Thrombopoietin regulates c-Myb expression by modulating micro RNA 150 expression.

Area of Science:

• Hematology
• Molecular Biology
• Gene Regulation

Background:

• c-Myb hypomorphic mutations enhance thrombopoiesis by increasing megakaryocytes.
• Thrombopoietin (TPO) induces similar effects, suggesting c-Myb modulation.
• c-Myb levels decrease during TPO-induced megakaryocyte (MK) maturation, with miR-150 binding sites in c-Myb's 3'UTR.

Purpose of the Study:

• To investigate the role of microRNA-150 (miR-150) in TPO-mediated c-Myb downregulation.
• To determine if TPO regulates c-Myb expression via miR-150 induction.

Main Methods:

• Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blotting to measure c-Myb and miR-150 levels.
• Reporter gene assays to assess miR-150's effect on c-Myb 3'UTR activity.
• Experiments with anti-miR-150 to confirm miR-150's inhibitory role.

Main Results:

• TPO reduced c-Myb mRNA and protein levels in megakaryocytes and UT7/TPO cells within 7 hours.
• miR-150 significantly reduced luciferase expression driven by the c-Myb 3'UTR, indicating functional binding sites.
• miR-150 decreased endogenous c-Myb mRNA and protein levels in UT7/TPO cells and mature megakaryocytes.
• TPO treatment increased miR-150 expression levels within 48 hours.

Conclusions:

• miR-150 directly downmodulates c-Myb expression.
• TPO induces miR-150 expression, thereby downregulating c-Myb.
• TPO's effect on c-Myb expression is mediated, in part, through miR-150 induction, influencing MK progenitor growth and maturation.