Identification of a third evolutionarily conserved gene within theRAG locus and itsRAG1-dependent and -independent regulation

Abstract

Recombination-activating gene (RAG)1 and RAG2 encode T and B lymphocyte-specific endonucleases indispensable for rearrangements of antigen-receptor gene segments but also capable of causing deleterious chromosome rearrangements. The mechanisms regulating RAG expression and repression are not clear. Here we identify NWC, a third evolutionarily conserved gene within the RAG locus, and show that it is ubiquitously expressed, with the notable exception of RAG-nonexpressing immature and mature T and B lymphocytes because in lymphocytes it is regulated by the RAG1 promoter and transcribed as RAG1-NWC hybrid mRNA molecules. We also show that in all other cells NWC is controlled by the RAG2 intragenic promoter, which in immature and mature T and B lymphocytes is silent. The possible implications of these findings for understanding the activation and inactivation of RAG genes in lymphocytes and their repression in other cells are discussed.

Proceedings of the Conference “Lymphocyte Development, Tolerance and Autoimmunity: Solved and Open Questions”, Held at the Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, on May 12, 2011 (Wrocław, Poland)

“…We called this gene Nwc, which is an acronym of polish words meaning ''very interesting'' or ''nobody knows what it is good for.'' What we found interesting is that in contrast to the lymphocyte specific Rag genes, Nwc is ubiquitously expressed but in lymphocytes, it is regulated by Rag1 promoter while Nwc promoter is inactivated (Cebrat et al 2005;Cebrat et al 2008). As a result, in addition to the Rag1 transcript, hybrid Rag1/Nwc transcripts are generated.…”

“…My own interest in this area is the consequence of unexpected findings made together with my present collaborators, mainly by Małgorzata Cebrat (Cebrat et al 2005;Kisielow and Cebrat 2007). Searching for new genes downregulating expression during positive selection we identified third strongly evolutionarily conserved gene within the locus of recombination activating genes whose transcription starts in Rag2 intron and runs through the whole Rag locus control region.…”

Identification of Genes Involved in Positive Selection of CD4+8+Thymocytes: Expanding the Inventory

“…One of the identified genes, hypothetical gene AKO 0101820, turned out to be especially interesting because, as we discovered (Cebrat et al, 2005) it represents third evolutionarily conserved gene within RAG locus, which in contrast to Rag genes is ubiquitously expressed but in T and B lymphocytes is differently regulated than in all other cells. We named this gene Nwc (Cebrat et al, 2005).…”

“…Using HB10 model we identified 9 genes: Pp11r (Tcl-30), Dntt (TdT), Ptcra (pre-Tα), G22p1 (Ku-70), Tarpp ) Gfra1, Fyb-130, Rag1 and hypothetical gene AKO 0101820 (Cebrat et al, 2005). To our knowledge, only the last one had not been previously described to be down-regulated during posi tive selection.…”

An insertional mutagenesis screen identifies genes that cooperate with Mll-AF9 in a murine leukemogenesis model

“…Several candidate genes were found in our screen in Mll-AF9-positive myeloid leukemia that had not been reported before and may specifically interact with Mll-AF9 in leukemogenesis, including Gimap genes, 37 Fosb, and the novel gene B230118H07Rik in the RAG locus. 38 However, relatively few CISs were found exclusively in myeloid leukemia from Mll-AF9 mice. Therefore, we suspect that many of the CIS-associated candidate genes can contribute to myeloid leukemia initiated by Mll-AF9, and may also contribute to leukemia formation in other genetic contexts.…”