Why Arabidopsis Why: Argonaute
Small-interfering RNAs (siRNAs), microRNAs (miRNAs), transacting siRNAs (tasiRNAs), and Piwi-interacting RNAs (piRNAs) are involved in gene silencing in animal and plant cells. Argonaute protein plays an important role in RNA-induced silencing processes. Argonaute protein plays a catalytic role by binding with non-coding RNAs such as siRNA, miRNA, tasiRNA and piRNA. Then, non-coding RNAs guide Argonaute proteins to bind their specific targets based on sequence similarity and cleaves mRNA or inhibits translation. Please follow the pciture below to get a quick review. (Source)
Research in plant science helped a lot to understand that RNA-induced post-transcriptional gene silencing. The first proof came with the example for 1-aminocyclopropane-1-carboxylate oxidase (ACO) of tomato plant. In transgenic plant they showed that after expressing specific 25 nucelotide complementray to ACO abolishes mRNA. This report gave the idea that small antisense RNA is involved in post-transcriptional gene silencing in plants.
But Arabidopsis research broaden our horizon about RNA-induced silencing processes due to availability of mutants and convenient phenotype characterization. The mutant for Argonaute proteins were identified in Arabidopsis for leaf development and cloned also to confirm that it is the candidate gene. The following figure shows 6-weeks-old wild type (left) and ago1-1 (right) plants.
Recent advancement in medical science showed the involvement of RNAi for disease (HVB, HIV, respiratory syncytial virus) treatment and misregulations of miRNAs lead to clinical complications such as fragile X-syndrome, autoimmune disease. And, Argonaute protein is in the pivotal point of RNA-induced silencing process. Understanding the mechanistic details about Argonaute proteins from Arabidopsis will help us to discover unknown mechanisms involved in human diseases and possible treatments as well as.
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