Anand
Saminathan
New
technology peers inside cells, may inspire new fields of research
Electricity
is a key ingredient in living bodies. We know that voltage differences are
important in biological systems; they drive the beating of the heart and allow
neurons to communicate with one another. But for decades, it wasn’t possible to
measure voltage differences between organelles—the membrane-wrapped structures
inside the cell—and the rest of the cell.
A
pioneering technology created by UChicago scientists, however, allows
researchers to peer into cells to see how many different organelles use
voltages to carry out functions.
Scientists
had noticed for a long time that charged dyes used for staining cells would get
stuck in the mitochondria,” explained graduate student Anand Saminathan, the
first author for the paper, which was published in Nature Nanotechnology. “But
little work has been done to investigate the membrane potential of other
organelles in live cells.”
The
Krishnan lab at UChicago specializes in building tiny sensors to travel inside
cells and report back on what’s happening, so that researchers can understand
how cells work—and how they break down in disease or disorders. Previously,
they have built such machines to study neurons and lysosomes, among others.
In this
case, they decided to use the technique to investigate the electric activities
of the organelles inside live cells.
In the
membranes of neurons, there are proteins called ion channels which act as
gateways for charged ions to enter and exit the cell. These channels are
essential for neurons to communicate. Previous research had shown that
organelles have similar ion channels, but we weren’t sure what roles they
played.
The
researchers’ new tool, called Voltair, makes it possible to explore this
question further. It works as a voltmeter measuring the voltage difference of
two different areas inside a cell. Voltair is constructed out of DNA, which
means it can go directly into the cell and access deeper structures.
In their
initial studies, the researchers looked for membrane potentials—a difference in
voltage inside an organelle versus outside. They found evidence for such
potentials in several organelles, such as trans-Golgi networks and recycling
endosomes, that were previously thought not to have membrane potentials at all.
“So I
think the membrane potential in organelles could play a larger role—maybe it
helps organelles communicate,” said Prof. Yamuna Krishnan, an expert in nucleic
acid-based molecular devices.
Their
studies are only the beginning, the authors said; Voltair offers a way for
researchers in many fields to answer questions they’ve never even been able to
ask. It can even be used in plants.
“This
new development will at least start conversations, and may even inspire a new
field of research,” said Saminathan.