B6.Cg-Ptprc^a Mir223^tm1Fcam/J

Stock number: 013198
Product name: miR-223-
Strain synonyms: Mir223 KO
Research areas: Hematological Research, Immunology, Inflammation and Autoimmunity Research, Internal/Organ Research

Description

In this strain, the allele replaces the entire coding region of the microRNA-223 (Mir223) gene with a frt-flanked neomycin (neo) resistance cassette, abolishing gene function. These mice also harbor the CD45.1 (Ly5.1 or Ptprc^a) allele rather than the CD45.2 (Ly5.2 or Ptprc^b) allele normally present in C57BL/6 mice. These mice may be useful for studying granulocyte production and inflammatory response.

Detailed description

In this strain, the allele replaces the entire coding region of the microRNA-223 (Mir223) gene with a frt-flanked neomycin (neo) resistance cassette, abolishing gene function. They also harbor the CD45.1 (Ly5.1 or Ptprc^a) allele rather than the CD45.2 (Ly5.2 or Ptprc^b) allele normally present in C57BL/6 mice. Homozygous miR-223^- mice are viable, fertile, and normal in size. After endotoxin challenge, these mice exhibit an increase in aspartate aminotransferase (ALT), blood urea nitrogen (BUN) and creatine kinase (CK) levels due to widespread tissue destruction, including hepatocyte necrosis and intralobular haemorrhage. MiR-223 plays a key role in controlling steatosis-to-non-alcoholic steatohepatitis (NASH) progression by inhibiting hepatic Cxcl10 and Taz expression in high-fat diet fed mice. They also develop inflammatory lung pathology characterized by areas of atelectasis, increased cellularity within the parenchyma, and inflammatory infiltration into the interstitium. Granulocytes from miR-223^- mice are hypermature, hypersensitive to activating stimuli, and display increased fungicidal activity. These mice have an expanded granulocytic compartment resulting from a cellautonomous increase in the number of granulocyte progenitors. These mice may be useful for studying granulocyte production and inflammatory response.

Development

A targeting vector was designed to replace the entire coding region of the microRNA-223 (Mir223) gene with a frt-flanked neomycin (neo) resistance cassette. The construct was electroporated into (C57BL/6 x 129S4Sv/Jae)F1-derived V6.5 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts and the resulting chimeric males were bred to C57BL/6 females to generate a colony of miR-223^- mice. The donating investigator reported that these mice were backcrossed for at least 5 generations to B6.SJL-Ptprc^a Pepc^b/BoyJ (Stock No. 002014) and thus also harbor the CD45.1 (Ly5.1 or Ptprc^a) allele (see SNP note below). These mice may still be segregating at the Pepc^b allele. Upon arrival at The Jackson Laboratory, mice were bred to B6.SJL-Ptprc^a Pepc^b/BoyJ for at least one generation to establish the colony.

A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository. At least 1 marker, on Chromosome 11, is segregating. Also,4 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.

 

Allele

Symbol: Mir223^tm1Fcam
Name: targeted mutation 1, Fernando D Camargo
MGI accession ID: MGI:3811186
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Mir223
Marker name: microRNA 223
Chromosome: X
Strain of origin: (C57BL/6 x 129S4/SvJae)F1
Molecular note: The entire 110 bp locus was replaced by a neomycin resistance cassette. Northern blot analysis of granulocyte RNA from hemizygous mice revealed a complete absence of locus expression.

Allele

Symbol: Ptprc^a
Name: a variant
MGI accession ID: MGI:4819849
Generation method: Not Applicable
Marker symbol: Ptprc
Marker name: protein tyrosine phosphatase, receptor type, C
Chromosome: 1
Strain of origin: Not Applicable
Site of expression: Widely expressed on all adaptive and innate immune cells.
Molecular note: Ptprc^a is found in strains SJL/J, STS/A, and DA. Ptprc^b is found in strains C57BL/6, C3H/An, DBA/2, AKR, and many others (J:13367, J:12054, J:12077, J:8603). Twelve nucleotide differences between the a and b alleles have been identified. These base substitutions correspond to five amino-acid changes within the extracellular domain of the encoded protein. These amino-acid differences are clustered in a region that also contains the greatest divergence between mouse and rat sequences (J:22485).

Note that the allele designations originally described were reversed in 1987 (J:8603); all publications prior to 1987 show SJL/J, STS/A, and DA as having the b allele and the C57BL/6J group as having the a allele (J:22341).