HIF-1α和hTERT shRNA双基因抑制脑胶质瘤生长的实验研究

目的 研究靶向缺氧诱导因子-1α(HIF-1α)和人端粒酶逆转录酶(hTERT)的短发夹RNA(shRNA),对裸鼠皮下人脑胶质瘤中HIF-1α、hTERT基因表达的抑制作用,及其对肿瘤增殖和细胞凋亡的影响.方法 体外培养人脑胶质瘤U251细胞;建立人脑胶质瘤裸鼠皮下接种模型;将HIF-1α shRNA、hTERT shRNA质粒转染入移植瘤中,观察肿瘤生长情况;HE染色法观察肿瘤组织的病理改变;Western blot检测HIF-1α、hTERT蛋白表达;Annexin V+PI双染流式细胞仪检测凋亡情况.结果 成功建立稳定的裸鼠U251皮下移植瘤模型;治疗5周后HIF-1α shRNA、hTERT shRNA组双基因干扰组肿瘤体积较单基因干扰组及对照组明显减小,抑瘤率为84.2%;病理结果显示双基因干扰组肿瘤生长受到抑制,微血管散在稀疏,大量肿瘤细胞坏死及凋亡;Western blot显示治疗组相应蛋白表达受抑制,双基因干扰组影响二者表达;流式细胞仪检测双基因干扰组肿瘤细胞凋亡率明显高于其他组(P＜0.01).结论 HIF-1α shRNA和hTERT shRNA均可在裸鼠移植瘤体内抑制相应蛋白表达及胶质瘤增殖生长,促进细胞凋亡,而双基因干扰作用更强.     

RWD结构小泛素化增强子与缺氧诱导因子-1α在AtT-20细胞的表达

目的研究RWD结构小泛素化增强子(RWD containing sumoylation enhancer,RSUME)调控缺氧诱导因子(hypoxia-inducible factor 1-alpha,HIF-1α)对At T-20细胞侵袭的影响。方法通过氯化钴模拟小鼠垂体腺瘤At T-20细胞的缺氧环境,并应用实时荧光定量PCR及蛋白质印迹法检测RSUME、HIF-1α的m RNA和蛋白水平的改变;然后运用HIF-1α小干扰RNA(small interfering RNA,si RNA)及阴性对照序列转染小鼠垂体腺瘤At T-20细胞,实时荧光定量PCR及蛋白质印迹法检测RSUME的m RNA和蛋白水平的改变;运用RSUME si RNA及阴性对照序列转染小鼠垂体腺瘤At T-20细胞后,实时荧光定量PCR及蛋白质印迹法检测HIF-1α的m RNA和蛋白水平的改变;并用Transwell及MTT法检测At T-20细胞侵袭的改变。结果氯化钴作用At T-20细胞后,细胞中RSUME的蛋白(P=0.003)和HIF-1α的蛋白(P=0.002)水平明显升高;HIF-1αsi RNA转染的At T-20细胞中RSUME m RNA(P=0.162)及蛋白(P=0.668)水平表达无明显变化;RSUME si RNA转染的At T-20细胞中HIF-1α蛋白水平表达明显降低(P0.001),而m RNA水平未见明显改变(P=0.136);RSUME si RNA转染组At T-20细胞侵袭率较RSUME阴性对照组及空白对照组低(侵袭抑制率=26.2%±8.4%)。结论缺氧可诱导RSUME的表达,RSUME可调控HIF-1α的蛋白水平的作用影响At T-20细胞的侵袭。     

沉默HIF-1α基因对U87细胞增殖、侵袭及转移能力的影响

目的 观察沉默低氧诱导因子1α(HIF-1a)基因后对胶质母细胞瘤U87细胞增殖、侵袭及转移能力的影响.方法 实验分3组,干扰组(转染表达HIF-1α-shRNA的质粒)、对照干扰组(转染阴性对照shRNA序列)及未处理组.干扰组利用前期构建的HIF-1α基因的短发夹RNA(shRNA)沉默HIF-1α基因,构建HIF-1α-shRNA慢病毒表达载体,在脂质体介导下转染人胶质母细胞瘤细胞U87.采用RT-PCR和Western blotting检测HIF-1α基因干扰效率,MTT法检测细胞生长增殖能力,迁移实验检测细胞的体外迁移能力,Transwell小室模型检测细胞的体外侵袭及转移能力.结果 RT-PCR和Western blotting实验证实,与对照干扰组及未处理组比较,干扰组细胞HIF-1αmRNA表达水平明显下降,蛋白条带明显减弱.MTT细胞增殖实验显示,干扰组细胞增殖水平较其他2组明显降低,差异有统计学意义(P<0.05).Transwell小室侵袭实验中,未处理组、对照干扰组、干扰组穿膜细胞数分别为(125.2±10.8)个、(118.3±8.3)个、(60.9±5.4)个,差异有统计学意义(P<0.05).结论 HIF-1α-shRNA能有效抑制U87细胞株HIF-1α mRNA及蛋白的表达,并能抑制U87细胞的增殖、侵袭及转移能力.

