O'Neill David E T, Aubrey F Kris, Zeldin David A, Michel Robin N, Noble Earl G
Thames Hall Rm. 2160C, School of Kinesiology, The Univ. of Western Ontario, London, ON, Canada N6A 3K7.
J Appl Physiol (1985). 2006 Mar;100(3):981-7. doi: 10.1152/japplphysiol.00831.2005. Epub 2005 Nov 17.
Heat shock protein 72 (Hsp70) is constitutively expressed in rat hindlimb muscles, reportedly in proportion to their content of type I myosin heavy chain. This distribution pattern has been suggested to result from the higher recruitment and activity of such muscles and/or a specific relationship between myosin phenotype and Hsp70 content. To differentiate between these possibilities, the fiber-specific distribution of Hsp70 was examined in male Sprague-Dawley rat plantaris under control conditions, following a fast-to-slow phenotypic shift in response to surgically induced overload (O) and in response to O when the phenotypic shift was prevented by 3,5,3'-triiodo-dl-thyronine administration. Constitutive expression of Hsp70 was restricted to type I and IIa fibers in plantaris from control rats, and this fiber-specific pattern of expression was maintained following O of up to 28 days, although Hsp70 content in the O muscle doubled. When O (for 40 days) of the plantaris was combined with 3,5,3'-triiodo-dl-thyronine administration, despite typical hypertrophy in the overloaded plantaris, prevention of the normal phenotypic transformation also blocked the increased expression of Hsp70 observed in euthyroid controls. Collectively, these data suggest that chronic changes in constitutive expression of Hsp70 with altered contractile activity appear critically dependent on fast-to-slow phenotypic remodeling.
热休克蛋白72（Hsp70）在大鼠后肢肌肉中持续表达，据报道其表达量与I型肌球蛋白重链的含量成正比。这种分布模式被认为是由于此类肌肉的更高募集和活性和/或肌球蛋白表型与Hsp70含量之间的特定关系所致。为了区分这些可能性，在对照条件下、在对手术诱导的过载（O）作出反应而发生从快到慢的表型转变后以及在通过给予3,5,3'-三碘-dl-甲状腺原氨酸防止表型转变的情况下对雄性Sprague-Dawley大鼠的比目鱼肌中Hsp70的纤维特异性分布进行了检测。Hsp70的组成性表达在对照大鼠的比目鱼肌中仅限于I型和IIa型纤维，并且在长达28天的过载后这种纤维特异性表达模式得以维持，尽管过载肌肉中的Hsp70含量增加了一倍。当比目鱼肌的过载（40天）与给予3,5,3'-三碘-dl-甲状腺原氨酸相结合时，尽管过载的比目鱼肌出现典型的肥大，但正常表型转变的阻止也阻断了在甲状腺功能正常的对照中观察到的Hsp70表达增加。总体而言，这些数据表明，随着收缩活性改变，Hsp70组成性表达的慢性变化似乎严重依赖于从快到慢的表型重塑。
