1. Cholangiocyte-specific Cre- recombinase transgenic mouse Arthur Kaser Dept of Medicine II Innsbruck Medical University

2. Background Conventional knock-outs ▫Can be embryonically lethal ▫Can‘t resolve divergent roles of single genes in different cell types  Hepatocytes  Cholangiocytes  Immune cells

3. Cre/loxP technology Allows specific deletion of genes in a living organism Cre recombinase recognizes specific ‚loxP‘ sequence......excises the DNA in-between two loxP sites and recombines the flanking stretches of DNA

4. Conditional Gene deletion Gene flox Gene flox.Cre Promoter Gene loxP

5. Cre trangenic lines >100 Cre transgenic mice reported so far Not a single one with reasonable specificity for cholangiocytes ▫Indirect approaches ▫Concomitant deletions in other organs/cell types

6. Process Identification of a cholangiocyte-specific promoter ▫Candidate genes ▫Bio-informatic analysis of cholangiocyte cell lines and primary cholangiocytes In vivo evaluation of promoter specificity ▫αGal-reporter mice ▫Cre-reporter mice Generation of Cre-ER T2 mice under this promoter Intercrossing with mice expressing the floxed gene of interest

7. Issues Fundamental ▫Can a cholangiocyte-specific promoter be identified? ▫Target large or small cholangiocytes, or both? Technical ▫How many reporter mice shall be generated? ▫Where shall those be generated?  Commercial vendors  Academic group(s) ▫Sharing policy

8. Implications Potential for in vivo dissection of mechanisms of disease Insight into novel loci identified through GWAS

9. Precedence of transformative insight gained from using Cre/loxP technology