Expression of cell adhesion molecules in the normal and T3 blocked development of the tadpole's kidney of Bufo arenarum (Amphibian, Anuran, Bufonidae)

Abstract

Cell adhesion molecules act as signal transducers from the extracellular environment to the cytoskeleton and the nucleus and consequently induce changes in the expression pattern of structural proteins. In this study, we showed the effect of thyroid hormone (TH) inhibition and arrest of metamorphosis on the expression of E-cadherin, β-and α-catenin in the developing kidney of Bufo arenarum. Cell adhesion molecules have selective temporal and spatial expression during development suggesting a specific role in nephrogenesis. In order to study mechanisms controlling the expression of adhesion molecules during renal development, we blocked the B. arenarum metamorphosis with a goitrogenic substance that blocks TH synthesis. E-cadherin expression in the proximal tubules is independent of thyroid control. However, the blockage of TH synthesis causes up-regulation of E-cadherin in the collecting ducts, the distal tubules and the glomeruli. The expression of β-and α-catenin in the collecting ducts, the distal tubules, the glomeruli and the mesonephric mesenchyme is independent of TH. TH blockage causes up-regulation of β-and α-catenin in the proximal tubules. In contrast to E-cadherin, the expression of the desmosomal cadherin desmoglein 1 (Dsg-1) is absent in the control of the larvae kidney during metamorphosis and is expressed in some interstitial cells in the KClO4 treated larvae. According to this work, the Dsg-1 expression is down-regulated by TH. We demonstrated that the expression of E-cadherin, Dsg-1, β-catenin and α-catenin are differentially affected by TH levels, suggesting a hormone-dependent role of these proteins in the B. arenarum renal metamorphosis.