Heydari A R, Conrad C C, Richardson A
Geriatric Research, Education and Clinical Center, Audie L. Murphy Memorial Veterans Hospital, San Antonio, TX.
J Nutr. 1995 Mar;125(3):410-8. doi: 10.1093/jn/125.3.410.
The objective of this study was to determine how food restriction altered the age-related changes in the basal and heat-induced expression of heat shock genes (hsc70, grp78, and ubiquitin) by hepatocytes isolated from young (4 to 6 mo old) and old (26 to 28 mo old) male Fischer 344 rats. The basal levels of the mRNA transcripts for hsc70 and ubiquitin were similar for hepatocytes isolated from young and old rats fed with free access to the diet (control) or from rats fed a restricted diet (40% restriction of food intake). However, the induction of the mRNA transcripts for hsc70 and ubiquitin by a heat shock (42.5 degrees C for 30 min) was significantly higher for hepatocytes isolated from old rats fed the restricted diet compared with old rats fed with free access to the diet. The changes in hsc70 mRNA levels were paralleled by similar changes in hsc70 transcription by isolated nuclei; therefore, the greater induction of hsc70 expression by food restriction results from changes in the transcription of hsc70 gene. In contrast with hsc70 and ubiquitin, the basal levels of grp78 were reduced with age and by food restriction. Therefore, the effect of aging and food restriction on the basal and heat-induced expression of heat shock genes varies considerably from gene to gene.
本研究的目的是确定食物限制如何改变从年轻（4至6月龄）和老年（26至28月龄）雄性Fischer 344大鼠分离的肝细胞中热休克基因（hsc70、grp78和泛素）基础表达和热诱导表达的年龄相关变化。对于自由进食（对照）的年轻和老年大鼠或进食限制饮食（食物摄入量限制40%）的大鼠分离的肝细胞，hsc70和泛素mRNA转录本的基础水平相似。然而，与自由进食的老年大鼠相比，进食限制饮食的老年大鼠分离的肝细胞经热休克（42.5℃，30分钟）诱导的hsc70和泛素mRNA转录本显著更高。hsc70 mRNA水平的变化与分离细胞核中hsc70转录的类似变化平行；因此，食物限制对hsc70表达的更大诱导是由hsc70基因转录的变化引起的。与hsc70和泛素相反，grp78的基础水平随年龄增长和食物限制而降低。因此，衰老和食物限制对热休克基因基础表达和热诱导表达的影响因基因而异。
