Perilipin-2 mediates ferroptosis in oligodendrocyte progenitor cells and myelin injury after ischemic stroke

Differentiation of oligodendrocyte progenitor cells into mature myelin-forming oligodendrocytes contributes to remyelination.Failure of remyelination due to oligodendrocyte progenitor cell death can result in severe nerve damage.Ferroptosis is an iron-dependent form of regulated cell death caused by membrane rupture induced by lipid peroxidation,and plays an important role in the pathological process of ischemic stroke.However,there are few studies on oligodendrocyte progenitor cell ferroptosis.We analyzed transcriptome sequencing data from GEO databases and identified a role of ferroptosis in oligodendrocyte progenitor cell death and myelin injury after cerebral ischemia.Bioinformatics analysis suggested that perilipin-2(PLIN2)was involved in oligodendrocyte progenitor cell ferroptosis.PLIN2 is a lipid storage protein and a marker of hypoxia-sensitive lipid droplet accumulation.For further investigation,we established a mouse model of cerebral ischemia/reperfusion.We found significant myelin damage after cerebral ischemia,as well as oligodendrocyte progenitor cell death and increased lipid peroxidation levels around the infarct area.The ferroptosis inhibitor,ferrostatin-1,rescued oligodendrocyte progenitor cell death and subsequent myelin injury.We also found increased PLIN2 levels in the peri-infarct area that co-localized with oligodendrocyte progenitor cells.Plin2 knockdown rescued demyelination and improved neurological deficits.Our findings suggest that targeting PLIN2 to regulate oligodendrocyte progenitor cell ferroptosis may be a potential therapeutic strategy for rescuing myelin damage after cerebral ischemia.

Exosomes originating from neural stem cells undergoing necroptosis participate in cellular communication by inducing TSC2 upregulation of recipient cells following spinal cord injury

We previously demonstrated that inhibiting neural stem cells necroptosis enhances functional recovery after spinal cord injury.While exosomes are recognized as playing a pivotal role in neural stem cells exocrine function,their precise function in spinal cord injury remains unclear.To investigate the role of exosomes generated following neural stem cells necroptosis after spinal cord injury,we conducted singlecell RNA sequencing and validated that neural stem cells originate from ependymal cells and undergo necroptosis in response to spinal cord injury.Subsequently,we established an in vitro necroptosis model using neural stem cells isolated from embryonic mice aged 16-17 days and extracted exosomes.The results showed that necroptosis did not significantly impact the fundamental characteristics or number of exosomes.Transcriptome sequencing of exosomes in necroptosis group identified 108 differentially expressed messenger RNAs,104 long non-coding RNAs,720 circular RNAs,and 14 microRNAs compared with the control group.Construction of a competing endogenous RNA network identified the following hub genes:tuberous sclerosis 2(Tsc2),solute carrier family 16 member 3(Slc16a3),and forkhead box protein P1(Foxp1).Notably,a significant elevation in TSC2 expression was observed in spinal cord tissues following spinal cord injury.TSC2-positive cells were localized around SRY-box transcription factor 2-positive cells within the injury zone.Furthermore,in vitro analysis revealed increased TSC2 expression in exosomal receptor cells compared with other cells.Further assessment of cellular communication following spinal cord injury showed that Tsc2 was involved in ependymal cellular communication at 1 and 3 days post-injury through the epidermal growth factor and midkine signaling pathways.In addition,Slc16a3 participated in cellular communication in ependymal cells at 7 days post-injury via the vascular endothelial growth factor and macrophage migration inhibitory factor signaling pathways.Collectively,these findings confirm that exosomes derived from neural stem cells undergoing necroptosis play an important role in cellular communication after spinal cord injury and induce TSC2 upregulation in recipient cells.

