Arabidopsis U6 small nuclear RNA （snRNA） promoters are those transcribed by RNA polymerase Ⅲ, but all the core elements for transcriptional initiation are located in the 5＇ promoter region. Previously, three Arabi...Arabidopsis U6 small nuclear RNA （snRNA） promoters are those transcribed by RNA polymerase Ⅲ, but all the core elements for transcriptional initiation are located in the 5＇ promoter region. Previously, three Arabidopsis U6 snRNA genes （U6-1, U6-26, and U6-29） were identified. Herein, we have further identified three new U6 loci （U6-4, U6-5, and U6-6） in the Arabidopsis genome. Alignment of these revealed that the upstream sequence element and TATA elements were contained in six U6 promoters. In addition, a unique, highly conserved element named the ＂CAT＂ element was observed in the promoter region. To understand the expression patterns of these U6 genes in Arabidopsis, we fused these promoters to the DNA segment of β-glucuronidase and then transferred these six constructs into Arabidopsis. Real-time reverse transcription-polymerase chain reaction analysis of these fused transcripts indicated that the newly identified U6 genes are active in Arabidopsis and that the U6-26 promoter seems to have higher transcriptional activity in leaf, stem, flower and silique. These results help to understand the function of these U6 snRNAs in Arabidopsis.展开更多
Regulation of gene expression at the post-transcriptional level is of crucial importance in the development of an organism. Here we present the characterization of a maize gene, U6 biogenesis-like 1 （UBL1）, which pl...Regulation of gene expression at the post-transcriptional level is of crucial importance in the development of an organism. Here we present the characterization of a maize gene, U6 biogenesis-like 1 （UBL1）, which plays an important role in kernel and seedling development by influencing pre-mRNA splicing. The ubll mutant, exhibiting small kernel and weak seedling, was isolated from a Mutator-tagged population. Trans- genic complementation and three independent mutant alleles confirmed that UBL1, which encodes a putative RNA exonuclease belonging to the 2H phosphodiesterase superfamily, is responsible for the phenotype of ubll. We demonstrated that UBL1 possess the RNA exonuclease activity in vitro and found that loss of UBL1 function in ubll causes decreased level and abnormal 3＇ end constitution of snRNA U6, resulting in splicing defect of mRNAs. Through the in vitro and in vivo studies replacing two histidines with alanines in the H-X-T/S-X （X is a hydrophobic residue） motifs we demonstrated that these two motifs are essential for the normal function of UBL1. We further showed that the function of UBL1 may be conserved across a wide phylogenetic distance as the heterologous expression of maize UBL1 could complement the Arabidopsis ubll mutant.展开更多
The posttranscriptional addition of nontemplated nucleotides to the 3′ ends of RNA molecules can have a significant impact on their stability and biological function. It has been recently discovered that nontemplated...The posttranscriptional addition of nontemplated nucleotides to the 3′ ends of RNA molecules can have a significant impact on their stability and biological function. It has been recently discovered that nontemplated addition of uridine or adenosine to the 3′ ends of RNAs occurs in different organisms ranging from algae to humans, and on different kinds of RNAs, such as histone m RNAs, m RNA fragments, U6 sn RNA, mature small RNAs and their precursors etc. These modifications may lead to different outcomes, such as increasing RNA decay, promoting or inhibiting RNA processing, or changing RNA activity. Growing pieces of evidence have revealed that such modifications can be RNA sequence-specific and subjected to temporal or spatial regulation in development. RNA tailing and its outcomes have been associated with human diseases such as cancer. Here, we review recent developments in RNA uridylation and adenylation and discuss the future prospects in this research area.展开更多
基金Supported by the State Key Basic Research and Development Plan of China （2001CB109002）, the National Natural Science Foundation of China （30370893）, Shanghai Municipal Committee of Science and Technology （03JC14061）, the Program for New Century Excellent Talents in University （NCET-04-0403）, and the ShuGuang Scholarship （04SG15）.
文摘Arabidopsis U6 small nuclear RNA （snRNA） promoters are those transcribed by RNA polymerase Ⅲ, but all the core elements for transcriptional initiation are located in the 5＇ promoter region. Previously, three Arabidopsis U6 snRNA genes （U6-1, U6-26, and U6-29） were identified. Herein, we have further identified three new U6 loci （U6-4, U6-5, and U6-6） in the Arabidopsis genome. Alignment of these revealed that the upstream sequence element and TATA elements were contained in six U6 promoters. In addition, a unique, highly conserved element named the ＂CAT＂ element was observed in the promoter region. To understand the expression patterns of these U6 genes in Arabidopsis, we fused these promoters to the DNA segment of β-glucuronidase and then transferred these six constructs into Arabidopsis. Real-time reverse transcription-polymerase chain reaction analysis of these fused transcripts indicated that the newly identified U6 genes are active in Arabidopsis and that the U6-26 promoter seems to have higher transcriptional activity in leaf, stem, flower and silique. These results help to understand the function of these U6 snRNAs in Arabidopsis.
文摘Regulation of gene expression at the post-transcriptional level is of crucial importance in the development of an organism. Here we present the characterization of a maize gene, U6 biogenesis-like 1 （UBL1）, which plays an important role in kernel and seedling development by influencing pre-mRNA splicing. The ubll mutant, exhibiting small kernel and weak seedling, was isolated from a Mutator-tagged population. Trans- genic complementation and three independent mutant alleles confirmed that UBL1, which encodes a putative RNA exonuclease belonging to the 2H phosphodiesterase superfamily, is responsible for the phenotype of ubll. We demonstrated that UBL1 possess the RNA exonuclease activity in vitro and found that loss of UBL1 function in ubll causes decreased level and abnormal 3＇ end constitution of snRNA U6, resulting in splicing defect of mRNAs. Through the in vitro and in vivo studies replacing two histidines with alanines in the H-X-T/S-X （X is a hydrophobic residue） motifs we demonstrated that these two motifs are essential for the normal function of UBL1. We further showed that the function of UBL1 may be conserved across a wide phylogenetic distance as the heterologous expression of maize UBL1 could complement the Arabidopsis ubll mutant.
基金supported by the National Institutes of Health(GM061146)National Science Foundation(IOS-1340001)the National Natural Science Foundation of China(91440105 and 31571332)
文摘The posttranscriptional addition of nontemplated nucleotides to the 3′ ends of RNA molecules can have a significant impact on their stability and biological function. It has been recently discovered that nontemplated addition of uridine or adenosine to the 3′ ends of RNAs occurs in different organisms ranging from algae to humans, and on different kinds of RNAs, such as histone m RNAs, m RNA fragments, U6 sn RNA, mature small RNAs and their precursors etc. These modifications may lead to different outcomes, such as increasing RNA decay, promoting or inhibiting RNA processing, or changing RNA activity. Growing pieces of evidence have revealed that such modifications can be RNA sequence-specific and subjected to temporal or spatial regulation in development. RNA tailing and its outcomes have been associated with human diseases such as cancer. Here, we review recent developments in RNA uridylation and adenylation and discuss the future prospects in this research area.
