜成纤维细胞（mouse periodontal Ligament: Normal Fibroblasts,mPDLFs）增殖及迁移的影响,探讨TXNIP/Nlrp3炎性体途径在其中的作用。方法：采用不同浓度的LPS-PG刺激小鼠mPDLFs细胞不同时间,CCK-8法检测细胞增殖抑制率。然后将细胞分为对照组（培养基作用24 h）和LPS-PG组（2 M的LPS-PG作用24 h）,划痕实验检测细胞迁移,ELISA法检测白细胞介素-1β（Interleukin-1β,IL-1β）和高迁移率族蛋白B1（High mobility group protein B1,HMGB1）的水平,Western Blot检测Nod样受体蛋白3（Nod-like receptor pyrin domain3,NLRP3）、凋亡相关斑点样蛋白（Apoptosis-associated speck-like protein,ASC）、活化半胱氨酸蛋白酶（cleaved-caspase-1）和硫氧还蛋白相互作用蛋白（Thioredoxin-interacting protein,TXNIP）的表达,免疫共沉淀检测以上蛋白间的相互作用。结果：与0 M的LPS-PG相比,1 M和2 M的LPS-PG可显著增加mPDLFs的细胞增殖抑制率（P<0.05）。与LPS-PG作用0 h相比,LPS-PG作用12 h、24 h和48 h均可显著增加mPDLFs的细胞增殖抑制率（P<0.05）。LPS-PG组细胞向中间''伤口''迁移的距离及细胞数量远远低于对照组。与对照组相比,LPS-PG组细胞中IL-1β和HMGB1的水平、NLRP3、cleaved-caspase-1和TXNIP蛋白表达均显著增加,且NLRP3和ASC、NLRP3和cleaved-caspase-1、TXNIP和NLRP3的蛋白互作能力显著增强（P<0.05）,而两组ASC蛋白的表达无显著差异（P＞0.05）。结论：LPS-PG可抑制mPDLFs细胞的增殖和迁移,其机制与Nlrp3炎性体的形成与活化有密切的关系。     

阿奇霉素序贯治疗联合麻杏石甘汤加味对痰热闭肺型肺炎支原体肺炎患儿Th17/Treg细胞因子和NLRP3炎症小体通路的影响

摘要 目的：观察阿奇霉素序贯治疗联合麻杏石甘汤加味对痰热闭肺型肺炎支原体肺炎（MPP）患儿辅助性T细胞17（Th17）/调节性T细胞（Treg）细胞因子和NOD样受体蛋白3（NLRP3）炎症小体通路的影响。方法：选择山东省中医院2019年4月~2021年5月期间收治的痰热闭肺型MPP患儿106例,根据随机数字表法分为对照组和研究组,各为53例,对照组患儿接受阿奇霉素序贯治疗,研究组患儿接受阿奇霉素序贯治疗联合麻杏石甘汤加味治疗,对比两组疗效、中医证候积分、Th17/Treg细胞因子和NLRP3炎症小体通路相关指标,记录两组不良反应发生情况。结果：与对照组相比,研究组的临床总有效率明显更高（P<0.05）。两组治疗后次证积分、主证积分、总积分均较治疗前下降,且研究组低于对照组（P<0.05）。两组治疗后白介素-17A（IL-17A）、白介素-25（IL-25）水平均较治疗前下降,白介素-10（IL-10）、白介素-35（IL-35）水平均较治疗前升高,且研究组的变化程度大于对照组（P<0.05）。两组治疗后NLRP3 mRNA、接头蛋白凋亡相关斑点样蛋白（ASC）mRNA、半胱天冬酶1（caspase-1） mRNA均较治疗前下降,且研究组的下降程度大于对照组（P<0.05）。两组在治疗期间均未曾出现明显不良反应。结论：阿奇霉素序贯治疗联合麻杏石甘汤加味治疗痰热闭肺型MPP患儿疗效显著,可促进症状改善,作用机制可能与调节Th17/Treg细胞因子和NLRP3炎症小体通路有关。     

