Lin28b Reprograms Adult Bone Marrow Hematopoietic Progenitors to Mediate Fetal-Like Lymphopoiesis

Abstract

Making Immune Cells Young Again Hematopoiesis, the development of the immune system, occurs in distinct waves. The immune system is first populated by cells that arise from fetal hematopoietic stem cells (HSCs) and then later by cells derived from adult HSCs. Furthermore, fetal HSCs give rise to lymphocytes with innate immunelike properties, whereas adult HSCs give rise to classical T and B cells. Yuan et al. (p. 1195 , published online 16 February) now uncover the molecular mechanism behind these distinct waves of hematopoiesis. Expression of the RNA binding proteins Lin28 and Lin28b is enriched in fetal hematopoietic stem/progenitor cells (HSPCs) in mice and humans. Ectopic expression of Lin28 in mouse adult HSPCs was sufficient to induce the differentiation of both classical and innate-like lymphocyte lineages.