What On Earth is a Peroxisome?December 27, 2020
What on Earth is a Peroxisome?
Ever heard of a peroxisome? Me neither. You should know this. They are little, tiny organelles in the cell that can self-replicate themselves but have no DNA. They have to import all the proteins to construct themselves from DNA kept in the nucleus of the cell. They are lined with their own membrane, usually next to the cell membrane. They are tiny. But they can duplicate, when called upon which has led to the hypothesis that, like mitochondria, they evolved from a tiny bacteria that came to live inside the first archaic cell, and was allowed to take up residence because it could do unique useful stuff. A key component of aging is that your peroxisomes get old. So, we need to understand this.
But before our peroxisomes get old, our mitochondria get in trouble. This kicks in our RTG (retrograde) pathway which compensates for mitochondrial dysfunction and works right where rapamycin helps out. It mitochondria get blocked, the peroxisome starts making more small, short-chain fatty acids and Acetyl-Co A to compensate and get energy flowing again. That's helpful. We've been saying "you get old when your mitochondria get old" but this line of physiology suggests that the peroxisomes may be first. We get old when our peroxisomes get old and fall apart.
But that's only one function. Better known is that peroxisomes are rich sources of enzymes that gobble up Reactive Oxygen Species (ROS) and protect the whole cell from all sorts of trouble. They can use oxygen direction to make peroxide to assist in scavenging and cleaning up the cell. The enzyme catalase seems to be in the center of this dance and as catalase levels drop, mitochondria droop. Restoring catalase function results in mitochondria recovering. So, once again, maybe it's the dysfunctional peroxisome that comes first, and the mitochondria second?
These little organelles have their fingers in more. They are integral to digesting fats and preparing the chopped up pieces for mitochondria to finish up. They are key to digesting all the branched-chain amino acids too. Finally, they contain two key enzymes for the "pentose phosphate shunt", one of the cellular backup glucose pathways.
But perhaps their most important function is blue-collar manufacturing. Peroxisomes are the site of making specialty lipids that allow our nervous system to develop, most notably plasmalogens. We could not have become complex, integrated neurological systems without the manufacturing of plasmalogens.
Plasmalogens are made in the peroxisome. And when you realize that they are as much as 70% of the lipids in neuron myelination, plasmalogens are front and center in making a neurological system tick. The miracle of nerves is that they talk to each other through synapses: junctions where little blips of chemical messengers signal to another nerve. That synapse wouldn't work without "cholesterol rafts" and other moieties make one with the unique chemistry of plasmalogens. Isn't that interesting?! This is getting right to the very core of how our cells work.
And last week's column delineated the cutting edge of plasmalogens: they vary in direct correlation with cognitive decline and vice versa. You can replace them with precise biochemistry and you can measure the results.
www.What will Work for me. Well, this is easy. I'm simply reading everything I can get my hands on. I certainly had never heard of "cholesterol rafts" in the synapse before. I've already ordered 5 more of the plasmalogen testing kits so that I can learn how all this works. I can't wait till this wicked pandemic is over. The measurement of our plasmalogens and their subsequent management will become a foundational step in our annual check-up. That day is coming. I hope to help hasten it.
1. Just what is a peroxisome? Answer: a teeny, tiny little cellular organelle in the cell that appears to be self-replicating.
2. Which is more important, the peroxisome or the mitochondria? Answer: They appear to act as a team. The peroxisome can make ketones to rescue a tired mitochondria when needed.
3. If you have a lot of reactive oxygen being released by damaged mitochondria, what enzyme does the peroxisome manufacture to rescue the cell? Answer: Catalase. Saves the whole cell
4. Can you name another critical function of a peroxisome? Answer: digesting fats to make short ketone bodies for the mitochondria and branched-chain amino acids, tough little characters to digest. Don't forget the pentose phosphate glucose pathway.
5. What essential fat do peroxisome manufacture that constitute 70% of the insulation of nerves cells and the key feature of synapses? Answer: plasmalogens.