Gene Expression, RNA Biology, and Epigenetic Regulation
Transcriptional control
Regulatory logic
Gene expression is controlled by transcription factors, cis-regulatory elements, chromatin accessibility, polymerase kinetics, and three-dimensional genome organization. At higher resolution, transcription is often bursty rather than continuous, producing stochastic gene expression.
Research frontier
Single-cell multi-omics has revealed that transcriptional states are often transient, heterogeneous, and spatially organized.
RNA processing and function
Beyond messenger RNA
Eukaryotic transcripts undergo capping, splicing, editing, export, localization, decay, and translation control. Noncoding RNAs, including miRNAs, lncRNAs, and piRNAs, shape gene regulation and genome defense.
Major RNA processing events
| Process | Consequence |
|---|---|
| 5' capping | Transcript stability and translation initiation |
| Splicing | Removal of introns and isoform diversification |
| Polyadenylation | Stability, export, and translational efficiency |
| RNA editing | Sequence diversification at the RNA level |
Which feature most directly enables isoform diversity from a single gene?
Alternative splicing can produce multiple mRNA isoforms from one pre-mRNA.
Correct answer: Alternative splicing
Name one class of small regulatory RNA.
microRNAs post-transcriptionally regulate gene expression, often by repressing translation or promoting decay.
Correct answer: microRNA
Epigenetic memory and chromatin
Chemical marks and 3D organization
Histone modifications, DNA methylation, nucleosome positioning, and chromatin looping contribute to cellular memory. An open challenge is distinguishing causal epigenetic regulation from correlated chromatin signatures.
Which statement best captures an epigenetic mechanism?
Epigenetic mechanisms alter gene activity states without changing the underlying nucleotide sequence.
Correct answer: A heritable change in gene expression without altering DNA sequence
What major open problem remains in many epigenetic studies?
Many chromatin marks correlate with gene activity, but proving direct causal roles requires perturbation experiments.
Correct answer: Separating causation from correlation