TRANSCRIPTION AND RNA PROCESSING: THE REQUISITE STEPS IN GENE EXPRESSION
🧬 The central dogma of molecular biology describes the directional flow of genetic information from DNA to RNA to protein. At the heart of this process lie transcription and RNA processing, two tightly regulated steps that determine how genetic information is converted into functional biological output.
🔹 Transcription is the first stage of gene expression, during which RNA polymerase synthesizes a complementary RNA strand from a DNA template. This process proceeds through initiation, elongation, and termination. Transcription begins when transcription factors bind promoter regions, recruiting RNA polymerase and enabling DNA strand separation. As elongation proceeds, ribonucleotides are added in a 5′→3′ direction, producing a growing RNA transcript. Termination occurs once RNA polymerase encounters sequence-specific signals, releasing the newly synthesized RNA.
🔹 In eukaryotic cells, the primary transcript (pre-mRNA) must undergo RNA processing before translation. This includes:
5′ capping, which enhances mRNA stability and promotes ribosomal recognition
3′ polyadenylation, which regulates transcript longevity and translation efficiency
Splicing, where introns are removed and exons joined by the spliceosome.
A key outcome of splicing is alternative splicing, allowing a single gene to generate multiple protein isoforms. This dramatically expands proteomic diversity & enables cells to respond dynamically to developmental and environmental cues.
🔹 Together, transcription & RNA processing serve as major regulatory checkpoints in gene expression. Chromatin structure, transcription factor networks, RNA-binding proteins, and regulatory RNAs (including microRNAs and long non-coding RNAs) collectively fine-tune when, where, and how genes are expressed.
➡️ Disruption at any stage; such as aberrant splicing or faulty transcriptional control can result in disease, including cancer, inherited disorders, and neurodegeneration. Understanding these processes is therefore central to both basic biology and the development of targeted RNA-based therapeutics.
⚠️ In an Oystershell, as research continues to uncover the multilayered regulation of RNA biology, transcription and RNA processing stand out as elegant examples of how cells balance stability with adaptability, ensuring precision without sacrificing flexibility.
Abubakar Abubakar ✍🏻
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• Lee, et al. (2015). Annual Review of Biochemistry, 84, 291-323.
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