Department of Pharmacology and Physiology, New Jersey Medical School of UMDNJ, 185 South Orange Avenue, Medical Sciences Building, Newark, NJ 07103, USA.
Nucleic Acids Res. 2012 Jan;40(2):712-25. doi: 10.1093/nar/gkr758. Epub 2011 Sep 21.
Human telomerase reverse transcriptase (hTERT) is localized to mitochondria, as well as the nucleus, but details about its biology and function in the organelle remain largely unknown. Here we show, using multiple approaches, that mammalian TERT is mitochondrial, co-purifying with mitochondrial nucleoids and tRNAs. We demonstrate the canonical nuclear RNA [human telomerase RNA (hTR)] is not present in human mitochondria and not required for the mitochondrial effects of telomerase, which nevertheless rely on reverse transcriptase (RT) activity. Using RNA immunoprecipitations from whole cell and in organello, we show that hTERT binds various mitochondrial RNAs, suggesting that RT activity in the organelle is reconstituted with mitochondrial RNAs. In support of this conclusion, TERT drives first strand cDNA synthesis in vitro in the absence of hTR. Finally, we demonstrate that absence of hTERT specifically in mitochondria with maintenance of its nuclear function negatively impacts the organelle. Our data indicate that mitochondrial hTERT works as a hTR-independent reverse transcriptase, and highlight that nuclear and mitochondrial telomerases have different cellular functions. The implications of these findings to both the mitochondrial and telomerase fields are discussed.
人类端粒酶逆转录酶 (hTERT) 定位于线粒体和细胞核，但关于其在细胞器中的生物学和功能的细节在很大程度上仍不清楚。在这里，我们使用多种方法表明，哺乳动物 TERT 是线粒体的，与线粒体核仁体和 tRNA 共同纯化。我们证明了规范的核 RNA[人类端粒酶 RNA (hTR)]不存在于人线粒体中，并且不需要端粒酶的线粒体效应，但端粒酶效应仍然依赖于逆转录酶 (RT) 活性。通过对全细胞和细胞器中的 RNA 免疫沉淀，我们表明 hTERT 结合各种线粒体 RNA，这表明 RT 活性在细胞器中是由线粒体 RNA 重建的。为了支持这一结论，TERT 在没有 hTR 的情况下在体外驱动第一链 cDNA 合成。最后，我们证明了线粒体中 hTERT 的缺失（同时维持其核功能）会对细胞器产生负面影响。我们的数据表明，线粒体 hTERT 作为一种不依赖 hTR 的逆转录酶发挥作用，并强调核和线粒体端粒酶具有不同的细胞功能。讨论了这些发现对线粒体和端粒酶领域的影响。
