TPO mRNA levels in marrow were higher in thrombocytopenic mice and lower in thrombocytotic mice compared to controls, supporting regulation by platelet demand.
Does platelet count modulate thrombopoietin mRNA levels in mice?
Thrombopoietin levels appear to be regulated, at least in part, by modulating mRNA levels in the marrow and spleen in response to platelet demand.
The activity of the c-Mpl ligand hematopoietic progenitors meets criteria expected for thrombopoietin (TPO). Bio-assays have shown that blood TPO levels are inversely related to platelet mass. We sought to identify the molecular basis for this regulation. To determine if TPO mRNA levels respond to platelet demand, RNA from selected organs of mice with high, normal or low platelet counts was subjected to semiquantitative reverse transcriptase-polymerase chain reaction. Although no differences in TPO mRNA levels between control and treated mice could be detected in liver or kidney, TPO-specific bands were more intense after 25 to 30 polymerase chain reaction cycles in marrow-derived mRNA from thrombocytopenic mice. The TPO-specific bands were less intense in thrombocytotic mouse marrow and spleen than control mouse marrow and spleen after 30 cycles. These data support the hypothesis that TPO levels are regulated, at least in part, by modulating mRNA levels in response to platelet demand.
McCarty et al. (Wed,) conducted a other in Platelet demand (thrombocytopenia and thrombocytosis). Altered platelet counts (thrombocytopenia or thrombocytosis) vs. Control mice (normal platelet counts) was evaluated on TPO mRNA levels in selected organs (liver, kidney, marrow, spleen). TPO mRNA levels in marrow were higher in thrombocytopenic mice and lower in thrombocytotic mice compared to controls, supporting regulation by platelet demand.
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