红毛藻多糖抑制大肠杆菌黏附Caco-2细胞的机制

基于体外人结肠腺癌细胞(Caco-2)单层模型,研究红毛藻多糖(Bangia fusco-purpurea polysaccharide,BFP)对大肠杆菌(Escherichia coli)黏附Caco-2细胞的影响以及潜在作用机制。采用CFDA-SE荧光标记技术分析BFP对E.coli黏附Caco-2细胞单层的影响;利用实时聚合酶链式反应分析BFP对Caco-2细胞表面整合素β1和E.coli黏附素fimH及E.coli黏附Caco-2细胞导致细胞产生的炎症因子(白细胞介素(interleukin,IL)-1β、IL-8、肿瘤坏死因子(tumor necrosis factor,TNF)-α)和细胞紧密连接蛋白(闭锁小带蛋白-1(zonula occludens-1,ZO-1)与Occludin)的基因表达情况,最终基于Western Blot分析验证ZO-1、Occludin蛋白表达。结果表明,BFP在质量浓度为400~800μg/mL时能够显著抑制E.coli黏附Caco-2细胞单层;BFP主要通过下调Caco-2细胞表面整合素β1和E.coli黏附素基因fimH的表达抑制细菌的黏附。此外,BFP可显著抑制E.coli及其培养上清液诱导Caco-2细胞产生的炎症细胞因子基因表达的上调、紧密连接蛋白(ZO-1与Occludin)及其基因表达的下调。综上所述,BFP能够抑制E.coli对Caco-2细胞单层的黏附,实验结果可为其开发新型的抗菌产品以及BFP的高值利用和精深加工提供参考。

染料木素-川芎嗪共晶在Caco-2细胞模型中的转运研究

旨在考察染料木素(genistein,GEN)、川芎嗪(tetramethylpyrazine,TMP)、染料木素-川芎嗪共晶(GEN-TMP)及染料木素与川芎嗪的物理混合物(GEN+TMP)在Caco-2细胞模型中的转运特征;建立Caco-2细胞模型,并以细胞跨膜电阻和标志物渗漏检查等指标进行验证,采用高效液相色谱法,考察并计算安全浓度下药物的累积转运量、表观渗透系数和外排率,并探讨P糖蛋白(P-gp)抑制剂维拉帕米、乳腺癌耐药蛋白(breast cancer resistant protein,BCRP)抑制剂KO143和多药耐药相关蛋白2(multidrug resistance-associated protein 2,MRP2)抑制剂MK571对转运的影响。结果显示,Caco-2细胞模型完整性与功能性良好,GEN浓度为40μg/mL时,GEN、TMP、GEN-TMP以及GEN+TMP的细胞存活率分别为90.06%、84.21%、97.60%和89.37%;GEN、TMP、GEN-TMP和GEN+TMP的表观渗透系数(P_(app))大于1.0×10^(-6)cm/s,属于吸收良好药物;GEN-TMP中GEN的累积转运量和P_(app)值分别为(2.78±0.11)μg和(8.61±0.33)×10^(-6)cm/s,比GEN的(1.92±0.15)μg和(5.96±0.47)×10^(-6)cm/s提高了44.79%和44.46%;GEN+TMP中GEN的累积转运量和P_(app)值与GEN无显著性差异。GEN只受BCRP的外排作用,GEN-TMP中的GEN同时受到P-gp和BCRP的外排作用,TMP、GEN-TMP和GEN+TMP中的TMP均受到MRP2的外排作用。结果表明,相同浓度下,GEN-TMP的细胞存活率高于GEN+TMP。GEN-TMP的吸收强于GEN和GEN+TMP中的GEN,共晶受外排蛋白的作用区别于GEN和GEN+TMP中的GEN,研究工作为共晶的转运研究提供了借鉴和参考。

羊血红蛋白水解物中新型抗氧化肽的纯化、鉴定和对H_(2)O_(2)损伤Caco-2细胞保护作用

以新鲜羊血为原料制备羊血红蛋白抗氧化肽,采用葡萄糖凝胶G-25色谱、DEAE葡萄糖凝胶A-50阴离子交换色谱、反相高效液相色谱和液相色谱-串联质谱对羊血红蛋白水解物进行分离纯化和鉴定,通过研究自由基清除能力、模拟胃肠消化后的稳定性及对H2O2诱导的Caco-2细胞保护作用评价羊血红蛋白肽的抗氧化活性。结果表明,从羊血红蛋白粗肽中纯化并鉴定出Ala-Tyr-Glu-Val-Asp(AYEVD)、Phe-His-Thr-Met-Glu(FHTME)、Ser-PheMet-Tyr-Glu-Lys(SFMYEK)3种新型抗氧化活性肽,分子质量分别为595.60、663.74、803.92 Da;其中AYEVD的1,1-二苯基-2-三硝基苯肼自由基清除能力最强;AYEVD在模拟胃肠道消化后显示出更强的抗氧化活性。此外,AYEVD还能抑制H2O2诱导Caco-2细胞的氧化损伤,显著减少活性氧积累、抑制早期细胞凋亡和丙二醛的形成,并提高细胞内抗氧化酶活性。该研究可为羊血红蛋白肽作为新型抗氧化剂应用于功能食品提供理论依据。

