The annexin 2-S100A10 complex and its association with TRPV6 is regulated by cAMP/PKA/CnA in airway and gut epithelia

The formation of a heterotetrameric complex between annexin 2 (anx 2) and S100A10 plays an important role in regulating the cellular distribution and biochemical properties of anx 2. A major distinction between the anx 2-S100A10 complex and other annexin-S100 complexes is that S100A10 binding to anx 2 occurs independently of calcium. Here we describe a cyclic 3',5'-adenosine monophosphate (cAMP) and cAMP-dependent protein kinase (PKA, EC 2.7.1.37)-dependent mechanism regulating anx 2-S100A10 complex formation and its interaction with the transient receptor potential vanilloid type 6 channel (TRPV6) in airway and gut epithelia. In both 16HBE14o- and Caco-2 cells, forskolin (FSK) stimulated increased anx 2-S100A10 complex formation, which was attenuated by either PKA inhibitors or calcineurin A (CnA) inhibitors. The anx 2-S100A10 complex association with TRPV6 was dependent on FSK-induced CnA-dependent dephosphorylation of anx 2. Analysis of the significance of the cAMP/PKA/CnA pathway on calcium influx showed that both PKA and CnA inhibitors attenuated Ca-45 uptake in Caco-2, but not 16HBE14o-, cells. Thus, the cAMP/PKA/CnA-induced anx 2-S100A10/TRPV6 complex may require additional factors for calcium influx or play a role independent of calcium influx in airway epithelia. In conclusion, our data demonstrates that cAMP/PKA/CnA signalling is important for anx 2-S100A10 complex formation and interaction with target molecules in both absorptive and secretary epithelia. (C) 2007 Elsevier Ltd. All rights reserved.