Patterns of RNA and Protein Synthesis in Post-Ischemic Livers

Abstract

The re-establishment of the blood supply to a formerly ischemic liver lobe, before the "point of no return" of the tissue is reached, induces a series of changes in protein and RNA metabolism that are functional to the repair of the damage suffered by the cells. Among these events there is the increase in synthesis of a group of proteins known as heat-shock (or stress) proteins, which are also induced in liver cells by different kinds of oxidative stress. The increase in synthesis of these proteins is largely due to the activation of their genes: some of these genes are also activated in cells stimulated to grow. These observations suggest a link between oxidative stress, repair of cell damage and cell multiplication.

Differential activation of some transcription factors during rat liver ischemia, reperfusion, and heat shock

“…The behavior of the constitutively expressed liverspecific TF HNF-1, which shows decreased binding during the late period of ischemia and early period of reperfusion and seems to recover slowly in the postischemic liver, can be explained by the injurious events occurring in the liver cell as were described in our previous studies (Bassi and Bernelli-Zazzera, 1964;Bernelli-Zazzera, 1989;Bernelli-Zazzera and Gaja, 1964;Cajone et al, 1971;Gaja et al, 1973).…”

“…An important regulatory mechanism allowing cells to respond to environmental changes is the activation of transcription and the induction of definite genes. One of the most prominent responses to postischemic reperfusion in the liver is the induction of stress (heat shock) genes, in particular of the hsp 70 gene (Cairo et al, 1985;Fujio et al, 1987;Bernelli-Zazzera, 1989;Schiaffonati et al, 1990;Tacchini et al, 1993). The process of transcription is the first stage of gene expres-resulting in the production of a primary RNA transcript from the DNA of a particular gene.…”