Alpha4beta1 integrin and 190-kDa CD44v constitute a cell surface docking complex for gelatinase B/MMP-9 in chronic leukemic but not in normal B cells.
As B-cell chronic lymphocytic leukemia (B-CLL) progresses, malignant cells extravasate and infiltrate lymphoid tissues. Several molecules, including gelatinase B/MMP-9, contribute to these processes. Although mainly a secreted protease, some MMP-9 is present at the B-CLL cell surface and the function, mode of anchoring, and interactions of this MMP-9 are unknown. Here we show that anti-MMP-9 antibodies immunoprecipitated a 190-kDa CD44v isoform and alpha4beta1 integrin from B-CLL cells, but not from normal B cells. Function-blocking antibodies to alpha4beta1 or CD44, or transfection with specific siRNAs, decreased cell-associated proMMP-9 and increased the secreted form. B-CLL cells attached to and bound proMMP-9 and active MMP-9, and this was inhibited by blocking the expression or function of alpha4beta1 or CD44. The MMP-9 hemopexin domain was critical in these interactions. alpha4beta1 and 190-kDa CD44v (but not CD44H) formed a complex at the cell surface, since they both coimmunoprecipitated with anti-alpha4, anti-beta1, or anti-CD44 antibodies. Immunofluorescence analyses confirmed that alpha4beta1 and CD44v colocalized with MMP-9. Binding of proMMP-9 inhibited B-CLL cell migration, and this required MMP-9 proteolytic activity. Thus, we have identified alpha4beta1 and CD44v as a novel proMMP-9 cell surface docking complex and show that cell-associated MMP-9 may regulate B-CLL cell migration and arrest.
Redondo-Muñoz
Javier
J
Departamento de Fisiopatología Celular y Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
Ugarte-Berzal
Estefanía
E
García-Marco
José A
JA
del Cerro
Mercedes Hernández
MH
Van den Steen
Philippe E
PE
Opdenakker
Ghislain
G
Terol
María José
MJ
García-Pardo
Angeles
A
D000368:Aged; D000369:Aged, 80 and over; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D002448:Cell Adhesion; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D002465:Cell Movement; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D014644:Genetic Variation; D006801:Humans; D018960:Hyaluronan Receptors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D039041:Integrin alpha4beta1 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000201:enzymology* / Q000276:immunology* / Q000473:pathology; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000737:chemistry / Q000378:metabolism*; D008875:Middle Aged; D008970:Molecular Weight; D046912:Multiprotein Complexes; D009361:Neoplasm Invasiveness; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics
C497483:CD44 protein, human; D004792:Enzyme Precursors; D018960:Hyaluronan Receptors; D039041:Integrin alpha4beta1; D046912:Multiprotein Complexes; D020033:Protein Isoforms; D034741:RNA, Small Interfering; C120487:pro-matrix metalloproteinase 9; D020780:Matrix Metalloproteinase 9