NOR‐2 (neuron‐derived orphan receptor), a brain zinc finger protein, is highly induced during liver regeneration

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Abstract
Zinc‐finger proteins are involved in several cellular processes. Some of these proteins are implicated in the primary cellular response in regenerating liver and mitogen‐stimulated cells. Using a rat cDNA brain library, we have isolated a clone designated NOR‐2, encoding a protein containing two zinc‐finger motifs and whose expression is highly induced during G0/G1 transition. We analysed the expression of NOR‐2 mRNAs during early growth in regenerating liver and in both insulin‐stimulated H4‐II cells and pheochromocytoma‐derived cell line PC12 treated by NGF. In these systems, there is an early, rapid and transient accumulation of NOR‐2 mRNAs. The induction of NOR‐2 mRNAs does not require de novo protein synthesis, since it is not prevented by cycloheximide treatment. Mobility shift assays show that NOR‐2 protein binds to NBRE, a target sequence for r‐NGFI‐B family. Structurally, NOR‐2 is closely related to the recently identified NOR‐1 factor. Therefore, like NOR‐1, NOR‐2 belongs to the r‐NGFI‐B sub‐family of nuclear receptors superfamily.