ExeGen

® ATM-/- MiniSwine

Homozygous Genotype

This model features targeted disruption of the endogenous ATM gene in Yucatan MiniSwine genetics to generate a model that recapitulates ataxia telangiectasia (AT) in humans.

Background

In humans, mutations in the ATM gene lead to a multisystemic disorder known as ataxia telangiectasia. This is primarily seen as a neurodegenerative disease characterized by cerebellar degeneration leading to motor impairment. Additional maladies seen in humans include fertility problems, thymic atrophy/hypoplasia, tumor development (mainly lymphoid organs), and immunological deficiencies.

Benefits of the Model:

Defined Yucatan miniature swine genetics that offers greater consistency, smaller size, and lower cost to house and manage.

Mimics many clinical manifestations of human AT including:
Cerebellar lesions characterized by Purkinje cell loss and cytoarchitecture change
Predictable reduction in growth rates
Clinical motor coordination impairment (ataxia)
Reproductive abnormalities (especially in females)
Abnormal architecture and reduced size of the thymus

Biochemical Characterization

ExeGen® ATM-/- MiniSwine lack ATM protein expression in sampled tissues (Fig. 1).

Figure 1.Western blots from heart, liver, cerebellum and cerebrum tissues harvested from ATM+/+, ATM+/- and ATM-/- pigs. A slight reduction of the ATM KD band (~370 kDa) was seen in the ATM+/- pigs; the band was completely absent in tissue derived from ATM-/- pigs.

Figure 1 graph

Cytoarchitecture of the AT Cerebellum

ExeGen® ATM-/- MiniSwine exhibit changes in cytoarchitecture. The cytoarchitecture of the cerebellum was analyzed in pigs at birth (1-day old) and as adults (4-month and 1-year old). In contrast to AT murine models who show no loss of Purkinje cells (PCs), ATM-/- MiniSwine exhibit reduced numbers of PCs when compared to controls (Fig. 2A). The inter-PC distance observations were also significantly increased in ATM-/- MiniSwine (Fig. 2B).

Figure 2: (A) Compared with controls (CTRL, N = six), the cerebellum of ATM-/- pigs (N = five) immunostained with anti-calbindin antibodies (bar 100 μm) had a reduced number of PC (black arrow) on day 1 (left graph, P = 0.02, Mann-Whitney test), and this change remained in adult pigs (right graph, P = 0.02), Mann-Whitney test). (B) PC loss (represented by red line length) was also evaluated by maximal inter-PC distance (left and right panels, H&E stain, bar = 100 µm). The inter-PC distance was elevated by ~14% in ATM-/- pigs compared with CTRL at 1d (left graph, P = 0.02, Mann-Whitney test), consistent with reduced PCs (black arrows). This difference increased during postnatal development to ~36% in adults (right graph, P = 0.005, Mann-Whitney test).

Figure 2 graphs

Weight Gain

ExeGen® ATM-/- MiniSwine exhibit reduced weight gain (Fig. 3).

Figure 3: Pig weights were collected over the course of 250 days from controls (CTRL, N = six) and ATM-/- female pigs (N = six).

Figure 3 graph

Ataxia

ExeGen® ATM-/- MiniSwine recapitulated clinical ataxic phenotype when balance beam walking distance data was collected (Fig. 4).

Figure 4: The walking distance over a period of 5 minutes of age- and gender-matched pigs (N = four per group) was measured on the balance beam at indicated ages (unpaired t-test; *P = 0.0273, **P = 0.0053).

Figure 4 graph