Production of Nurr-1 Specific Polyclonal Antibodies Free of Cross-reactivity Against Its Close Homologs, Nor1 and Nur77.

The nuclear receptor subfamily 4 (NR4A) is composed of 3 related proteins sharing a DNA binding domain (DBD) and a ligand-binding domain (LBD). The nuclear receptor related 1 protein (Nurr1 or NR4A2) plays a key role in the maintenance of the dopaminergic system. Dopamine dysfunctions associated with the Nurr1 gene include Parkinson's disease, schizophrenia and manic depression among others. Furthermore, recent evidence indicates that Nurr1 is also expressed in other brain areas such as the hippocampus and plays critical roles for learning and memory. The other members of the family are nerve growth factor IB (Nur77 or NR4A1) and neuron-derived orphan receptor 1 (NOR1 or NR4A3). To help investigate the precise functional roles of Nurr1 in dopaminergic and other brain region-related neuronal dysfunctions antibodies devoid of cross-reactivities against Nur77 and NOR1 were needed. Since the proteins are more divergent in their LBDs than in their DNA binding domains immunization with purified LBDs should yield antibodies specific for Nurr1 with minimal reactivities against Nur77 and/or NOR1. Although anti-Nurr1 antibodies were successfully generated these showed significant immunoreactivity against the other members of the family. Affinity chromatography over immobilized Protein A followed by pre-adsorption against immobilized Nur77 and NOR1 LBDs yielded Nurr1 specific antibodies free of cross-reactivity. Here, we selectively target antibodies against a specific member of a highly conserved family of proteins by immunizing animals with their most divergent regions followed by removing cross reactive antibodies by pre-adsorption. The goal of the protocol is to increase polyclonal antibodies specificity through pre-adsorption against cross-reactive antigens.