C3FeB6 A/A^w-J-Ank^ank/J

Stock number: 000200
Product name: progressive ankylosis
Research areas: Dermatology Research, Developmental Biology Research, Immunology, Inflammation and Autoimmunity Research, Mouse/Human Gene Homologs

Detailed description

The progressive ankylosis allele (ank) is a spontaneous recessive mutation that causes a severe phenotype of joint calcification and degeneration. Few homozygotes survive beyond 5 months of age, although the adults can breed. Generally no more than 2 litters are produced by homozygotes of either sex. At 4 or 5 weeks of age, homozygotes can be identified by their inability to grasp a wire cage lid with their front paws when suspended above it. The joints swell with a milky fluid, and undergo a process proceeding through mononuclear inflammatory infiltration, hydroxyapatite deposition and increased calcification, hyperplasia, and fibrous and bony ankylosis. (for details see Mahowald et al., 1989; Hakim et al., 1984; Sweet and Green, 1981.) The front feet are affected before the hind feet and the phenotype is more severe in the most distal joints of the limbs. Hyperplasia and degeneration of the joint tissues, and ankylosis occur progressively, decreasing mobility and resulting in a rigid, crouched posture in the adult. Their gate becomes slow, halting, and flatfooted. The morphological changes underlying the stiffening of the vertebral column and resulting thoracic kyphosis are detailed by Sampson, 1988a and 1988b, and Sampson et al., 1991.

There is an immune cell involvement in the joints secondary to the central defect. Treatment of ank/ank mice with hydrocortisone beginning at 5 weeks of age resulted in reduced synovial and subsynovial hyperplasia, reduced growth of cartilaginous and bony bridges, and increased accumulation of intra-articular apatite possibly due to the reduction in macrophage activity (Hakim et al., 1986.). Reconstitution of wild type mice with bone marrow or spleen cells from ank/ank mice does not transfer disease and reconstitution of ank/ank mice with wild type bone marrow or spleen cells does not prevent disease (Krug et al., 1997). Additionally, there is an immune cell defect. There is a reduction in the response of spleen cells to phytohaemagglutinin or concanavalin A although the response to LPS appears normal. Spleen cells or macrophages from ank/ank mice do not suppress normal spleen cell responses to phytohaemagglutinin and wild type spleen cells or macrophages do not restore phytohaemagglutinin responsiveness to spleen cells from ank/ank mice (Krug et al., 1989). Fibroblasts from ank/ank mice are Hyperproliferative in response to transforming growth factor beta 1 (Krug, 1998). No impact was found on the phenotype of ank/+ or ank/ank mice when transgenic HLA-B27 was co-expressed (Krug and Taurog, 2000).

In addition to progressive ankylosis and calcification of the peripheral joints and axial skeleton, homozygotes have a smaller overall body size, and some develop balanitis, priapism, and scaling skin lesions on the plantar surface of the paws. The hypermineralization phenotype is associated with abnormal inorganic pyrophophate levels and the downregulation of osteopontin (Harmey et al., 2004).

Development

The progressive ankylosis mutation arose spontaneously in the strain JGBF/Le (Stock No. 000260), a balanced stock for jagged tail (jg) and buff (bf). An affected female displaying a flat-footed gait with rigid toes was the founder for the ank strain. This female's progeny were bred onto a C3FeB6 background via an outcross-intercross breeding scheme. Thus homozygotes were bred to C3FeB6F1 then their obligate heterozygous offspring were sibling mated to produce homozygous breeders for the next generation. The initial characterization was done on N5F1 mice. In June 1976 this strain was at N6, in early 1979 it was at N11, and in November 1983 it reached N24. Neither jg nor bf have been found in this strain since N2. C3FeB6-A/A^w-J-ank was frozen in 1987 by breeding N32 homozygotes to C3FeB6-A/A^w-J to get heterozygous N33 embryos.

Allele

Symbol: A^w-J
Name: white bellied agouti Jackson
MGI accession ID: MGI:1855946
Generation method: Spontaneous
Marker symbol: a
Marker name: nonagouti
Chromosome: 2
Strain of origin: C57BL/6J

Allele

Symbol: A
Name: wild-type agouti
MGI accession ID: MGI:1856464
Generation method: Spontaneous
Marker symbol: a
Marker name: nonagouti
Chromosome: 2
Strain of origin: various
Molecular note: This allele, often referred to as wild-type, comprises a novel 131 amino acid protein encoded in a gene comprising four exons, three coding, spanning 18kb. Unique changes in this gene account for all other alleles that have been molecularly characterized. The expression of this allele is almost always dominant to other alleles of this gene.
General note: The A allele is usually regarded as a wild-type allele. For example,the C3H and CBA mouse sublines are homozygous for agouti. Hairs are black with a subapical yellow band. This black-yellow-black pattern is referred to as agouti. The general appearance is yellowish brown, slightly lighter on the belly than on the back.

Allele

Symbol: Ank^ank
Name: progressive ankylosis
MGI accession ID: MGI:1856651
Generation method: Spontaneous
Marker symbol: Ank
Marker name: progressive ankylosis
Chromosome: 15
Strain of origin: JGBF/LeJ
Molecular note: A single nucleotide G to T substitution is predicted to result in a substitution at codon 440 from Glu to a stop codon in the encoded protein.