title: Expression and polarity reversal of V-type H+-ATPase during the mineralization-demineralization cycle in Porcellio scaber sternal epithelial cells.
abstract: The formation and resorption of CaCO(3) by epithelial cell layers require epithelial transport of protons. We used the anterior sternal epithelium of the terrestrial isopod Porcellio scaber as a model to study the expression pattern and immunolocalization of a V-type H(+)-ATPase during the mineralization and demineralization of intermittent CaCO(3) deposits. Semiquantitative RT-PCR revealed that the expression of the V-type H(+)-ATPase increases from non Ca(2+)-transporting control stages to the stages of CaCO(3) deposit formation and resorption. In the Ca(2+)-transporting stages the expression was larger in the anterior than in the posterior sternal epithelium, which is not involved in deposit formation and transports just moderate amounts of CaCO(3). Immunocytochemistry of the B-subunit of the V-type H(+)-ATPase in the anterior sternal epithelium reveals an increase in the abundance of the protein within the basolateral membrane, from undetectable to strong signals in the control stage to the stages of CaCO(3) deposit formation, respectively. From the stage of CaCO(3) deposit formation to that of CaCO(3) resorption the signal decreased within the basolateral plasma membrane and increased within the apical plasma membrane. For the first time the results indicate a contribution of a V-type H(+)-ATPase to CaCO(3) deposition and a reversal of its polarity from the basolateral to the apical plasma membrane compartment within the same cells.
authors.affiliation: Central Facility for Electron Microscopy, University of Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany. andreas.ziegler@medizin.uni-ulm.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Ziegler
authors.forename: Dirk
authors.initials: D
authors.lastname: Weihrauch
authors.forename: Monica
authors.initials: M
authors.lastname: Hagedorn
authors.forename: David W
authors.initials: DW
authors.lastname: Towle
authors.forename: Reiner
authors.initials: R
authors.lastname: Bleher
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002119:Calcium Carbonate / Q000378:metabolism*; D017931:DNA Primers; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D015870:Gene Expression; D015151:Immunoblotting; D007150:Immunohistochemistry; D033321:Isopoda / Q000201:enzymology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D018978:Molting / Q000502:physiology*; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D006180:Proton-Translocating ATPases; D002119:Calcium Carbonate