清肠温中方含药血清调控NLRP6途径对Caco-2/HT29-MTX细胞共培养模型MUC2表达的影响

目的:研究清肠温中方含药血清调控NLRP6途径影响Caco-2/HT29-MTX细胞共培养模型MUC2分泌的作用机制。方法:使用SD大鼠制备清肠温中方含药血清;Caco-2/HT29-MTX细胞共培养构建单层肠上皮细胞模型;IL-1β刺激共培养细胞模拟体外肠道炎症模型;si-NLRP6质粒转染干扰NLRP6,研究清肠温中方作用机制。qPCR检测NLRP6、IL-18的mRNA表达水平;Western blot检测NLRP6、IL-18蛋白表达水平;免疫荧光染色观察MUC2表达。结果:正常培养的Caco-2/HT29-MTX细胞中,NLRP6敲除后,MUC2表达明显减少。清肠温中方含药血清增加IL-1β诱导的细胞炎症模型中NLRP6和IL-18 mRNA及蛋白表达水平(P<0.05,P<0.01),且一定程度上抵消si-NLRP6的抑制作用。与模型组相比,清肠温中方含药血清干预后,促进MUC2蛋白表达恢复,si-NLRP6后一定程度上削弱了清肠温中方的作用。结论:清肠温中方含药血清通过调控NLRP6信号途径,进一步调节MUC2分泌,修复UC黏液屏障损伤。

内皮细胞特异性骨形态发生蛋白2对血管新生的影响:生物信息学分析和实验验证

背景:血管新生是心血管疾病的主要干预靶点,骨形态发生蛋白2具有调控血管新生作用,但内皮细胞特异性骨形态发生蛋白2对血管新生的调控作用不清楚。目的:探讨内皮细胞特异性骨形态发生蛋白2对血管新生的影响。方法:(1)生物信息学分析:通过Panglao DB公共基因表达数据库单细胞转录组荟萃分析观察骨形态发生蛋白2细胞群表达丰度和定位。血管新生小鼠和内皮(心内膜)过表达骨形态发生蛋白2小鼠转录组测序数据集探索内皮细胞骨形态发生蛋白2对血管新生信号通路的调控作用。(2)体内实验验证:建立小鼠后肢缺血模型,对比模型小鼠患侧与健侧缺血后肢7,14和21 d血流灌注情况,免疫荧光和免疫组织化学染色评估小鼠骨形态发生蛋白2和CD31的表达定位情况。(3)体外实验验证:体外培养人脐静脉内皮细胞,分为对照组、缺氧组和骨形态发生蛋白2抑制剂(Noggin蛋白)干预组,培养24 h,观察各组内皮细胞血管新生情况。结果与结论:(1)内皮细胞是表达骨形态发生蛋白2的重要细胞亚群,在血管新生内皮细胞和骨形态发生蛋白2过表达内皮细胞转录组再分析均发现骨形态发生蛋白2表达明显升高,血管新生通路明显激活。(2)缺血7 d小鼠新生血管周围骨形态发生蛋白2阳性血管明显增加(P<0.05),缺血2周骨形态发生蛋白2阳性血管明显减少(P<0.001)。(3)体外培养人脐静脉内皮细胞,缺氧干预后,内皮细胞迁移能力和血管出芽明显增加,血管新生因子血管内皮生长因子和血小板衍生生长因子的表达明显升高,Noggin明显减少了缺氧诱导的内皮细胞血管新生(P<0.001),并下调血管内皮生长因子和血小板衍生生长因子的表达(P<0.01)。(4)结果证实,内皮细胞特异性骨形态发生蛋白2具有调控血管新生作用,靶向性内皮细胞骨形态发生蛋白2可望改善血管新生。

