Interaction between cardiac calsequestrin and drugs with known cardiotoxicity.
Ca(2+) regulation is coupled to critical signals in eucaryotic cells, and calsequestrin is one of the crucial components for this calcium regulation. Our previous observations of calsequestrins revealed the existence of three thioredoxin-like folds, a basic motif that often provides the platform for small molecule binding. Therefore, we have examined the previously reported trifluoperazine and other pharmaceuticals that have similar heart-related side effects (such as tachycardia; bradycardia; palpitation; changing PR, QRS, QTc intervals in electrocardiogram; heart failure) for their binding affinity to cardiac calsequestrin (cCSQ) using isothermal titration calorimetry. Our results showed that several antipsychotic phenothiazine derivatives, tricyclic antidepressants, and anthracycline derivatives bind cCSQ with K(d) in the micromolar range. For these compounds that have a significantly low K(d), their effect on Ca(2+) binding capacity of cCSQ was checked using equilibrium dialysis and atomic absorption spectroscopy, which clearly showed a significant reduction in Ca(2+) binding capacity of cCSQ as a result of this interaction. Furthermore, 8-anilino-1-naphthalene sulfonate (ANS) binding to cCSQ closely resembles ANS binding to flavine or nucleotide binding sites. The combination of this information with the high abundance of CSQ in SR and the high membrane permeability of those drugs led us to the specific hypothesis that there are undesirable and damaging interactions between cCSQ and tricyclic antidepressants, phenothiazine derivatives, anthracyclines, and many other pharmaceutical compounds and to the corollary hypothesis that better understanding of the molecular details of cCSQ-drug interactions could lead to modified drug molecules with reduced heart-related side effects.
Park
Il Yeong
IY
264 Fulmer, School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4660, USA.
Kim
Eun Jung
EJ
Park
HaJeung
H
Fields
Kelly
K
Dunker
A Keith
AK
Kang
ChulHee
C
D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology; D014150:Antipsychotic Agents / Q000494:pharmacology; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D002151:Calorimetry; D002155:Calsequestrin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D003630:Daunorubicin / Q000494:pharmacology; D004285:Dogs; D004317:Doxorubicin / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D010640:Phenothiazines / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D013054:Spectrophotometry, Atomic
D000929:Antidepressive Agents, Tricyclic; D014150:Antipsychotic Agents; D002155:Calsequestrin; D017931:DNA Primers; D010640:Phenothiazines; D004317:Doxorubicin; D002118:Calcium; D003630:Daunorubicin