研究报告: 组织蛋白酶B介导NLRP3小体在砷致小胶质细胞炎症激活中的作用

目的 探究组织蛋白酶B（CTSB）介导NLRP3小体在砷致小胶质细胞（BV-2）炎症激活中的作用。方法 取处于对数生长期的BV-2细胞，分别暴露于终浓度为0、2、4、8 μmol/L亚砷酸钠（NaAsO₂）溶液培养24 h，检测细胞活性，测定各组细胞内CTSB和细胞焦亡相关蛋白NLRP3、Caspase-1、IL-18、IL-1β的表达水平。流式细胞仪检测胞内溶酶体膜稳定性。基于实验结果，增设CTSB抑制剂组（5 μmol/L CA074-Me +8 μmol/L NaAsO₂、10 μmol/L CA074-Me+8 μmol/L NaAsO₂），检测两组细胞内炎症相关蛋白NLRP3、Caspase-1和IL-1β、IL-18的表达水平。结果 与对照组比较，各染砷组细胞抑制率增高，呈现剂量效应关系，溶酶体膜稳定性下降，差异有统计学意义（P<0.01），胞内CTSB、NLRP3、IL-1β、IL-18、Caspase-1表达增高，差异有统计学意义（P<0.01）；与对照组（8 μmol/L NaAsO₂）比较，抑制剂组BV-2细胞胞内CTSB、NLRP3、IL-1β、IL-18、Caspase-1水平均降低，差异有统计学差异（P<0.01）。结论 NaAsO₂通过诱导小胶质细胞内CTSB水平的上升，介导NLRP3炎症小体激活小胶质细胞，促其释放炎性因子，致神经系统损伤。     

苍耳子对慢性鼻-鼻窦炎大鼠炎症反应、NLRP3炎症小体及JAK2STAT3信号通路的影响

摘要 目的：探讨苍耳子对慢性鼻-鼻窦炎大鼠炎症反应、NLRP3炎症小体及JAK2STAT3信号通路的影响。方法：选择清洁级SD大鼠40只作为研究对象。将40只大鼠随机分为5组。采用鼻腔内注射金黄色葡萄球菌悬浊液的方法构建慢性鼻-鼻窦炎大鼠模型。空白对照组（8只）、模型组（8只）、低剂量组（7.5 mg/kg,8只）、中剂量组（15 mg/kg,8只）和高剂量组（30 mg/kg,8只）。采用埋藏食物小球实验进行嗅觉功能检查,采用qRC-PCR检测JAK2/STAT3信号通路和NLRP3、ACS、caspase-1的mRNA表达水平并采用ELISA法检查大鼠血液样本中肿瘤坏死因子-α（TNF-α）和IL-1β、IL-18的表达水平。结果：建模前,各组大鼠找到食物小球的时间比较（P＞0.05）;治疗后7 d和治疗完成时,与对照组相比,模型组、低剂量组、中剂量组和高剂量组找到食物小球的时间明显更长（P＜0.05）,高剂量组找到食物小球的时间明显短于模型组、低剂量组、中剂量组（P＜0.05）。与对照组相比,模型组、低剂量组、中剂量组和高剂量组JAK2 mRNA、STAT3 mRNA相对表达水平明显更高（P＜0.05）,高剂量组JAK2 mRNA、STAT3 mRNA相对表达水平明显低于模型组、低剂量组、中剂量组（P＜0.05）。与对照组相比,模型组、低剂量组、中剂量组和高剂量组TNF-α、IL-1β、IL-18表达水平明显更高（P＜0.05）,高剂量组TNF-α、IL-1β、IL-18表达水平明显低于模型组、低剂量组、中剂量组（P＜0.05）。与对照组相比,模型组、低剂量组、中剂量组和高剂量组NLRP3 mRNA、ACS mRNA、caspase-1 mRNA相对表达水平明显更高（P＜0.05）,高剂量组NLRP3 mRNA、ACS mRNA、caspase-1 mRNA相对表达水平明显低于模型组、低剂量组、中剂量组（P＜0.05）。结论：CRS大鼠采用苍耳子挥发油进行治疗可通过调控JAK2/STAT3信号通路的表达和NLRP3炎症小体的表达,从而抑制下游炎症因子的过度分泌,最终为缓解CRS病情和改善嗅觉功能做出贡献。     

