biology

MiR166 microRNA precursor family

MiR166 microRNA precursor family 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 MiR166 microRNA precursor family rather than just read about it. In short: miR165/166 is a conserved family of plant microRNAs that regulate gene expression by targeting transcripts encoding class III homeodomain–leucine zipper (HD-ZIP III) transcription factors. Members of the family include the closely related microRNAs miR165 and miR166, whose mature sequences differ by only one or two nucleotides and typically regulate the same targets.

Key takeaways

MiR166 microRNA precursor family belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MiR166 microRNA precursor family to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MiR166 microRNA precursor family from memory before moving on to harder problems.

Reference excerpt

miR165/166 is a conserved family of plant microRNAs that regulate gene expression by targeting transcripts encoding class III homeodomain–leucine zipper (HD-ZIP III) transcription factors. Members of the family include the closely related microRNAs miR165 and miR166, whose mature sequences differ by only one or two nucleotides and typically regulate the same targets. The miR165/166 family regulates key developmental processes by repressing HD-ZIP III transcription factors such as PHABULOSA (PHB), PHAVOLUTA (PHV), and REVOLUTA. These transcription factors control developmental patterning including shoot apical meristem maintenance, vascular differentiation, and adaxial–abaxial leaf polarity.

Target genes The principal targets of miR165/166 are class III HD-ZIP transcription factors, a conserved gene family involved in plant developmental patterning. In Arabidopsis thaliana, several HD-ZIP III genes contain miR165/166 complementary sites in their transcripts. Mutations that disrupt these target sites prevent miRNA-directed cleavage and lead to strong developmental phenotypes, demonstrating the importance of this regulatory interaction. HD-ZIP III transcription factors regulated by miR165/166 include PHABULOSA, PHAVOLUTA, and REVOLUTA, which control meristem activity, vascular patterning, and organ polarity.

Role in leaf polarity Leaf polarity depends on antagonistic patterning between adaxial (upper) and abaxial (lower) tissues. miR165/166 accumulates preferentially in abaxial regions of developing leaves and restricts the expression of HD-ZIP III genes to the adaxial domain. This spatial regulation is essential for establishing the flattened morphology of plant leaves. HD-ZIP II and HD-ZIP III transcription factors can also repress MIR165/166 transcription, forming a feedback regulatory circuit that stabilizes leaf polarity and organ patterning.

Shoot apical meristem regulation The miR165/166 family also contributes to maintenance of the shoot apical meristem (SAM). In Arabidopsis, the ARGONAUTE protein AGO10 binds miR165/166 and limits their activity in the meristem, preventing excessive repression of HD-ZIP III genes. Loss of AGO10 function leads to increased miR165/166 levels and defects in meristem maintenance. AGO10 acts as a molecular decoy that preferentially binds miR165/166, preventing their incorporation into AGO1 complexes that mediate target repression.

Roles in stress responses In addition to developmental functions, the miR165/166 regulatory module has roles in environmental responses. In Arabidopsis, heat stress induces MIR165/166 expression, reducing levels of the target transcription factor PHB. Through regulation of PHB and its interaction with heat shock transcription factors such as HSFA1, the miR165/166–PHB module contributes to thermotolerance and transcriptional reprogramming during heat stress.

Evolution and conservation Members of the miR165/166 family are conserved across land plants and regulate developmental patterning through highly conserved interactions with HD-ZIP III transcription factors.

See also MicroRNA miR156 microRNA precursor family miR529 microRNA precursor family miR535 microRNA precursor family

References

External links

Page for mir-166 microRNA precursor at Rfam

Illustrations

Worked examples

Example 1 — a first encounter with MiR166 microRNA precursor family

Start with the simplest possible case. Write down what MiR166 microRNA precursor family 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 MiR166 microRNA precursor family 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 MiR166 microRNA precursor family 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 MiR166 microRNA precursor family

In research: MiR166 microRNA precursor family 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 MiR166 microRNA precursor family 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: MiR166 microRNA precursor family is common in secondary-school and first-year university syllabi. It links to neighbouring topics MicroRNA, MicroRNA precursor families, Molecular and cellular biology stubs, so understanding it makes those chapters shorter.
In everyday life: Look for MiR166 microRNA precursor family 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 MiR166 microRNA precursor family in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MiR166 microRNA precursor family 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.
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Frequently asked questions

What is MiR166 microRNA precursor family in simple terms?

Why does MiR166 microRNA precursor family 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 MiR166 microRNA precursor family?

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 MiR166 microRNA precursor family.