Trivalent methylated arsenical-induced phosphatidylserine exposure and apoptosis in platelets may lead to increased thrombus formation.
Trivalent methylated metabolites of arsenic, monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)), have been found highly reactive and toxic in various cells and in vivo animal models, suggesting their roles in the arsenic-associated toxicity. However, their effects on cardiovascular system including blood cells, one of the most important targets for arsenic toxicity, remain poorly understood. Here we found that MMA(III) and DMA(III) could induce procoagulant activity and apoptosis in platelets, which play key roles in the development of various cardiovascular diseases (CVDs) through excessive thrombus formation. In freshly isolated human platelets, treatment of MMA(III) resulted in phosphatidylserine (PS) exposure, a hallmark of procoagulant activation, accompanied by distinctive apoptotic features including mitochondrial membrane potential disruption, cytochrome c release, and caspase-3 activation. These procoagulant activation and apoptotic features were found to be mediated by the depletion of protein thiol and intracellular ATP, and flippase inhibition by MMA(III), while the intracellular calcium increase or reactive oxygen species generation was not involved. Importantly, increased platelet procoagulant activity by MMA(III) resulted in enhanced blood coagulation and excessive thrombus formation in a rat in vivo venous thrombosis model. DMA(III) also induced PS-exposure with apoptotic features mediated by protein thiol depletion, which resulted in enhanced thrombin generation. In summary, we believe that this study provides an important evidence for the role of trivalent methylated arsenic metabolites in arsenic-associated CVDs, giving a novel insight into the role of platelet apoptosis in toxicant-induced cardiovascular toxicity.
Bae
Ok-Nam
ON
College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea.
Lim
Kyung-Min
KM
Noh
Ji-Yoon
JY
Chung
Seung-Min
SM
Kim
Se-Hwan
SH
Chung
Jin-Ho
JH
D000293:Adolescent; D000328:Adult; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001777:Blood Coagulation / Q000187:drug effects; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D002101:Cacodylic Acid / Q000031:analogs & derivatives* / Q000633:toxicity; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D004195:Disease Models, Animal; D006801:Humans; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D009942:Organometallic Compounds / Q000633:toxicity*; D010718:Phosphatidylserines / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D020246:Venous Thrombosis / Q000097:blood / Q000139:chemically induced* / Q000378:metabolism; D055815:Young Adult
D009942:Organometallic Compounds; D010718:Phosphatidylserines; D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; C472511:dimethylarsinous acid; C406082:monomethylarsonous acid; D045304:Cytochromes c; D002101:Cacodylic Acid; D053148:Caspase 3; D002118:Calcium