Abstract：

Objective To observe the influence of silencing hypoxia-inducible factor-1α(HIF-1α)gene on the proliferation, invasion and metastasis of glioblastoma U87 cells. Methods The samples were divided into 3 groups: blank group: samples without giving any treatments, control group: cells with empty shRNA vector, and experimental group: cells with HIF-1α-shRNA transfection complex. HIF-1α gene was silenced by shRNA constructed in early time; and HIF-1α-shRNA lentivirus vector was constructed in the experimental group, and then transfected into glioblastoma U87 cells with the mediation of liposome. The interference efficiency was detected by using RT-PCR and Western blotting, and cell proliferation was measured by MTT assay; cell migration in vitro was observed by migration test, and invasion and metastasis abilities were detected by Transwell booth model. Results As compared with those in cells of the control and blank groups, the mRNA and protein expressions of HIF-1α in cells of the experimental group were significantly decreased; MTT assay showed that the cell proliferation in the experimental group was significantly lower than that in the other 2 groups (P<0.05). The number of penetrating cells of the blank group, control group and experimental group in Transwell chamber invasion assay were (125.2±10.8), (118.3±8.3), (60.9±5.4), respectively, and significant differences were noted between each 2 groups (P<0.05). Conclusion The mRNA and protein levels of HIF-1α in U87 cells are efficiently depressed by HIF-1α-shRNA, and so are the proliferation, invasion and metastasis abilities of U87 cells.     

缺氧诱导因子1α小干扰RNA对骨髓间充质干细胞缺氧诱导因子1α、基质细胞衍生因子1α和血管内皮生长因子基因表达的影响*

背景：缺氧可以影响骨髓间充质干细胞分泌细胞因子,其机制可能是通过缺氧诱导因子1α起作用的。 目的：观察缺氧诱导因子1α RNA干扰对骨髓间充质干细胞缺氧诱导因子1α、基质细胞衍生因子1α和血管内皮生长因子基因表达的影响。 方法：贴壁法培养骨髓间充质干细胞,取第3~5代细胞用于实验,倒置显微镜下观察细胞形态,并用流式细胞仪检测其表面标志物CD34、CD44、CD90表达。将骨髓间充质干细胞分四组：常氧对照组(无干预因素)、缺氧组(缺氧24 h)、脂质体对照组(转染空载脂质体后缺氧24 h)、RNA干扰组(转染脂质体介导的RNA干扰序列后缺氧24 h)。RT-PCR法检测骨髓间充质干细胞的缺氧诱导因子1α、基质细胞衍生因子1α和血管内皮生长因子 mRNA表达水平, ELISA检测骨髓间充质干细胞培养上清缺氧诱导因子1α、基质细胞衍生因子1α和血管内皮生长因子蛋白表达水平。 结果与结论：同常氧对照组比较,缺氧组缺氧诱导因子1α、基质细胞衍生因子1 α和血管内皮生长因子基因及蛋白表达增高(P < 0.05);同脂质体对照组比较,RNA干扰组缺氧诱导因子1α、基质细胞衍生因子1α和血管内皮生长因子基因及蛋白表达降低(P < 0.05)。证实了缺氧条件可以使骨髓间充质干细胞血管内皮生长因子和基质细胞衍生因子1α的表达增加,抑制缺氧诱导因子1α的表达可以使血管内皮生长因子和基质细胞衍生因子1α的表达减少,缺氧诱导因子1α很可能是干细胞移植细胞因子分泌的调控因素。     

