Pharmacological Distinction between Soluble and Transmembrane Adenylyl Cyclases

Abstract

The second messenger cAMP is involved in a number of cellular signaling pathways. In mammals, cAMP is produced by either the hormonally responsive, G protein-regulated transmembrane adenylyl cyclases (tmACs) or by the bicarbonate-and calcium-regulated soluble adenylyl cyclase (sAC). To develop tools to differentiate tmAC and sAC signaling, we determined the specificity and potency of commercially available adenylyl cyclase inhibitors. In cellular systems, two inhibitors, KH7 and catechol estrogens, proved specific for sAC, and 29,59-dideoxyadenosine proved specific for tmACs. These tools provide a means to define the specific contributions of the different families of adenylyl cyclases in cells and tissues, which will further our understanding of cell signaling.

Compartmentalization of Distinct cAMP Signaling Pathways in Mammalian Sperm

“…The same authors observed regulation by GTP analogs as well as with mastoparan, a wasp venom toxin known to activate G proteins. In addition, in this study, the effect of FK was blocked by SQ22536, a compound known to inactivate tmACs in several cell types with an IC 50 value that varies depending on the tmAC isoform but not by the specific AdCy10 inhibitor KH7 (44).…”

Crystal structures of human soluble adenylyl cyclase reveal mechanisms of catalysis and of its activation through bicarbonate

“…3D and 4A, GST-tagged sAC-cat lysate was used in a radioactivitybased assay in 50 mM Tris (pH 7.5) under the conditions indicated in a reaction containing ∼1,000,000 counts of α-32 P-labeled ATP as described previously (47). Generated cAMP was purified using sequential Dowex and Alumina chromatography as described previously (48).…”

International Union of Basic and Clinical Pharmacology. CI. Structures and Small Molecule Modulators of Mammalian Adenylyl Cyclases

“…Overall, there is reasonably good agreement in the obtained pIC 50 values (Table 7). SQ22,536, NKY80, and vidarabine exhibit some degree of selectivity among AC isoforms, AC2 being relatively insensitive compared with ACs 5 and 6 (Bitterman et al, 2013). ACs 8 and 9 and sAC are very resistant to inhibition by SQ22,536, NKY80, and vidarabine.…”

“…Data for mACs 1, 2, and 5 and 5C1:2C2 were taken from the literature as noted by the footnotes. Bitterman et al, 2013;Braeunig et al, 2013;Braeunig et al, 2014). Table 7 lists the pIC 50 values of these compounds for inhibition of ACs and pK i values for interaction with adenosine receptors.…”

“…The compound has only been incompletely characterized so far at defined AC isoforms. MDL 12,330A inhibits a lysate of mAC with a pIC 50 of 3.4 and purified sAC with a pIC 50 of 3.6 (Bitterman et al, 2013). Thus, MDL 12,330A does not discriminate between mACs and sAC, and the potency of the compound is lower than the potency of many membrane-permeable P-site inhibitors (Table 7).…”