The Wave2 scaffold Hem-1 is required for transition of fetal liver hematopoiesis to bone marrow.

ABSTRACT: The transition of hematopoiesis from the fetal liver (FL) to the bone marrow (BM) is incompletely characterized. We demonstrate that the Wiskott-Aldrich syndrome verprolin-homologous protein (WAVE) complex 2 is required for this transition, as complex degradation via deletion of its scaffold Hem-1 causes the premature exhaustion of neonatal BM hematopoietic stem cells (HSCs). This exhaustion of BM HSC is due to the failure of BM engraftment of Hem-1^-/- FL HSCs, causing early death. The Hem-1^-/- FL HSC engraftment defect is not due to the lack of the canonical function of the WAVE2 complex, the regulation of actin polymerization, because FL HSCs from Hem-1^-/- mice exhibit no defects in chemotaxis, BM homing, or adhesion. Rather, the failure of Hem-1^-/- FL HSC engraftment in the marrow is due to the loss of c-Abl survival signaling from degradation of the WAVE2 complex. However, c-Abl activity is dispensable for the engraftment of adult BM HSCs into the BM. These findings reveal a novel function of the WAVE2 complex and define a mechanism for FL HSC fitness in the embryonic BM niche.

SUBMITTER: Shao L 

PROVIDER: S-EPMC6006146 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature