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The four Rs of RNA-directed evolution
1Department of Genetics and Genomics, Boston University School of Medicine, 715 Albany Street, Boston, Massachusetts 02118, USA. aherbert@bu.edu
Nature Genetics
|January 1, 2004
Summary
The human genome is increasingly viewed through an RNA-centric lens, with significant portions derived from retrotransposition, alternative splicing, and non-coding RNAs. This perspective highlights RNA
Area of Science:
- Genomics
- Evolutionary Biology
- Molecular Biology
Background:
- Human genome quantification has undergone significant revisions.
- Previous estimates of genomic components are being updated.
- The role of RNA in genome evolution is increasingly recognized.
Purpose of the Study:
- To present an updated view of the human genome based on recent quantitative estimates.
- To support an RNA-centric model of evolution.
- To elucidate the roles of various RNA types in genetic information processing and inheritance.
Main Methods:
- Analysis of current estimates for retrotransposition, alternative splicing, antisense transcription, and non-protein coding RNA.
- Comparison of updated estimates with previous genomic models.
- Integration of findings to support an RNA-centric evolutionary framework.
Main Results:
- Retrotransposition accounts for 45% of the human genome.
- Alternative splicing affects 41-60% of multiexon genes.
- Non-protein coding RNA constitutes approximately 7% of full-length cDNAs.
- The estimated number of protein-coding genes has decreased to approximately 24,500.
- Sense-antisense transcription units (SATs) and coregulatory RNAs (coRNAs) play crucial roles in genetic regulation and epigenetic inheritance.
Conclusions:
- The human genome is characterized by extensive RNA processing and RNA-directed DNA modification.
- Phenotypic diversity arises from complex RNA processing.
- RNA plays a central role in evolution, encompassing information processing, regulation, and inheritance through the 'four Rs': reading, 'riting, 'rithmetic, and replication.