猕猴桃皮多酚对脂多糖应激Caco-2细胞抗氧化能力的影响

目的:探讨猕猴桃皮多酚(kiwifruit peel polyphenols,KPP)对脂多糖(lipopolysaccharide,LPS)应激Caco-2细胞抗氧化能力的影响。方法:采用CCK-8法测定不同处理组Caco-2的细胞活力,荧光分光光度计测定活性氧和线粒体膜电位,分光光度计测定超氧化物歧化酶(superoxide dismutase,SOD)活力和谷胱甘肽(glutathione,GSH)、丙二醛(malonaldehyde,MDA)含量,实时荧光定量聚合酶链式反应测定核红细胞2相关因子2(nuclear factor erythroid 2-related factor 2,Nrf2)、Kelch样ECH相关蛋白1(Kelch-like ECH-associated protein 1,Keap1)、NAD(P)H:醌氧化还原酶1(NAD(P)H:quinone oxidoreductase 1,NQO1)、超氧化物歧化酶1(superoxide dismutase 1,S O D 1)、S O D 2基因的表达;蛋白印迹测定N r f 2、Ke a p 1及N Q O 1蛋白表达水平。结果:与L P S组相比,经50μg/mL KPP干预后细胞活力显著升高(P<0.05);活性氧水平和MDA含量分别显著下降至1.82±0.28、5.08 nmol/mg(P<0.05),线粒体膜电位显著升高至1.84±0.10(P<0.05),SOD活力和GSH含量分别显著升高至52.57 U/mg和69.46μmol/g(P<0.05);同时KPP干预能显著提高Nrf2、NQO1基因和蛋白表达(P<0.05),显著降低Keap1基因和蛋白表达(P<0.05)。结论:KPP能够通过Keap1/Nrf2/NQO1信号通路提高Caco-2的抗氧化水平,缓解LPS应激造成的细胞损伤。

基于Caco-2细胞模型的辣椒素与槲皮素协同调节小肠糖代谢的分子机制

为探究辣椒素与槲皮素协同调节小肠糖代谢的分子机制,借助Caco-2细胞单层模型,研究辣椒素与槲皮素单一及联合处理对Caco-2细胞存活率、细胞膜通透性的影响。采用免疫印迹法测定跨膜蛋白Occludin、胞质蛋白ZO-1、表面生长因子受体EGFR和纤维状肌蛋白F-actin以及葡萄糖转运关键蛋白GLUT2、SGLT1、Na^(+)/K^(+)-ATPase的表达量。结果显示:各试验处理组Caco-2细胞的增殖率均大于75%,表明药物对细胞没有明显毒性,可进行后续试验。Caco-2细胞单层模型的跨膜电阻值为(315.70±26.65)Ω·cm^(2),加药后各试验组的跨膜电阻值均呈现上升趋势,表明膜通透性变小,细胞屏障功能增强,可延缓小肠对葡萄糖的吸收。同时与空白对照组相比,各试验组上调了跨膜蛋白Occludin(>0.65)、胞质蛋白ZO-1 (>0.51)、表面生长因子受体EGFR(>0.19)和纤维状肌蛋白F-actin(>0.04)的相对表达量,并且下调了葡萄糖转运关键蛋白GLUT2(>1.00)、SGLT1(>0.78)、Na^(+)/K^(+)-ATPase(>0.87)的相对表达水平。综合来看,辣椒素与槲皮素在调节小肠糖代谢方面具有协同效应,二者在高剂量水平以1∶3比例混合效果最佳,主要通过增强肠道黏膜屏障功能,下调葡萄糖转运关键蛋白水平,从而抑制小肠对葡萄糖的吸收来达到调节糖代谢的效果。

天冬氨酸和谷氨酸及其甘氨酸二肽调控Caco-2细胞钙离子吸收的研究

为了探究天冬氨酸和谷氨酸及其甘氨酸二肽对钙离子吸收的影响机理,本文利用等温滴定量热技术、电化学、Caco-2细胞模型结合量子化学计算(密度泛函理论)对天冬氨酸和谷氨酸及其甘氨酸二肽与钙离子的相互作用进行了探究。结果表明,天冬氨酸和谷氨酸通过焓和熵驱动的放热反应与钙离子形成复合物,而其形成的二肽则是通过熵驱动的吸热反应与钙离子结合。此外,二肽比单独的氨基酸表现出更强的钙离子结合能力。量子化学计算表明,氨基酸/二肽中的羧基为钙离子的主要结合位点,在碱性条件下,会导致钙离子结合位点转移,氨基也可以参与钙离子结合。Caco-2细胞吸收实验表明,天冬氨酸和谷氨酸及其二肽均可促进钙的吸收,其中甘氨酸-谷氨酸二肽(Gly-Glu)的促进效果最好,促钙吸收率为1.33±0.115。此外,促钙吸收能力与钙离子结合能力之间没有明确的相关性,与其电子亲和力的关系更为密切。研究结果解释了天冬氨酸、谷氨酸及其甘氨酸二肽与钙之间的相互作用,为进一步开发钙补充剂提供科学依据。

