Col6a3d16 mice lack the triple-helical domain of collagen, type VI, alpha 3, abolishing function. These mice may be useful for studying the dominant collagen VI disorder Ullirch congenital muscular dystrophy.
Mon-Li Chu, Thomas Jefferson University
Col6a3d16 mice lack exon 16 of the collagen, type VI, alpha 3 (Col6a3) gene, which encodes the triple-helical domain, abolishing function. Collagen VI is a triple-helical microfibrillar extracellular matrix protein made up of
three different alpha chains encoded by the COL6A1, COL6A2 and COL6A3 genes. Sequences in and flanking the triple-helical domain of each alpha chain are required for the assembly and stability of microfibrils. Recessive and dominant mutations in any of the three genes cause a spectrum of muscle disorders, ranging from the severe Ullrich congenital muscular dystrophy (UCMD) to the milder Bethlem myopathy. Heterozygous mutations in COL6A3, leading to skipping of exon 16, have been associated with severe UCMD which is characterized by muscle weakness, joint contractures, distal hyperlaxity, and skeletal and skin anomalies. Homozygous Col6a3d16 mice are viable and fertile. Heterozygous mutant mice produce comparable amounts of wildtype and exon 16-deleted Col6a3 RNA. Homozygous and heterozygous mice display compromised muscle contractile functions and reduced levels of collagen VI microfibrils. Variation in muscle fiber size, myofibers with centrally located nuclei, and increased endomysial connective tissue in limb and diaphragm muscles are evidence of progressive myopathy. In the skeletal muscle, mitochondria are enlarged and irregularly shaped, and the sarcoplasmic reticulum are distended. Collagen fibrils in the endomysial connective tissue is disorganized
A targeting vector was designed to replace exon 16 of the collagen, type VI, alpha 3 (Col6a3) gene with a loxP-flanked neomycin resistance (neo) cassette. The construct was electroporated into 129S/Sv-derived 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. These Col6a3d16N mice were bred to transgenic mice expressing cre recombinase under control of the β-actin promoter to remove the neo cassette. Col6a3d16 mice were backcrossed for at least 10 generations to C57BL/6J background. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the colony.
|Allele Name||targeted mutation 2.1, Mon-Li Chu|
|Allele Type||Targeted (Hypomorph)|
|Gene Symbol and Name||Col6a3, collagen, type VI, alpha 3|
|Strain of Origin||129/Sv|
|Molecular Note||A targeting vector was designed to replace exon 16 of the gene with a loxP-flanked neomycin resistance (neo) cassette. Cre-mediated recombination removed the floxed neo cassette.RT-PCR analysis confirmed expression of a truncated transcript with in-frame deletion of six Gly-X-Y repeats; expression is comparable to mRNA from normal mice. The mutant collagen chain forms triple-helical collagen VI molecules with the alpha 1 and 2 chains and is secreted.|
When maintaining a live colony, homozygous mice may be bred together.
When using the B6.129(Cg)-Col6a3tm2.1Chu/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #024972 in your Materials and Methods section.