FAILED COMPENSATORY HEPATIC REGENERATION PARALLELS E2F-1 ACTIVATION IN LATE SEPSIS

Abstract

Objective: E2F-1 is a well-known transcription factor responsible for regulating cell proliferation. Inturn, E2F is regulated by the retinoblastoma protein (pRB). Previous work in our lab suggests that failed compensatory regeneration parallels mortality in a fulminant murine sepsis model. Since hepatocellular regeneration in sepsis has not been well defined, we hypothesize that dysfunctional phosphophorylated pRB (PpRB)/ E2F-1 signaling may be responsible for the sepsis-induced impairment of compensatory regeneration. Methods: 6-8 w/o C57 B1/6 mice underwent cecal ligation and double puncture (2CLP). Sham operated (SO) and unoperated mice (T0) served as controls. Livers were harvested at 3,6,16,24,48 and 72 hours after SO/2CLP and the nuclear protein fractions were isolated. Electromobility shift assays (EMSA) and immunoblots were used to evaluate E2F-1 binding activity and nuclear abundance of E2F-1 and P-pRb. Results: P-pRb and E2F-1 nuclear protein levels were markedly decreased at 48 and 72 hours after 2CLP compared to T0 and SO controls. Although there was an increase in E2F-1 DNA binding activity at 48 hours post 2 CLP binding was undetectable at 72 hours. Conclusions: Although the pathologic significance of failed hepatic regeneration remains unknown, it may be important in the recovery from sepsis. Our findings suggest that failed E2F-1 activation may limit compensatory regeneration in fulminant sepsis.