不同缺氧方法诱导皮质神经元表达缺氧诱导因子1α及促红素的实验方法比较

目的研究不同缺氧方法刺激皮质神经元后细胞变化及HIF-1α、EPO的表达。方法原代培养皮质神经元,分为正常对照组、环境缺氧组、氯化钴组和去铁敏组4组培养,CCK-8法检测细胞活力。应用western blot方法检测HIF-1α及EPO蛋白的表达,RT-PCR分析其mRNA的表达。结果不同的缺氧条件均能减低细胞活力,其中氯化钴组下降最明显。3组均可诱导HIF-1α及EPO蛋白表达:去铁敏组HIF-1α、EPO蛋白表达均高于氯化钴组(P<0.05)。3组均能上调HIF-1α及EPO mRNA表达:去铁敏组、环境缺氧组与氯化钴组比较有明显升高(P<0.01)。结论不同缺氧方法均可以诱导皮质神经元表达HIF-1α、EPO蛋白和mRNA表达。去铁敏化学缺氧法是更为合适的皮质神经元缺氧研究的方法。     

NAC调控HIF-1α抑制胶质瘤细胞生长的作用研究

目的研究N-乙酰半胱氨酸(NAC)通过抑制低氧诱导因子-1α(HIF-1α)表达,进而抑制SHG-44胶质瘤细胞生长的作用研究。方法对照组为常规培养的SHG-44胶质瘤细胞,NAC组为常规培养基础上加入N-乙酰半胱氨酸,两组培养48 h后实时荧光定量逆转录酶聚合酶联反应(RTPCR)检测HIF-1αmRNA的表达,四甲基偶氮唑盐比色法(MTT)检测SHG-44胶质瘤细胞增殖情况,流式细胞仪检测SHG-44胶质瘤细胞凋亡情况。结果 NAC组HIF-1αmRNA的表达水平明显低于对照组,差异有统计学意义(P0.05)。MTT检测SHG-44胶质瘤细胞增殖情况,NAC组明显低于对照组,差异有统计学意义(P0.05)。NAC组早期凋亡率、晚期凋亡及坏死率均高于对照组,差异有统计学意义(P0.05)。结论 N-乙酰半胱氨酸具有下调低氧诱导因子-1α表达,进而抑制SHG-44胶质瘤细胞生长,加速凋亡的作用。     

瘢痕疙瘩成纤维细胞生长与小干扰RNA分子抑制细胞周期蛋白D1表达的影响☆

目的: 细胞周期蛋白是细胞周期调控的决定性因子,RNA干涉是一种高效特异的基因沉默技术,能诱使细胞表现出特定基因缺失表型。通过RNA干扰阻断细胞周期蛋白D1基因表达，观察瘢痕疙瘩成纤维细胞增殖和细胞周期的影响。 方法：实验于2006-07/2007-05在南方医科大学基因工程研究所（BSL-2级）完成。①实验材料：小干扰性RNA设计采用软件是ambion公司的在线软件siRNA target finder，合成采用化学合成法，委托上海吉凯基因有限公司合成，再经过变性退火处理后得到双链小干扰性RNA；瘢痕疙瘩成纤维细胞标本取自南方医院整形外科瘢痕疙瘩患者（均获得患者或其家属同意）。②实验过程及分组：将瘢痕疙瘩成纤维细胞应用脂质体法将针对细胞周期蛋白D1基因的小干扰RNA分子转染为实验组，细胞用等量脂质体处理为脂质体组，未处理组作为对照。③实验评估：于转染后24，48，72 h，光学显微镜观察细胞形态变化；流式细胞术分析细胞周期；MTT法检测成纤维细胞的活性并绘制细胞生长曲线。 结果：①转染特异性小干扰RNA后，细胞形态发生了异常改变，细胞由正常的长梭形变为圆形或椭圆形，提示可能是凋亡或坏死细胞。②转染后细胞周期G1期延长，S期缩短。转染特异性小干扰RNA 24，48，72 h后G1期细胞高于未处理组（依次为60.13%，66.22%，67.53%，54.53%）；S期细胞低于未处理组（依次为18.25%，17.11%，11.15%，22.31%），表明细胞阻滞在G1期，进入S期细胞减少。 ③小干扰RNA-细胞周期蛋白D1转染后MTT法检测瘢痕疙瘩成纤维细胞增值明显受到抑制，细胞生长曲线图表明，转染特异性小干扰RNA组细胞生长明显减缓。 结论：特异性小干扰RNA分子能够抑制细胞周期蛋白D1基因的表达，使细胞阻滞于G1期，并诱导细胞凋亡。     