人参皂苷Rg3通过调节自噬减轻脓毒症心肌损伤

摘要 目的：探讨人参皂苷Rg3（ginsenoside Rg3,Rg3）对脓毒症介导的心肌损伤的作用效果及机制。方法：本研究通过对小鼠进行盲肠结扎穿孔手术的方法构建脓毒症模型。32只BALB/c小鼠随机分为假手术组（Sham组）、脓毒症组（CLP组）、人参皂苷Rg3治疗组（Rg3+CLP组）以及自噬抑制剂干预组（3-MA+Rg3+CLP组）,每组8只。术后18 h分别留取各组小鼠血浆及心肌组织。通过ELISA方法检测白细胞介素-1β（IL-1β）、白细胞介素-18（IL-18）、乳酸脱氢酶（LDH）、肌酸激酶同工酶MB（CK-MB）及半胱氨酸蛋白酶-3（Caspase-3）表达水平。通过HE染色观察心肌组织形态结构的变化。应用Western-blot方法检测自噬及NLRP3炎性小体相关蛋白（NLRP3、ASC、Caspase-1）的表达。结果：与Sham组相比,CLP组小鼠心肌组织结构紊乱,炎性细胞浸润明显。另外,Caspase-3活性增加,NLRP3炎性小体相关蛋白（NLRP3、ASC、Caspase-1）表达升高,差异均有统计学意义（P＜0.05）。与CLP组相比,外源应用Rg3组小鼠心肌组织炎性细胞浸润减少,并且Caspase-3活性降低,NLRP3炎性小体相关蛋白表达下降,差异有统计学意义（P＜0.05）,而部分自噬相关蛋白表达升高。应用自噬抑制剂后,较单纯应用Rg3组,心肌组织损伤明显,而NLRP3炎性小体活性增加,差异有统计学意义（P＜0.05）。结论：脓毒症时NLRP3炎性小体激活,释放大量的细胞因子,进而导致心肌损伤。而Rg3治疗后,可以调节心肌细胞自噬,抑制NLRP3炎性小体激活,进而减轻细胞因子对心肌细胞的损伤。本研究表明Rg3可能通过调节心肌自噬,抑制NLRP3炎性小体的激活,进而减轻脓毒症时心脏的损伤。     

MLL3基因对宫颈癌细胞放射敏感性和DNA损伤修复能力的影响

摘要 目的：探究髓系/淋巴系或混合谱系白血病3基因（myeloid/lymphoid or mixed-lineage leukemia 3,MLL3）对宫颈癌细胞生长、转移、放射敏感性的影响。方法：选择60例宫颈鳞癌患者的癌组织及配对癌旁组织,采用实时定量聚合酶链式反应（qRT-PCR）检测检测MLL3 mRNA水平。体外培养SiHa细胞,将其分为以下5组：Control组（不转染）、NC-sh组（转染阴性对照shRNA慢病毒）、MLL3-sh组（转染MLL3 shRNA慢病毒）、NC-OE组（转染阴性对照过表达慢病毒）和MLL3-OE组（转染MLL3过表达慢病毒）。进一步采用2300EX直线加速器9 MeV ?茁射线照射细胞建立放射抵抗SiHa细胞（SiHaR）,然后将其分为：NC-sh组、MLL3-sh组、8 Gy+NC-sh组和8 Gy+MLL3-sh组。NC-sh组和MLL3-sh组细胞不照射,8 Gy+NC-sh组和8 Gy+MLL3-sh组细胞用9 MeV β射线照射8 Gy。采用MTT法检测细胞增殖情况;Annexin V-FITC/PI双染色法检测细胞凋亡;Transwell检测细胞侵袭能力;qRT-PCR检测MLL3、共济失调毛细血管扩张征突变基因（ATM）、ATM-Rad3相关基因（ATR）、乳腺癌易感基因（BRCA1）和RAD50双链断裂修复蛋白（RAD50）的mRNA水平;Western blot检测MLL3、Bcl-2相关X蛋白基因（Bax）、B细胞淋巴瘤/白血病-2基因（Bcl-2）、cleaved caspase 3、基质金属蛋白酶（MMP）2、MMP9和γ-H2AX的表达;免疫荧光染色检测γ-H2AX的表达。结果：与癌旁组织相比,宫颈鳞癌组织中的MLL3 mRNA水平显著降低（P<0.001）。与NC-sh组比较,MLL3-sh组SiHa细胞的MLL3 mRNA和蛋白相对表达量降低,细胞活力升高,细胞凋亡率、Bax和cleaved caspase 3蛋白相对表达量降低,Bcl-2蛋白相对表达量升高,侵袭细胞数量、MMP2和MMP9蛋白相对表达量升高（P<0.05）。与NC-OE组比较,MLL3-OE组SiHa细胞的MLL3 mRNA和蛋白相对表达量升高,细胞活力降低,细胞凋亡率、Bax和cleaved caspase 3蛋白相对表达量升高,Bcl-2蛋白相对表达量降低,侵袭细胞数量、MMP2和MMP9蛋白相对表达量降低（P<0.05）。与SiHa细胞相比,SiHaR细胞中的MLL3 mRNA和蛋白相对表达量均升高（P<0.001）。与8 Gy+NC-sh组比较,8 Gy+MLL3-sh组SiHaR细胞的细胞活力降低,γ-H2AX的蛋白相对表达量和γ-H2AX foci数目升高,ATM、ATR、BRCA1和RAD50的mRNA水平降低（P<0.05）。结论：宫颈癌细胞MLL3的表达下调促进了其生长和转移,但降低DNA损伤修复能力,提高宫颈癌细胞的放射敏感性。     

