TY - JOUR
T1 - The transmembrane domains of L-selectin and CD44 regulate receptor cell surface positioning and leukocyte adhesion under flow
AU - Buscher, Konrad
AU - Riese, Sebastian B.
AU - Shakibaei, Mehdi
AU - Reich, Christian
AU - Dernedde, Jens
AU - Tauber, Rudolf
AU - Ley, Klaus
PY - 2010/4/30
Y1 - 2010/4/30
N2 - During inflammation and immune surveillance, initial contacts (tethering) between free-flowing leukocytes and the endothelium are vitally dependent on the presentation of the adhesion receptor L-selectin on leukocyte microvilli. Determinants that regulate receptor targeting to microvilli are, however, largely elusive. Therefore, we systematically swapped the extracellular (EC), transmembrane (TM), and intracellular (IC) domains of L-selectin and CD44, a hyaluronan receptor expressed on the cell body and excluded from microvilli. Electron microscopy of transfected human myeloid K562 cells showed that the highly conserved TM domains are responsible for surface positioning. The TM segment of L-selectin forced chimeric molecules to microvilli, and the CD44 TM domain evoked expression on the cell body, whereas the IC and EC domains hardly influenced surface localization. Transfectants with microvillus-based chimeras showed a significantly higher adhesion rate under flow but not under static conditions compared with cells with cell body-expressed receptors. Substitution of the IC domain of L-selectin caused diminished tethering but no change in surface distribution, indicating that both microvillus positioning and cytoskeletal anchoring contribute to leukocyte tethering. These findings demonstrate that TM domains of L-selectin and CD44 play a crucial role in cell adhesion under flow by targeting receptors to microvilli or the cell body, respectively.
AB - During inflammation and immune surveillance, initial contacts (tethering) between free-flowing leukocytes and the endothelium are vitally dependent on the presentation of the adhesion receptor L-selectin on leukocyte microvilli. Determinants that regulate receptor targeting to microvilli are, however, largely elusive. Therefore, we systematically swapped the extracellular (EC), transmembrane (TM), and intracellular (IC) domains of L-selectin and CD44, a hyaluronan receptor expressed on the cell body and excluded from microvilli. Electron microscopy of transfected human myeloid K562 cells showed that the highly conserved TM domains are responsible for surface positioning. The TM segment of L-selectin forced chimeric molecules to microvilli, and the CD44 TM domain evoked expression on the cell body, whereas the IC and EC domains hardly influenced surface localization. Transfectants with microvillus-based chimeras showed a significantly higher adhesion rate under flow but not under static conditions compared with cells with cell body-expressed receptors. Substitution of the IC domain of L-selectin caused diminished tethering but no change in surface distribution, indicating that both microvillus positioning and cytoskeletal anchoring contribute to leukocyte tethering. These findings demonstrate that TM domains of L-selectin and CD44 play a crucial role in cell adhesion under flow by targeting receptors to microvilli or the cell body, respectively.
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U2 - 10.1074/jbc.M110.102640
DO - 10.1074/jbc.M110.102640
M3 - Article
C2 - 20212041
AN - SCOPUS:77951562762
SN - 0021-9258
VL - 285
SP - 13490
EP - 13497
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 18
ER -