Exocytosis of vacuolar apical compartment (VAC) in Madin-Darby canine kidney epithelial cells: CAMP is involved as second messenger

Mirtha Brignoni, Ernesto J. Podesta, Pablo Mele, Marcelo L. Rodriguez, Dora E. Vega-Salas, Pedro J Salas

Research output: Contribution to journalArticle

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Abstract

Vacuolar apical compartment (VAC) is a transient organelle originally observed in Madin-Darby canine kidney (MDCK) epithelial cells impaired from forming cell-cell contacts. VACs are large vacuoles which contain microvilli and apical plasma membrane markers (among others, a 184-kDa plasma membrane protein, AP2), but exclude basolateral membrane markers. Upon reestablishment of cell-cell contacts, VACs are rapidly (within 1 h) exocytosed toward intercellular spaces, after which the apical plasma membrane drifts toward its final destination (Vega-Salas, Salas, and Rodriguez-Boulan. 1988. J. Cell Biol. 107, 1717-1728). In this work, we studied the role of cAMP as a mediator for the exocytosis of VACs. We shifted confluent cells from low to normal calcium medium (thus reestablishing cell-cell contacts and causing VAC exocytosis), a shift which resulted in a significant rise of cellular levels of both total intracellular and protein-bound cAMP. The 8-Br analog of cAMP (8-Br-cAMP) (5-50 μM) caused externalization of the intracellular compartment of AP2 as measured by radioimmunoassay. A similar effect was observed with 3-isobutyl-1-methylxanthine. 8-Br-cAMP also caused the appearance of AP2-positive VAC images in nonpermeabilized cells, namely, VACs that become accessible to extracellular antibodies upon fusion with the plasma membrane. Lanthanum, which abolishes the peak of intracellular free calcium during a calcium switch, failed to block the exocytosis. On the other hand, 12-O-tetradecanoylphorbol-13-acetate induced only a modest exocytic response. Finally, 8-Br-cAMP induced VAC exocytosis in sparse MDCK cells grown in normal calcium medium. These data indicate that cAMP is a mediator between the extracellular signal provided by cell-cell contacts and VAC exocytosis.

Original languageEnglish
Pages (from-to)171-178
Number of pages8
JournalExperimental Cell Research
Volume205
Issue number1
StatePublished - Dec 1 1993

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Madin Darby Canine Kidney Cells
Exocytosis
Second Messenger Systems
Epithelial Cells
Cell Membrane
Calcium
1-Methyl-3-isobutylxanthine
Lanthanum
Extracellular Space
Tetradecanoylphorbol Acetate
Microvilli
Vacuoles
Organelles
Radioimmunoassay
Blood Proteins
Membrane Proteins

ASJC Scopus subject areas

  • Cell Biology

Cite this

Exocytosis of vacuolar apical compartment (VAC) in Madin-Darby canine kidney epithelial cells : CAMP is involved as second messenger. / Brignoni, Mirtha; Podesta, Ernesto J.; Mele, Pablo; Rodriguez, Marcelo L.; Vega-Salas, Dora E.; Salas, Pedro J.

In: Experimental Cell Research, Vol. 205, No. 1, 01.12.1993, p. 171-178.

Research output: Contribution to journalArticle

Brignoni, Mirtha ; Podesta, Ernesto J. ; Mele, Pablo ; Rodriguez, Marcelo L. ; Vega-Salas, Dora E. ; Salas, Pedro J. / Exocytosis of vacuolar apical compartment (VAC) in Madin-Darby canine kidney epithelial cells : CAMP is involved as second messenger. In: Experimental Cell Research. 1993 ; Vol. 205, No. 1. pp. 171-178.
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