Epigenetics: Adapting Genetic Inheritance

by   |   vantigna@bju.edu   |  
DNA strand

Wouldn’t it be interesting if we could “train” our genes the way athletes train in preparation for a game? Recent studies in epigenetics show that our bodies use mechanisms to accelerate, slow down or even turn off certain genes’ expression.

To think about epigenetics, let’s first review the basis of genetics: DNA and genes. The order of the nucleotide “letters” that make up DNA encodes the genes that determine what cells do and ultimately direct the make-up of the whole organism. But this explanation of genetics is oversimplified. An organism’s DNA sequence is only one factor affecting its or its offspring’s physical characteristics. Narrowing down to DNA structure, other factors change the way DNA is stored and inherited. These outside influences are termed epigenetics.

What is epigenetics?

Epigenetics contributes to phenomena at all levels, from why identical twins have different characteristics to why we have diverse types of cells (e.g., skin cells, nerve cells, cells that form our immune system, and cells that receive light to help us see). These cells all have the same DNA. It is simply stored and tagged differently.

Epigenetics (epi: over, above; as in, over or above the DNA sequence) generally refers to changes in chromatin structure. The long strand of DNA wraps around proteins, then coils and organizes and wraps again to form a chromosome. Chromatin is the “yarn”—composed of the DNA strand and the proteins it wraps around—that knits together to produce a whole chromosome “scarf.”

Epigenetic changes are changes to the structure of this chromatin, making a cell’s gene-expression machinery read the DNA code differently. The DNA and its proteins can be tagged so they are read less, packaged up and not read at all, or modified so the cell machinery reads the DNA more often.

Chromatin structure influences how the cell’s DNA produces the gene’s products, and these structural changes can be inherited. The overall implication is that changes not in the DNA sequence could be passed down to future cells and possibly even to offspring.

How does epigenetics work?

Now that we know what epigenetics is, how does it happen? And how does it affect us?

Structural changes in chromatin can be shaped by the organism’s environment. Environmental factors signal to cells. The cells react to these outside influences by changing what genes it uses, eventually tagging different genes and reorganizing chromatin.

Scientists link some cancers to changes caused by genes expressed either too much or too little. Diet can also affect epigenetics. If a rat is underfed while pregnant, its offspring will likely develop obesity, possibly from epigenetic changes that produce a “starvation” metabolism. Even the father’s diet can produce epigenetic influence in offspring. Epigenetics and environment are linked in ways not yet discovered and that continue to surprise scientists.

Are epigenetic modifications the exception or the rule?

This is a difficult question, but we can say that the right answer is both. While epigenetic factors might be present in cells, they may or may not have a clear effect on the organism. Yet those factors can still dramatically influence that organism’s offspring.

A recent study on acquired traits shows that parents suffering from pre-diabetes have a higher chance to produce offspring susceptible to the same condition due to epigenetic mechanisms. Even something as innocuous as experiencing smell can not only cause epigenetic changes but can also trigger the same changes in offspring. Researchers from the molecular embryology unit at the University College in London found that when male rats were treated with a smell associated with a negative experience, their sperm contain olfactory membrane receptors. The sperm are then preprogrammed to be sensitive to the same smell the parent experienced as negative.

Can science use epigenetics to create “perfect” humans and eradicate genetic diseases?

The interesting thing about epigenetic therapy is that it does not impact the information contained in the genome. In other words, epigenetics is not about fixing a gene gone wrong or about adding new foreign genes. That being said, it’s possible that new insights in epigenetics may provide the background information for genetic modifications.

Researchers are currently testing epigenetic drugs to control “dangerous” genes, and while there is hope that some of them will help us curing diseases, we need to acknowledge some facts:

  • While these drugs may attenuate the symptoms of a certain disease, they may not cure genetic defects.
  • We do not know much about possible side effects from taking epigenetic drugs long term.
  • Certain genetic diseases are related to the malfunctioning of multiple genes, and in these cases, the epigenetic approach might not be effective.

How is epigenetics related to evolution?

According to the theory of evolution, organisms change over time due to beneficial mutations transferred from generation to generation. Practically speaking, evolutionary theory relies on the inheritance of altered genes.

But we know from science (epigenetics) that not all of the traits transmitted to the next generation are results of genetic mutations. To put it simply, data from experiments is more complex than what the evolutionary theory can handle. And as a matter of fact, neither traditional nor modern evolutionary theories offer an explanation that is both logical and includes all of our understanding of genetics and epigenetics.

How is epigenetics related to a biblical worldview?

To gain a better sense of the level of intricacy we are talking about, imagine you go to a car dealership to purchase a vehicle. Let’s assume you have no idea which model you want to buy. The dealer shows you everything from MINI Coopers to F-250s. Compare this variety to the genetic diversity between different individuals of the same species.

Now, let’s say you settle in for a mid-size luxury car, and the dealer shows you the upgrade options for that specific model. This second level of customization is in some ways comparable to epigenetics. It does not change the car model but fine-tunes it to your tastes and needs.

Buying a car is simple in comparison to biological systems. We do not know how and why organisms have such complex genetic programs. But we can realize the enormous wisdom in creating a system both stable yet capable of adapting the next generation without losing information.

Let’s consider a final analogy from the Mona Lisa by Leonardo da Vinci. What would you say is more important in this masterpiece, the canvas or the paint? Which is more valuable? Truly, the Mona Lisa’s value is not in its material components or the way da Vinci arranged them. The value comes from the creative genius that realized an awesome idea.

Similarly, every time science discovers a new detail in the book of creation, every time we stand in awe at the amazing complexity of a tiny new spot on the canvas of life, let us remember we are studying a masterpiece made by God. Let’s recognize and praise the wisdom and the perfection of the One who knits us together and holds the whole world in His hands.

A final take on epigenetics

Disease is the direct effect of God’s curse on nature, and genetic abnormalities—whether we are talking about a structurally defective gene or a badly regulated gene—fall into this category. We should be empathetic toward those who suffer as a result of these sicknesses and offer them hope since, even in this distorted version of God’s perfect creation, God included us in His redemptive plan.

God has mandated us to keep and subdue nature and to care for our neighbors. However, as we consider the fantastic advancements and achievements of science, we need to ponder the limits that God poses to the spiritual mandate of science. Today, we possess the technology to “improve” the human race through genetic selection and modification. But is this really part of our mandate? Various passages in the Bible teach that God knows and forms us in our mother’s womb. In other words, He is the maker of our deepest identity. So, how are our genes part of our identity, and is altering them for the sake of fighting the curse within our “redemptive authority”?

Food for thought, food for discussion, and food for future articles.

 

This article was co-authored by student Christina Ross and biology professor Vincenzo Antignani.

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Dr. Vincenzo Antignani is both researcher and professor. He currently teaches biology courses at BJU and has been published in scientific journals.