LncRNA-UCA1对MMP2/MMP9对脑胶质瘤细胞生物学行为的影响

目的探讨长链非编码RNA-尿路上皮癌相关蛋白1(LncRNA-UCA1)对基质金属蛋白酶2/基质金属蛋白酶9(MMP2/MMP9)对脑胶质瘤细胞生物学行为的影响。方法选择人脑胶质细胞瘤U251细胞并分为空白对照组、阴性对照组、UCA1干扰组,培养48 h后进行后续实验;实时荧光定量PCR(qRT-PCR)检测各组细胞LncRNA-UCA1表达水平;细胞增殖-毒性检测试剂盒(CCK8)和流式细胞术检测细胞增殖、凋亡水平;划痕实验和细胞侵袭实验(transwell)检测细胞迁移、侵袭能力;qRTPCR检测MMP2/MMP9 mRNA表达水平;蛋白质印迹检测MMP2/MMP9蛋白表达。结果两UCA1表达水平在空白对照组、阴性对照组和UCA1干扰组中分别为(1.00±0.06)、(1.01±0.07)和(0.54±0.09),UCA1干扰组UCA1表达水平显著低于空白对照组和阴性对照组(F=40.304,P 0.05)。干扰UCA1表达后U251细胞增殖水平、迁移和侵袭能力均受到显著抑制,而U251细胞凋亡水平显著升高(P 0.05);干扰UCA1表达可降低U251细胞MMP2、MMP9基因蛋白及mRNA表达水平(P 0.05)。结论干扰UCA1的表达可能通过抑制MMP2、MMP9基因的表达抑制U251细胞增殖、侵袭和迁移,并促进U251细胞凋亡。     

RNAi沉默Gli1基因对人胶质瘤细胞U251增殖与凋亡的影响

目的 研究RNA干扰技术(RNAi)沉默Hedgehog(Hh)信号转导途径中核心转录因子Gli1基因表达后对U251细胞增殖与凋亡以及下游因子Bcl-2、Bax、cycin D1表达的影响。 方法 合成、转染4对针对Gli1 mRNA不同位点序列的siRNA (58、59、60、61)至人胶质瘤U251细胞,RT-PCR检测细胞Gli1 mRNA的表达,筛选最有效抑制Gli1 mRNA表达的siRNA干扰片段(siRNA-Gli1);RT-PCR、Western blotting分别检测转染SiRNA-Gli后不同时间U251细胞Gli1mRNA和蛋白的表达,确定转染干扰的时间规律;实验分为3组：siRNA-Gli1组（转染筛选后siRNA-Gli1片断）、siRNA-NC组（转染阴性对照siRNA片断）、siRNA-N组（空白对照）。RT-PCR、Western blotting分别检测各组转染48 h后U251细胞cyclin D1、Bcl-2及Bax mRN和蛋白的表达,MTT、流式细胞术分别检测细胞增殖、凋亡及细胞周期的变化。 结果 干扰片断58、59、60、61、NC的转染效率均达69.2％;RT-PCR检测显示转染后48 h U251-60细胞无明显Gli1 mRNA表达,选择60作为最佳干扰片段siRNA-Gli1转染U251细胞,48h时无明显Gli1 mRNA和蛋白表达,确定48 h为转染干扰的最佳时间;转染48 h后与siRNA-N和siRNA-NC组相比,siRNA-Gli1组U251细胞Bcl-2、cyclin D1 mRNA和蛋白表达下调、Bax mRNA和蛋白上调,差异均有统计学意义(P＜0.05)。MTT检测显示24、48和72 h时siRNA-Gli1组细胞增殖抑制率均明显高于siRNA-NC和siRNA-N组,差异均有统计学意义(P＜0.05)。流式细胞术结果显示siRNA-Gli1组细胞凋亡率高于siRNA-NC和siRNA-N组,差异有统计学意义(P＜0.05),且siRNA-Gli1组G1/G0期细胞比例增加,S期细胞明显减少。 结论 针对Gli1基因设计合成的siRNA-Gli1能明显抑制人胶质瘤U251细胞生长并能诱导其凋亡,其机制可能与下调cyclin D1、Bcl-2的表达,上调Bax的表达有关。     

