Contribution of Phosphates and Adenine to the Potency of Adenophostins at the IP<sub>3</sub> Receptor: Synthesis of All Possible Bisphosphates of Adenophostin A

Sureshan, Kana M.; Riley, Andrew M.; Thomas, Mark; Tovey, Stephen C.; Taylor, Colin W.; Potter, Barry V. L.

doi:10.1021/jm201571p

Cited by 23 publications

(44 citation statements)

References 54 publications

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“…This is consistent with previous analyses by both functional and binding assays of IP 3 R1 [28], [46]. 3″-dephospho-AdA did, however, cause detectable Ca 2+ release albeit with much reduced potency (Figure 6B).…”

Section: Resultssupporting

confidence: 92%

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Adenophostin A and Its Analogues

et al. 2013

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Inositol 1,4,5-trisphosphate receptors (IP3R) are intracellular Ca2+ channels. Most animal cells express mixtures of the three IP3R subtypes encoded by vertebrate genomes. Adenophostin A (AdA) is the most potent naturally occurring agonist of IP3R and it shares with IP3 the essential features of all IP3R agonists, namely structures equivalent to the 4,5-bisphosphate and 6-hydroxyl of IP3. The two essential phosphate groups contribute to closure of the clam-like IP3-binding core (IBC), and thereby IP3R activation, by binding to each of its sides (the α- and β-domains). Regulation of the three subtypes of IP3R by AdA and its analogues has not been examined in cells expressing defined homogenous populations of IP3R. We measured Ca2+ release evoked by synthetic adenophostin A (AdA) and its analogues in permeabilized DT40 cells devoid of native IP3R and stably expressing single subtypes of mammalian IP3R. The determinants of high-affinity binding of AdA and its analogues were indistinguishable for each IP3R subtype. The results are consistent with a cation-π interaction between the adenine of AdA and a conserved arginine within the IBC α-domain contributing to closure of the IBC. The two complementary contacts between AdA and the α-domain (cation-π interaction and 3″-phosphate) allow activation of IP3R by an analogue of AdA (3″-dephospho-AdA) that lacks a phosphate group equivalent to the essential 5-phosphate of IP3. These data provide the first structure-activity analyses of key AdA analogues using homogenous populations of all mammalian IP3R subtypes. They demonstrate that differences in the Ca2+ signals evoked by AdA analogues are unlikely to be due to selective regulation of IP3R subtypes.

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Section: Resultssupporting

confidence: 92%

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Adenophostin A and Its Analogues

et al. 2013

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“…Contamination of (4,5)IP 2 with (1,4,5)IP 3 cannot explain this activity because (4,5)IP 2 was prepared by total synthesis and purified by ion-exchange chromatography [26]. This is consistent with previous functional analyses of native IP 3 R [45] and with the ability of (4,5)IP 2 to compete with 3 H-(1,4,5)IP 3 for binding to these IP 3 R subtypes heterologously expressed in Sf9 cells [46].…”

Section: Resultsmentioning

confidence: 99%

“…[25]. (4,5)IP 2 [26], 2-deoxy(1,4,5)IP 3 [27] and synthetic (1,3,4,5)IP 4 [28] were synthesized as previously described. All synthesized ligands were purified by ion-exchange chromatography, fully characterized by the usual spectroscopic methods and accurately quantified by total phosphate assay.…”

Section: Methodsmentioning

confidence: 99%

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Analogues of IP3

et al. 2013

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Most animal cells express mixtures of the three subtypes of inositol 1,4,5-trisphosphate receptor (IP3R) encoded by vertebrate genomes. Activation of each subtype by different agonists has not hitherto been examined in cells expressing defined homogenous populations of IP3R. Here we measure Ca2+ release evoked by synthetic analogues of IP3 using a Ca2+ indicator within the lumen of the endoplasmic reticulum of permeabilized DT40 cells stably expressing single subtypes of mammalian IP3R. Phosphorylation of (1,4,5)IP3 to (1,3,4,5)IP4 reduced potency by ∼100-fold. Relative to (1,4,5)IP3, the potencies of IP3 analogues modified at the 1-position (malachite green (1,4,5)IP3), 2-position (2-deoxy(1,4,5)IP3) or 3-position (3-deoxy(1,4,5)IP3, (1,3,4,5)IP4) were similar for each IP3R subtype. The potency of an analogue, (1,4,6)IP3, in which the orientations of the 2- and 3-hydroxyl groups were inverted, was also reduced similarly for all three IP3R subtypes. Most analogues of IP3 interact similarly with the three IP3R subtypes, but the decrease in potency accompanying removal of the 1-phosphate from (1,4,5)IP3 was least for IP3R3. Addition of a large chromophore (malachite green) to the 1-phosphate of (1,4,5)IP3 only modestly reduced potency suggesting that similar analogues could be used to measure (1,4,5)IP3 binding optically. These data provide the first structure-activity analyses of key IP3 analogues using homogenous populations of each mammalian IP3R subtype. They demonstrate broadly similar structure-activity relationships for all mammalian IP3R subtypes and establish the potential utility of (1,4,5)IP3 analogues with chromophores attached to the 1-position.

