biology

MEG3

MEG3 is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand MEG3 rather than just read about it. In short: MEG3 (maternally expressed 3) is a maternally expressed, imprinted long non-coding RNA gene. Gene MEG3 is a genomically imprinted, maternally expressed long non-coding RNA (lncRNA) gene located within the DLK1-MEG3 imprinted locus on human chromosome 14q32.3, paired with the paternally expressed protein-coding gene DLK1 in the same domain.

Key takeaways

MEG3 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MEG3 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MEG3 from memory before moving on to harder problems.

Reference excerpt

MEG3 (maternally expressed 3) is a maternally expressed, imprinted long non-coding RNA gene.

Gene MEG3 is a genomically imprinted, maternally expressed long non-coding RNA (lncRNA) gene located within the DLK1-MEG3 imprinted locus on human chromosome 14q32.3, paired with the paternally expressed protein-coding gene DLK1 in the same domain. The gene generates multiple alternatively spliced transcripts, all of which are non-coding, and is expressed across many normal tissues. At least 12 different isoforms of MEG3 are generated by alternative splicing. The non-Mendelian inheritance pattern, known as polar overdominance, likely results from the combination of the cis-effect on the expression levels of genes in the DLK1-GTL2 imprinted domain, and trans interaction between the products of reciprocally imprinted genes.

Function In mouse models, maternal deletion of Meg3 causes skeletal muscle defects and perinatal death, indicating a role in normal tissue development. Meg3 constrains angiogenesis under normal conditions. Its loss increases expression of angiogenesis-promoting genes and microvessel formation in the brain, indicating that MEG3 normally restrains new blood vessel formation. MEG3 supports normal endothelial cell function by regulating the DNA damage response, contributing to vascular integrity. MEG3 forms RNA–DNA triplex structures at GA-rich chromatin sites, acting as a molecular adaptor that guides PRC2/EZH2 to target genes such as those of the TGF-β pathway. MEG3 is involved in negative regulation of cell growth under normal conditions, indicating that healthy tissues rely on baseline MEG3 activity to keep proliferation properly restrained.

Clinical significance

Camcer MEG3 expression is lost or reduced, frequently through promoter hypermethylation, in an expanding list of primary human tumors and cancer cell lines across many tissue types, making it one of the first lncRNAs identified as a tumor suppressor. It acts as a growth suppressor in tumour cells, and activates p53. A conserved pseudoknot in exon 3 was shown to be essential for p53 pathway upregulation. MEG3 normally stabilizes and increases p53 protein levels and enhances transcription of p53 target genes; its loss removes this brake on proliferation and apoptosis resistance. MEG3 loss de-represses RB, MYC, and PTEN regulation and the Wnt/β-catenin, PI3K/AKT, JAK/STAT, and VEGF pathways, permitting uncontrolled proliferation, epithelial–mesenchymal transition, and angiogenesis. MEG3 normally sequesters specific microRNAs (e.g., miR-21, miR-127, miR-421); its loss releases these oncogenic miRNAs to silence tumor-suppressive targets. Low or absent MEG3 expression correlates with faster tumor growth, earlier metastasis, worse prognosis, and reduced chemosensitivity (e.g., to cisplatin, paclitaxel, oxaliplatin, and gemcitabine). Specific MEG3 polymorphisms (rs7158663, rs4081134, rs11160608) are associated with increased cancer risk, and rs10132552 with therapeutic response. MEG3 dysregulation has been implicated as a mechanism in cancers driven by exposure to carcinogenic metals. Loss of MEG3 expression is strongly associated with tumor grade in meningioma, with allelic loss and promoter hypermethylation of MEG3 increasing in prevalence in higher-grade tumors.

Developmental abnormalities The expression profile in mouse of the co-regulated Meg3 and Dlk1 genes suggests a causative role in the pathologies found in uniparental disomy animals, characterized by defects in skeletal muscle maturation, bone formation, placenta size and organization and prenatal lethality. The sheep homolog is associated with the callipyge mutation which in heterozygous individuals affects a muscle-specific long-range control element located in the DLK1-GTL2 intergenic region and results in the callipyge muscular hypertrophy.

Alzheimer's disease MEG3 is thought to play a role in the development of Alzheimer's disease by triggering necroptosis.

References

Illustrations

Worked examples

Example 1 — a first encounter with MEG3

Start with the simplest possible case. Write down what MEG3 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MEG3 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MEG3 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MEG3

In research: MEG3 appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MEG3 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MEG3 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alzheimer's disease, Genes on human chromosome 14, Non-coding RNA, so understanding it makes those chapters shorter.
In everyday life: Look for MEG3 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study MEG3 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MEG3 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MEG3 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MEG3 in simple terms?

MEG3 (maternally expressed 3) is a maternally expressed, imprinted long non-coding RNA gene. Gene MEG3 is a genomically imprinted, maternally expressed long non-coding RNA (lncRNA) gene located within the DLK1-MEG3 imprinted locus on human chromosome 14q32.3, paired with the paternally expressed pr…

Why does MEG3 matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MEG3?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MEG3.