构建过表达TRPV1基因的Caco-2细胞株

采用慢病毒载体系统构建辣椒素受体基因TRPV1过表达的人结直肠腺癌细胞Caco-2稳定重组株.将双酶切后的慢病毒空载体pCDH和TRPV1全基因PCR产物通过T4 DNA Ligase连接,构建包含TRPV1基因的过表达载体pCDH-TRPV1.将过表达载体pCDH-TRPV1转化DH 5α感受态细菌,大量扩繁后提取过表达载体pCDH-TRPV1的质粒,与psPAX2和pMD两种含有慢病毒包装所必需元件的质粒混合,再与脂质体混合制备脂质体-载体混合液.将脂质体-载体混合液转染至单层的293T细胞中,培养48h进行病毒包装.收集富含慢病毒颗粒的293T细胞上清液,超离心纯化成浓缩病毒,然后再与polybrene一起感染单层Caco-2细胞,通过GFP绿荧光信号来筛选获得TRPV1基因过表达的稳定细胞株.通过Realtime PCR方法和Western-blot检测TRPV1的mRNA表达量及蛋白表达量,结果表明,Caco-2-TRPV1重组细胞株的TRPV1的mRNA表达量及蛋白表达量均显著高于Caco-2-GFP对照细胞(P<0.05).成功构建了TRPV1基因过表达的稳定细胞株,为后续辣椒素降脂机理的研究提供了正向调控细胞模型.

Caco-2细胞单层缺氧再复氧损伤的模型构建

目的构建Caco-2细胞单层缺糖、缺血清、缺氧,再复糖、复血清、复氧的损伤模型,探究一氧化碳释放分子3(CORM-3)对Caco-2细胞单层缺氧再复氧损伤模型的影响。方法首先,培养Caco-2细胞,于37℃、含5%CO_(2)、1%O_(2)与94%N_(2)的培养箱中缺氧,建立Caco-2细胞单层缺糖、缺血清、缺氧/复糖、复血清、复氧(H/R)模型。根据缺氧时间分4组,空白对照组(Control组)、H/R 1组(缺氧4 h、复氧4 h)、H/R 2组(缺氧8h、复氧4h)和H/R 3组(缺氧12 h、复氧4 h)。其次,溶解CORM-3药物粉末并制备无活性的CORM-3(iCORM-3),按药物浓度分6组,空白对照组(Control组)、缺氧、复氧损伤模型组(H/R组)、H/R+300μmol/L CORM-3(H/R+C1组)、H/R+400μmol/L CORM-3(H/R+C2组)、H/R+500μmol/L CORM-3(H/R+C3组)和H/R+500μmol/L iCORM-3(H/R+C4组)。主要采用Cell counting kit-8(CCK8)试剂盒检测细胞活力,倒置显微镜观察细胞形态变化,测定Caco-2细胞单层渗透性。结果随着缺氧时间的延长,可观察到Caco-2细胞间连接消失,细胞皱缩从培养瓶底脱落漂浮,细胞活力下降,细胞单层通透性增大。给予CORM-3药物干预处理后,相比于未干预损伤组Caco-2细胞均有不同程度的改善,细胞活力随着药物浓度的增加而上升。结论本研究成功构建Caco-2细胞单层缺氧再复氧的损伤模型,并发现CORM-3对Caco-2细胞单层H/R损伤模型可能有保护作用。

Evaluation of the intracellular lipid-lowering effect of polyphenols extract from highland barley in HepG2 cells

