The role of aquaporins in dendritic cell macropinocytosis.
Immature dendritic cells (DCs) constitutively take up large volumes of fluid by macropinocytosis and concentrate the macrosolutes in the endocytic compartment. This concentration mechanism that is the basis of their high capacity to present soluble antigens requires that DCs be capable of rapidly exchanging water across their membranes. We report that two members of the aquaporin family, AQP3 and AQP7, are expressed in immature DCs and are downregulated after maturation. Treatment of DCs with p-chloromercuribenzenesulphonate (pCMBS), a mercuric drug that blocks aquaporins, inhibited uptake and concentration of macrosolutes taken up by fluid phase endocytosis and led to dramatic cell swelling. In contrast, pCMBS did not affect receptor-mediated endocytosis via the mannose receptor. These findings indicate that aquaporins represent essential elements of a volume control mechanism that allows DCs to concentrate macrosolutes taken up via macropinocytosis.
de Baey
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Basel Institute for Immunology, CH-4005 Basel, Switzerland.
Lanzavecchia
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D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D051400:Aquaporin 3; D020346:Aquaporins / Q000235:genetics / Q000502:physiology*; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006801:Humans; D007473:Ion Channels / Q000235:genetics / Q000502:physiology*; D007700:Kinetics; D009000:Monocytes / Q000166:cytology / Q000276:immunology; D010873:Pinocytosis / Q000187:drug effects / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
C496027:AQP3 protein, human; C114141:AQP7 protein, human; D020346:Aquaporins; D007473:Ion Channels; D051400:Aquaporin 3; D002731:4-Chloromercuribenzenesulfonate