P2 receptors in the thymus: expression of P2X and P2Y receptors in adult rats, an immunohistochemical and in situ hybridisation study

Abstract

The expression of the seven P2X receptor subtypes and of two P2Y receptors was examined immunohistochemically and by in situ hybridisation in thymi of adult male rats. P2X4, P2Y2 and 4 receptor mRNA colocalisation studies combining in situ hybridisation and immunohistochemistry were also carried out. P2X and P2Y receptors were found on thymocytes. P2X receptors were also abundant in cells of the thymic microenvironment, involved in control of T-cell maturation in vivo. We are the first to describe the expression of P2X4 receptors on thymocytes and confirm the finding of P2X1 and P2Y2 receptors on subpopulations of lymphocytes. P2X1,2,3,4 and 5 receptors were present in blood vessels of the thymus. P2X1,2 and 4 receptors were detected in vascular smooth muscle, while P2X3 receptors appeared to be associated with endothelial cells; some small arteries were positive for P2X5, possibly labelling vascular smooth muscle or fibroblasts in the adventitia. P2X2,3,6 and 7 receptors were found on thymic epithelial cells. P2X2 and 3 receptors were abundant on medullary epithelial cells, whilst P2X6 receptors were prominent in Hassall's corpuscles. P2X2 receptors were found on subcapsular and perivascular epithelial cells. P2X2,6 and 7 receptors were detected in epithelial cells along the thymic septa. Expression of P2X receptors was also investigated by Western blotting of crude thymic tissue extracts under reducing conditions. All seven P2X receptor subtypes were found to be dimers of approximately 70 kDa and 140 kDa molecular weight. ATP-mediated apoptosis and cell proliferation of thymocytes are discussed.

Functional Regulation of P2X6 Receptors by N-Linked Glycosylation: Identification of a Novel αβ-Methylene ATP-Sensitive Phenotype

“…P2X 6 receptor protein has been detected as an ϳ49-kDa band from whole rat brain homogenates (5 days postnatal; Rubio and Soto, 2001) and as an ϳ70-kDa product from adult molpharm.aspetjournals.org rat midbrain homogenate (Worthington et al, 1999a), atrium, bladder, kidney (Worthington et al, 1999b), and thymocytes (Glass et al, 2000). It has also been reported at ϳ60 kDa from human superior cervical ganglia, HEK-293 cells, rat ventricle, bladder, and kidney (Worthington et al, 1999b).…”

P2X and P2Y purinergic receptors on human intestinal epithelial carcinoma cells: effects of extracellular nucleotides on apoptosis and cell proliferation

“…This receptor is expressed mainly on nociceptive sensory neurons of the dorsal root and trigeminal and nodose ganglia (9,10), and its activation was associated with the sensation of pain (7). However, recently P2X 3 receptors have also been found in murine endothelial and epithelial cells (28,29). We showed that both mRNA and protein for the P2X 3 receptor are expressed on Caco-2 and HCT8 cells, which may be functionally relevant considering that the activity of the P2X 3 receptor may be modulated in the human gut during inflammatory disease (63).…”

Purinergic Signaling and Blood Vessels in Health and Disease

“…Electron microscopic immunolabeling showed P2X 2 receptors localized on endothelial cells in rat brain (Loesch and Burnstock, 2000). P2X 3 receptors were shown to be localized on endothelial cells in blood vessels of the rat thymus Purinergic Signaling and Blood Vessels (Glass et al, 2000). Endothelial cells in the rat thyroid immunostained for P2X 3 , P2X 4 , and P2X 7 receptors, and it was suggested that this unusually rich expression of endothelial P2X receptors may reflect the constant dynamic changes in thyroid activities and the special need for regulation of vascular tone in endothelial barrier formation (Glass and Burnstock, 2001).…”