Correction: The Endocytic Adaptor Eps15 Controls Marginal Zone B Cell Numbers

Eps15 is an endocytic adaptor protein involved in clathrin and non-clathrin mediated endocytosis.In Caenorhabditis elegans and Drosophila melanogaster lack of Eps15 leads to defects in synaptic vesicle recycling and synapse formation.We generated Eps15-KO mice to investigate its function in mammals.Eps15-KO mice are born at the expected Mendelian ratio and are fertile.Using a large-scale phenotype screen covering more than 300 parameters correlated to human disease, we found that Eps15-KO mice did not show any sign of disease or neural deficits.Instead, altered blood parameters pointed to an immunological defect.By competitive bone marrow transplantation we demonstrated that Eps15-KO hematopoietic precursor cells were more efficient than the WT counterparts in repopulating B220 + bone marrow cells, CD19 2 thymocytes and splenic marginal zone (MZ) B cells.Eps15-KO mice showed a 2-fold increase in MZ B cell numbers when compared with controls.Using reverse bone marrow transplantation, we found that Eps15 regulates MZ B cell numbers in a cell autonomous manner.FACS analysis showed that although MZ B cells were increased in Eps15-KO mice, transitional and pre-MZ B cell numbers were unaffected.The increase in MZ B cell numbers in Eps15 KO mice was not dependent on altered BCR signaling or Notch activity.In conclusion, in mammals, the endocytic adaptor protein Eps15 is a regulator of B-cell lymphopoiesis.