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“…The bisphosphate analogues of AdA were synthesized via three bespoke routes to analyse the role of each phosphate group in binding to the IP 3 -binding core (IBC) of the IP 3 R. The IBC consists of α-and β-domains which operate like a clam, the closure of which activates channel opening [20]. The contrasting agonist activity of these analogues at the IP 3 R led to a proposed binding model in which any active analogue must engage both domains ( Figure 1B).…”

Section: Agonists and Antagonists For The Ip 3 Rmentioning

confidence: 99%

“…Furthermore, the activity of 2 -dephospho-AdA (107 nM at IP 3 R1, cf. 23 nM for IP 3 ) [20] suggests it is possible to design less polar IP 3 R agonists. At their simplest, future analogues might consist of a simple linker connecting groups to interact with each of the α-and β-domains.…”

Section: Agonists and Antagonists For The Ip 3 Rmentioning

confidence: 99%

Designer small molecules to target calcium signalling

Swarbrick

Riley

Mills

et al. 2015

Biochemical Society Transactions

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Synthetic compounds open up new avenues to interrogate and manipulate intracellular Ca2+ signalling pathways. They may ultimately lead to drug-like analogues to intervene in disease. Recent advances in chemical biology tools available to probe Ca2+ signalling are described, with a particular focus on those synthetic analogues from our group that have enhanced biological understanding or represent a step towards more drug-like molecules. Adenophostin (AdA) is the most potent known agonist at the inositol 1,4,5-trisphosphate receptor (IP3R) and synthetic analogues provide a binding model for receptor activation and channel opening. 2-O-Modified inositol 1,4,5-trisphosphate (IP3) derivatives that are partial agonists at the IP3R reveal key conformational changes of the receptor upon ligand binding. Biphenyl polyphosphates illustrate that simple non-inositol surrogates can be engineered to give prototype IP3R agonists or antagonists and act as templates for protein co-crystallization. Cyclic adenosine 5'-diphosphoribose (cADPR) can be selectively modified using total synthesis, generating chemically and biologically stable tools to investigate Ca2+ release via the ryanodine receptor (RyR) and to interfere with cADPR synthesis and degradation. The first neutral analogues with a synthetic pyrophosphate bioisostere surprisingly retain the ability to release Ca2+, suggesting a new route to membrane-permeant tools. Adenosine 5'-diphosphoribose (ADPR) activates the Ca2+-, Na+- and K+-permeable transient receptor potential melastatin 2 (TRPM2) cation channel. Synthetic ADPR analogues provide the first structure-activity relationship (SAR) for this emerging messenger and the first functional antagonists. An analogue based on the nicotinic acid motif of nicotinic acid adenine dinucleotide phosphate (NAADP) antagonizes NAADP-mediated Ca2+ release in vitro and is effective in vivo against induced heart arrhythmia and autoimmune disease, illustrating the therapeutic potential of targeted small molecules.

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Contribution of Phosphates and Adenine to the Potency of Adenophostins at the IP₃ Receptor: Synthesis of All Possible Bisphosphates of Adenophostin A

Cited by 23 publications

References 54 publications

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Adenophostin A and Its Analogues

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Adenophostin A and Its Analogues

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Analogues of IP3

Designer small molecules to target calcium signalling

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Contribution of Phosphates and Adenine to the Potency of Adenophostins at the IP3 Receptor: Synthesis of All Possible Bisphosphates of Adenophostin A

Cited by 23 publications

References 54 publications

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Adenophostin A and Its Analogues

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Adenophostin A and Its Analogues

Stimulation of Inositol 1,4,5-Trisphosphate (IP3) Receptor Subtypes by Analogues of IP3

Designer small molecules to target calcium signalling

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Contribution of Phosphates and Adenine to the Potency of Adenophostins at the IP₃ Receptor: Synthesis of All Possible Bisphosphates of Adenophostin A