Regucalcin

Key takeaways

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

Reference excerpt

Regucalcin is a protein that in humans is encoded by the RGN gene The protein encoded by this gene is a highly conserved, calcium-binding protein, that is preferentially expressed in the liver, kidney and other tissues. It may have an important role in calcium homeostasis. Studies in rats indicate that this protein may also play a role in aging, as it shows age-associated down-regulation. This gene is part of a gene cluster on chromosome Xp11.3-Xp11.23. Alternative splicing results in two transcript variants having different 5' UTRs, but encoding the same protein. Regucalcin is a proposed name for a calcium-binding protein that was discovered in 1978 This protein is also known as Senescence Marker Protein-30 (SMP30). Regucalcin differs from calmodulin and other Ca2+-related proteins as it does not contain an EF-hand motif of Ca2+-binding domain. It may regulate the effect of Ca2+ on liver cell functions. From many investigations, regucalcin has been shown to play a multifunctional role in many cell types as a regulatory protein in the intracellular signaling system.

Gene Regucalcin and its gene (rgn) are identified in 16 species consisting of regucalcin family. Regucalcin is greatly expressed in the liver of rats, although the protein is found in small amounts in other tissues and cells. The rat regucalcin gene consists of seven exons and six introns, and several consensus regulatory elements exist upstream of the 5’-flanking region. The gene is localized on the proximal end of rat chromosome Xq11.1-12 and human Xp11.3-Xp11.23. AP-1, NFI-A1, RGPR-p117, and Wnt/β-catenin/TCF4 can bind to the promoter region of the rat regucalcin gene to mediate the Ca2+ and other signaling responses with various hormones and cytokines for transcriptional activation.

Function Regucalcin plays a pivotal role in the keep of intracellular Ca2+ homeostasis due to activating Ca2+ pump enzymes in the plasma membrane (basolateral membrane), microsomes (endoplasmic reticulum) and mitochondria of many cells. Regucalcin is localized in the cytoplasm, mitochondria, microsomes and nucleus. Regucalcin is translocated from cytoplasm to nucleus with hormone stimulation. Regucalcin has a suppressive effect on calcium signaling from the cytoplasm to the nucleus in the proliferative cells. Also, regucalcin has been demonstrated to transport into the nucleus of cells, and it can inhibit nuclear protein kinase, protein phosphatase, and deoxyribonucleic acid and ribonucleic acid synthesis. Regucalcin can control enhancement of cell proliferation due to hormonal stimulation. Moreover, regucalcin has been shown to have an inhibitory effect on aminoacyl t-RNA synthetase, a rate limiting enzyme at translational process of protein synthesis and an activatory effect on cystein protease and superoxide dismutase in liver and kidney cells. Regucalcin is expressed in the neuron of brain tissues, and the decrease of brain regucalcin causes accumulation of calcium in the brain microsomes. Regucalcin has an inhibitory effect on protein kinase and protein phosphatase activity dependent on Ca signaling. Regucalcin has been shown to have an activatory effect on Ca pumping enzyme (Ca-ATPase) in heart sarcoplasmic reticulum. Regucalcin plays a role in the promotion of urinary calcium transport in the epithelial cells of kidney cortex. Overexpression of regucalcin suppresses cell death and apoptosis in the cloned rat hepatoma cells and normal rat kidney epithelial cells (NRK52E) induced by various signaling factors. Thus, regucalcin plays a multifunctional role in the regulation of cell functions in liver, kidney cortex, heart and brain. Thus, regucalcin plays a pivotal role in keep of cell homeostasis and function. Regucalcin plays a pivotal role as a suppressor protein for cell signaling systems in many cell types.

Pathophysiologic role Overexpressing of regucalcin in rats (transgenic rats) has been shown to induce bone loss and hyperlipidemia with increasing age, indicating a pathophysiologic role. Regucalcin transgenic rat may be a useful tool as animal model in osteoporosis and hyperlipidemia. Also, regucalcin/SMP30-knockout mice are known to induce a suppression in ascorbic acid biosynthesis. The disorder of regucalcin expression has been proposed to be induced cancer, brain function, heart injury, kidney failure, osteoporosis, and hyperlipidemia. Regucalcin plays a novel role as a suppressor in carcinogenesis of human patients with various types of cancer including pancreatic cancer, breast cancer, hepatoma, and lung cancer. Of note, it has been conducted a systematic search to identify biomarker candidates for a frailty biomarker panel. Gene expression databases were to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified. Regucalcin (RGN) was proposed to be a core gene (protein) with high priority of frailty biomarkers in order to ascertain their diagnostic, prognostic and therapeutic potential. Notably, it has been shown that epigenetic modifications of survivin and regucalcin in non-small cell lung cancer tissues contribute to malignancy.

References

Illustrations

Worked examples

Example 1 — a first encounter with Regucalcin

Start with the simplest possible case. Write down what Regucalcin 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 Regucalcin 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 Regucalcin 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 Regucalcin

In research: Regucalcin 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 Regucalcin 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: Regucalcin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aging-related proteins, Calcium signaling, Genes on human chromosome X, so understanding it makes those chapters shorter.
In everyday life: Look for Regucalcin 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.

How to study Regucalcin in 20 minutes

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

Frequently asked questions

What is Regucalcin in simple terms?

Regucalcin is a protein that in humans is encoded by the RGN gene The protein encoded by this gene is a highly conserved, calcium-binding protein, that is preferentially expressed in the liver, kidney and other tissues. It may have an important role in calcium homeostasis.

Why does Regucalcin 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 Regucalcin?

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 Regucalcin.