Active ingredients from highland barley have received considerable attention as natural products for developing treatments and dietary supplements against obesity.In practical application,the research of food combinations is more significant than a specific food component.This study investigated the lipid-lowering effect of highland barley polyphenols via lipase assay in vitro and HepG2 cells induced by oleic acid(OA).Five indexes,triglyceride(TG),total cholesterol(T-CHO),low density lipoprotein-cholesterol(LDL-C),aspartate aminotransferase(AST),and alanine aminotransferase(ALT),were used to evaluate the lipidlowering effect of highland barley extract.We also preliminary studied the lipid-lowering mechanism by Realtime fluorescent quantitative polymerase chain reaction(q PCR).The results indicated that highland barley extract contains many components with lipid-lowering effects,such as hyperoside and scoparone.In vitro,the lipase assay showed an 18.4%lipase inhibition rate when the additive contents of highland barley extract were 100μg/m L.The intracellular lipid-lowering effect of highland barley extract was examined using 0.25 mmol/L OA-induced HepG2 cells.The results showed that intracellular TG,LDL-C,and T-CHO content decreased by 34.4%,51.2%,and 18.4%,respectively.ALT and AST decreased by 51.6%and 20.7%compared with the untreated hyperlipidemic HepG2 cells.q PCR results showed that highland barley polyphenols could up-regulation the expression of lipid metabolism-related genes such as PPARγand Fabp4.

Effect of dephytinization on bioavailability of iron,calcium and zinc from infant cereals assessed in the Caco-2 cell model

AIM： To test the effect of the dephytinization of three different commercial infant cereals on iron, calcium, and zinc bioavailability by estimating the uptake, retention, and transport by Caco-2 cells. METHODS： Both dephytinized （by adding an exogenous phytase） and non-dephytinized infant cereals were digested using an in vitro digestion protocol adapted to the gastrointestinal conditions of infants younger than 6 too. Mineral cell retention, transport, and uptake from infant cereals were measured using the soluble fraction of the simulated digestion and the Caco-2 cells. RESULTS： Dephytinization of infant cereals significantly increased （P 〈 0.05） the cell uptake efficiency （from 0.66%-6.05% to 3.93%-13%）, retention （from 6.04%-16.68% to 14.75%-20.14%） and transport efficiency （from 0.14%-2.21% to 1.47%-6.02%）, of iron, and the uptake efficiency （from 5.0%-35.4% to 7.3%-41.6%） and retention （from 4.05%-20.53% to 14.45%-61.3%） of zinc, whereas calcium only cell uptake showed a significant increase （P 〈 0.05） after removing phytate from most of the samples analyzed. A positive relationship （P 〈 0.05） between mineral solubility and the cell uptake and transport efficiencies was observed. CONCLUSION： Removing phytate from infant cereals had a beneficial effect on iron and zinc bioavailability when infant cereals were reconstituted with water. Since in developing countries cereal-based complementary foods for infants are usually consumed mixed with water, exogenous phytase additions could improve the nutritional value of this weaning food.

Transepithelial transport of putrescine across monolayers of the human intestinal epithelial cell line, Caco-2

AIM: To study the transepithelial transport characteristics of the polyamine putrescine in human intestinal Caco-2 cell monolayers to elucidate the mechanisms of the putrescine intestinal absorption. METHODS: The transepithelial transport and the cellular accumulation of putrescine was measured using Caco-2 cell monolayers grown on permeable filters. RESULTS: Transepithelial transport of putrescine in physiological concentrations (】 0.5 mM) from the apical to basolateral side was linear. Intracellular accumulation of putrescine was higher in confluent than in fully differentiated Caco-2 cells, but still negligible (less than 0.5%) of the overall transport across the monolayers in apical to basolateral direction.EGF enhanced putrescine accumulation in Caco-2 cells by four fold, as well as putrescine conversion to spermidine and spermine by enhancing the activity of S adenosylmethionine decarboxylase. However, EGF did not have any significant influence on putrescine flux across the Caco-2 cell monolayers. Excretion of putrescine from Caco-2 cells into the basolateral medium did not exceed 50 picomoles, while putrescine passive flux from the apical to the basolateral chamber, contributed hundreds of micromoles polyamines to the basolateral chamber. CONCLUSION :Transepithelial transport of putrescine across Caco2 cell monolayers occurs in passive diffusion, and is not influenced when epithelial cells are stimulated to proliferate by a potent mitogen such as EGF.

