Last week, as everyone was preparing for Christmas celebrations, researchers at the pharmaceutic company Novartis published new research on a gene that is involved with Parkinson’s, called PARKIN (or PARK2).
They used a new gene editing technology – called CRISPR – to conduct a large screening study to identify proteins that are involved with the activation of PARKIN.
In today’s post we will look at what PARKIN does, review the research report, and discuss how these results could be very beneficial for the Parkinson’s community.
As many people within the Parkinson’s community will be aware, 2017 represented the 200th anniversary of the first report of Parkinson’s disease by James Parkinson.
It also the 20th anniversary of the discovery of first genetic mutation (or variant) that increases the risk of developing Parkinson’s. That genetic variation occurs in a region of DNA (a gene) called ‘alpha synuclein’. Yes, that same alpha synuclein that seems to play such a critical role in Parkinson’s (Click here to read more about the 20th anniversary).
In 2018, we will be observing the 20th anniversary of the second genetic variation associated with Parkinson.
That gene is called PARKIN:
Title: Mutations in the parkin gene cause autosomal recessive juvenile parkinsonism.
Authors: Kitada T, Asakawa S, Hattori N, Matsumine H, Yamamura Y, Minoshima S, Yokochi M, Mizuno Y, Shimizu N
Journal: Nature. 1998 Apr 9; 392(6676):605-8
In 1998, Japanese researchers published this report based on 5 individuals from 4 Japanese families who were affected by juvenile-onset Parkinson’s. In family 1, the affected individual was a female, 43 years old, born of first-cousin parents, and her two younger brothers are healthy. Her condition was diagnosed in her teens and it had then progressed very slowly afterwards. Her response to L-dopa was very positive, but L-dopa-induced dyskinesia were frequent. In family 2-4, affected individuals (born to unrelated parents) exhibited very similar clinical features to the subject in family 1. The age of onset was between 18 to 27 years of age.
Using previous research and various techniques the investigators were able to isolate genetic variations that were shared between the 5 affected individuals. They ultimately narrowed down their search to a section of DNA containing 2,960 base pairs, which encoded a protein of 465 amino acids.
They decided to call that protein PARKIN.
PARKIN Protein. Source: Wikipedia
How much of Parkinson’s is genetic?
This week Denali Therapeutics released the results of a phase I clinical trial of their primary product, called DNL-201.
DNL-201 is a LRRK2 inhibitor that the company is attempting to take to the clinic for Parkinson’s disease.
In today’s post we will look at what LRRK2 is, how an inhibitor might help in Parkinson’s, and what the results of the trial actually mean.
Denali. Source: Wikipedia
Denali (Koyukon for “the high one”; also known as Mount McKinley) in Alaska is the highest mountain peak in North America, with a summit elevation of 20,310 feet (6,190 m) above sea level. The first verified ascent to Denali’s summit occurred on June 7, 1913, by four climbers Hudson Stuck, Harry Karstens, Walter Harper, and Robert Tatum.
Tatum (left), Karstens (middle), and Harper (right). Source: Gutenberg
Robert Tatum later commented, “The view from the top of Mount McKinley is like looking out the windows of Heaven!”
More recently another adventurous group associated with ‘Denali’ have been trying to scale lofty heights, but of a completely different sort from the mountaineering kind.
Gene therapy involves treating medical conditions at the level of DNA – that is, altering or enhancing the genetic code inside cells to provide therapeutic benefits rather than simply administering drugs. Usually this approach utilises specially engineered viruses to deliver the new DNA to particular cells in the body.
For Parkinson’s, gene therapy techniques have all involved direct injections of these engineered viruses into the brain – a procedure that requires brain surgery. This year, however, we have seen the EXTREMELY rapid development of a non-invasive approach to gene therapy for neurological condition, which could ultimately see viruses being injected in the arm and then travelling up to the brain where they will infect just the desired population of cells.
Last week, however, this approach hit a rather significant obstacle.
In today’s post, we will have a look at this gene therapy technology and review the new research that may slow down efforts to use this approach to help to cure Parkinson’s.
Gene therapy. Source: rdmag
When you get sick, the usual solution is to visit your doctor.
