Human mitochondrial mRNAs are stabilized with polyadenylation regulated by mitochondria-specific poly(A) polymerase and polynucleotide phosphorylase
Human mitochondrial mRNAs are stabilized with polyadenylation regulated by mitochondria-specific poly(A) polymerase and polynucleotide phosphorylase
复制标题
DOI：
10.1074/jbc.m500804200
复制
发表时间：
2005-05-20
影响因子：
4.8
通讯作者：
Ueda, T
中科院分区：
文献类型：
--
作者：
Nagaike, T;Suzuki, T;Ueda, T
哺乳动物线粒体（mt） mrna在其3'末端具有短的poly(A)尾巴，由mt poly(A)聚合酶（PAP）转录后合成。已知mt mrna的聚腺苷化是产生不在mtDNA中编码的UAA终止密码子所需的关键过程。在某些情况下，通过编辑tRNA的3'端，多聚腺苷化是其成熟所必需的。然而，对于mt mrna的聚(A)尾在mt翻译和RNA转换中所起的功能作用知之甚少。在这里，我们展示了人mtPAP （hmtPAP）和人多核苷酸磷酸化酶（hPNPase）控制人线粒体中poly(A)的合成。在HeLa细胞中使用小干扰RNA对htmtpap进行部分失活，导致poly(A)尾巴缩短，降低一些mt mrna及其翻译产物的稳态水平。此外，敲低hmtPAP会产生明显的mt膜电位缺陷和氧消耗减少。相反，敲除hPNPase显示mt mrna的聚(A)尾部明显延长。这些结果表明，人mt mrna的poly(A)长度由hmtPAP的聚腺苷化和hPNPase的死烯化控制，并且mt mrna的稳定性需要聚腺苷化。
Mammalian mitochondrial (mt) mRNAs have short poly(A) tails at their 3' termini that are post-transcriptionally synthesized by mt poly(A) polymerase (PAP). The polyadenylation of mt mRNAs is known to be a key process needed to create UAA stop codons that are not encoded in mtDNA. In some cases, polyadenylation is required for the tRNA maturation by editing of its 3' terminus. However, little is known about the functional roles the poly(A) tail of mt mRNAs plays in mt translation and RNA turnover. Here we show human mt PAP (hmtPAP) and human polynucleotide phosphorylase (hPNPase) control poly(A) synthesis in human mitochondria. Partial inactivation of hmtPAP by RNA interference using small interfering RNA in HeLa cells resulted in shortened poly(A) tails and decreased steady state levels of some mt mRNAs as well as their translational products. Moreover, knocking down hmtPAP generated markedly defective mt membrane potentials and reduced oxygen consumption. In contrast, knocking down hPNPase showed significantly extended poly(A) tails of mt mRNAs. These results demonstrate that the poly(A) length of human mt mRNAs is controlled by polyadenylation by hmtPAP and deadenylation by hPNPase, and polyadenylation is required for the stability of mt mRNAs.