Compensatory regulation of RI alpha protein levels in protein kinase A mutant mice
Compensatory regulation of RI alpha protein levels in protein kinase A mutant mice
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DOI：
10.1074/jbc.272.7.3993
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发表时间：
1997-02-14
影响因子：
4.8
通讯作者：
McKnight, GS
中科院分区：
文献类型：
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作者：
Amieux, PS;Cummings, DE;McKnight, GS
cAMP依赖性蛋白激酶全酶由以组织特异性模式表达的调节（R）和催化（C）亚基组装而成。尽管R和C亚基基因分散于不同的染色体基因座，但存在协调调节R和C蛋白的细胞内水平的机制，使得cAMP依赖性调节得以保留，我们已经在小鼠的RI β和RII β调节亚基基因中创建了无效突变，并发现两者都导致通常表达β亚型的组织中RI α蛋白水平的增加。对野生型和RII β突变小鼠中RI α mRNA水平和RI α蛋白合成速率的检查揭示，RI α的这种生化补偿机制不涉及转录或翻译控制。这些体内发现与细胞培养中的观察结果一致，其中我们证明了NIH 3 T3细胞中C α的过表达导致RI α蛋白的增加，而RI α合成速率或RI α mRNA水平没有增加。脉冲追踪实验表明，RI α蛋白的半衰期增加了4-5倍，因为它被纳入全酶。RI α稳定的补偿可能代表了一个重要的生物学机制，保护细胞不受调节的催化亚基活性。
The cAMP-dependent protein kinase holoenzyme is assembled from regulatory (R) and catalytic (C) subunits that are expressed in tissue-specific patterns, Despite the dispersion of the R and C subunit genes to different chromosomal loci, mechanisms exist that coordinately regulate the intracellular levels of R and C protein such that cAMP-dependent regulation is preserved, We have created null mutations in the RI beta and RII beta regulatory subunit genes in mice, and find that both result in an increase in the level of RI alpha protein in tissues that normally express the beta isoforms. Examination of RI alpha mRNA levels and the rates of RI alpha protein synthesis in wild type and RII beta mutant mice reveals that the mechanism of this biochemical compensation by RI alpha does not involve transcriptional or translational control, These in vivo findings are consistent with observations made in cell culture, where we demonstrate that the overexpression of C alpha in NIH 3T3 cells results in increased RI alpha protein without increases in the rate of RI alpha synthesis or the level of RI alpha mRNA. Pulse-chase experiments reveal a 4-5-fold increase in the half-life of RI alpha protein as it becomes incorporated into the holoenzyme, Compensation by RI alpha stabilization may represent an important biological mechanism that safeguards cells hom unregulated catalytic subunit activity.