Runx2 regulates peripheral nerve regeneration to promote Schwann cell migration and re-myelination

Runx2 is a major regulator of osteoblast differentiation and function;however,the role of Runx2 in peripheral nerve repair is unclea r.Here,we analyzed Runx2expression following injury and found that it was specifically up-regulated in Schwann cells.Furthermore,using Schwann cell-specific Runx2 knocko ut mice,we studied peripheral nerve development and regeneration and found that multiple steps in the regeneration process following sciatic nerve injury were Runx2-dependent.Changes observed in Runx2 knoc kout mice include increased prolife ration of Schwann cells,impaired Schwann cell migration and axonal regrowth,reduced re-myelination of axo ns,and a block in macrophage clearance in the late stage of regeneration.Taken together,our findings indicate that Runx2 is a key regulator of Schwann cell plasticity,and therefore peripheral nerve repair.Thus,our study shows that Runx2 plays a major role in Schwann cell migration,re-myelination,and peripheral nerve functional recovery following injury.

Effects of extracellular iron concentration on calcium absorption and relationship between Ca^(2+) and cell apoptosis in Caco-2 cells

AIM: To determine the method of growing small intestinal epithelial cells in short-term primary culture and to investigate the effect of extracellular iron concentration ([Fe3+]) on calcium absorption and the relationship between the rising intracellular calcium concentration ([Ca2+]i) and cell apoptosis in human intestinal epithelial Caco-2 cells. METHODS: Primary culture was used for growing small intestinal epithelial cells. [Ca2+]i was detected by a confocal laser scanning microscope. The changes in [Ca2+]i were represented by fluorescence intensity (FI). The apoptosis was evaluated by flow cytometry. RESULTS: Isolation of epithelial cells and preservation of its three-dimensional integrity were achieved using the digestion technique of a mixture of collagenase Ⅺ and dispase Ⅰ. Purification of the epithelial cells was facilitated by using a simple differential sedimentation method. The results showed that proliferation of normal gut epithelium in vitro was initially dependent upon the maintenance of structural integrity of the tissue. If 0.25% trypsin was used for digestion, the cells were severely damaged and very difficult to stick to the Petri dish for growing. The Fe3+ chelating agent desferrioxamine (100, 200 and 300 μmol/L) increased the FI of Caco-2 cells from 27.50±13.18 (control, n = 150) to 35.71±13.99 (n = 150, P<0.01), 72.19±35.40 (n = 150, P<0.01) and 211.34±29.03 (n = 150,P<0.01) in a concentration-dependent manner. There was a significant decrease in the FI of Caco-2 cells treated by ferric ammonium citrate (FAC, a Fe3+ donor; 10, 50 and 100 μmol/L). The FI value of Caco-2 cells treated by FAC was 185.85±33.77 (n = 150, P<0.01), 122.73±58.47 (n = 150, P<0.01), and 53.29±19.82 (n= 150,P<0.01), respectively, suggesting that calcium absorption was influenced by [Fe3+]. Calcium ionophore A23187(0.1,1.0 and 10 μmol/L) increased the FI of Caco-2 cells from 40.45±13.95 (control, n = 150) to 45.19±21.95 (n = 150, P<0.01), 89.87±43.29 (n = 150, P<0.01) and 104.64±51.07 (n = 150,P<0.01) in a concentration-dependent manner. The positive apoptotic cell number of the Caco-2 cells after being treated with A23187 increased from 0.32% to 0.69%, 0.90% and 1.10%, indicating that the increase in the positive apoptotic cell number was positively correlated with [Ca2+]i. CONCLUSION: Ca2+ absorbability is increased with the decrease of extracellular iron concentration Fe3+ and hindered with the increase of Fe3+ consistence out of them. Furthermore, increase of [Ca2+]i can induce apoptosis in Caco-2 cells.

