Immunohistochemical studies on disabled-2 protein in the spinal cords of rats with experimental autoimmune encephalomyelitis

Abstract

Disabled-2 (Dab-2), an adaptor protein of transforming growth factor beta (TGF-β) signaling, was studied in the spinal cords of rats with experimental autoimmune encephalomyelitis (EAE) to evaluate the possible involvement of Dab-2 in the pathogenesis of EAE using Western blot and immunohistochemical analyses. Western blot analysis showed that two isoforms (p96 kDa and p67 kDa) of Dab-2 were detected in the spinal cords of rats used as controls. Both isoforms of Dab-2 were significantly elevated in the EAE spinal cord at the peak stage of EAE ( P < 0.05) and declined at the recovery stage. However, only the p96 kDa isoform was markedly phosphorylated in the EAE spinal cord. Immunohistochemistry showed that Dab-2 and p-Dab-2 were detected in some vascular endothelial cells, glial cells, and some neurons in the rat spinal cords of normal and immunized CFA-alone controls. In EAE lesions, Dab-2 and p-Dab-2 were immunodetected in some inflammatory cells (mainly in ED1-positive macrophages and R73-positive T cells), while the enhanced immunoreactivity of Dab-2 in spinal cord cells suggested constitutive expression. Additionally, TGF-β1 immunoreactivity showed a similar expression pattern of Dab-2 in EAE lesions. These findings suggest that Dab-2 is transiently upregulated and phosphorylated (particularly the p96 kDa isoform) in EAE, a CNS autoimmune disease, and may be involved in TGF- β signaling.