Flotillins are involved in the polarization of primitive and mature hematopoietic cells.
BACKGROUND
Migration of mature and immature leukocytes in response to chemokines is not only essential during inflammation and host defense, but also during development of the hematopoietic system. Many molecules implicated in migratory polarity show uniform cellular distribution under non-activated conditions, but acquire a polarized localization upon exposure to migratory cues.


RESULTS
Here, we present evidence that raft-associated endocytic proteins (flotillins) are pre-assembled in lymphoid, myeloid and primitive hematopoietic cells and accumulate in the uropod during migration. Furthermore, flotillins display a polarized distribution during immunological synapse formation. Employing the membrane lipid-order sensitive probe Laurdan, we show that flotillin accumulation in the immunological synapse is concomittant with membrane ordering in these regions.


CONCLUSIONS
Together with the observation that flotillin polarization does not occur in other polarized cell types such as polarized epithelial cells, our results suggest a specific role for flotillins in hematopoietic cell polarization. Based on our results, we propose that in hematopoietic cells, flotillins provide intrinsic cues that govern segregation of certain microdomain-associated molecules during immune cell polarization.
Rajendran
Lawrence
L
Systems and Cell Biology of Neurodegeneration, Department of Psychiatry Research, University of Zurich, Zurich, Switzerland. rajendran@bli.uzh.ch
Beckmann
Julia
J
Magenau
Astrid
A
Boneberg
Eva-Maria
EM
Gaus
Katharina
K
Viola
Antonella
A
Giebel
Bernd
B
Illges
Harald
H
D000199:Actins / Q000378:metabolism; D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D016764:Cell Polarity / Q000187:drug effects; D054377:Chemokine CXCL12 / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D006801:Humans; D054992:Immunological Synapses / Q000187:drug effects / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects
D000199:Actins; D018952:Antigens, CD34; D015415:Biomarkers; D054377:Chemokine CXCL12; D008565:Membrane Proteins; C106354:flotillins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor