These mutant mice do not express the long isoform of the beta 1,4-galactosyltransferase enzyme. Homozygotes exhibit abnormal acrosomal exocytosis and mammary gland morphogenesis. This mutant mouse strain may be useful in studies of glycosidic molecular interactions and function, and cell-to-extracellular matrix (ECM) interactions.
Barry D Shur, Emory University
These mice carry a mutant allele that has a point mutation in the first translation initiation codon in exon 1, which initiates translation of the long isoform of beta 1,4-galactosyltransferase. The second translation initiation codon in exon 1 is not affected. These mice express only the shorter isoform of beta 1,4-galactosyltransferase. No long isoform protein is detected in mammary tissue by Western blot analysis. Mice that are homozygous for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. Total Beta 1,4-galactosyltransferase activity is reduced to 72% of wildtype levels in mammary gland epithelial cells while activity on mammary epithelial cell surfaces is diminished by over 60%. Sperm and testis exhibit near wildtype levels of enzyme activity and glycoprotein galactosylation. The short isoform is expressed ectopically in sperm. Although able to undergo normal acrosomal exocytosis induced by calcium ionophore, homozygous sperm do not exhibit acrosome reaction to zona pellucida glycoproteins or anti-galactosyltransferase antibodies. Homozygous females exhibit abnormal mammary gland morphology including excessive mammary epithelial duct branching. Approximately 20% of homozygous females do not support their young. Mutants have elevated levels of expression of metalloproteinases (Mmp14 and Mmp7). Laminin espression in basal lamina is abnormal. This mutant mouse strain may be useful in studies of glycosidic molecular interactions and function, and cell-to-extracellular matrix (ECM) interactions.
This strain was transferred from the collection of the Consortium for Functional Glycomics.
A targeting vector containing a neomycin resistance and herpes simplex virus thymidine kinase genes was used to insert a point mutation into the first translation initiation codon in exon 1, which initiates translation of the long isoform. The construct was electroporated into 129S7/SvEvBrd-Hprt1+ derived AB1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting chimeric animals were crossed to C57BL/6J mice, and then backcrossed to C57BL/6J for 4 generations before arriving at The Jackson Laboratory. The mice were then crossed to C57BL/6J for one generation.
|Allele Name||targeted mutation 2, Barry D Shur|
|Allele Type||Targeted (Modified isoform(s))|
|Allele Synonym(s)||GalT-null; Long GalT-Null; long gt-|
|Gene Symbol and Name||B4galt1, UDP-Gal:betaGlcNAc beta 1,4- galactosyltransferase, polypeptide 1|
|Promoter||B4galt1, UDP-Gal:betaGlcNAc beta 1,4- galactosyltransferase, polypeptide 1, mouse, laboratory|
|Strain of Origin||129S7/SvEvBrd-Hprt+|
|Molecular Note||A targeting vector containing neomycin resistance and herpes simplex virus thymidine kinase genes was used to insert a point mutation into the first translation initiation codon in exon 1, which initiates translation of the long isoform. Expression of the long isoform is eliminated. Expression of the short isoform is unaffected.|
|Mutations Made By|| |
Peter Sobieszczuk, Consortium for Functional Glycomics,TSRI
When maintaining a live colony, these mice can be bred as homozygotes.
When using the B6.129S7-B4galt1tm2Shur/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #006943 in your Materials and Methods section.