SARS-CoV2 Nsp3 protein triggers cell death and exacerbates amyloid β42-mediated neurodegeneration

Infection caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV2)virus,responsible for the coronavirus disease 2019(COVID-19)pandemic,induces symptoms including increased inflammatory response,severe acute respiratory syndrome(SARS),cognitive dysfunction like brain fog,and cardiovascular defects.Long-term effects of SARS-CoV2 COVID-19 syndrome referred to as post-COVID-19 syndrome on age-related progressive neurodegenerative disorders such as Alzheimer's disease remain understudied.Using the targeted misexpression of individual SARS-CoV2 proteins in the retinal neurons of the Drosophila melanogaster eye,we found that misexpression of nonstructural protein 3(Nsp3),a papain-like protease,ablates the eye and generates dark necrotic spots.Targeted misexpression of Nsp3 in the eye triggers reactive oxygen species production and leads to apoptosis as shown by cell death reporters,terminal deoxynucleotidyl transferase(TdT)dUTP Nick-end labeling(TUNEL)assay,and dihydroethidium staining.Furthermore,Nsp3 misexpression activates both apoptosis and autophagy mechanism(s)to regulate tissue homeostasis.Transient expression of SARS-CoV2 Nsp3 in murine neuroblastoma,Neuro-2a cells,significantly reduced the metabolic activity of these cells and triggers cell death.Misexpression of SARS-CoV2 Nsp3 in an Alzheimer's disease transgenic fly eye model(glass multiple repeats[GMR]>amyloidβ42)further enhances the neurodegenerative rough eye phenotype due to increased cell death.These findings suggest that SARS-CoV2 utilizes Nsp3 protein to potentiate cell death response in a neurodegenerative disease background that has high pre-existing levels of neuroinflammation and cell death.

Assessment of Iron Bioavailability in Ten Kinds of Chinese Wheat Flours Using an in vitro Digestion/Caco-2 cell Model

Abstract Objective To compare iron bioavailability （Fe BV） from ten selected kinds of Chinese wheat flours in order to provide scientific basis for further human trials and enable plant breeding programs to screen biofortified wheat cultivars. Methods An in vitro digestion/Caco-2 cell model was used to assess Fe BV of ten flour samples from six leading Chinese wheat cultivars and the stability of Fe BV in one cultivar was studied across three growing environments. Results Significant differences were observed in both Fe BV and Fe bioavailability per gram of food （Fe BVPG） among cultivars （P〈0.01） grown at the same location with the same flour extraction rate. Zhongyou 9507 and Jingdong 8 had Fe BV 37%-54% and Fe BVP（3 103%-154% higher than the reference control. In the Anyang environment, Zhongyou 9507 had a higher wheat flour-Fe level and Fe BVPG. Differences in Fe BV were detected in cultivars with different flour extraction rates. Conclusion Zhongyou 9507 and Jingdong 8 were identified as the most promising cultivars for further evaluation of efficacy by using human subjects. The growing environments had no effect on Fe BV, but did have a significant effect on Fe BVPG. Fe bioavailabilities in low-extraction （40%） flours were higher than those in high-extraction （78%） flours.

Gastric digestion of pea ferritin and modulation of its iron bioavailability by ascorbic and phytic acids in caco-2 cells

AIM： To understand the digestive stability and mechanism of release and intestinal uptake of pea ferritin iron in caco-2 cell line model.METHODS： Pea seed ferritin was purified using salt fractionation followed by gel filtration chromatography.The bioavailability of ferritin iron was assessed using coupled in vitro digestion/Caco-2 cell model in the presence or absence of ascorbic acid and phytic acid.Caco-2 cell ferritin formation was used as a surrogate marker of iron uptake. Structural changes of pea ferritin under simulated gastric pH were characterized using electrophoresis, gel filtration and circular dichroism spectroscopy.RESULTS： The caco-2 cell ferritin formation was significantly increased （P 〈 0.001） with FeSO4 （19.3±9.8 ng/mg protein） and pea ferritin （13.9 ± 6.19 ng/mg protein） compared to the blank digest （3.7 ± 1.8 ng/mg protein）. Ascorbic acid enhanced while phytic acid decreased the pea ferritin iron bioavailability. However,either in the presence or absence of ascorbic acid, the ferritin content of caco-2 cells was significantly less with pea ferritin than with FeSO4. At gastric pH, no band corresponding to ferritin was observed in the presence of pepsin either on native PAGE or SDS-PAGE. Gel filtration chromatography and circular dichroism spectroscopy revealed a pH dependent loss of quaternary and secondary structure.CONCLUSION： Under gastric conditions, the iron core of pea ferritin is released into the digestive medium due to acid induced structural alterations and dissociation of protein. The released iron interacts with dietary factors leading to modulation of pea ferritin iron bioavailability,resembling the typical characteristics of non-heme iron.