title: Distinct roles of integrins alpha6 and alpha4 in homing of fetal liver hematopoietic stem and progenitor cells.
abstract: Homing of hematopoietic stem cells (HSCs) into the bone marrow (BM) is a prerequisite for establishment of hematopoiesis during development and following transplantation. However, the molecular interactions that control homing of HSCs, in particular, of fetal HSCs, are not well understood. Herein, we studied the role of the alpha6 and alpha4 integrin receptors for homing and engraftment of fetal liver (FL) HSCs and hematopoietic progenitor cells (HPCs) to adult BM by using integrin alpha6 gene-deleted mice and function-blocking antibodies. Both integrins were ubiquitously expressed in FL Lin(-)Sca-1(+)Kit(+) (LSK) cells. Deletion of integrin alpha6 receptor or inhibition by a function-blocking antibody inhibited FL LSK cell adhesion to its extracellular ligands, laminins-411 and -511 in vitro, and significantly reduced homing of HPCs to BM. In contrast, the anti-integrin alpha6 antibody did not inhibit BM homing of HSCs. In agreement with this, integrin alpha6 gene-deleted FL HSCs did not display any homing or engraftment defect compared with wild-type littermates. In contrast, inhibition of integrin alpha4 receptor by a function-blocking antibody virtually abrogated homing of both FL HSCs and HPCs to BM, indicating distinct functions for integrin alpha6 and alpha4 receptors during homing of fetal HSCs and HPCs.
authors.affiliation: Hematopoietic Stem Cell Laboratory, Lund Strategic Research Center for Stem Cell Biology and Cell Therapy, Lund University, Lund, Sweden.
authors.forename: Hong
authors.initials: H
authors.lastname: Qian
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Georges-Labouesse
authors.forename: Alexander
authors.initials: A
authors.lastname: Nyström
authors.forename: Anna
authors.initials: A
authors.lastname: Domogatskaya
authors.forename: Karl
authors.initials: K
authors.lastname: Tryggvason
authors.forename: Sten Eirik W
authors.initials: SE
authors.lastname: Jacobsen
authors.forename: Marja
authors.initials: M
authors.lastname: Ekblom
mesh_terms: D000375:Aging / Q000502:physiology; D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001853:Bone Marrow / Q000378:metabolism; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D053686:Fetal Stem Cells / Q000166:cytology* / Q000378:metabolism*; D005786:Gene Expression Regulation; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D039441:Integrin alpha4 / Q000378:metabolism*; D039503:Integrin alpha6 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D000906:Antibodies; D039503:Integrin alpha6; D012333:RNA, Messenger; D016179:Granulocyte Colony-Stimulating Factor; D039441:Integrin alpha4