Mice with targeted disruption of p8 gene show increased sensitivity to lipopolysaccharide and DNA microarray analysis of livers reveals an aberrant gene expression response.
BACKGROUND
p8 is a DNA-binding protein induced in many tissues in response to LPS treatment. Hence, p8 could be a mediator of LPS-associated effects or, on the contrary, p8 expression may be part of the protective mechanism of the tissues in response to LPS. Finally, p8 expression in response to LPS could also be a simple epiphenomenon.


METHODS
To investigate the role of p8 in vivo, we generated p8-deficient mice by gene targeting. Because p8 is a stress protein, we analyzed the response of p8-/- mice to a systemic stress induced by LPS injection. Liver was chosen as model organ to monitor alterations in gene expression.


RESULTS
LPS resulted in higher serum TNF-alpha concentration and higher mortality rate in p8-deficient mice than in wild-type. Also, liver and pancreas, but not lung, from p8-/- mice showed increased amounts of MPO and HPO. To gain insight into the molecular bases of such susceptibility, we used high density DNA microarrays consisting of ~6000 genes and ESTs to compare gene regulation in response to LPS in p8+/+ and p8-/- livers. In wild-type, 105 genes and 73 ESTs were up-regulated and 232 genes and 138 ESTs down-regulated. By contrast, 212 genes and 125 ESTs were found up-regulated and 90 genes and 85 ESTs down regulated in p8-/- mice. Among them, only 93 (51 induced and 42 repressed) corresponded to the wild-type pattern, demonstrating that p8 deficiency hinders the normal response to LPS, which may account for the increased sensitivity of p8-/-mice to the endotoxin.


CONCLUSIONS
The large number of genes showing abnormal regulation after LPS suggests that p8 is an important regulatory factor involved in many cellular defence pathways.
Vasseur
Sophie
S
Centre de Recherche INSERM, EMI 0116, 163 Avenue de Luminy, 13009 Marseille, France. vasseur@marseille.inserm.fr
Hoffmeister
Albrecht
A
Garcia-Montero
Andrés
A
Barthet
Marc
M
Saint-Michel
Laure
L
Berthézène
Patrice
P
Fiedler
Fritz
F
Closa
Daniel
D
Dagorn
Jean Charles
JC
Iovanna
Juan Lucio
JL
D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects* / Q000235:genetics; D024243:HMGB1 Protein / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D020411:Oligonucleotide Array Sequence Analysis; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D013312:Stress, Physiological / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D004268:DNA-Binding Proteins; D024243:HMGB1 Protein; D008070:Lipopolysaccharides; D009363:Neoplasm Proteins; C491644:Nupr1 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; D009195:Peroxidase