Abstract
Transthyretin (TTR) is a homotetrameric protein involved in human amyloidosis, including familial amyloid polyneuropathy (FAP). Discovering small-molecule stabilizers of the TTR tetramer is a therapeutic strategy for these diseases. Tafamidis, the only approved drug for FAP treatment, is not effective for all patients. Herein, we discovered that benzbromarone (BBM), a uricosuric drug, is an effective TTR stabilizer and inhibitor against TTR amyloid fibril formation. BBM rendered TTR more resistant to urea denaturation, similarly to iododiflunisal (IDIF), a very potent TTR stabilizer. BBM competes with thyroxine for binding in the TTR central channel, with an IC50 similar to IDIF and tafamidis. Results obtained by isothermal titration calorimetry (ITC) demonstrated that BBM binds TTR with an affinity similar to IDIF, tolcapone and tafamidis, confirming BBM as a potent binder of TTR. The crystal structure of the BBM-TTR complex shows two molecules binding deeply in the thyroxine binding channel, forming strong intermonomer hydrogen bonds and increasing the stability of the TTR tetramer. Finally, kinetic analysis of the ability of BBM to inhibit TTR fibrillogenesis at acidic pH and comparison with other stabilizers revealed that benzbromarone is a potent inhibitor of TTR amyloidogenesis, adding a new interesting scaffold for drug design of TTR stabilizers.
Highlights
Transthyretin (TTR) is a protein of 127 amino acids that self-assembles as a 55 kDa homotetramer that is secreted into the bloodstream by the liver [1,2] and into the cerebrospinal fluid (CSF) by the choroid plexus [3]
BceBnMtraml oclhecaunlneeslb. inTdhedecehpalynnweilthdinispthlaeyths ytrwoxoinheobrimndoinneg-bpioncdkientg, wsiitthesb,roAmAin’ eaantdomBsBa’,t twheitihnnseirmsiildaer otofptohleocgayv. iBtyBM(Fimguorleec6u).leIsnbtihnedcdryeestpallyswtruitchtiunrethoeftthhyeroaxpion-eTTbiRn,dSinerg11p7ocskideet, cwhiatihnsbrfoamceintheeactoamvitsieast athnedinhnyderrosgideenobfotnhdeecdavtoitycr(yFsitgaullroeg6r)a.pIhnicthwe actreyrstmalosletrcuucletus.reBoBfMthbeinapdoin-TgTinRd, uSceer1s1t7hesirdoetacthioaninosffathcee sthideecraevsiitdieusesanodf sheyridnreo1g1e7n obfoanldl efodutromcorynsotmalleorgs,rapprohmic pwtiantgerthmeofloercmulaetsi.onBBoMf stbrionndginingteinrmduocneosmtheer hroytdartioognenofbtohnedssidwehricehsidpureessuomf asbelryinienc1r1e7asoef tahlel fsotaubrimlitoynoofmtheersT,TpRrotmetpratminegr.the formation of strong intermonomer hydrogen bonds which presumably increase the stability of the TTR tetramer
We have shown that BBM stabilizes the TTR tetramer and in vitro and ex vivo approaches demonstrated that the binding occurs in the T4-binding pocket, with a capacity similar to IDIF, tafamidis and tolcapone, known as strong TTR stabilizers
Summary
Transthyretin (TTR) is a protein of 127 amino acids that self-assembles as a 55 kDa homotetramer that is secreted into the bloodstream by the liver [1,2] and into the cerebrospinal fluid (CSF) by the choroid plexus [3]. TTR transports holo-retinol-binding protein in the blood, forming a macromolecular complex [4,5]. The protein acts as a backup carrier of thyroxine (T4) in serum (crystal structure in Figure 1), where the principal transporters are thyroid-binding globulin (TBG) and albumin, while being the primary carrier of T4 in CSF. The T4-binding sites at the weaker of the two dimer–dimer interfaces of.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