Loss of Yme1L perturbates mitochondrial dynamics

Yme1L is an AAA protease that is embedded in the mitochondrial inner membrane with its catalytic domain facing the mitochondrial inner-membrane space. However, how Yme1L regulates mammalian mitochondrial function is still obscure. We find that endogenous Yme1L locates at punctate structures of mitochondria, and that loss of Yme1L in mouse embryonic fibroblast (MEF) cells results in mitochondrial fragmentation and leads to significant increased ‘kiss-and-run'' type of mitochondrial fusion; however, Yme1L knockdown (shYme1L (short hairpin-mediated RNA interference of Yme1L)) cells still remain normal mitochondrial fusion although shYme1L mitochondria have a little bit less fusion and fission rates, and the shYme1L-induced fragmentation is due to a little bit more mitochondrial fission than fusion in cells. Furthermore, shYme1L-induced mitochondrial fragmentation is independent on optic atrophy 1 (OPA1) S1 or S2 processing, and shYme1L results in the stabilization of OPA1 long form (L-OPA1); in addition, the exogenous expression of OPA1 or L-OPA1 facilitates the shYme1L-induced mitochondrial fragmentation, thus this fragmentation induced by shYme1L appears to be associated with L-OPA1''s stability. ShYme1L also causes a slight increase of mitochondrial dynamics proteins of 49 kDa and mitochondrial fission factor (Mff), which recruit mitochondrial key fission factor dynamin-related protein 1 (Drp1) into mitochondria in MEF cells, and loss of Drp1 or Mff inhibits the shYme1L-induced mitochondrial fragmentation. In addition, there is interaction between SLP-2 with Yme1L and shYme1L cells retain stress-induced mitochondrial hyperfusion. Taken together, our results clarify how Yme1L regulates mitochondrial morphology.     

PINK1 is activated by mitochondrial membrane potential depolarization and stimulates Parkin E3 ligase activity by phosphorylating Serine 65

Missense mutations in PTEN-induced kinase 1 (PINK1) cause autosomal-recessive inherited Parkinson's disease (PD). We have exploited our recent discovery that recombinant insect PINK1 is catalytically active to test whether PINK1 directly phosphorylates 15 proteins encoded by PD-associated genes as well as proteins reported to bind PINK1. We have discovered that insect PINK1 efficiently phosphorylates only one of these proteins, namely the E3 ligase Parkin. We have mapped the phosphorylation site to a highly conserved residue within the Ubl domain of Parkin at Ser(65). We show that human PINK1 is specifically activated by mitochondrial membrane potential (Δψm) depolarization, enabling it to phosphorylate Parkin at Ser(65). We further show that phosphorylation of Parkin at Ser(65) leads to marked activation of its E3 ligase activity that is prevented by mutation of Ser(65) or inactivation of PINK1. We provide evidence that once activated, PINK1 autophosphorylates at several residues, including Thr(257), which is accompanied by an electrophoretic mobility band-shift. These results provide the first evidence that PINK1 is activated following Δψm depolarization and suggest that PINK1 directly phosphorylates and activates Parkin. Our findings indicate that monitoring phosphorylation of Parkin at Ser(65) and/or PINK1 at Thr(257) represent the first biomarkers for examining activity of the PINK1-Parkin signalling pathway in vivo. Our findings also suggest that small molecule activators of Parkin that mimic the effect of PINK1 phosphorylation may confer therapeutic benefit for PD.     

