Thrombopoietin enhances rapid current responses mediated by P2X1 receptors on megakaryocytic cells in culture.
The effect of thrombopoietin (TPO), a magakaryocytopoietic cytokine, on the functional maturation of megakaryocytes was studied by using cell culture and patch-clamp techniques focusing on purinergic 2X(1) (P2X(1))-receptors, which are expressed specifically on platelets and their progenitors. Meg-01 cells, one of the typical human megakaryocytic cell lines, were cultured and studied by using a whole-cell patch electrode. In control cells cultured in RPMI1640 medium, an application of adenosine nucleotide (ADP, 40 microM) evoked transient inward currents with amplitudes of 45 +/- 19 pA (at -43 mV). Based on kinetic, ionic, and pharmacological properties as well as on previously reported findings, these currents were thought to be mediated by P2X(1) receptors. When Meg-01 cells were cultured for 7-9 d in a medium to which the differentiation-inducing agent phorbol ester (PMA; 10 nM) or TPO (100 ng/ml) had been added, the responses of the cells to ADP increased to about 150% of the control with PMA and to about 200% of the control value with TPO. A combination of the two agents enhanced the response of the cells to ADP to about 570% of the control value. These results suggest that phorbol ester and TPO cause cellular differentiation of Meg-01 cells and enhance the level of expression of P2X(1)-receptors on cell membranes in a synergetic manner. The effect of TPO on the induction of P2X(1)-receptors on mouse megakaryocytes in culture was more obvious.
Kawa
Kazuyoshi
K
Department of Neurophysiology, Tohoku University Graduate School of Medicine, Sendai, 980-8575 Japan. kawa-k@mail.cc.tohoku.ac.jp
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D004594:Electrophysiology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008533:Megakaryocytes / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018408:Patch-Clamp Techniques; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D058469:Receptors, Purinergic P2X; D013926:Thrombopoietin / Q000494:pharmacology*
D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D013926:Thrombopoietin