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Triarylmethanes, a new class of cx50 inhibitors.

Bodendiek SB, Rubinos C, Trelles MP, Coleman N, Jenkins DP, Wulff H, Srinivas M - Front Pharmacol (2012)

Bottom Line: We initially screened a library of common ion channel modulating pharmacophores for their inhibitory effects on Cx50 GJ channels, and identified four new classes of compounds.The SAR studies also indicated that the TRAM pharmacophore required for connexin inhibition is significantly different from the pharmacophore required for blocking the calcium-activated KCa3.1 channel.In addition, our results indicate that a similar approach may be used to find specific inhibitors of other connexin subtypes.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of California Davis, CA, USA.

ABSTRACT
The paucity of specific pharmacological agents has been a major impediment for delineating the roles of gap junction (GJ) channels formed by connexin proteins in physiology and pathophysiology. Here, we used the selective optimization of side activities (SOSA) approach, which has led to the design of high affinity inhibitors of other ion channels, to identify a specific inhibitor for channels formed by Cx50, a connexin subtype that is primarily expressed in the lens. We initially screened a library of common ion channel modulating pharmacophores for their inhibitory effects on Cx50 GJ channels, and identified four new classes of compounds. The triarlymethane (TRAM) clotrimazole was the most potent Cx50 inhibitor and we therefore used it as a template to explore the structure activity relationship (SAR) of the TRAMs for Cx50 inhibition. We describe the design of T122 (N-[(2-methoxyphenyl)diphenylmethyl]-1,3-thiazol-2-amine) and T136 (N-[(2-iodophenyl)diphenylmethyl]-1,3-thiazol-2-amine), which inhibit Cx50 with IC(50)s of 1.2 and 2.4 μM. Both compounds exhibit at least 10-fold selectivity over other connexins as well as major neuronal and cardiac voltage-gated K(+) and Na(+) channels. The SAR studies also indicated that the TRAM pharmacophore required for connexin inhibition is significantly different from the pharmacophore required for blocking the calcium-activated KCa3.1 channel. Both T122 and T136 selectively inhibited Cx50 GJ channels in lens epithelial cells, suggesting that they could be used to further explore the role of Cx50 in the lens. In addition, our results indicate that a similar approach may be used to find specific inhibitors of other connexin subtypes.

No MeSH data available.


Related in: MedlinePlus

T122 and T136 reduce junctional conductance in lens epithelial cells. (A) Effect of 10 μM T122 (top) and 10 μM T136 (bottom) on junctional currents in epithelial cells isolated from P6 lenses. The magnitude of inhibition is similar to that produced by quinine. The recordings in T122 and T136 are from two different cell pairs. (B) Bar graph summarizing the effect of T122 (10 μM) and T136 (10 μM), compared to that of quinine on coupling in epithelial cells. Each bar represents the mean ± SEM of four to six cell pairs.
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Figure 8: T122 and T136 reduce junctional conductance in lens epithelial cells. (A) Effect of 10 μM T122 (top) and 10 μM T136 (bottom) on junctional currents in epithelial cells isolated from P6 lenses. The magnitude of inhibition is similar to that produced by quinine. The recordings in T122 and T136 are from two different cell pairs. (B) Bar graph summarizing the effect of T122 (10 μM) and T136 (10 μM), compared to that of quinine on coupling in epithelial cells. Each bar represents the mean ± SEM of four to six cell pairs.

Mentions: Cx50 is strongly expressed in the lens in both the epithelium and in fibers. In the epithelium, the functional contribution of Cx50 to epithelial cell coupling is highest during the first postnatal week (∼70–75% of total coupling on average) with the remainder being contributed by Cx43. Therefore, we determined whether T122 and T136 (10 μM) also inhibited coupling provided by Cx50 in epithelial cells (Figure 8). The effect of T122 and T136 on junctional currents between epithelial cells isolated from mouse lenses on postnatal day 6 is shown in Figure 8A. Both compounds strongly reduced junctional currents, an effect that was reversible on washout of the drug. The reduction of junctional currents caused by T122 and T136 ranged from 65 to 87% of the initial conductance (means ± SEM are 67 ± 9%, n = 7 for T122; and 64 ± 8%, n = 6 for T136). These values were similar to the reduction produced by quinine, which also selectively inhibits Cx50, but not Cx43 GJ channels (Figure 8B).


