Homozygous Usp18 (or Ubp43) mutant mice on the FVB/N genetic background are viable and fertile, exhibiting none of the severe neurologic disorders that lead to embryonic lethality or early death reported for Ubp43-deficient mice on a C57BL/6 or mixed B6;129 genetic background. In contrast to wildtype mice, thymi from homozygous mice injected with LPS exhibit no protein from the targeted gene. Expression of the lacZ cassette is observed in both heterozygous and homozygous brain tissues. Homozygous mice are hypersensitive to type I interferon (IFN) and undergo apoptosis upon IFN stimulation. Ubp43-deficiency results in enhanced and prolonged STAT1 phosphorylation, DNA binding, and increased induction of hundreds of interferon stimulated genes (ISGs). Homozygous mice exhibit greater resistance to the cytopathic effects caused by a number of viruses (including lymphocytic choriomeningitis virus (LCMV), vesicular stomatitis virus (VSV), and Sindbis virus (SNV)). Ubp43-deficient cells exhibit high levels of ISG15 modified proteins. These Usp18 (or Ubp43)-mutant mice may be useful in studying interferons and their receptors, cellular function, signal transduction, and the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway.
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. 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.
