Aphthasol
Three distinct anti-allergic drugs, amlexanox, cromolyn and tranilast, bind to S100A12 and S100A13 of the S100 protein family.

Shishibori T, Oyama Y, Matsushita O, Yamashita K, Furuichi H, Okabe A, Maeta H, Hata Y, Kobayashi R.

Department of Chemistry, Kagawa Medical University, 1750-1, Miki-cho, Kita-gun, 761-0793 Kagawa, Japan.

To investigate the roles of calcium-binding proteins in degranulation, we used three anti-allergic drugs, amlexanox, cromolyn and tranilast, which inhibit IgE-mediated degranulation of mast cells, as molecular probes in affinity chromatography. All of these drugs, which have different structures but similar function, scarcely bound to calmodulin in bovine lung extract, but bound to the same kinds of calcium-binding proteins, such as the 10-kDa proteins isolated in this study, calcyphosine and annexins I-V. The 10-kDa proteins obtained on three drug-coupled resins and on phenyl-Sepharose were analysed by reversed-phase HPLC. It was found that two characteristic 10-kDa proteins, one polar and one less polar, were bound with all three drugs, although S100A2 (S100L), of the S100 family, was bound with phenyl-Sepharose. The cDNA and deduced amino acid sequence proved our major polar protein to be identical with the calcium-binding protein in bovine amniotic fluid (CAAF1, S100A12). The cDNA and deduced amino acid sequence of the less-polar protein shared 95% homology with human and mouse S100A13. In addition, it was demonstrated that the native S100A12 and recombinant S100A12 and S100A13 bind to immobilized amlexanox. On the basis of these findings, we speculate that the three anti-allergic drugs might inhibit degranulation by binding with S100A12 and S100A13.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10051426&dopt=Abstract amlexanox Aphthasol



Aphthasol
Interaction of S100 proteins with the antiallergic drugs, olopatadine, amlexanox, and cromolyn: identification of putative drug binding sites on S100A1 protein.

Okada M, Tokumitsu H, Kubota Y, Kobayashi R.

Department of Chemistry, Department of Dermatology, Kagawa Medical University, 1750-1, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.

S100 proteins are a multigenic family of low-molecular-weight Ca(2+)-binding proteins comprising 19 members. These proteins undergo a conformational change by Ca(2+)-binding and consequently interact with their target proteins. Recently, we reported that two antiallergic drugs, Amlexanox and Cromolyn, bind to S100A12 and S100A13 of the S100 protein family. In the present study, we used a newly developed antiallergic drug, Olopatadine, as a ligand for affinity chromatography and examined binding specificity of the drug to S100 protein family. Olopatadine binds specifically to S100 proteins, such as S100A1, S100B, S100L, S100A12, and S100A13, in a Ca(2+)-dependent manner but not to calmodulin. Mutagenesis study showed that amino acid residues 76-85 in S100A1 are necessary for its binding to Olopatadine. In contrast, residues 89-94 were identified as an Amlexanox-binding site in S100A1. Moreover, Olopatadine did not competitively inhibit S100A1-binding site of Amlexanox. Furthermore, we showed that Olopatadine inhibited the binding of S100A1 target protein's binding site peptides to S100A1. These results indicate that C-terminal region of S100A1 is important for antiallergic drug binding, although the drug binding sites are different according to each antiallergic drug. Differences in the binding sites of S100A1 to antiallergic drugs suggest that the regulatory functions of S100 proteins may exist in several regions. Therefore, these drugs may serve as useful tools for evaluating the physiological significance of S100 protein family. (c)2002 Elsevier Science (USA).

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11944917&dopt=Abstract amlexanox Aphthasol



Aphthasol
Hsp90 is a direct target of the anti-allergic drugs disodium cromoglycate and amlexanox.

Okada M, Itoh H, Hatakeyama T, Tokumitsu H, Kobayashi R.

Department of Signal Transduction Sciences, Kagawa Medical University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.

Hsp90 (heat-shock protein 90) alone can act to prevent protein aggregation and promote refolding in vitro, but in vivo it operates as a part of a multichaperone complex, which includes Hsp70 and cohort proteins. Since the physiological function of Hsp90 is not yet fully understood, the development of specific antagonists might open new lines of investigation on the role of Hsp90. In an effort to discover Hsp90 antagonists, we screened many drugs and found that the anti-allergic drugs DSCG (disodium cromoglycate) and amlexanox target Hsp90. Both drugs were found to bind directly wild-type Hsp90 via the N- and C-terminal domains. Both drugs strongly suppressed the in vitro chaperone activity of native Hsp90 towards citrate synthase at 1.5-3.0 microM. Amlexanox suppressed C-terminal chaperone activity in vitro, but not N-terminal chaperone activity, and inhibited the association of cohort proteins, such as cyclophilin 40 and Hsp-organizing protein, to the C-terminal domain of Hsp90. These data suggest that amlexanox might disrupt the multichaperone complex, including Hsp70 and cohort proteins, both in vitro and in vivo. Although DSCG inhibited the in vitro chaperone activity of the N-terminal domain, the drug had no effect either on the C-terminal chaperone activity or on the association of the cohort proteins with the C-terminus of Hsp90. The physiological significance of these interactions in vivo remains to be investigated further, but undoubtedly must be taken into account when considering the pharmacology of anti-allergic drugs. DSCG and amlexanox may serve as useful tools for evaluating the physiological significance of Hsp90.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12803546&dopt=Abstract amlexanox Aphthasol