靶向PTTG1基因的微小RNA转染后诱导人脑胶质瘤细胞凋亡的研究

目的 构建表达靶向抑制垂体瘤转化基因1 (PTTG1)基因表达的RNA干扰载体microRNA,导入人脑胶质瘤细胞株U251中,研究靶向抑制PTTG1基因对U251细胞的凋亡诱导作用.方法 以PTG1为靶基因,根据pcDNATM6.2-GW/EmGFP-miR载体要求,设计针对PTIG1的microRNA序列,脂质体转染法将重组质粒转入U251细胞,采用荧光定量多聚酶链反应(PCR)以及Western blot分别从mRNA和蛋白水平检测干扰效果;膜联蛋白Ⅴ与碘化丙啶(annexinⅤ/PI)双色标记的流式细胞仪法检测microRNA诱导的细胞凋亡,碘化丙锭(PI)染色检测细胞周期阻滞.结果 实时荧光定量PCR以及Western blot检测显示,PTTG1基因的mRNA转录水平以及蛋白水平的表达均得到显著抑制;转染后,流式细胞仪检测分析显示,PTTG1基因表达被抑制后,U251细胞凋亡率明显增高,细胞周期出现明显的G2/M阻滞.结论 靶向PTTG1基因的重组microRNA干扰载体pcDNA6.2-GW/EmGFP-miR-PTTG1介导的RNAi显著靶向抑制了PTTG1基因在人脑胶质瘤细胞中的表达,并明显地诱导了脑胶质瘤细胞发生凋亡和G2/M期细胞周期阻滞.     

Adult GM1 gangliosidosis--biochemical studies--1]

To address the pathogenesis of GM1 gangliosidosis, especially adult form, intracellular signal transduction pathway of EGF in skin fibroblasts from patients with this disorder was examined. For this purpose, skin fibroblasts from 2 different patients with adult form of the disorder and from 4 different normal controls were used. The results showed that 1) EGF-receptor autophosphorylation was diminished in skin fibroblasts from patients with altered time course of phosphorylation-dephosphorylation reaction. 2) The amount of EGF-receptor protein was decreased in cells from patients compared with that of controls. 3) 125I-EGF binding + internalization studies revealed decreased rate of EGF binding and internalization in patient cells. 4) Ribosomal S6 protein phosphorylation was strongly enhanced in naive cells from patients, but the reactivity to EGF was diminished compared with control cells. These data strongly suggest that patient fibroblasts have abnormalities in the intracellular signal transduction pathway of EGF. This paper is considered to be the first report demonstrating abnormalities in EGF-signal transducing system in human disorders.     

CYP1A1 and GSTM1/T1 Genetic Variation in Predicting Risk for Cerebral Infarction

Cytochrome P450 1A1 (CYP1A1) is involved in the production of arachidonic acid-derived vasoactive substance. We hypothesized that CYP1A1 polymorphism might be related to pathological conditions associated with cerebral infarction (CI). We investigated the effect of genetic polymorphism in the 3′-flanking region (T6235C) of CYP1A1 gene in 353 patients with CI and 376 controls. The distributions of T6235C CYP1A1 genotypes in patients with (TT: 36.0%; TC/CT: 64.0%; n = 353) and without CI (TT: 44.7%; TC/CT: 55.3%; n = 376) indicate that the C allele is associated with CI (P = 0.017, odds ratio (O.R.) = 1.44; 95% confidence interval (C. I.) = 1.07–1.94). Furthermore, we examined whether the glutathione S-transferase (GST) gene, which is one of detoxification enzyme, influence the risk of CI. GST M1 null genotype increased the relative risk for the CI in the subjects with the CYP1A1 C allele (P = 0.015, O.R. = 1.47; C. I. = 1.08–2.00). We conclude that T6235C CYP1A1 polymorphism is a risk factor for the development of CI and suggest that GST polymorphism contribute to the odds of CI.     

DRB1*1502-DQB1*0601-DQA1*0103 and DRB1*04-DQB1*0302 in Jewish hypersomnolent patients

OBJECTIVES: Narcolepsy is a sleep disorder with a genetic association with the haplotype DRB1*1501, DQA1*0102, DQB1*0602. This haplotype has been described in different ethnic groups suffering from narcolepsy (Japanese, Caucasian, African Americans, Jews). In a recent study we have found the haplotype DRB1*1502, DQB1*0601, DQA1*0103 in three patients with hypersomnolence. The similarity of this haplotype to the narcoleptic haplotype DRB1*1501, DQB1*0602 and DQA1*0102 has raised the question of whether this haplotype is a marker for sleepiness, or rather indicates a variant of non-cataplectic narcolepsy. This study was conducted to further investigate this question. METHODS: HLA-DNA analysis was carried out in 20 healthy Jewish patients (age 23.9+/-6.3 years; 13 Ashkenazi, seven non-Ashkenazi) who had objective measures of hypersomnolence. All underwent whole-night polysomnography, multiple sleep latency test and tissue typing. RESULTS: HLA-DNA analysis revealed HLA-DR2 in eight patients of whom five (25%) carried the haplotype DRB1*1502, DQB1*0601, DQA1*0103 (vs. 1.4% in the Israeli population, P<0.0001). Six patients were diagnosed as non-cataplectic narcoleptics. Five of them carried the haplotype DRB1*1502, DQB1*0601, DQA1*0103. Forty percent of the patients carried the haplotype DRB1*04, DQB1*0302, which was not statistically different from its prevalence in the healthy Israeli population (25%). CONCLUSIONS: This is the first report describing the haplotype DRB1*1502, DQB1*0601, DQA1*0103 in narcoleptic patients (non-cataplectic). This haplotype is close but different from the already known narcoleptic haplotype DRB1*1501, DQA1*0102, DQB1*0602. We assume that this haplotype represents a variant of non-cataplectic narcolepsy rather than association with hypersomnolence. However, in order to conclude whether this haplotype is a marker for the lack of cataplexy, or represents a variant of non-cataplectic narcolepsy, a larger group of patients should be investigated.     

