TY - JOUR
T1 - Tubulin polymerization modifies cardiac sodium channel expression and gating
AU - Casini, Simona
AU - Tan, Hanno L.
AU - Demirayak, Ilker
AU - Remme, Carol Ann
AU - Amin, Ahmad S.
AU - Scicluna, Brendon P.
AU - Chatyan, Houssine
AU - Ruijter, Jan M.
AU - Bezzina, Connie R.
AU - van Ginneken, Antoni C. G.
AU - Veldkamp, Marieke W.
PY - 2010
Y1 - 2010
N2 - Treatment with the anticancer drug taxol (TXL), which polymerizes the cytoskeleton protein tubulin, may evoke cardiac arrhythmias based on reduced human cardiac sodium channel (Na(v)1.5) function. Therefore, we investigated whether enhanced tubulin polymerization by TXL affects Na(v)1.5 function and expression and whether these effects are beta(1)-subunit-mediated. Human embryonic kidney (HEK293) cells, transfected with SCN5A cDNA alone (Na(v)1.5) or together with SCN1B cDNA (Na(v)1.5 + beta(1)), and neonatal rat cardiomyocytes (NRCs) were incubated in the presence and in the absence of 100 mu M TXL. Sodium current (I-Na) characteristics were studied using patch-clamp techniques. Na(v)1.5 membrane expression was determined by immunocytochemistry and confocal microscopy. Pre-treatment with TXL reduced peak I-Na amplitude nearly two-fold in both Na(v)1.5 and Na(v)1.5 + beta(1), as well as in NRCs, compared with untreated cells. Accordingly, HEK293 cells and NRCs stained with anti-Na(v)1.5 antibody revealed a reduced membrane-labelling intensity in the TXL-treated groups. In addition, TXL accelerated I-Na decay of Na(v)1.5 + beta(1), whereas I-Na decay of Na(v)1.5 remained unaltered. Finally, TXL reduced the fraction of channels that slow inactivated from 31% to 18%, and increased the time constant of slow inactivation by two-fold in Na(v)1.5. Conversely, slow inactivation properties of Na(v)1.5 + beta(1) were unchanged by TXL. Enhanced tubulin polymerization reduces sarcolemmal Na(v)1.5 expression and I-Na amplitude in a beta(1)-subunit-independent fashion and causes I-Na fast and slow inactivation impairment in a beta(1)-subunit-dependent way. These changes may underlie conduction-slowing-dependent cardiac arrhythmias under conditions of enhanced tubulin polymerization, e.g. TXL treatment and heart failure
AB - Treatment with the anticancer drug taxol (TXL), which polymerizes the cytoskeleton protein tubulin, may evoke cardiac arrhythmias based on reduced human cardiac sodium channel (Na(v)1.5) function. Therefore, we investigated whether enhanced tubulin polymerization by TXL affects Na(v)1.5 function and expression and whether these effects are beta(1)-subunit-mediated. Human embryonic kidney (HEK293) cells, transfected with SCN5A cDNA alone (Na(v)1.5) or together with SCN1B cDNA (Na(v)1.5 + beta(1)), and neonatal rat cardiomyocytes (NRCs) were incubated in the presence and in the absence of 100 mu M TXL. Sodium current (I-Na) characteristics were studied using patch-clamp techniques. Na(v)1.5 membrane expression was determined by immunocytochemistry and confocal microscopy. Pre-treatment with TXL reduced peak I-Na amplitude nearly two-fold in both Na(v)1.5 and Na(v)1.5 + beta(1), as well as in NRCs, compared with untreated cells. Accordingly, HEK293 cells and NRCs stained with anti-Na(v)1.5 antibody revealed a reduced membrane-labelling intensity in the TXL-treated groups. In addition, TXL accelerated I-Na decay of Na(v)1.5 + beta(1), whereas I-Na decay of Na(v)1.5 remained unaltered. Finally, TXL reduced the fraction of channels that slow inactivated from 31% to 18%, and increased the time constant of slow inactivation by two-fold in Na(v)1.5. Conversely, slow inactivation properties of Na(v)1.5 + beta(1) were unchanged by TXL. Enhanced tubulin polymerization reduces sarcolemmal Na(v)1.5 expression and I-Na amplitude in a beta(1)-subunit-independent fashion and causes I-Na fast and slow inactivation impairment in a beta(1)-subunit-dependent way. These changes may underlie conduction-slowing-dependent cardiac arrhythmias under conditions of enhanced tubulin polymerization, e.g. TXL treatment and heart failure
U2 - https://doi.org/10.1093/cvr/cvp352
DO - https://doi.org/10.1093/cvr/cvp352
M3 - Article
C2 - 19861310
SN - 0008-6363
VL - 85
SP - 691
EP - 700
JO - Cardiovascular research
JF - Cardiovascular research
IS - 4
ER -