Phosphorylation of Parkin at Serine65 is essential for activation: elaboration of a Miro1 substrate-based assay of Parkin E3 ligase activity

Mutations in PINK1 and Parkin are associated with early-onset Parkinson''s disease. We recently discovered that PINK1 phosphorylates Parkin at serine65 (Ser⁶⁵) within its Ubl domain, leading to its activation in a substrate-free activity assay. We now demonstrate the critical requirement of Ser⁶⁵ phosphorylation for substrate ubiquitylation through elaboration of a novel in vitro E3 ligase activity assay using full-length untagged Parkin and its putative substrate, the mitochondrial GTPase Miro1. We observe that Parkin efficiently ubiquitylates Miro1 at highly conserved lysine residues, 153, 230, 235, 330 and 572, upon phosphorylation by PINK1. We have further established an E2-ubiquitin discharge assay to assess Parkin activity and observe robust discharge of ubiquitin-loaded UbcH7 E2 ligase upon phosphorylation of Parkin at Ser⁶⁵ by wild-type, but not kinase-inactive PINK1 or a Parkin Ser65Ala mutant, suggesting a possible mechanism of how Ser⁶⁵ phosphorylation may activate Parkin E3 ligase activity. For the first time, to the best of our knowledge, we report the effect of Parkin disease-associated mutations in substrate-based assays using full-length untagged recombinant Parkin. Our mutation analysis indicates an essential role for the catalytic cysteine Cys431 and reveals fundamental new knowledge on how mutations may confer pathogenicity via disruption of Miro1 ubiquitylation, free ubiquitin chain formation or by impacting Parkin''s ability to discharge ubiquitin from a loaded E2. This study provides further evidence that phosphorylation of Parkin at Ser⁶⁵ is critical for its activation. It also provides evidence that Miro1 is a direct Parkin substrate. The assays and reagents developed in this study will be important to uncover new insights into Parkin biology as well as aid in the development of screens to identify small molecule Parkin activators for the treatment of Parkinson''s disease.     

Heightened NTPDase-1/CD39 expression and angiogenesis in radiation proctitis

Radiation proctitis is an inflammatory process associated with persistent and refractory lower gastrointestinal bleeding. Purinergic signaling regulates hemostasis, inflammation, and angiogenesis. For example, CD39, the vascular ectonucleotidase, blocks platelet activation and is required for angiogenesis. Whether CD39 expression is affected by radiation injury is unknown. The aim of this work was to study CD39 expression patterns after clinical radiation injury to the rectum. We prospectively enrolled eight patients with radiation proctitis and five gender-matched controls. Biopsies were taken from normal-appearing rectal mucosa of controls and from the normal sigmoid and abnormal rectum of patients. Expression patterns of CD39, P2Y2 receptor, CD31, CD61 integrin, and vascular endothelial growth factor receptor 2 were examined by immunostaining; levels of CD39 were further evaluated by Western blots. Chronic inflammatory lesions of radiation proctitis were associated with heightened levels of angiogenesis. Immunohistochemical stains showed increased vascular expression of CD39, as confirmed by Western blots. CD39 was co-localized with vascular endothelial markers CD31 and CD61 integrin, as well as expressed by stromal tissues. Development of neovasculature and associated CD39 expression in radiation proctitis may be associated with the chronic, refractory bleeding observed in this condition.     

Vascular smooth muscle cell expression of ectonucleotidase CD39 (ENTPD1) is required for neointimal formation in mice

Vascular smooth muscle cell (VSMC) migration and proliferation are critical steps in the pathogenesis of atherosclerosis, post-angioplasty restenosis, neointimal hyperplasia, and chronic allograft rejection. Extracellular nucleotides are known to influence both migration and proliferation of VSMC. Although it is well established that vascular endothelial Cd39/ENTPD1 regulates blood nucleotide concentrations, whether Cd39 associated with VSMC also impacts vascular wall pathology has not been investigated. The objective of this paper is to determine levels of expression of Cd39 on VSMC and functional consequences of gene deletion in vitro and in vivo. Cd39 is the major ectonucleotidase in VSMC, as shown by substantive decreases in ecto-ATPase and -ADPase activity in Cd39-null cells compared to wild type. Significant decreases in neointimal lesion formation are observed in Cd39-null mice at 21 days post arterial balloon injury. Stimulated Cd39-null VSMC have pronounced proliferative responses in vitro. However, using Transwell systems, we show that Cd39-null VSMC fail to migrate in response to ATP, UTP, and PDGF. Cd39 is the dominant ectonucleotidase expressed by VSMC. Deletion of Cd39 in mice results in decreased neointimal formation after vascular injury and is associated with impaired VSMC migration responses in vitro.     

