ENGINEERING OF p65(-1)-/- KNOCK-IN MOUSE, A NEW ALTERNATIVE SPLICED ISOFORM OF p65, A PROTEIN OF NF-KB COMPLEX.

NF-kB is defined by a family of structurally related transcription factors that in mammals includes RelA (p65), c-Rel, RelB, p50 (NFKB1) and p52 (NFKB2). NF-kB regulates many biological process, including inflammation, immunoregulation, apoptosis, neuronal function, cell growth and transportation, and cell proliferation. (1). NF-kBs are defined by an highly conserved amino acid domain, named Rel Homology Domain (RHD), responsible for dimerization, binding with inhibitors (IkB), nuclear translocation and DNA-binding domains (2). We have discovered both in mouse and human a new splicing isoform of p65, named p65(-1) (3). p65(-1) contains an unknown exon (named exon -1) located upstream to the first known exon of Rel A, coding to p65. Transcription of the exon -1 leads to an alternative splicing between exon -1 and exon 1, thus skipping exon 0. As consequence of this alternative splicing, p65(-1) lacks some amino acid residues belonging to the RHD. Our results show that p65(-1), compared to p65, has different biochemical properties in some cellular mechanism like transcriptional activity on kB consensus, apoptosis and regulation of the glucocorticoid receptor (GR) activation (4). In order to better understand the biological property of this new isoform, we are engineering a Knock In p65 (-1)-/- mouse. Here we propose our rationale and results for the specific construct.