biology

Urocortin II

Urocortin II 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 Urocortin II rather than just read about it. In short: Urocortin 2 (Ucn2) is an endogenous peptide in the corticotrophin-releasing factor (CRF) family. Urocortin II is a 38-amino acid peptide that is a member of the CRF family of peptides.

Key takeaways

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

Reference excerpt

Urocortin 2 (Ucn2) is an endogenous peptide in the corticotrophin-releasing factor (CRF) family. Urocortin II is a 38-amino acid peptide that is a member of the CRF family of peptides. Unlike Urocortin I, Urocortin II is highly selective for the CRF2 receptor and does not show affinity for the CRF binding protein.

Function Urocortin (UCN) II, also known as stresscopin-related peptide, is a 38 amino acid member of the mammalian corticotropin-releasing hormone (CRH) peptide family, which also includes CRH, UCN I, and UCN III. CRH mainly binds to type 1 CRH receptors (CRH1), while UCN II and III bind primarily to type 2 CRH receptors, and UCN I binds to both (CRH2). Each of these hormones has distinctive distribution patterns in the central nervous system and the periphery, suggesting each peptide may have distinct behavioral and physiological effects, although all have been associated with anxiety. In general, agonism of CRH1 receptors is posited to be anxiogenic and agonism of CRH2 receptors is posited to be anxiolytic. Urocortin II has been shown to have anorexigenic effects and hypotensive effects similar to Urocortin, but does not induce secretion of ACTH.

Receptor The activation of cAMP/PKA by Ucn2 gives similar effects to the β-adrenergic pathway. Ucn2 increases left ventricular function independent of the β-adrenergic receptor but dependent on the binding of Ucn2 to CFR2. Ucn2 is an agonist for the G-protein coupled CRF1 and CRF2 receptors. It is highly selective for CRF2 which is predominantly found in the myocardium, blood vessels and peripheral tissues. This association provides reason for its strong cardiovascular effects. When Ucn2 binds CRF2 it activates adenyl-cyclase to increase cAMP which activates PKA and results in the noted changes to cardiovascular function. The ability of Ucn2 to produce PKA and alter calcium flux has led to the hypothesis that administration of Ucn2 may increase the risk of arrhythmias.

Clinical significance Immunohistochemistry analysis of human myocytes has shown greater immunoreactivity of Ucn2 in myocytes of the failing heart compared to those of the healthy heart. This is a result of an innate mechanism in which Ucn2 acts to improve function of the failing heart. The pathophysiology of heart failure is often a consequence of improper calcium handling and relaxation resulting in a lower cardiac output, decreased blood flow and overall decreased heart function. Infusion of Ucn2 in healthy humans has shown a dose dependent increase in cardiac output, heart rate and left ventricle ejection fraction and a decrease in systemic vascular resistance. Ucn2 has been studied as potential treatment for individuals with heart failure.

Animal studies Infusion of Ucn2 into rat hearts resulted in an immediate and significant improvement in left ventricle function, increased coronary flow, significantly altered intracellular calcium handling and increased SR calcium. These relaxation effects can be explained by the increased calcium clearance into the SR would assist in relaxation of the cell. Increased calcium in the SR by Ucn2 is a result of Ucn2 mediated production of cAMP and phosphokinase A (PKA). Ucn2 increases cAMP levels in myocytes and nonmyocytes. The production of PKA results in the phosphorylation of phospholamban and inhibition of its block on the sarcoendoplasmic reticulum calcium ATPase (SERCA). In rat coronary vessels, PKA mediates inhibition of calcium-independent phospholipase A and calcium influx which results in relaxation of the vasculature. This suggests Ucn2 may be beneficial in improving blood but these findings have less biological applicability to human medicine as they were completed on rats. In 2011 a similar relationship was found in human heart. Ucn2 produced a dose dependent relaxation of coronary. This correlation was a result of the cAMP/ PKA pathway and independent of endothelial function. Ucn2 may be a beneficial drug in damaged hearts where the endothelium is not intact.

References

Worked examples

Example 1 — a first encounter with Urocortin II

Start with the simplest possible case. Write down what Urocortin II 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 Urocortin II 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 Urocortin II 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 Urocortin II

In research: Urocortin II 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 Urocortin II 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: Urocortin II is common in secondary-school and first-year university syllabi. It links to neighbouring topics Human genes, Peptide hormones, so understanding it makes those chapters shorter.
In everyday life: Look for Urocortin II 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 Urocortin II in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Urocortin II 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 Urocortin II out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Urocortin II in simple terms?

Urocortin 2 (Ucn2) is an endogenous peptide in the corticotrophin-releasing factor (CRF) family. Urocortin II is a 38-amino acid peptide that is a member of the CRF family of peptides.

Why does Urocortin II 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 Urocortin II?

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 Urocortin II.