Lpsd/Ran of endotoxin-resistant C3H/HeJ mice is defective in mediating lipopolysaccharide endotoxin responses

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Abstract
C3H/HeJ inbred mice are defective in that they are highly resistant to endotoxic shock as compared with normal responder mice. Their B cells and macrophages do not respond significantly when exposed to lipopolysaccharide (LPS), whereas cells from the responder mice do. Using a functional assay, we previously isolated a cDNA, which encodes for Ran/TC4 GTPase. We now show that this gene is mutated in C3H/HeJ mice, which accounts for their resistance to endotoxin stimulation. Sequence analysis of independent mutant Lpsd/Ran cDNAs isolated from splenic B cells of C3H/HeJ mice reveals a consistent single base substitution at position 870, where a thymidine is replaced with a cytidine.In situhybridization maps the Lpsd/Ran cDNA to mouse chromosome 4. By retroviral gene transfer, the wild-type Lpsn/Ran cDNA but not the mutant Lpsd/Ran cDNA can restore LPS responsiveness of C3H/HeJ cells. Adenoviral gene transferin vivowith the mutant Lpsd/Ran cDNA but not the wild-type Lpsn/Ran cDNA rescues endotoxin-sensitive mice from septic shock. Thus Lps/Ran is an important target for LPS-mediated signal transduction, and theLpsd/Rangene may be useful as a therapeutic sequence in gene therapy for endotoxemia and septic shock.