Triarylmethanes, a new class of cx50 inhibitors.

Bodendiek SB, Rubinos C, Trelles MP, Coleman N, Jenkins DP, Wulff H, Srinivas M - Front Pharmacol (2012)

T122 and T136 reduce junctional conductance in lens epithelial cells. (A) Effect of 10 μM T122 (top) and 10 μM T136 (bottom) on junctional currents in epithelial cells isolated from P6 lenses. The magnitude of inhibition is similar to that produced by quinine. The recordings in T122 and T136 are from two different cell pairs. (B) Bar graph summarizing the effect of T122 (10 μM) and T136 (10 μM), compared to that of quinine on coupling in epithelial cells. Each bar represents the mean ± SEM of four to six cell pairs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368247&req=5

Figure 8: T122 and T136 reduce junctional conductance in lens epithelial cells. (A) Effect of 10 μM T122 (top) and 10 μM T136 (bottom) on junctional currents in epithelial cells isolated from P6 lenses. The magnitude of inhibition is similar to that produced by quinine. The recordings in T122 and T136 are from two different cell pairs. (B) Bar graph summarizing the effect of T122 (10 μM) and T136 (10 μM), compared to that of quinine on coupling in epithelial cells. Each bar represents the mean ± SEM of four to six cell pairs.
Mentions: Cx50 is strongly expressed in the lens in both the epithelium and in fibers. In the epithelium, the functional contribution of Cx50 to epithelial cell coupling is highest during the first postnatal week (∼70–75% of total coupling on average) with the remainder being contributed by Cx43. Therefore, we determined whether T122 and T136 (10 μM) also inhibited coupling provided by Cx50 in epithelial cells (Figure 8). The effect of T122 and T136 on junctional currents between epithelial cells isolated from mouse lenses on postnatal day 6 is shown in Figure 8A. Both compounds strongly reduced junctional currents, an effect that was reversible on washout of the drug. The reduction of junctional currents caused by T122 and T136 ranged from 65 to 87% of the initial conductance (means ± SEM are 67 ± 9%, n = 7 for T122; and 64 ± 8%, n = 6 for T136). These values were similar to the reduction produced by quinine, which also selectively inhibits Cx50, but not Cx43 GJ channels (Figure 8B).

Bottom Line: We initially screened a library of common ion channel modulating pharmacophores for their inhibitory effects on Cx50 GJ channels, and identified four new classes of compounds.The SAR studies also indicated that the TRAM pharmacophore required for connexin inhibition is significantly different from the pharmacophore required for blocking the calcium-activated KCa3.1 channel.In addition, our results indicate that a similar approach may be used to find specific inhibitors of other connexin subtypes.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of California Davis, CA, USA.

ABSTRACT
The paucity of specific pharmacological agents has been a major impediment for delineating the roles of gap junction (GJ) channels formed by connexin proteins in physiology and pathophysiology. Here, we used the selective optimization of side activities (SOSA) approach, which has led to the design of high affinity inhibitors of other ion channels, to identify a specific inhibitor for channels formed by Cx50, a connexin subtype that is primarily expressed in the lens. We initially screened a library of common ion channel modulating pharmacophores for their inhibitory effects on Cx50 GJ channels, and identified four new classes of compounds. The triarlymethane (TRAM) clotrimazole was the most potent Cx50 inhibitor and we therefore used it as a template to explore the structure activity relationship (SAR) of the TRAMs for Cx50 inhibition. We describe the design of T122 (N-[(2-methoxyphenyl)diphenylmethyl]-1,3-thiazol-2-amine) and T136 (N-[(2-iodophenyl)diphenylmethyl]-1,3-thiazol-2-amine), which inhibit Cx50 with IC(50)s of 1.2 and 2.4 μM. Both compounds exhibit at least 10-fold selectivity over other connexins as well as major neuronal and cardiac voltage-gated K(+) and Na(+) channels. The SAR studies also indicated that the TRAM pharmacophore required for connexin inhibition is significantly different from the pharmacophore required for blocking the calcium-activated KCa3.1 channel. Both T122 and T136 selectively inhibited Cx50 GJ channels in lens epithelial cells, suggesting that they could be used to further explore the role of Cx50 in the lens. In addition, our results indicate that a similar approach may be used to find specific inhibitors of other connexin subtypes.

No MeSH data available.


Related in: MedlinePlus