A novel form of integrin dysfunction involving beta1, beta2, and beta3 integrins.
The adhesion receptors known as integrins perform key functions for hematopoietic cells. The platelet integrin alphaIIbbeta3 is critical in hemostasis, and the beta1 and beta2 integrins on leukocytes have many roles in cell-mediated immunity. Mutations in the beta2 subunit lead to integrin nonexpression and to an immune deficiency, leukocyte adhesion deficiency-1. Mutations in either the alpha or beta subunit of alphaIIbbeta3 usually lead to integrin nonexpression and a bleeding tendency termed Glanzmann thrombasthenia. Here we describe a unique patient with clinical features of both Glanzmann thrombasthenia and leukocyte adhesion deficiency-1. The patient has normal expression of beta1, beta2, and beta3 integrins, but all are dysfunctional. The key findings are that "inside-out" signaling pathways leading to integrin activation are defective and that this is associated with abnormal integrin clustering. The integrins themselves are intact and capable of function following extracellular stimulation. T cell motility is normal, as are the expression levels and electrophoretic characteristics of all cytoskeletal and signaling proteins tested, except PKC-alpha, which has enhanced expression in the patient's cells. To our knowledge, this is the first description of a dysfunction affecting three classes of integrins. We propose that it is caused by a lesion in an intracellular factor or signaling pathway essential for integrin activation in hematopoietic cells and results in lack of regulation of clustering, an essential component of integrin-mediated adhesion.
McDowall
Alison
A
Leukocyte Adhesion Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom.
Inwald
David
D
Leitinger
Birgit
B
Jones
Alison
A
Liesner
Ri
R
Klein
Nigel
N
Hogg
Nancy
N
D001792:Blood Platelets / Q000378:metabolism; D015153:Blotting, Western; D018821:CD18 Antigens / Q000096:biosynthesis / Q000502:physiology*; D002448:Cell Adhesion; D002675:Child, Preschool; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005434:Flow Cytometry; D006487:Hemostasis; D006801:Humans; D039041:Integrin alpha4beta1 / Q000096:biosynthesis; D039081:Integrin alpha5beta1 / Q000096:biosynthesis; D019012:Integrin beta1 / Q000096:biosynthesis / Q000502:physiology*; D039661:Integrin beta3 / Q000096:biosynthesis / Q000502:physiology*; D016023:Integrins / Q000096:biosynthesis; D007527:Isoenzymes / Q000096:biosynthesis; D018370:Leukocyte-Adhesion Deficiency Syndrome / Q000378:metabolism*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000096:biosynthesis; D016177:Macrophage-1 Antigen / Q000096:biosynthesis; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D009504:Neutrophils / Q000378:metabolism; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000096:biosynthesis; D011485:Protein Binding; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000096:biosynthesis / Q000378:metabolism; D051571:Protein Kinase C-alpha; D015398:Signal Transduction; D013915:Thrombasthenia / Q000378:metabolism*; D013997:Time Factors
D018821:CD18 Antigens; D039041:Integrin alpha4beta1; D039081:Integrin alpha5beta1; D019012:Integrin beta1; D039661:Integrin beta3; D016023:Integrins; D007527:Isoenzymes; D016169:Lymphocyte Function-Associated Antigen-1; D016177:Macrophage-1 Antigen; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D020033:Protein Isoforms; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha