کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8474845 1550433 2014 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Combined troponin I Ser-150 and Ser-23/24 phosphorylation sustains thin filament Ca2 + sensitivity and accelerates deactivation in an acidic environment
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی بیولوژی سلول
پیش نمایش صفحه اول مقاله
Combined troponin I Ser-150 and Ser-23/24 phosphorylation sustains thin filament Ca2 + sensitivity and accelerates deactivation in an acidic environment
چکیده انگلیسی
The binding of Ca2 + to troponin C (TnC) in the troponin complex is a critical step regulating the thin filament, the actin-myosin interaction and cardiac contraction. Phosphorylation of the troponin complex is a key regulatory mechanism to match cardiac contraction to demand. Here we demonstrate that phosphorylation of the troponin I (TnI) subunit is simultaneously increased at Ser-150 and Ser-23/24 during in vivo myocardial ischemia. Myocardial ischemia decreases intracellular pH resulting in depressed binding of Ca2 + to TnC and impaired contraction. To determine the pathological relevance of these simultaneous TnI phosphorylations we measured individual TnI Ser-150 (S150D), Ser-23/24 (S23/24D) and combined (S23/24/150D) pseudo-phosphorylation effects on thin filament regulation at acidic pH similar to that in myocardial ischemia. Results demonstrate that while acidic pH decreased thin filament Ca2 + binding to TnC regardless of TnI composition, TnI S150D attenuated this decrease rendering it similar to non-phosphorylated TnI at normal pH. The dissociation of Ca2 + from TnC was unaltered by pH such that TnI S150D remained slow, S23/24D remained accelerated and the combined S23/24/150D remained accelerated. This effect of the combined TnI Ser-150 and Ser-23/24 pseudo-phosphorylations to maintain Ca2 + binding while accelerating Ca2 + dissociation represents the first post-translational modification of troponin by phosphorylation to both accelerate thin filament deactivation and maintain Ca2 + sensitive activation. These data suggest that TnI Ser-150 phosphorylation induced attenuation of the pH-dependent decrease in Ca2 + sensitivity and its combination with Ser-23/24 phosphorylation to maintain accelerated thin filament deactivation may impart an adaptive role to preserve contraction during acidic ischemia pH without slowing relaxation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular and Cellular Cardiology - Volume 72, July 2014, Pages 177-185
نویسندگان
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