Liu Rushi

Identification of target genes of transcription factor activator protein 2 gamma in breast cancer cells

BackgroundActivator protein 2 gamma (AP-2γ) is a member of the transcription factor activator protein-2 (AP-2) family, which is developmentally regulated and plays a role in human neoplasia. AP-2γ has been found to be overexpressed in most breast cancers, and have a dual role to inhibit tumor initiation and promote tumor progression afterwards during mammary tumorigensis.MethodsTo identify the gene targets that mediate its effects, we performed chromatin immunoprecipitation (ChIP) to isolate AP-2γ binding sites on genomic DNA from human breast cancer cell line MDA-MB-453.Results20 novel DNA fragments proximal to potential AP-2γ targets were obtained. They are categorized into functional groups of carcinogenesis, metabolism and others. A combination of sequence analysis, reporter gene assays, quantitative real-time PCR, electrophoretic gel mobility shift assays and immunoblot analysis further confirmed the four AP-2γ target genes in carcinogenesis group: ErbB2, CDH2, HPSE and IGSF11. Our results were consistent with the previous reports that ErbB2 was the target gene of AP-2γ. Decreased expression and overexpression of AP-2γ in human breast cancer cells significantly altered the expression of these four genes, indicating that AP-2γ directly regulates them.ConclusionThis suggested that AP-2γ can coordinate the expression of a network of genes, involving in carcinogenesis, especially in breast cancer. They could serve as therapeutic targets against breast cancers in the future.

Observation of chloroplast ultrastructure of zebra leaf in rice mutant B411.

采用透射电镜技术,对水稻突变体B411＂斑马叶＂出现过程中叶片的叶绿体超微结构进行了研究。结果表明,在叶片包于叶鞘内的心叶期,叶片绿区叶绿体呈纺锤形,类囊体片层纵向整齐排列;黄区叶绿体呈不规则椭圆形,类囊体片层排列不规则。在叶片抽出叶鞘1d的嫩叶期,叶片绿区叶绿体类囊体片层增多并垛叠形成基粒结构,它们沿长轴整齐排列;黄区叶绿体类囊体膜断裂,片断化。在成熟期,叶片绿区叶绿体类囊体片层变得丰富和形成许多基粒结构;叶片黄区叶绿体内部结构严重解体,整个叶绿体呈高电子密度的囊泡状结构。在复绿期,叶片黄区逐渐变成绿色,叶绿体结构恢复正常,类囊体膜系统重建,且有序地沿叶绿体长轴方向排列,在基质中形成淀粉粒,表明其光合能力恢复。