They will prescribe a medication for you to take, and then all things going well (fingers crossed/knock on wood) you will start to feel better. It is a rather simple and straight forward process, and it has largely worked well for most of us for quite some time.
As the overall population has started to live longer, however, we have begun to see more and more chronic conditions which require long-term treatment regimes. The “long-term” aspect of this means that some people are regularly taking medication as part of their daily lives. In many cases, these medications are taken multiple times per day.
A good example of this is Levodopa (also known as Sinemet or Madopar) which is the most common treatment for the chronic condition of Parkinson’s disease.
When you swallow your Levodopa pill, it is broken down in the gut, absorbed through the wall of the intestines, transported to the brain via our blood system, where it is converted into the chemical dopamine – the chemical that is lost in Parkinson’s disease. This conversion of Levodopa increases the levels of dopamine in your brain, which helps to alleviate the motor issues associated with Parkinson’s disease.
Levodopa. Source: Drugs
This pill form of treating a disease is only a temporary solution though. People with Parkinson’s – like other chronic conditions – need to take multiple tablets of Levodopa every day to keep their motor features under control. And long term this approach can result in other complications, such as Levodopa-induced dyskinesias in the case of Parkinson’s.
Yeah, but is there a better approach?
Genetic mutations (or ‘variants’) in the Leucine-rich repeat kinase 2 (or LRRK2; also known as Dardarin) gene are associated with increased risk of Parkinson’s. As a result this gene has become the focus of a lot of genetic research.
But what about LRRK2’s less well-known, rather neglected sibling LRRK1?
In today’s post, we will look at new research that suggests the LRRK siblings could both be involved with Parkinson’s disease.
I recommend to the reader that today’s post should be read with the following music playing in the background:
Inspired by a poem of the same title, English composer Ralph Vaughan Williams wrote ‘The Lark Ascending’ in 1914. It is still to this day, a tune that remains a firm favourite with BBC listeners here in the UK (Source).
On to business:
While the music and the poem are about a songbird, today’s SoPD post deals with a different kind of Lark.
Or should I say LRRK.
This is Sergey Brin.
He was one of the founders of a small company you may have heard of – it’s called “Google”.
Having changed the way the world searches the internet, he is now turning his attention to other projects.
One of those other projects is close to our hearts: Parkinson’s disease.
Dipeptidyl peptidase-4 (or DPP-4) is an enzyme that breaks down the protein (GLP-1) that stimulates insulin release in your body.
Inhibitors of DPP-4 are used in the treatment of Type 2 diabetes, because they help increase insulin levels in the body.
Recently some Swedish researchers noticed something curious about DPP-4 inhibitors: They appear to reduce the risk of developing Parkinson’s disease.
In today’s post, we will review what DPP-4 inhibitors do and look at how this could be reducing the risk of Parkinson’s disease.
Sitagliptin. Source: Diabetesmedicine
Last year an interesting research report about a class of medications that could possibly reduce the risk of developing Parkinson’s disease was published in the journal Movement disorders:
Title: Reduced incidence of Parkinson’s disease after dipeptidyl peptidase-4 inhibitors-A nationwide case-control study.
Authors: Svenningsson P, Wirdefeldt K, Yin L, Fang F, Markaki I, Efendic S, Ludvigsson JF.
Journal: Movement Disorders 2016 Jul 19.
In this study, the investigators used the Swedish Patient Register, to find the medical records of 980 people who were diagnosed with Parkinson’s disease but also had type 2 diabetes. Importantly, all of the subjects had been treated with Type 2 diabetes medication for at least 6 months prior to the date of Parkinson’s being diagnosed.
For comparative sake, they selected 5 controls (non-Parkinsonian) with Type 2 diabetes (n = 4,900) for each of their Parkinsonian+diabetes subjects. They next looked at whether GLP-1R agonists (such as Exenatide), Dipeptidyl peptidase-4 (or DPP-4) inhibitors, or any other oral Type 2 diabetic medication can influence the incidence of Parkinson’s disease.
Now, if all things are considered equal, then when looking at each diabetes medication there should be 1 person in the Parkinson’s disease + Type 2 diabetes for every 5 people in the Type 2 diabetes control group taking each medication right? That is because there are almost 1000 people in the first group and 5000 in the second group.
But this is not what the researchers found.