Injury induces rapid changes in hepatocyte nuclear factor-1: DNA binding.

BACKGROUND

Transcriptional regulation in the liver plays a critical role in mediating the acute phase response to injury. The molecular mechanisms driving these transcriptional events, however, are poorly defined in vivo. The liver-specific transcription factor hepatocyte nuclear factor (HNF)-1 binds to the 5' upstream region of many acute phase genes. To explore the connection between injury and transcriptional regulatory mechanisms, we investigated the effect of injury on HNF-1 binding activity.

METHODS

Liver nuclear extracts were prepared from animals after burn or anesthetized sham burn injury. HNF-1 binding activity, affinity, and off rate were assessed by electrophoretic mobility shift analysis.

RESULTS

HNF-1 binding activity decreased by 28% 1 1/2 hours after injury. The dissociation constant for HNF-1 increased from 0.6 nm to 11.8 nm at 1 1/2 hours after burn injury partly because of an increase in off rate for the HNF-1: DNA complex.

CONCLUSIONS

Burn injury leads to a significant decrease in HNF-1 binding activity as a result of decreased affinity of HNF-1 for DNA. These injury-induced alterations in binding of a liver-specific transcription factor for its DNA binding site represent a mechanism for rapidly modulating acute phase gene transcription in vivo.