Mice homozygous for this targeted mutation die in utero, apparently from a failure to produce erythrocytes in the liver, demonstrating that the endogenous gene is essential for normal development. Heterozygous mice, which are analogous to human carrier individuals, do not develop retinal tumors, but do develop pituitary tumors by 8 months of age.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for this strain. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
This mutant strain was developed in the laboratory of Dr. Tyler Jacks at the Center for Cancer Research at the Massachusetts Institute of Technology. The 129-derived D3 ES cell line was used. This strain was made by backcrossing mutant mice to C3H/HeOuJ. As of February 1996 this strain had been backcrossed five times (N5). In 1999 it had been backcrossed to C3H/HeOuJ for 10 generations.
|Allele Name||targeted mutation 1, Tyler Jacks|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||pRb-; Rb-; Rbx3t; Rb1-|
|Gene Symbol and Name||Rb1, RB transcriptional corepressor 1|
|Strain of Origin||129S2/SvPas|
|General Note||This is one of several targeted null mutations of Rb1 that have been created. Results appear to be similar for all the mutations (J:2498, J:2511, J:2516). Heterozygotes for the mutations show no predisposition to retinoblastoma. Homozygotes die in utero with neuronal and hematopoietic system abnormalities. Transfer of a human RB1 mini-transgene into the mutant mice corrects the defects (J:2516). On the other hand, transfer of the human gene into mice with a normal Rb1 genotype, causing overexpression of the gene product, produces mice dwarfed in proportion to the number of extra RB1 copies they carry (J:15042).Homozygous Rb1tm1Tyj mutant mice given a transgene producing low levels of Rb1 product survive to birth, but die at that stage due to failure of myogenesis. Myoblasts undergo massive apoptosis, and surviving cells do not undergo terminal differentiation (J:37145).|
|Molecular Note||A PGK-neomycin resistance cassette replaced part of intron 3 and introduced three nucleotide changes into exon 3, creating two termination codons and a new PstI site. The authors predict translation of a truncated protein by the mutant allele. Immunoblot analysis of E12.5 brain did not detect full length RB1 protein in homozygous mice.|
|Mutations Made By|| |
Dr. Tyler Jacks, Massachusetts Institute of Technology
The Rb1tm1Tyj strain is maintained by mating heterozygous mice to normal wildtype siblings. Heterozygous mice and normal wildtype siblings may be ordered.
When using the Rbx3t mouse strain in a publication, please cite the originating article(s) and include JAX stock #002546 in your Materials and Methods section.