Lps(d)/Ran of endotoxin-resistant C3H/HeJ mice is defective in mediating lipopolysaccharide endotoxin responses

C3H/HeJ inbred mice are defective in that they are highly resistant to endo toxic shock as compared with normal responder mice. Their B cells and macro phages do not respond significantly when exposed to lipopolysaccharide (LPS ), whereas cells from the responder mice do. Using a functional assay, we p reviously isolated a cDNA, which encodes for Ran/TC4 GTPase. We now show th at this gene is mutated in C3H/HeJ mice, which accounts for their resistanc e to endotoxin stimulation. Sequence analysis of independent mutant Lps(d)/ Ran cDNAs isolated from splenic B cells of C3H/HeJ mice reveals a consisten t single base substitution at position 870, where a thymidine is replaced w ith a cytidine. In situ hybridization maps the Lpsd/Ran cDNA to mouse chrom osome 4. By retroviral gene transfer, the wild-type Lps(n)/Ran cDNA but not the mutant Lpsd/Ran cDNA can restore LPS responsiveness of C3H/HeJ cells, adenoviral gene transfer in viva with the mutant Lpsd/Ran cDNA but not the wild-type Lps(n)/Ran cDNA rescues endotoxin-sensitive mice from septic shoc k Thus Lps/Ran is an important target for LPS-mediated signal transduction, and the Lpsd/Ran gene may be useful as a therapeutic sequence in gene ther apy for endotoxemia and septic shock.