Plasticity in the epithelial polarity of renal intercalated cells :
targeting of the h+ atpase and band 3 .
Al-Awqati, Qais.
College of Physicians and Surgeons of Columbia University, 630 W.
168th St, New York, NY, 10032, Tel212-305-3512, Fax212-305-3475, E
-mail qa1@columbia.edu
APStracts 2:0376C, 1995.
The intercalated cell is an epithelial cell of the renal collecting
tubule that is specialized for H+ and HCO3 transport. These cells
exist in two types, [alpha] and [beta]. The [alpha] cell secretes H+
into the lumen by an apical H+ ATPase and a basolateral Cl:HCO3
exchanger that is a form of band 3 (AE1). The [beta] cell secretes
HCO3- into the lumen by an apical Cl:HCO3 and a basolateral H+
ATPase. In a previous study, we suggested that a reversal in
epithelial polarity of these cells occurs during the repsonse of the
kidney to an acid load (Nature 318:368-371. 1985). Recent studies,
however have shown that there are many other subtypes where the
distribution of these two proteins does not fit into this neat
bipolar classification. We recently generated an immortalized cell
line of the [beta] intercalated cell and found that the apical
Cl:HCO3 is also AE1. Further, when these cells were seeded at high
densities, the polarized targeting of the apical band 3 was reveresed
to the basolateral membrane. This was produced by the secretion of
extracellular matrix proteins which by themselves were capable of
reversing the polarity of band 3 (Cell 76:1053-1061. 1995). A large
new extracellular matrix protein, hensin was identified and found to
be present exclusively in the collecting tubule.
Received 6 July 1995; accepted in final form 10 October 1995.
APS Manuscript Number C407-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95