Klf5 controls bone marrow homing of stem cells and progenitors through Rab5-mediated membrane Beta1/Beta2-integrin expression

The Kruppel-like factor 5 (Klf5) regulates pluripotent stem cell self-renewal but its role in somatic stem cells is unknown. Klf5 deficient hematopoietic stem cells and progenitors (HSC/P) fail to engraft after transplantation. This HSC/P defect was associated with impaired bone marrow (BM) homing and lodging and decreased retention in BM. The Klf5/ HSC/P homing defect associated with decreased adhesion to fibronectin and expression of membrane-bound 1/2-integrins. In vivo inducible gain-of-function of Klf5 in HSC translated into increased HSC/P adhesion. The expression of Rab5 family members, mediators of 1/2-integrin recycling in the early endosome, was decreased in Klf5/ HSC/P. Klf5 binds directly to the promoter of Rab5a/b and overexpression of Rab5b rescued the expression of activated 1/2-integrins, adhesion and BM homing of Klf5/ HSC/P. Altogether, these data indicate that Klf5 is indispensable for adhesion, homing, lodging and retention of HSC/P in the BM through Rab5-dependent post-translational regulation of Beta1/Beta2 integrins.

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Taniguchi Ishikawa E, Chang KH, Nayak R, Olsson HA, Ficker AM, Dunn SK, Madhu MN, Sengupta A, Whitsett JA, Grimes HL, Cancelas JA