CXCR4 is required for the quiescence of primitive hematopoietic cells

• Published in: The Journal of experimental medicine Vol. 205; no. 4; pp. 777 - 783
• Main Authors: Nie, Yuchun, Han, Yoon-Chi, Zou, Yong-Rui
• Format: Journal Article
• Language: English
• Published: United States The Rockefeller University Press 14.04.2008
• Subjects: Animals; Bone Marrow Cells - cytology; Brief Definitive Reports; Cell Cycle; Cell Proliferation; Chemokine CXCL12 - metabolism; Hematopoiesis; Hematopoietic Stem Cells - cytology; Hematopoietic System - cytology; Mice; Multipotent Stem Cells - cytology; Receptors, CXCR4 - deficiency; Receptors, CXCR4 - metabolism; Signal Transduction
• ISSN: 0022-1007; 1540-9538; 1892-1007
• DOI: 10.1084/jem.20072513

The quiescence of hematopoietic stem cells (HSCs) is critical for preserving a lifelong steady pool of HSCs to sustain the highly regenerative hematopoietic system. It is thought that specialized niches in which HSCs reside control the balance between HSC quiescence and self-renewal, yet little is known about the extrinsic signals provided by the niche and how these niche signals regulate such a balance. We report that CXCL12 produced by bone marrow (BM) stromal cells is not only the major chemoattractant for HSCs but also a regulatory factor that controls the quiescence of primitive hematopoietic cells. Addition of CXCL12 into the culture inhibits entry of primitive hematopoietic cells into the cell cycle, and inactivation of its receptor CXCR4 in HSCs causes excessive HSC proliferation. Notably, the hyperproliferative Cxcr4(-/-) HSCs are able to maintain a stable stem cell compartment and sustain hematopoiesis. Thus, we propose that CXCR4/CXCL12 signaling is essential to confine HSCs in the proper niche and controls their proliferation.