分子生物学分子生物学 (36).pdf

《分子生物学分子生物学 (36).pdf》由会员分享，可在线阅读，更多相关《分子生物学分子生物学 (36).pdf（12页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、 Chapter 13 Gene Therapy 13.4 The controlled expression of therapeutic genes The controlled expression of therapeutic genes mainly involves three aspects:the temporal,spatial(cell or tissue types)and quantitative control of therapeutic gene expression commonly used strategies:innate and adopted mech

2、anisms of gene expression regulation and taking advantage of focal microenvironmental factors Inherent regulatory elements within a gene including promoters,enhancers and so on,which comes from either normal cells,e.g.tyrosinase genes,or disease cells,e.g.,alpha-fetoprotein(AFP)gene.13.4.1 Direct us

3、e of endogeneous mechanisms of gene expression regulation 13.4.2 Adoption of conditionally established regulational mechanisms e.g.by adopting the promoter of HSP70 protein gene in the therapeutic gene,enhanced post-transfer expression could be obtained by applying external stimuli,such as heat trea

4、tment or ionizing radiation to the local part of the lesion.13.4.3 Making use of focal microenvironmental factors to urge or induce the therapeutic gene to express Using particular microenvironmen factors of the lesion different from normal conditions to control the therapeutic gene expression e.g.T

5、umor tissue often appears glucose deficiency or hypoxia as well as other changes in cellular microenvironment.Special inflammatory tissue microenvironment,etc.13.4.4 Induced expression of therapeutic genes Inducible gene expression system Composition:transcriptional activator whose binding activity

6、to DNA is controlled by some inducible drug specific gene expression regulatory element that responds only to this transcriptional activator Principle of tetracycline resistance operon Transcription of tetracycline resistance genes is negatively regulated by Tet repressor proteins.In the absence of

7、tetracycline,the expression of tetracycline resistance gene was blocked by the combination of repressor protein to tetracycline resistance operon sequence.In the presence of tetracycline,the repressor protein turned to combine with the latter due to an extremely high affinity with it,thus resulting

8、in the unoccupied operon sequence,available for the binding of RNA polymerase leading to downstream transcriptional events.。Tet-Off system.Tet controlled transcriptional activators(tTA)are fusions of wild-type Tet repressor proteins(TetR)and one activator protein(AD).Tet-On system.Four amino acid changes in the TetR turn its binding property to be in the inverted direction(rTetR).Review：1.What are the main content of the controlled therapeutic gene expression?2.Retell the examples given to illustrate the applications of controlled gene expression in gene therapy.