title: Transepithelial projections from basal cells are luminal sensors in pseudostratified epithelia.
abstract: Basal cells are by definition located on the basolateral side of several epithelia, and they have never been observed reaching the lumen. Using high-resolution 3D confocal imaging, we report that basal cells extend long and slender cytoplasmic projections that not only reach toward the lumen but can cross the tight junction barrier in some epithelia of the male reproductive and respiratory tracts. In this way, the basal cell plasma membrane is exposed to the luminal environment. In the epididymis, in which luminal acidification is crucial for sperm maturation and storage, these projections contain the angiotensin II type 2 receptor (AGTR2). Activation of AGTR2 by luminal angiotensin II, increases proton secretion by adjacent clear cells, which are devoid of AGTR2. We propose a paradigm in which basal cells scan and sense the luminal environment of pseudostratified epithelia and modulate epithelial function by a mechanism involving crosstalk with other epithelial cells.
authors.affiliation: Center for Systems Biology, Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Winnie Wai Chi
authors.initials: WW
authors.lastname: Shum
authors.forename: Nicolas
authors.initials: N
authors.lastname: Da Silva
authors.forename: Mary
authors.initials: M
authors.lastname: McKee
authors.forename: Peter J S
authors.initials: PJ
authors.lastname: Smith
authors.forename: Dennis
authors.initials: D
authors.lastname: Brown
authors.forename: Sylvie
authors.initials: S
authors.lastname: Breton
mesh_terms: D000818:Animals; D002450:Cell Communication; D062445:Claudin-1; D004822:Epididymis / Q000166:cytology; D004847:Epithelial Cells / Q000166:cytology; D004848:Epithelium / Q000378:metabolism*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism; D019108:Tight Junctions; D014132:Trachea / Q000166:cytology
chemical_list: C568108:CLDN1 protein, human; D062445:Claudin-1; C568114:Cldn1 protein, rat; D008565:Membrane Proteins; D044139:Receptor, Angiotensin, Type 2