Feb 2009 The Tsix/Xist-deficient Strains Models for Epigenetics Study


The Tsix/Xist-deficient Strains
Models for Epigenetics Study

B6.Cg-Xisttm2Sado (Xist1loxGFP) RBRC 01260
B6.Cg-Tsixtm1Sado (TsixdeltaSA) RBRC 01949
B6.Cg-Xisttm1SadoTsixtm1Enl (Xist1lox TsixAA2delta1.7) RBRC 01950
B6.Cg-Tsix/Xisttm3Sado (XistpA) RBRC 02653
B6.Cg-Xisttm4Sado (XistIVS19) RBRC 02654
B6.Cg-Xisttm5Sado (XistdeltaA) RBRC 02655
Tsix : X (inactive)-specific transcript, antisense gene on Chr X
Xist : inactive X specific transcripts gene on Chr X


Xist1loxGFP mice RBRC 01260


mn0902_0102 mn0902_0103   In mammals, females have twice as many copies of genes on X chromosome as males do and develop a mechanism to equalize dosage of X-linked gene products by inactivating one of two X chromosomes (Lyon, 1961).
The X-inactivation, also known as Lyonization, is regulated by the noncoding Xist gene and its antisense non-coding Tsix gene on Chr X (Sado et al., 2001).
The targeted disruption of the Xist gene demonstrated that the expression of the Xist gene is essential to initiate inactivating X chromosome in cis (Marahrens et al., 1997; Penny et al., 1996).
The expression of the Xist gene was shown to be suppressed by the Tsix gene through modifications of chromatin structure (Sado et al., 2005).
These strains provide unique and useful models to study the mechanism of X-inactivation in mammals and biological functions of noncoding RNA (Table 1).
(↑) Female embryos carrying mutated Xist1lox allele derived from the father died soon after implantation due to a dysplasia of extra-embryonic tissues. (←) Normal embryos. scale bar = 200μm.


Depositor :  Dr. Takashi Sado, Division of Human Genetics, National Institute of Genetics
References : [1]  Lyon M.F. 1961. Gene action in the X-chromosome of the mouse (Mus musculus L.).
Nature 190: 372-373.
[2] Marahrens Y., Panning B., Dausman J., Strauss W., Jaenisch R., 1997. Xist-deficient mice are defective in dosage compensation but not spermatogenesis.Genes Dev 11 (2): 156-166.
[3] Penny G.D., Kay G.F., Sheardown S.A., Rastan S., Brockdorff N. 1996. Requirement for Xistin X chromosome inactivation. Nature 379 (6561): 131-137.
[4] Sado, T., Hoki, Y., and Sasaki, H. 2005. Tsix silences Xist through modification of chromatin structure. Dev Cell 9: 159-165.
[5] Sado T., Wang Z., Sasaki H., Li E. 2001. Regulation of imprinted X-chromosome inactivation in mice by TsixDevelopment 128 (8): 1275-1286.

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