B6J(B6N)-Tg(Nr4a1-EGFP/cre)820Khog/PalcaJ

Stock number: 040426
Product name: C57BL/6J Nur77^GFP
Strain synonyms: C57BL/6J NUR-GFP
Research areas: Cancer Research, Cell Biology Research, Developmental Biology Research, Hematological Research, Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

C57BL/6J Nur77^GFP transgenic mice have the Nr4a1 (Nur77) promoter driving expression of a Cre recombinase/green fluorescent protein fusion protein mainly in a subset of myeloid lineage cells of the spleen. This strain is congenic on the C57BL/6J background. These mice may be useful in studying thymocyte positive- and negative-selection as well as lymphocyte activation.

Of note, this transgene is also available on an incipient congenic C57BL/6N background (~N5; Stock No. 016617), on a fully C57BL/6N congenic background (~N10+; Stock No. 018974), and on a NOD/ShiLtJ congenic background (Stock No. 037122).

Detailed description

Nur77^GFP transgenic mice, originally created by Dr. Kristin A. Hogquist (University of Minnesota), express an enhanced green fluorescent protein/codon-optimized "humanized" Cre recombinase fusion protein (eGFP-hCre) under control of the Nr4a1 (Nur77) promoter/enhancer regions within the BAC transgene. Specifically, GFP is highly expressed in a subset of myeloid lineage cells of the spleen (but not lymph node), while low levels of GFP are observed in T and B lymphocytes. GFP is up-regulated by antigen receptor stimulation in Nur77^GFP transgenic mice, but unlike the CD69 marker of T cell activation, GFP is not induced by inflammatory stimuli. Furthermore, the level of GFP expressed during acute activation reflects the strength of T cell receptor (TCR) stimulation, and the low basal level of GFP expressed in mature naïve T cells is dependent on continued interaction with MHC. Dr. Pilar Alcaide purchased some Nur77^GFP transgenic animals, on an incipient C57BL/6N background (~N5; Stock No. 016617), and backcrossed these at least 8 generations to the C57BL/6J background (Stock No. 000664).

Mice hemizygous for the C57BL/6J Nur77^GFP transgene are viable and fertile with normal lymphoid and myeloid development. Homozygous transgenic mice have not been generated by the donating laboratory. The creator of this transgene reports that Cre recombinase activity is observed in all hematopoietic cells at some point in their development (June 2011). Because GFP expression level correlates to the strength of antigen receptor signaling in Nur77^GFP transgenic mice, these mice may be useful in studying thymocyte positive- and negative-selection as well as lymphocyte activation; specifically T- and B-cell receptor (TCR and BCR) signal strength perceived by different T- and B-cell subsets during development or activation.

In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. It should be noted that the phenotype of these C57BL/6J-congenic mice could vary from that originally described on a mixed genetic background. We may modify the strain description if necessary, as published results become available.

Of note, this Nur77^GFP transgene is also available on an incipient congenic C57BL/6N background (~N5; Stock No. 016617), on a fully C57BL/6N congenic background (~N10+; Stock No. 018974), and on a NOD/ShiLtJ congenic background (Stock No. 037122).

Development

The Nur77-GFPCre BAC transgene was originally designed in the laboratory of Dr. Jennifer Punt (Haverford College), and transgenic mice were produced and evaluated by Dr. Kristin A. Hogquist (University of Minnesota). The ~170 kbp C57BL/6J mouse bacterial artificial chromosome (BAC) RP24-366J14, containing the entire Nr4a1 locus (Nur77) was obtained. An eGFP-hCre fusion protein cDNA sequence (enhanced green fluorescent protein fused to a codon-optimized "humanized" Cre to improve translational efficiency in eukaryotic cells), a frt-flanked neo cassette, and a TGA STOP codon was inserted into the ATG start site of the Nr4a1 gene on the RP24-366J14 BAC via homologous recombination/BAC recombineering. The frt-flanked neo was removed via L-arabinose treatment in EL250 BAC host cells during the BAC recombineering. A ~135 kbp fragment from the modified BAC harboring the targeted Nr4a1 locus as well as ~60 kbp sequence flanking each side of the Nr4a1 locus (including the Acvr1b, A330009N23Rik, Grasp, 9430023L20Rik and 6030408B16Rik loci) was purified and then microinjected into C57BL/6J embryos. The resulting Nur77^GFP BAC transgenic founder mice were bred with C57BL/6NCr mice. Transgenic mice from the B6-820 founder line were found with high GFP expression levels in myeloid lineage cells from spleen (but not lymph node), as well as low GFP expression levels in T and B lymphocytes. Nur77^GFP BAC transgenic mice from this founder line were bred with C57BL/6NCr wildtype mice for five generations prior to arriving at The Jackson Laboratory as Stock No. 016617.

Dr. Pilar Alcaide purchased some Stock No. 016617 transgenic animals, on an incipient C57BL/6N background, and then backcrossed them at least 8 generations to the C57BL/6J background (Stock No. 000664), before sending mice back to The Jackson Laboratory. The resulting C57BL/6J-congenic strain is called B6J.B6N-Tg(Nr4a1-EGFP/cre)820Khog/PalcaJ (Stock No. 040426). Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes.

Allele

Symbol: Tg(Nr4a1-EGFP/cre)820Khog
Name: transgene insertion 820, Kristin A Hogquist
MGI accession ID: MGI:5007644
Generation method: Transgenic
Attributes: Recombinase-expressing
Synonyms: B6-820; Nur77^GFP; Nur77-GFPCre B6-820
Marker symbol: Tg(Nr4a1-EGFP/cre)820Khog
Marker name: transgene insertion 820, Kristin A Hogquist
Chromosome: UN
Strain of origin: C57BL/6J
Expressed genes: GFP,Green Fluorescent Protein,; cre,cre recombinase,bacteriophage P1
Site of expression: GFP is highly expressed in a subset of myeloid lineage cells of the spleen (but not lymph node), while low levels of GFP are observed in T and B lymphocytes.
Molecular note: The 170 kb C57BL/6J mouse bacterial artificial chromosome (BAC) RP24-366J14, containing the entire Nr4a1 locus (Nur77) was obtained. An eGFP-hCre fusion protein cDNA sequence (enhanced green fluorescent protein fused to a codon-optimized "humanized" Cre to improve translational efficiency in eukaryotic cells), a frt-flanked neo cassette, and a TGA STOP codon was inserted into the ATG start site of the Nr4a1 gene on the RP24-366J14 BAC via homologous recombination/BAC recombineering. The frt-flanked neo was removed via arabinose treatment during BAC recombineering. A ~135 kb fragment from the modified BAC harboring the targeted Nr4a1 locus as well as 60 kb sequence flanking each side of the Nr4a1 locus (including the Acvr1b, A330009N23Rik, Grasp, 9430023L20Rik and 6030408B16Rik loci) was purified and then microinjected into C57BL/6J embryos. The resulting Nur77GFP BAC transgenic founder mice were bred with C57BL/6NCr mice. Transgenic mice from the B6-820 founder line were found with high GFP expression levels in myeloid lineage cells from spleen (but not lymph node), as well as low GFP expression levels in T and B lymphocytes.