Figure 2.

Molecular processes involved in hematopoietic and neurogenic niches regulation. The molecules that are involved in the regulation of hematopoiesis and neurogenesis could be divided into three main groups, according to their roles in niches. 1. Stem cell homing: the couple CXCL12/CRCR4-7 are the most important component as they allow HSC or NSC homing and stemness into the niche. 2. Stem cell retention. After stem cells recruitment and homing, adhesion molecules and their ligands are involved in stem cells retention by blocking their differentiation and migration. 3. Control of niche size: BMP signaling pathway regulates niches size through the promotion of stem cells differentiation and or mobilization. 4. Control of quiescence and differentiation in HSC and NCSC niches: Angiopoietin-1 and its receptor Tie2 play different roles within the two niches from HSC quiescence maintenance to NSC proliferation and differentiation. Other actors could be involved, like sympathetic neurons regulating HSC attraction and mobilization into the blood flow.