Reference : Expression and functional properties of four slow skeletal troponin T isoforms in rat...
Scientific journals : Article
Life sciences : Anatomy (cytology, histology, embryology...) & physiology
http://hdl.handle.net/2268/12067
Expression and functional properties of four slow skeletal troponin T isoforms in rat muscles
English
Kischel, Philippe mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Labo de recherche sur les métastases >]
Bastide, Bruno [Université des Sciences et Technologies de Lille - USTL > Institut Fédératif de Recherches 118 > Laboratoire de Plasticité Neuromusculaire > >]
Muller, Marc [Université de Liège - ULg > Département des sciences de la vie > Biologie et génétique moléculaire > > >]
Dubail, Fabien [Université de Liège - ULg > > > > > >]
Offredi, Fabrice [Université de Liège - ULg > > > > Biologie et génétique moléculaire > > >]
Jin, Jian-Ping [Evanston Hospital, Evanston, Illinois > Section of Molecular Cardiology > > >]
Mounier, Yvonne [Université des Sciences et Technologies de Lille - USTL > Institut Fédératif de Recherches 118 > Laboratoire de Plasticité Neuromusculaire > >]
Martial, Joseph [Université de Liège - ULg > Département des sciences de la vie > Biologie et génétique moléculaire >]
Aug-2005
American Journal of Physiology - Cell Physiology
Amer Physiological Soc
289
2
C437-C443
Yes (verified by ORBi)
International
0363-6143
Bethesda
[en] skinned fibers ; skeletal muscle ; troponin subunit exchange ; hindlimb unloading ; atrophy
[en] We investigated the expression and functional properties of slow skeletal troponin T(sTnT) isoforms in rat skeletal muscles. Four sTnT cDNAs were cloned from the slow soleus muscle. Three isoforms were found to be similar to sTnT1, sTnT2, and sTnT3 isoforms described in mouse muscles. A new rat isoform, with a molecular weight slightly higher than that of sTnT3, was discovered. This fourth isoform had never been detected previously in any skeletal muscle and was therefore called sTnTx. From both expression pattern and functional measurements, it appears that sTnT isoforms can be separated into two classes, high-molecular-weight ( sTnT1, sTnT2) and low-molecular-weight ( sTnTx, sTnT3) isoforms. By comparison to the apparent migration pattern of the four recombinant sTnT isoforms, the newly described low-molecular-weight sTnTx isoform appeared predominantly and typically expressed in fast skeletal muscles, whereas the higher-molecular-weight isoforms were more abundant in slow soleus muscle. The relative proportion of the sTnT isoforms in the soleus was not modified after exposure to hindlimb unloading (HU), known to induce a functional atrophy and a slow-to-fast isoform transition of several myofibrillar proteins. Functional data gathered from replacement of endogenous troponin complexes in skinned muscle fibers showed that the sTnT isoforms modified the Ca2+ activation characteristics of single skeletal muscle fibers, with sTnT2 and sTnT1 conferring a similar increase in Ca2+ affinity higher than that caused by low-molecular-weight isoforms sTnTx and sTnT3. Thus we show for the first time the presence of sTnT in fast muscle fibers, and our data show that the changes in neuromuscular activity on HU are insufficient to alter the sTnT expression pattern.
Région wallonne : Direction générale des Technologies, de la Recherche et de l'Energie - DGTRE
MICADO
Researchers ; Professionals ; Students
http://hdl.handle.net/2268/12067
10.1152/ajpcell.00365.2004

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