More Than Just a Meme – How I Found Out I’d Live To 100 Using My Mitochondrial DNA (Part 3)

Spoiler alert – if you haven’t already, please check out part 1 and 2 of the series first:
More Than Just A Meme Part 1 – The Secrets Behind the Infamous Mitochondria.
More Than Just A Meme Part 2 – How We Traced Our Maternal Lineage Using Our Mitochondria

We explain the evolution of the mitochondria and how we collected and sequenced our own mitochondrial DNA to map out our maternal ancestry.

By Calvin J.

If you’ve been following this series – and hopefully you have – we’ve been working on a little DIY project in the lab. By extracting and sequencing our own mitochondrial DNA, we determined our own haplogroups – a set of mutations in our mitochondria that define our maternal ancestry. In secret, I was hoping to reveal in myself something unexpectedly life changing. That perhaps I was not who I thought I was. Maybe my great great grandmother was a wealthy British aristocrat, or an Iranian merchant, perhaps even a humble South African poet. But alas, a quick Google search of my haplogroup revealed to me that my ancestry was more plain than the oatmeal I had for breakfast. I was East Asian through and through.

The first couple links from my Google search provided some basic background information regarding my haplogroup, D4b2b.

  1. It’s believed to have originated somewhere in East Asia approximately 48,000 years ago.
  2. The D4 subgroup is found predominantly amongst Japanese and Koreans, but is also found throughout China and Southeast Asia.

No surprises there, but as I scrolled through the Google search results, a specific link caught my eye.  Third one down from the list was a research article entitled “Enrichment of longevity phenotype in mtDNA haplogroups D4b2b, D4a, and D5 in the Japanese population“.

Screen Shot 2017-06-28 at 10.24.41 AM.png
The top 3 hits when Googled my mitochondrial haplotype D4b2b. The third link turned out to be particularly interesting.

In the paper, the researchers analyzed 672 mitochondrial DNA genomes from unrelated donors, in search for any specific links between mitochondrial haplogroups and individuals with diabetes, Alzheimer’s and Parkinson’s. But what they found instead, wasn’t any of the above, but rather a link to longevity.

Their study found that individuals were more likely to live longer if they had mitochondrial haplogroups D4a, D5, or D4b2b.

When the authors grouped centenarians (people who are 100 years or older) from their sample, they found that over 90% of these individuals had either D4a, D5 or D4b2b haplotypes. D4b2b alone accounted for almost 50% of the centenarians they tested.

Of the 96 centenarians they tested, almost half of them belonged to the D4b2b mitochondrial haplogroup. Figure from the Alexe et al., research article. 

How could that be? Well, the authors don’t claim to have the answer. Obviously, things like, diet, exercise and whether you smoke or drink all have a huge role to play.

But at the level of individual cells, scientists have long known that the mitochondria was a major contributor to the aging process.

You might recall from high school biology, that the mitochondria’s primary role is to generate energy for the cell – hence the infamous phrase “powerhouse of the cell” (check out part 1 of our series if you need a quick refresher). But energy production also comes at a cost, and as our mitochondria chug away fuelling our bodies with precious life-sustaining energy, they also generate toxic cellular waste – I guess our cells haven’t embraced the concept of “clean energy” either.

Things like free radicals and reactive oxygen species produced, damage not only the mitochondria themselves, but also other parts of our cells – including our DNA – which leads to cell death, aging and even cancer. They can also trigger unwarranted immune responses, leading to chronic inflammation and tissue damage. So anything that might help the mitochondria run more efficiently, or make our cells better at cleaning up the toxic cellular waste, could all slow down the aging process – thus boosting your life span.

The mitochondria plays such an important role in aging, that when a couple of researchers from Newcastle University removed them completely from their aging lab-grown cells, they found that they slowly became rejuvenated. It’s like the symptoms of aging completely disappeared, with free radical levels and inflammatory signals dropping back down to what was typically only sees in healthy, young cells.

The mitochondrial researchers Dr. Joao Passos and Dr. Clara Correia-Melo working in the lab. Image from Newcastle University.

At this point more research is needed to figure out what’s unique about haplogroups D5, D4a or D4b2b that link it to longevity. Could it be due to genes on their mitochondrial genomes that boost energy efficiency? Or perhaps they provide resistance to the toxic reactive oxygen species that promote aging? By further understanding the links between the mitochondria and our aging process, perhaps someday scientists will unlock the secrets to immortality.




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