Last week I ran across an article in the journal Science Advances titled “Primate-restricted KRAB zinc finger proteins and target retrotransposons control gene expression in human neurons.” As a bit of a science nerd, a title like that must be investigated. The article is one of the more challenging reads I have encountered, but there is a free version if you wish to take the plunge.
The abstract mentioned transposable elements and endogenous retroviruses, two things I cover in my courses, so I jumped in headfirst. My summary of the article is that the researchers found a couple of relatively recent and primate-specific KRAB zinc finger proteins, or KZFPs, named ZNF417 and ZNF587. The KRAB box has been known to regulate the expression of genes for many years, typically repressing activity. Here they appear to be controlling a couple of transposable element sequences in early brain development. One of these, called human endogenous retrovirus K, has been linked to neurological disease like ALS already. The activity of the KZFPs appears to continue into adulthood, not just early brain development. Perhaps this article will provide a clearer picture of the genetics behind brain development and neurological diseases.
The details of developmental biology get very tedious. The transition from a single cell with one genetic code into a walking, talking human requires a complex and timely network of switching genes on and off. This massive crosstalk between genes is how cells become different or migrate to new locations. It is the very heart of understanding developmental biology, literally explaining form and function at the same time. I show a very catchy video in class, telling students, “I hope you take enough biology to understand this song one day.” Google “Evo-Devo (Despacito Biology Parody)” and enjoy it!
To learn more about transposable elements, you must start by investigating the work of the Nobel Prize-winning scientist Dr. Barbara McClintock and the discovery of her “jumping genes.” One of my favorite quotes from this brilliant lady is: “With the tools and the knowledge, I could turn a developing snail’s egg into an elephant. It is not so much a matter of chemicals because snails and elephants do not differ that much; it is a matter of timing the action of genes.” She has a few more excellent quotes, and her tireless childlike love for her work should inspire anyone! If you are a book person, hopefully, you are if you are reading this, pick up Evelyn Fox Keller’s “A Feeling for the Organism.”
To learn more about endogenous retroviruses or ERV’s you need only Google the term and begin exploring the many articles and videos about these ancient hijackers. You will find that our genome has plenty of ancient viral genes; some cause harm while others do good. The article “Endogenous Retroviruses: With Us and against US” covers this in more detail if you wish to investigate.
Viruses are not all bad; it seems and is even linked to placental formation in pregnancy. Google “The placenta goes viral: Retroviruses control gene expression in pregnancy.”