Oncomodulin

Key takeaways

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

Reference excerpt

Oncomodulin is a parvalbumin-family calcium-binding protein expressed and secreted by macrophages (that typically traffic to tissue as an inflammatory response or after injury). Oncomodulin is present in the eye. It is small, acidic, has a high calcium-binding activity, and consists of 108 amino acid residues. It is released by macrophages in the vitreous and the retina to promote nerve regeneration in the eye. This regeneration can be done in response to inflammation in the eye and promote regrowth in the eye to repair retinal injury. The regeneration effects of oncomodulin outcompetes other neurotrophic factors like BDNF, CNTF, and GDNF. When added to retinal nerve cells in a petri dish with no other growth factors present, oncomodulin has been shown to promote neuron regrowth at 5-7 times the normal rate. Oncomodulin has been found in cytotrophoblasts of human and rat placenta and in the early stages of embryos. In vivo, oncomodulin promotes regeneration of the optic nerve in rats. It has also been found in different types of human and rodent tumors. However, it has never been found in healthy human or rat tissues. To date, it has been found in the central nervous system in inner ear hair cells and retinal ganglion cells. Oncomodulin promotes axon regeneration in retinal ganglion cells and maintains functioning in mouse cochlear hair cells.

Structure Oncomodulin is highly conserved across vertebrate evolution (NCBI database). It is a smaller calcium-binding protein (11.7-kDa) which resembles the EF-hand domain of calmodulin (32% sequence identity), alpha-parvalbumin (54%), S100-beta (34%), and calbindin (25%) and resembles alpha-parvalbumin in its N-terminal region (52%). It has a 40-residue N-terminal domain with an inactive calcium binding site and a 70-residue EF-hand domain with one low affinity Ca2+ and Mg2+ binding site and one high-affinity Ca2+ site. Oncomodulin has a crystal structure and is a 12,000 Mr protein. Two Ca2+ atoms in oncomodulin are co-ordinated with seven oxygen atoms and one water molecule. The third Ca2+ atom is co-ordinated with five oxygen atoms and two water molecules. Both of the Ca2+ molecules are bound to the CD and EF loops. The distances between Ca and O in the molecular structure range from 2.07 A to 2.64 A, which indicates that the molecule is tightly bound together. The backbone structure of oncomodulin closely resembles parvalbumin. It has a 50% amino acid identity to parvalbumin and a very similar structure. The oncomodulins, sometimes called "beta-1 parvalbumins," are an ancient family of parvalbumins that can be found at conserved genome locations in species as different as cartilaginous fish, bony fish, and mammals.

Mechanism of Action For oncomodulin to work properly, it must have elevated levels of cAMP and the sugar mannose, which is present in the vitreous of the eye. cAMP increases the effectiveness of oncomodulin several times more than just having oncomodulin and cAMP alone. Oncomodulin is activated by activating downstream signaling of Ca2+, calmodulin kinase, and gene transcription. Oncomodulin mRNA production peaks within a day of an inflammatory response. During inflammation, macrophages are released into the eye in order to promote axon regeneration. Inducing an inflammatory response enables the ability of sensory neurons to regenerate their axons through the dorsal roots. The secretion of oncomodulin from macrophages stimulates the growth of neurons. The identity of the receptor for oncomodulin that allows axon regeneration is unknown. It is also unknown whether oncomodulin promotes regeneration elsewhere in the immune system. Signaling complexes that may be important to work with oncomodulin include PI 3 Kinase, MAP Kinase, JAK/STAT, and CaM Kinase II. The depletion of oncomodulin from media in which macrophages grow removes the axon-promoting activity of the media. Neutrophils are also an important component of oncomodulin activation. Without neutrophils present, macrophages are less effective at stimulating extensive regeneration of neurons. This is because neutrophils enter the area of inflammation before macrophages do. In addition to macrophages, neutrophils are also a major source of oncomodulin production. In rats, the gene that encodes oncomodulin is under control of a solo oncomodulin LTR that comes from an endogenous intracisternal A-particle. The oncomodulin LTR is only present in rats. Oncomodulin levels are highest in the rat out of all other species that have been previously investigated.

Uses Oncomodulin plays a key role in patients with eye injuries. It is thought that it can reverse eye damage caused from glaucoma. Oncomodulin is also thought to switch on a variety of genes that are associated with axon regrowth. Eye drops with oncomodulin can be a useful method of promoting nerve regrowth in mild cases of optic gliomas. Oncomodulin has also been seen to stimulate outgrowth from peripheral sensory neurons. Injections with zymosan can promote macrophages to enter the eye and secrete oncomodulin. This is an effective method of treatment in patients with minor eye damage. Injections into patients with severed spinal cords has shown to restore partial motor function.

Worked examples

Example 1 — a first encounter with Oncomodulin

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

In research: Oncomodulin 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 Oncomodulin 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: Oncomodulin is common in secondary-school and first-year university syllabi. It links to neighbouring topics EF-hand-containing proteins, Growth factors, so understanding it makes those chapters shorter.
In everyday life: Look for Oncomodulin 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 Oncomodulin in 20 minutes

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

Frequently asked questions

What is Oncomodulin in simple terms?

Oncomodulin is a parvalbumin-family calcium-binding protein expressed and secreted by macrophages (that typically traffic to tissue as an inflammatory response or after injury). Oncomodulin is present in the eye.

Why does Oncomodulin 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 Oncomodulin?

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 Oncomodulin.