Silly me. I thought I could write some posts in technical language and others on different topics in plain English. But I find that I just don’t have the heart to leave my non-technical readers in the dark about exciting research findings, even if the payoff for patients is years away. So here’s a brief, non-technical translation of my last post on DNA methylation.
A paper in a prestigious journal this week reports that the DNA of people with PSP has an unusual pattern of small chemical markings in a few areas, including the area that includes the gene that makes tau protein.
Time out for some basics:
DNA is the chemical that bears the genetic code. It’s like a language with an alphabet of only four letters. Each word has three letters and there are 20 available words. The “letters” are A, C, G and T, which are abbreviations for the four chemical components that make up the DNA strand. Each three-letter “word” specifies an amino acid. A string of amino acids that the cell produces according that that instruction (like a sentence, to continue our analogy) is called a protein. All of the chemical processes and structures of the body rely on proteins of many different varieties that are determined mostly by the order of their amino acids.
Tau is the protein that forms the abnormal blobs in brain cells in PSP, called “neurofibrillary tangles.” Its normal function is to help maintain the internal skeleton of the brain cells, which doubles as monorail system to transport nutrients to where they’re needed.
These chemical markings, called “methyl groups,” are very simple – each is just one carbon atom with three hydrogen atoms on it. It’s been known for many years that such “methylation” of the amino acids in DNA is one way to regulate the coding of the DNA into proteins. In PSP, the tau protein is abnormal in several ways, and abnormal methylation of the tau protein’s gene, it’s now been discovered, could be the reason.
We already know that the gene that encodes the tau protein is abnormal in other ways. But those are actual genetic mutations – alterations in the DNA code itself. The new research article concludes that the mutation in the order of bases in the DNA causes the abnormal methylation, which then causes the damage of PSP.
We’ve also long known that methylation can be influenced by the chemical environment of the cell, examples being certain toxins or nutritional deficiencies. So this new finding suggests that we should look more closely at those sorts of things as possible causes of PSP. It also suggests that drugs that affect methylation could potentially stop or slow progression of the disease.
As you’d imagine, this opens the door to a whole new area of research in PSP. These are exciting times!