Expression of the thrombopoietin gene in tissues from healthy dogs

Thrombopoietin (THPO) is the major cytokine that regulates megakaryopoiesis and platelet production. Several human and murine studies have demonstrated that THPO is primarily synthesized in the liver, but the kidney, spleen and bone marrow are also sites of expression. The aim of this study was to determine THPO mRNA levels in a range of canine tissues by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). Samples of bone marrow (n = 5), liver (n = 10), lung (n = 10), renal cortex (n = 10), renal medulla (n = 5) and spleen (n = 10) were obtained from 10 healthy, hound-cross dogs aged 6-8 months. The highest THPO mRNA levels were found in the liver, followed by the bone marrow, spleen, lung and kidney. There was a 13-fold difference in expression between liver and kidney. The bone marrow showed high levels of THPO mRNA in the absence of disease. The liver and bone marrow are likely to be the major sites of THPO production in the dog.