Mice lacking the signaling molecule CalDAG-GEFI represent a model for leukocyte adhesion deficiency type III

• Published in: The Journal of clinical investigation Vol. 117; no. 6; pp. 1699 - 1707
• Main Authors: Bergmeier, Wolfgang, Goerge, Tobias, Wang, Hong-Wei, Crittenden, Jill R, Baldwin, Andrew C W, Cifuni, Stephen M, Housman, David E, Graybiel, Ann M, Wagner, Denisa D
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 01.06.2007
• Subjects: Animals; Blood Platelets - metabolism; CD18 Antigens - metabolism; Disease Models, Animal; Genetically modified mice; Guanine Nucleotide Exchange Factors - deficiency; Guanine Nucleotide Exchange Factors - genetics; Guanine Nucleotide Exchange Factors - metabolism; Humans; In Vitro Techniques; Integrin beta1 - metabolism; Integrin beta3 - metabolism; Leukocyte disorders; Leukocyte-Adhesion Deficiency Syndrome - etiology; Leukocyte-Adhesion Deficiency Syndrome - genetics; Leukocyte-Adhesion Deficiency Syndrome - metabolism; Male; Mice; Mice, Inbred BALB C; Mice, Knockout; Neutrophils - metabolism; Platelet Activation; rap1 GTP-Binding Proteins - metabolism; Thrombosis - etiology; Thrombosis - prevention & control; United States
• ISSN: 0021-9738
• DOI: 10.1172/jci30575

Single gene mutations in beta integrins can account for functional defects of individual cells of the hematopoietic system. In humans, mutations in beta(2) integrin lead to leukocyte adhesion deficiency (LAD) syndrome and mutations in beta(3) integrin cause the bleeding disorder Glanzmann thrombasthenia. However, multiple defects in blood cells involving various beta integrins (beta(1), beta(2), and beta(3)) occur simultaneously in patients with the recently described LAD type III (LAD-III). Here we show that the product of a single gene, Ca(2+) and diacylglycerol-regulated guanine nucleotide exchange factor I (CalDAG-GEFI), controlled the activation of all 3 integrins in the hematopoietic system. Neutrophils from CalDAG-GEFI(-/-) mice exhibited strong defects in Rap1 and beta(1) and beta(2) integrin activation while maintaining normal calcium flux, degranulation, and ROS generation. Neutrophils from CalDAG-GEFI-deficient mice failed to adhere firmly to stimulated venules and to migrate into sites of inflammation. Furthermore, CalDAG-GEFI regulated the activation of beta(1) and beta(3) integrins in platelets, and CalDAG-GEFI deficiency caused complete inhibition of arterial thrombus formation in mice. Thus, mice engineered to lack CalDAG-GEFI have a combination of defects in leukocyte and platelet functions similar to that of LAD-III patients.