| 1. |
- Alvarez, Alberto, et al.
(författare)
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Tamoxifen-independent recombination of reporter genes limits lineage tracing and mosaic analysis using CreER(T2) lines
- 2020
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Ingår i: Transgenic research. - : Springer Nature. - 0962-8819 .- 1573-9368. ; 29:1, s. 53-68
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Tidskriftsartikel (refereegranskat)abstract
- The CreER(T2)/loxP system is widely used to induce conditional gene deletion in mice. One of the main advantages of the system is that Cre-mediated recombination can be controlled in time through Tamoxifen administration. This has allowed researchers to study the function of embryonic lethal genes at later developmental timepoints. In addition, CreER(T2) mouse lines are commonly used in combination with reporter genes for lineage tracing and mosaic analysis. In order for these experiments to be reliable, it is crucial that the cell labeling approach only marks the desired cell population and their progeny, as unfaithful expression of reporter genes in other cell types or even unintended labeling of the correct cell population at an undesired time point could lead to wrong conclusions. Here we report that all CreER(T2) mouse lines that we have studied exhibit a certain degree of Tamoxifen-independent, basal, Cre activity. Using Ai14 and Ai3, two commonly used fluorescent reporter genes, we show that those basal Cre activity levels are sufficient to label a significant amount of cells in a variety of tissues during embryogenesis, postnatal development and adulthood. This unintended labelling of cells imposes a serious problem for lineage tracing and mosaic analysis experiments. Importantly, however, we find that reporter constructs differ greatly in their susceptibility to basal CreER(T2) activity. While Ai14 and Ai3 easily recombine under basal CreER(T2) activity levels, mTmG and R26R-EYFP rarely become activated under these conditions and are therefore better suited for cell tracking experiments.
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| 2. |
- Bergstrom, A, et al.
(författare)
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Severe liver disease resembling PSC in mice with K5-Cre mediated deletion of Krüppel-like factor 5 (Klf5)
- 2021
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Ingår i: Transgenic research. - : Springer Science and Business Media LLC. - 1573-9368 .- 0962-8819. ; 30:5, s. 701-707
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Tidskriftsartikel (refereegranskat)abstract
- Chronic cholestatic liver diseases including primary sclerosing cholangitis (PSC) present a complex spectrum with regards to the cause, age of manifestation and histopathological features. Current treatment options are severely limited primarily due to a paucity of model systems mirroring the disease. Here, we describe the Keratin 5 (K5)-Cre; Klf5fl/fl mouse that spontaneously develops severe liver disease during the postnatal period with features resembling PSC including a prominent ductular reaction, fibrotic obliteration of the bile ducts and secondary degeneration/necrosis of liver parenchyma. Over time, there is an expansion of Sox9+ hepatocytes in the damaged livers suggestive of a hepatocyte-mediated regenerative response. We conclude that Klf5 is required for the normal function of the hepatobiliary system and that the K5-Cre; Klf5fl/fl mouse is an excellent model to probe the molecular events interlinking damage and regenerative response in the liver.
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