The movement of leukocytes from the blood into peripheral tissues is a central feature of immune surveillance, but also contributes to the pathogenesis of inflammatory and autoimmune diseases. Integrins are a family of adhesion and signaling molecules made up of paired alpha and beta subunits, and the integrin alpha4beta1 plays a prominent role in the trafficking of mononuclear leukocytes. We have previously described the direct interaction of the signaling adaptor molecule paxillin with the cytoplasmic domain of the alpha4 integrin subunit. This interaction is critical for alpha4beta1 integrin dependent cell adhesion under shear flow conditions as it provides a needed connection to the actin cytoskeleton. Furthermore, the alpha4-paxillin interaction is required for effective alpha4beta1 dependent leukocyte migration and does so through the temporal and spatial regulation of the small GTPase Rac. These findings make the alpha4-paxillin interaction a potentially attractive therapeutic target in controlling leukocyte trafficking.
Protein Binding ; Paxillin/*metabolism/physiology ; Models, Biological ; Leukocytes/cytology/*metabolism ; Integrin alpha4beta1/metabolism/physiology ; Integrin alpha4/*metabolism/physiology ; Humans ; Cell Movement/*physiology ; Cell Adhesion/physiology

To demonstrate the effect of AB serum on terminal erythroid differentiation ex vivo.
 Methods: After separation of CD34+ cells from cord blood, the cells were cultured and divided into a control group and an experimental group. The effects of AB serum were examined by the expressions of different markers (GPA, Band3 and α4-integrin) for erythroblast differentiation and enucleation by flow cytometry. 
 Results: The CD34+ cells were successfully differentiated to enucleated red blood cells. There were evident differences among the expressions of GPA, Band3 and α4-integrin between the 2 groups. The percentage of GPA positive cells in the experimental group was bigger than that in the control group in every time point. The expression of Band3 in the experimental group was higher than that in the control group. The expression of α4-integrin in the experimental group was lower than that in the control group. In addition, the enucleation rate in the experimental group was higher than that in the control group.
 Conclusion: AB serum can promote the cell differentiation and enucleation during terminal erythroid differentiation in vitro.
ABO Blood-Group System ; blood ; physiology ; Anion Exchange Protein 1, Erythrocyte ; metabolism ; Antigens, CD34 ; blood ; Cell Differentiation ; genetics ; physiology ; Cell Nucleus ; Cells, Cultured ; Erythrocytes ; physiology ; ultrastructure ; Erythropoiesis ; genetics ; physiology ; Fetal Blood ; cytology ; physiology ; Flow Cytometry ; Glycophorins ; metabolism ; Humans ; Integrin alpha4beta1 ; metabolism

To investigate whether lymphocyte function-associated antigen 1 (LFA-1) and very late antigen 4 (VLA-4) are involved in vasoendothelial adhesion and transendothelial migration of high proliferative potential endothelial progenitor cells (HPP-EPCs), flow cytometry was used to analyze the expression of integrin beta1 and beta2, the expression of intercellular adhesion molecule (ICAM-1, 2) and vascular cell adhesion molecule (VCAM-1) in mouse bone marrow endothelial cells (mBMECs). The adhesion and transmigration through endothelial cells of the HPP-EPCs blocked by functional grade neutralizing antibodies of VLA-4 and LFA-1 were studied in vitro. The results revealed that HPP-EPCs were positive for CD11a and CD49d in HPP-EPCs. The expression of ICAM-1and VCAM-1 of mBMECs increased after activated by IL-1beta and TNF-alpha. The results of adhesion in vitro revealed that the numbers of the adhered and migrated cells in the CD11a antibody group, in the CD49d antibody group and in the combinational antibody group were less than those in the isotype control antibody group. Furthermore, the number of adhered and migrated cells in the combinational antibody group was less than that in the CD11a or the CD49d antibody group (p < 0.05). It is concluded that both LFA-1 and VLA-4 are involved in vasoendothelial adhesion and transendothelial migration of HPP-EPCs.
Animals ; Antigens, CD ; metabolism ; Bone Marrow Cells ; cytology ; Cell Adhesion ; Cell Adhesion Molecules ; metabolism ; Cell Movement ; Cells, Cultured ; Endothelial Cells ; cytology ; Humans ; Integrin alpha4beta1 ; physiology ; Intercellular Adhesion Molecule-1 ; metabolism ; Lymphocyte Function-Associated Antigen-1 ; physiology ; Mice ; Stem Cells ; cytology ; Vascular Cell Adhesion Molecule-1 ; metabolism

To clarify the relationship between VLA-4 (CD49d) expression and hematopoietic cell migrating direction, mice were injected subcutaneously with diluted rhG-CSF for different times. The expressions of CD49d on Sca-1(+) cells were examined by flow cytometry. The relations between CD49d expression and Sca-1(+) cell enumerations were performed by statistical analysis. The results showed that with the administration of G-CSF, the expressions of CD49d in bone marrow (BM) and peripheral blood (PB) declined, meanwhile the number of Sca-1(+) cells in peripheral blood reached the peak in sharp contrast to BM nucleated cell number dropping on the seventh to ninth day. When CD49d expression rose again, the PB Sca-1(+) cells descended with the rising of BM nucleated cell number. In conclusion, VLA-4 mediates the hematopoietic cell adhesion to BM microenvironment. The regulation of CD49d expression may result in different migrating direction of hematopoietic cell between bone marrow and peripheral blood.
Animals ; Bone Marrow Cells ; cytology ; drug effects ; metabolism ; Cell Count ; Cell Movement ; drug effects ; Female ; Flow Cytometry ; Granulocyte Colony-Stimulating Factor ; pharmacology ; Hematopoietic Stem Cell Mobilization ; Hematopoietic Stem Cells ; cytology ; drug effects ; physiology ; Integrin alpha4beta1 ; blood ; Mice ; Mice, Inbred BALB C ; Time Factors