By Louise Lerner
UChicago chemists create sensors to track potassium, sodium in organelles
Two studies by scientists at the University of Chicago have demonstrated a new way to look into the inner workings of cells—in particular, to track the flow of ions inside the many tiny organelles inside the cell.
Their findings not only show these sensors can work but also revealed evidence that organelles do regulate ions—a biological question which had been previously debated.
The technique can help reveal new information about how cells function, which could boost our understanding of and treatments for diseases and disorders such as Parkinson’s.
‘An underexplored area’
We know that cells need ions like sodium and potassium to function—that’s why you need to drink not just water, but electrolytes when you run a marathon. Cells use these ions for many functions, like signaling and muscle contractions, so they keep very tight control over the flow of ions in and out of the cell.
But we know less about the role of ions inside the individual parts inside the cell. These are the organelles—the Golgi bodies, the lysosomes, the mitochondria, etc., which each carry out special functions.
“This is an underexplored area because we haven’t had the tools to measure ions inside organelles,” said UChicago chemist and co-author Junyi Zou. “But there are good reasons to believe ion concentrations are important inside organelles.”
Zou and colleague Palapuravan, who uses one name, are both members of the laboratory of UChicago Prof. Yamuna Krishnan, who specializes in creating tiny “devices” made out of DNA to investigate the inner workings of cells.
Because they are made of DNA, they are biologically compatible and nontoxic, so they can be used to peek in on live cells as they go about their business—a significant advantage over more commonly used methods that cannot be used in vivo. The devices can also withstand pH levels that would normally disable other kinds of sensors.
For this task, To achieve this feat, the team needed to get the sensors to reach a specific kind of organelle inside particular cells. To do so, they attached a molecule that lets the sensors hitch-hike on a protein that normally shuttles between the cell membrane and a specific organelle as part of normal function.
Once inside the organelle, the sensors react with nearby ions and cause them to light up, which scientists can see under a microscope. “This allows us to quantify the level of ions by measuring the brightness of the sensor,” explained Zou.