Ali A, Fernando P, Smith W L, Ovsenek N, Lepock J R, Heikkila J J
Department of Biology, University of Waterloo, Ontario, Canada.
Cell Stress Chaperones. 1997 Dec;2(4):229-37. doi: 10.1379/1466-1268(1997)002<0229:paohba>2.3.co;2.
We have examined the effect of mild hyperthermia on the pattern of heat shock transcription factor (HSF) binding activity, heat shock protein 70 (hsp70) and hsp30 gene expression and protein denaturation in selected tissues of adult Xenopus namely, heart, hind limb muscle, eye, liver and spleen. In these studies it was found that heart tissue was the most thermally sensitive of all of the tissues examined since maintenance of adult frogs at 26 degrees C resulted in a preferential activation of HSF binding. Thus, heart has a lowered set point temperature for HSF activation compared to the other tissues examined. At 30 degrees C HSF activation was observed in all of the tissues examined. Heart HSF activation at 26 degrees C was correlated with an increase in hsp70 mRNA and Hsp70 protein accumulation. At 28 degrees C the largest amount of hsp70 and hsp30 mRNA accumulation was detected in heart and skeletal muscle compared to other tissues while hsp70 mRNA accumulation was relatively low in spleen and hsp30 mRNA accumulation was not detectable in eyes, liver and spleen. Incubation of adult frogs at 30 degrees C resulted in enhanced hsp70 and hsp30 mRNA accumulation in all of the tissues. Finally, we have used differential scanning calorimetry (DSC) to compare the temperatures at which protein denaturation occurs in heart and liver tissue. The onset of protein denaturation (T0) occurred approximately 8.5 degrees C lower in heart compared to liver. Also the midpoint of the DSC profile (T1/2) was approximately 10.4 degrees C lower in heart than in liver. Thus, heart proteins are generally more thermolabile than proteins in liver tissue. Taken together these data suggest that heart is more sensitive than the other tissues examined with respect to moderate increases in environmental temperature.
我们研究了轻度热疗对成年非洲爪蟾特定组织（即心脏、后肢肌肉、眼睛、肝脏和脾脏）中热休克转录因子（HSF）结合活性、热休克蛋白70（hsp70）和hsp30基因表达以及蛋白质变性模式的影响。在这些研究中发现，心脏组织是所有检测组织中对热最敏感的，因为将成年青蛙维持在26摄氏度会导致HSF结合的优先激活。因此，与其他检测组织相比，心脏中HSF激活的设定点温度较低。在30摄氏度时，在所有检测组织中均观察到HSF激活。26摄氏度时心脏HSF激活与hsp70 mRNA和Hsp70蛋白积累的增加相关。在28摄氏度时，与其他组织相比，在心脏和骨骼肌中检测到的hsp70和hsp30 mRNA积累量最大，而脾脏中hsp70 mRNA积累相对较低，在眼睛、肝脏和脾脏中未检测到hsp30 mRNA积累。将成年青蛙在30摄氏度下孵育导致所有组织中hsp70和hsp30 mRNA积累增强。最后，我们使用差示扫描量热法（DSC）比较心脏和肝脏组织中蛋白质发生变性的温度。心脏中蛋白质变性的起始温度（T0）比肝脏低约8.5摄氏度。此外，DSC曲线的中点（T1/2）在心脏中比在肝脏中低约10.4摄氏度。因此，心脏蛋白质通常比肝脏组织中的蛋白质更不耐热。综合这些数据表明，就环境温度的适度升高而言，心脏比其他检测组织更敏感。