电针对SAMP8小鼠海马区PS1蛋白表达的影响

目的:研究电针对于SAMP8模型小鼠海马区早老蛋白1(presenilian 1,PS1)表达的影响,探讨电针治疗阿尔兹海默病(AD)的作用机制。方法:将20只SAMP8小鼠(早老化小鼠)随机分为模型对照组、电针治疗组,每组10只;10只SAMR1小鼠(正常老化小鼠)组成正常对照组。正常对照组和模型对照组正常饲养15天,在电针治疗组治疗时抓取束缚一次,不做任何治疗;电针治疗组每天治疗前抓取束缚之后再进行电针治疗,治疗穴位选取"百会"、"印堂"、"人中"三穴,频率2 Hz,电流强度以小鼠头部微颤为宜,留针20 min,每日1次,共15天。电针治疗结束后,通过Morris水迷宫实验观察小鼠的行为学变化;通过免疫组化观察SAMP8小鼠海马区PS1蛋白表达情况;通过Western blot方法检测各组海马区的PS1蛋白表达水平。结果:行为学中Morris水迷宫检测显示:模型组与正常对照组比较逃避潜伏时增加,空间探索实验穿越平台次数和平台象限游泳时间明显减少(P0.05,P0.01);电针治疗组逃避潜伏时明显减少,空间探索实验穿越平台次数和平台象限游泳时间明显增加(P0.05);免疫组化观察各组海马区PS1蛋白表达,电针治疗组较模型组明显降低;Western blot结果显示PS1蛋白在海马区表达水平,模型组高于正常对照组(P0.01),而电针治疗组低于模型组(P0.01)。结论:电针可以改善小鼠的学习记忆能力,而且电针治疗组海马区PS1蛋白含量明显低于模型组,电针治疗可能参与减弱PS1蛋白的表达,降低Aβ水平,对于AD治疗有益。     

Phosphoproteomic screening identifies Rab GTPases as novel downstream targets of PINK1

Mutations in the PTEN‐induced kinase 1 (PINK1) are causative of autosomal recessive Parkinson''s disease (PD). We have previously reported that PINK1 is activated by mitochondrial depolarisation and phosphorylates serine 65 (Ser⁶⁵) of the ubiquitin ligase Parkin and ubiquitin to stimulate Parkin E3 ligase activity. Here, we have employed quantitative phosphoproteomics to search for novel PINK1‐dependent phosphorylation targets in HEK (human embryonic kidney) 293 cells stimulated by mitochondrial depolarisation. This led to the identification of 14,213 phosphosites from 4,499 gene products. Whilst most phosphosites were unaffected, we strikingly observed three members of a sub‐family of Rab GTPases namely Rab8A, 8B and 13 that are all phosphorylated at the highly conserved residue of serine 111 (Ser¹¹¹) in response to PINK1 activation. Using phospho‐specific antibodies raised against Ser¹¹¹ of each of the Rabs, we demonstrate that Rab Ser¹¹¹ phosphorylation occurs specifically in response to PINK1 activation and is abolished in HeLa PINK1 knockout cells and mutant PINK1 PD patient‐derived fibroblasts stimulated by mitochondrial depolarisation. We provide evidence that Rab8A GTPase Ser¹¹¹ phosphorylation is not directly regulated by PINK1 in vitro and demonstrate in cells the time course of Ser¹¹¹ phosphorylation of Rab8A, 8B and 13 is markedly delayed compared to phosphorylation of Parkin at Ser⁶⁵. We further show mechanistically that phosphorylation at Ser¹¹¹ significantly impairs Rab8A activation by its cognate guanine nucleotide exchange factor (GEF), Rabin8 (by using the Ser111Glu phosphorylation mimic). These findings provide the first evidence that PINK1 is able to regulate the phosphorylation of Rab GTPases and indicate that monitoring phosphorylation of Rab8A/8B/13 at Ser¹¹¹ may represent novel biomarkers of PINK1 activity in vivo. Our findings also suggest that disruption of Rab GTPase‐mediated signalling may represent a major mechanism in the neurodegenerative cascade of Parkinson''s disease.     