IL-1Rrp2 expression and IL-1F9 (IL-1H1) actions in brain cells

The recently discovered IL-1F9 (IL-1H1) is a putative member of the interleukin (IL)-1 family of cytokines that has been shown to activate nuclear factor-kappa B (NFkappaB) in Jurkat cells transfected with the orphan receptor IL-1 receptor-related protein (IL-1Rrp)2. The aim of the present study was therefore to investigate expression of IL-1Rrp2 and to determine if IL-1F9 induces known IL-1 signaling pathways in the different cell types of the mouse brain in culture. Messenger RNA for IL-1Rrp2 was not detected in primary neurones by RT-PCR, but significant constitutive expression was found in mixed glial cells, particularly in astrocytes and microglia, which was strongly decreased by exposure to bacterial lipopolysaccharide (LPS). LPS induced the release of IL-6, and activated NFkappaB and the mitogen-activated protein kinases (MAPKs) p38, extracellular signal-regulated protein kinase (ERK1/2) and c-Jun N-terminal kinase (JNK) in microglial cultures. IL-1beta induced release of IL-6 and activated NFkappaB, p38, JNK and ERK1/2 in mixed glial cultures, which was completely abolished in the presence of IL-1 receptor antagonist (IL-1ra). When injected intracerebroventrically in the rat, IL-1beta increased core body temperature, and reduced body weight and food intake. In contrast, IL-1F9 failed to induce any of these responses either in vivo or in vitro. These results demonstrate that glial cells may be a target for the new ligand IL-1F9, since high expression of IL-1Rrp2 mRNA was detected in these cells. However, IL-1F9 failed to induce any of the classical IL-1beta responses, suggesting that it may trigger alternative pathway(s).     

Polycystin-1 can interact with homer 1/Vesl-1 in postnatal hippocampal neurons

Polycystin-1 (PC-1) has been identified as critical to development of the nervous system, but the significance of PC-1 expression in neurons remains undefined, and little is known of its roles outside the kidney, where mutation results in autosomal dominant polycystic kidney disease (ADPKD). In kidney, PC-1 interacts with cadherins, catenins, and its cognate calcium channel polycystin-2 (PC-2), which in turn interacts with a number of actin-regulatory proteins. Because some of the proteins that interact with PC-1 in kidney also participate in synaptic remodeling and plasticity in the hippocampus, we decided to test PC-1's potential to interact with a recently discovered type of plasticity-associated protein (homer 1a/Vesl-1S) in postnatal mouse hippocampus. Homer 1a/Vesl-1S is an activity-induced protein believed to participate in synaptic remodeling/plasticity responses to temporal lobe seizure and learning. Here we report the following. 1) PC-1 contains a homer-binding motif (PPxxF), which lies within its purported cytoplasmic domain. 2) Immunoreactivity for PC-1 (PC-1-ir) is highly colocalized with homer 1a immunoreactivity (H1a-ir) in primary cultured hippocampal neurons. 3) PC-1-ir and H1a-ir are present and appear to be colocalized in mouse hippocampus but not cortex on postnatal day 2 (P2), when higher frequencies of spontaneous activity are normal for hippocampus compared with cortex. 4) An endogenous PC-1-ir band with the correct size for the reported C-terminal G-protein-sensitive domain cleavage product of PC-1 (approximately 150 kDa) coimmunoprecipitates with endogenous homer 1/Vesl-1 proteins from mouse brain, suggesting that PC-1 can interact with homer 1/Vesl-1 proteins in postnatal hippocampal neurons.