Gomez Tara A, Banfield Kelley L, Trogler Dorothy M, Clarke Steven G
Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California-Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095, USA.
Dev Biol. 2007 Mar 15;303(2):493-500. doi: 10.1016/j.ydbio.2006.11.023. Epub 2006 Nov 21.
The protein L-isoaspartyl-O-methyltransferase, coded by the pcm-1 gene in Caenorhabditis elegans, participates in the repair of age-damaged proteins. We tested the ability of pcm-1-deficient nematodes to survive starvation stress as developmentally-arrested L1 larvae. We found that pcm-1 mutant L1 larvae do not survive as well as wild-type L1 larvae when incubated in M9 medium without nutrients. We then tested whether the starved L1 larvae could continue development when allowed access to food in a recovery assay. A loss of recovery ability with age was observed for all larvae, with little or no difference between the pcm-1 mutant and wild-type N2 larvae. Interestingly, when L1 larvae were starved in cholesterol-containing S medium or M9 medium supplemented with cholesterol, the survival rates of both mutant and wild-type animals nearly doubles, with pcm-1 larvae again faring more poorly than N2 larvae. Furthermore, L1 larvae cultured in these cholesterol-containing media show an increase in Sudan Black staining over animals cultured in M9 medium. The longevity defects of pcm-1 mutants previously seen in dauer larvae and here in L1 larvae suggest a defect in the ability of pcm-1 mutants to recycle and reuse old cellular components in pathways such as autophagy. Using an autophagosomal marker, we found evidence suggesting that the pcm-1 mutation may inhibit autophagy during dauer formation, suggesting that the absence of protein repair may also interfere with protein degradation pathways.
由秀丽隐杆线虫中的pcm-1基因编码的蛋白质L-异天冬氨酰-O-甲基转移酶参与衰老损伤蛋白质的修复。我们测试了pcm-1缺陷型线虫作为发育停滞的L1幼虫在饥饿胁迫下的存活能力。我们发现,在不含营养物质的M9培养基中培养时,pcm-1突变型L1幼虫的存活情况不如野生型L1幼虫。然后,我们在恢复试验中测试了饥饿的L1幼虫在获得食物时是否能够继续发育。所有幼虫都观察到随着年龄增长恢复能力的丧失,pcm-1突变型和野生型N2幼虫之间几乎没有差异。有趣的是,当L1幼虫在含胆固醇的S培养基或补充了胆固醇的M9培养基中饥饿时,突变型和野生型动物的存活率几乎都提高了一倍,pcm-1幼虫的情况再次比N2幼虫差得多。此外,在这些含胆固醇的培养基中培养的L1幼虫与在M9培养基中培养的动物相比,苏丹黑染色增加。先前在 dauer 幼虫和此处的L1幼虫中观察到的pcm-1突变体的寿命缺陷表明,pcm-1突变体在自噬等途径中回收和再利用旧细胞成分的能力存在缺陷。使用自噬体标记物,我们发现有证据表明pcm-1突变可能在 dauer 形成过程中抑制自噬,这表明蛋白质修复的缺失也可能干扰蛋白质降解途径。