TPO/Mpl studies in agnogenic myeloid metaplasia

被引：3

作者：

Hemavathy K.C. ^{[1
]}

Suppiah K. ^{[1
]}

Hashmi G. ^{[1
]}

Novetsky A.D. ^{[1
]}

Wang J.C. ^{[1
]}

机构：

[1] Division of Hematology/Oncology, Department of Medicine, Maimonides Medical Center, Brooklyn, NY

来源：

Cell Communication and Signaling | / 3卷 / 1期

关键词：

Polycythemia Vera; Essential Thrombocythemia; Human Embryonic Kidney Cell; Bone Marrow Fibrosis; Agnogenic Myeloid Metaplasia;

D O I：

10.1186/1478-811X-3-4

中图分类号：

学科分类号：

摘要：

Background: Agnogenic myeloid metaplasia (AMM) is one of the Philadelphia chromosome negative myeloproliferative disorder and is diagnosed by hyperplasia of atypical megakaryocytes, hepatosplenomegaly, extramedullary hematopoiesis and bone marrow fibrosis. Fibrosis is considered to be a secondary consequence of enhanced levels of fibrogenic growth factors such as TGF β1, bFGF and PDGF produced by enhanced numbers of megakaryocytes, while the primary cause is considered to be the enhanced proliferation of a defective stem cell. We have previously reported that thrombopoietin (TPO) is elevated in patients with AMM. Others have reported that Mp1 protein is decreased in these patients. Since TPO is essential for the development of megakaryocytes, and Mp1 protein is the receptor for TPO, we extended the study of TPO/Mp1 to in vitro and in vivo cell culture systems to better understand the mechanism that leads to reduced Mp1 protein in AMM patients. Results: Plasma TPO levels were significantly elevated and Mpl protein levels were significantly reduced in AMM patients in concordance with previous studies. Platelet Mp1 transcripts in AMM were however similar to those in controls. We also cloned Mpl cDNA from AMM patients and tested for their ability to make functional proteins in vitro and in the in vivo system of 293 T human embryonic kidney cells. Their expression including the glycosylated forms was similar to those from the controls. We also measured the level of translation initiation factor, e1F4E and found it to be increased in patients with AMM demonstrating that the reduced Mpl protein may not be due to translation defects. Conclusions: Our studies using the in vitro and in vivo systems further confirm that reduced Mpl protein levels are not due to defects in its transcription/translation. Reduced Mpl protein could be due to its increased internalisation owing to enhanced plasma TPO or in vivo intrinsic defects in patients with AMM. © 2005 Hemavathy et al; licensee Biomed Central Ltd.

引用

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