Micro RNA s in platelet production and activation

Summary Recent work by the E ncyclopedia of DNA Elements project showed that non‐protein‐coding RNA s account for an unexpectedly large proportion of the human genome. Among these non‐coding RNA s are micro RNA s (mi RNA s), which are small RNA molecules that modulate protein expression by degrading m RNA or repressing m RNA translation. Mi RNA s have been shown to play important roles in hematopoiesis including embryonic stem cell differentiation, erythropoiesis, granulocytopoiesis/monocytopoiesis, lymphopoiesis, and megakaryocytopoiesis. Additionally, disordered mi RNA biogenesis and quantitative or qualitative alterations in mi RNA s and their targets are associated with hematological pathologies. Platelets contain machinery to process pre‐mi RNA s into mature mi RNA s, and specific platelet mi RNA levels have been found to correlate with platelet reactivity. This review summarizes the current state of knowledge of mi RNA s in megakaryocytes and platelets, and the exciting possibilities for future megakaryocyte–platelet transcriptome research.