Genomic abnormalities of the murine model of Fabry disease after disease-related perturbation, a systems biology approach

Abstract

Fabry disease is a disorder of alpha-D-galactosyl-containing glycolipids resulting from a deficiency of alpha-galactosidase A. Patients have a poorly understood vascular dysregulation. We hypothesized that disease-related perturbation by using enzyme replacement therapy in the murine model of Fabry disease would provide insight into abnormal biological processes in Fabry disease. Gene expression analyses of the heart, aorta, and liver of male alpha-galactosidase A knockout mice 28 weeks of age were compared with that of WT mice. Microarray analyses were performed before and after six weekly injections of alpha-galactosidase A. Alteration of Rpgrip1 ranked highest statistically in all three organs when knockout mice were compared with WT, and its splice variants responded in a unique way to alpha-galactosidase A. Enzyme replacement therapy tended to not only normalize gene expression, e.g., reduce the overexpression of securin, but also specifically modified gene expression in each tissue examined. Following multiple comparison analysis, gene expression correlation graphs were constructed, and a priori hypotheses were examined by using structural equation modeling. This systems biology approach demonstrated multiple and complex parallel cellular abnormalities in Fabry disease. These abnormalities form the basis for informed, in a Bayesian sense, sequential, hypothesis-driven research that can be subsequently tested experimentally.

Fig. 1.

Genes that are specifically modified by ERT. Comparative list of genes significantly expressed in the aorta of Fabry-ERT mouse vs. WT (Left) and Fabry vs. WT (Right). Genes in both lists have a white background, and unique genes for either list are in color.

Fig. 2.

Western blot for RPGRIP1γ in liver tissue. In Fabry mice, the expression of an immunoreactive RPGRIP1γ-related isoform is suppressed, whereas upon ERT its expression is induced again (arrow). Conversely, another RPGRIP1γ-related isoform seems to be suppressed upon treatment only (dashed arrow).

Fig. 3.

SEM analysis of superoxide dismutase in aorta of Fabry mice that received ERT. (A) Graphical Gaussian model of Sod3-related gene expression in aortic tissue of the Fabry KO mouse after disease-related perturbation with agalsidase-α. (B) Path diagram of simplified Sod3 model based on the graphical Gaussian network illustrated in A (χ² = 4.7, df = 5, P = 0.44).

Fig. 4.

SEM analysis of superoxide dismutase in ERT Fabry aorta using a more complex instantiation of the differential gene expression relations. (A) Complex graphical Gaussian model (correlational graph network) of Sod3-related gene expression in aortic tissue of the Fabry KO mouse after disease-related perturbation with agalsidase-α. (B) Corresponding Sod3 SEM showing the latent variables for ERT and glycolipidopathy based on the graphical Gaussian model illustrated in A (χ² = 3.1, df = 11, P = 0.99)