Syndecan-4 is expressed by B lineage lymphocytes and can transmit a signal for formation of dendritic processes.
Our previous studies indicated that stromal cell-derived syndecan-4 might mediate some form of communication with pre-B cells in bone marrow. We now report additional aspects of this recognition and show that syndecan-4 is also present on pre-B cells. Indeed, the molecule is acquired at an early stage of differentiation and retained until mature B cells undergo Ig isotype switching. mAbs developed to two portions of the syndecan-4 protein core were used to probe possible functions on B lineage lymphocytes. Syndecan-4 ligation had no obvious influence on B lymphocyte formation or activation, but this treatment caused a dramatic morphological change in appropriately stimulated leukocytes. Extended filopodia appeared on transfected Ba/F3 or FDCP-1 cells, as well as activated B cell blasts that were placed on syndecan-4 Ab-coated surfaces. The dendritic processes contained polymerized actin as well as pp52(LSP1), a prominent F-actin binding protein in lymphocytes. The cytoplasmic domain of syndecan-4 was not required for this response. Shape changes of this type could facilitate interactions between B lymphocytes and other components of the immune system. Not only is syndecan-4 a useful marker for discriminating normal B lineage lymphocyte subsets, but our results suggest new ways for the syndecans to participate in immune responses.
Yamashita
Y
Y
Oklahoma Medical Research Foundation, Immunobiology and Cancer Program, Oklahoma City, OK 73104, USA.
Oritani
K
K
Miyoshi
E K
EK
Wall
R
R
Bernfield
M
M
Kincade
P W
PW
D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D001854:Bone Marrow Cells / Q000276:immunology; D019070:Cell Lineage; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D006497:Heparan Sulfate / Q000378:metabolism; D017578:Immunoglobulin Class Switching; D008213:Lymphocyte Activation; D008221:Lymphoid Tissue / Q000276:immunology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D010537:Peritoneum / Q000166:cytology / Q000276:immunology; D011509:Proteoglycans / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011554:Pseudopodia; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D017154:Stromal Cells / Q000276:immunology; D053671:Syndecan-4
D006497:Heparan Sulfate; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D011509:Proteoglycans; D011993:Recombinant Fusion Proteins; D053671:Syndecan-4; C508306:Sdc4 protein, mouse