RESUMEN
Krüppel-like factor 5 regulates pluripotent stem cell self-renewal, but its role in somatic stem cells is unknown. Here we show that Krüppel-like factor 5-deficient haematopoietic stem cells and progenitors fail to engraft after transplantation. This haematopoietic stem cell and progenitor defect is associated with impaired bone marrow homing and lodging and decreased retention in bone marrow, and with decreased adhesion to fibronectin and expression of membrane-bound ß1/ß2-integrins. In vivo-inducible gain-of-function of Krüppel-like factor 5 in haematopoietic stem cells increases haematopoietic stem cell and progenitor adhesion. The expression of Rab5 family members, mediators of ß1/ß2-integrin recycling in the early endosome, is decreased in Klf5(Δ/Δ) haematopoietic stem cells and progenitors. Krüppel-like factor 5 binds directly to the promoter of Rab5a/b, and overexpression of Rab5b rescues the expression of activated ß1/ß2-integrins, adhesion and bone marrow homing of Klf5(Δ/Δ) haematopoietic stem cells and progenitors. Altogether, these data indicate that Krüppel-like factor 5 is indispensable for adhesion, homing, lodging and retention of haematopoietic stem cells and progenitors in the bone marrow through Rab5-dependent post-translational regulation of ß1/ß2 integrins.
Asunto(s)
Células de la Médula Ósea/citología , Antígenos CD18/metabolismo , Integrina beta1/metabolismo , Factores de Transcripción de Tipo Kruppel/fisiología , Células Madre/citología , Proteínas de Unión al GTP rab5/metabolismo , Animales , Adhesión Celular , Fibronectinas/metabolismo , Ratones , Ratones Endogámicos C57BL , Transporte de Proteínas , ARN Mensajero/genética , Proteínas de Unión al GTP rab5/genéticaRESUMEN
Basic fuchsin has been established as an effective testing agent in determining the extent of microleakage present under restorations. Recently, the presence of microleakage in vivo has been studied through the use of hydroxyl ions as is present in proprietary cavity liners such as Dycal. The purpose of this study was to determine a correlation between the use of these two systems in measuring microleakage. A series of restored human teeth containing a calcium hydroxide liner were thermocycled and then tested with pH indicating paper. The same samples were then given additional thermocycles in 0.5% basic fuchsin dye. The teeth were sectioned in two planes and ranked as to the amount of dye penetration. Over an 18-week period the number of positive pH tests began to diminish while the dye penetration values remained relatively constant. The dye penetration method continued to record microleakage after the pH paper had ceased to detect hydroxyl ions. The dye penetration method appeared to be more dependable as the age of the restoration increased.
