Stress protein and fiber type

α-晶体蛋白的序列与小分子热休克蛋白(HSPs#)的序列有惊人的相似性，越来越多的证据表明它也与小HSPs有功能上的相似性。α-晶体蛋白的表达是在应激条件下诱导的。类似地，缺血后形成无定形的α-结晶蛋白聚集体。α-晶状体蛋白可以作为分子伴侣，通过抑制其他蛋白质的热诱导聚集，并通过帮助变性蛋白质的复性来发挥作用。这些来自体外实验的观察表明，α-晶体蛋白必须被认为是小的热休克蛋白的成员。似乎有理由认为，比目鱼肌需要结构性表达，因为比目鱼肌持续承受着比其他肌肉更大的压力环境，如高温、氧化损伤和更高的蛋白质周转率，并且需要α-晶体蛋白提供的应激相关功能。这就引出了一个问题：应激肌肉中α-晶体蛋白的表达是通过其高募集率直接调节的，还是以一种纤维型特异性蛋白的表达方式间接调节的？为探讨应激蛋白α-晶体蛋白的表达与纤维类型的关系，我们用小鼠抗肌球蛋白单抗和兔抗α-晶体蛋白多克隆抗体，研究了应激蛋白α-晶体蛋白在正常大鼠体内的分布、后肢悬吊引起的肌肉萎缩的相对变化以及甲状旁腺激素和PTU治疗后的相对变化。在比目鱼肌中，I型纤维与抗α-晶体蛋白Ig的反应比IIA型纤维强得多。在EDL肌中，I型纤维对抗α-晶体蛋白Ig的反应性强于II型纤维。除了TY和TY之间的差异

The sequence of alphaB-crystallin has striking similarity to the suquence of small heat shock proteins (HSPs#) and increasing evidence indicates that it has also functional similarities with the small HSPs. The expression of alphaB-crystallin is induced upon stress. Similarly, amorphous alphaB-acrystallin aggregates are formed after ischemia. alphaB-crystallin can function as a molecular chaperone, by suppressing heat induced aggregation of other proteins, and by assisting refolding of denatured protein. These observations from in vitro experiments suggest that alphaB-crystallin has to be considered a member of the small HSPs. It seems reasonable to assume that the constitutive expression is required in soleus muscle because this muscle is continuously subjected to a more stressful environment, such as high temperature, oxidant injury, and higher rate of protein turnover, than other muscles and requires stress related functions provided by alphaB-crystallin. This drives us to the question whether the expression of alphaB-crystallin in stressful muscle is directly regulated with its high rate recruitment, which causes stressful environment, or indirectly regulated in a manner of expression as a fiber type specific protein. The relationship between the expression of alphaB-crystallin as stress protein and fiber-type were examined in three experiments of 1) those distributions in control rats, 2) relative changes due to muscle atropphy by hindlimb suspension, and 3) relative changes due to the treatment of thiroid hormone and PTU.For this purpose we used immuno-histochemical method to investigate these relationship using mouse monoclonal anti-myosin antibodies and rabbit anti-alphaB-crystallin polyclonal antibodies. In soleus muscles, type I fibers reacted much stronger with anti-alphaB-crystallin Ig, than type IIA fibers. In EDL muscles, type I fibers showed strong reactivity for anti-alphaB-crystallin Ig than type II fibers. In addition to the differences between ty