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A role for annexin IV in epithelial cell function. Inhibition of calcium-activated chloride conductance.

1994; Elsevier BV; Volume: 269; Issue: 7 Linguagem: Inglês

10.1016/s0021-9258(17)37687-1

1083-351X

Marcia A. Kaetzel, Hsiao Chang Chan, William P. Dubinsky, John Dedman, Deborah J. Nelson,

Ion channel regulation and function

The cellular function of annexin IV was evaluated by correlating tissue expression, cellular localization, and whole-cell electrophysiology. Immunolocalization and biochemical data demonstrate that annexin IV is concentrated along the apical membranes of many epithelia. Introduction of purified exogenous annexin IV into colonic T84 cells through a patch pipette specifically prevented Ca(2+)-dependent Cl- current activation. Affinity-purified antibody against annexin IV applied in the same manner enhanced the activation. Reduction of the endogenous level of annexin IV with a derivatized oligodeoxynucleotide antisense to annexin IV mRNA lowered the threshold for the Ca(2+)-induced current response, mimicking the enhancement of current activation exerted by anti-annexin IV antibody. The inhibitory effect of annexin IV on Ca(2+)-dependent Cl- conductance represents a novel mechanism by which Ca(2+)-binding proteins modulate membrane channel activity.