Mouse ZIP1 and ZIP3 genes together are essential for adaptation to dietary zinc deficiency during pregnancy

Subfamily II of the solute-linked carrier 39A superfamily contains three well-conserved zinc transporters (ZIPs1, 2, 3) whose physiological functions are unknown. We generated mice homozygous for knockout alleles of ZIP1 and both ZIP1 and ZIP 3 (double-knockout). These mice were apparently normal when dietary zinc was replete, but when dietary zinc was limited during pregnancy embryos from ZIP1 or ZIP3 knockout mice were two to three times more likely to develop abnormally than those in wildtype mice, and 91% (71/78) of embryos developed abnormally in ZIP1, ZIP3 double-knockout mice. Analysis of the patterns of expression of these genes in mice revealed predominate expression in intestinal stromal cells, nephric-tubular epithelial cells, pancreatic ductal epithelial cells, and hepatocytes surrounding the central vein. This suggests that these zinc transporters function, at least in part, in the redistribution and/or retention of zinc rather than its acquisition from the diet. In conclusion, mutations in the ZIP1 and ZIP3 zinc transporter genes are silent when dietary intake of zinc is normal, but can dramatically compromise the success of pregnancy when dietary intake of zinc is limiting.     

Alzheimer's disease‐causing proline substitutions lead to presenilin 1 aggregation and malfunction

Do different neurodegenerative maladies emanate from the failure of a mutual protein folding mechanism? We have addressed this question by comparing mutational patterns that are linked to the manifestation of distinct neurodegenerative disorders and identified similar neurodegeneration‐linked proline substitutions in the prion protein and in presenilin 1 that underlie the development of a prion disorder and of familial Alzheimer's disease (fAD), respectively. These substitutions were found to prevent the endoplasmic reticulum (ER)‐resident chaperone, cyclophilin B, from assisting presenilin 1 to fold properly, leading to its aggregation, deposition in the ER, reduction of γ‐secretase activity, and impaired mitochondrial distribution and function. Similarly, reduced quantities of the processed, active presenilin 1 were observed in brains of cyclophilin B knockout mice. These discoveries imply that reduced cyclophilin activity contributes to the development of distinct neurodegenerative disorders, propose a novel mechanism for the development of certain fAD cases, and support the emerging theme that this disorder can stem from aberrant presenilin 1 function. This study also points at ER chaperones as targets for the development of counter‐neurodegeneration therapies.     

Death-associated protein kinase 1 has a critical role in aberrant tau protein regulation and function

The presence of tangles composed of phosphorylated tau is one of the neuropathological hallmarks of Alzheimer''s disease (AD). Tau, a microtubule (MT)-associated protein, accumulates in AD potentially as a result of posttranslational modifications, such as hyperphosphorylation and conformational changes. However, it has not been fully understood how tau accumulation and phosphorylation are deregulated. In the present study, we identified a novel role of death-associated protein kinase 1 (DAPK1) in the regulation of the tau protein. We found that hippocampal DAPK1 expression is markedly increased in the brains of AD patients compared with age-matched normal subjects. DAPK1 overexpression increased tau protein stability and phosphorylation at multiple AD-related sites. In contrast, inhibition of DAPK1 by overexpression of a DAPK1 kinase-deficient mutant or by genetic knockout significantly decreased tau protein stability and abolished its phosphorylation in cell cultures and in mice. Mechanistically, DAPK1-enhanced tau protein stability was mediated by Ser71 phosphorylation of Pin1, a prolyl isomerase known to regulate tau protein stability, phosphorylation, and tau-related pathologies. In addition, inhibition of DAPK1 kinase activity significantly increased the assembly of MTs and accelerated nerve growth factor-mediated neurite outgrowth. Given that DAPK1 has been genetically linked to late onset AD, these results suggest that DAPK1 is a novel regulator of tau protein abundance, and that DAPK1 upregulation might contribute to tau-related pathologies in AD. Therefore, we offer that DAPK1 might be a novel therapeutic target for treating human AD and other tau-related pathologies.