Using these engineered proteins, researchers can record histories that reveal when certain genes are activated or how cells respond to a drug – Zoo House News

Using these engineered proteins, researchers can record histories that reveal when certain genes are activated or how cells respond to a drug – Zoo House News

  • Science
  • January 3, 2023
  • No Comment
  • 7

As cells go about their day-to-day functions, they turn on a variety of genes and cellular signaling pathways. MIT engineers have now got cells to write the history of these events into a long chain of proteins that can be imaged with a light microscope.

Cells programmed to produce these chains continually add building blocks that encode specific cellular events. Later, the ordered protein chains can be tagged with fluorescent molecules and read under a microscope, allowing researchers to reconstruct the timing of events.

This technique could help elucidate the steps underlying processes such as memory formation, response to drug treatment and gene expression.

“There are many changes that take place at an organ or body level over hours to weeks that cannot be tracked over time,” says Edward Boyden, Y. Eva Tan Professor of Neurotechnology, Professor of Bioengineering and the Brain and Cognitive Sciences at MIT, a researcher at the Howard Hughes Medical Institute and a member of MIT’s McGovern Institute for Brain Research and Koch Institute for Integrative Cancer Research.

If the technique could be extended to longer periods of time, it could also be used to study processes such as aging and disease progression, the researchers say.

Boyden is the senior author of the study, which appears today in Nature Biotechnology. Changyang Linghu, a former J. Douglas Tan Postdoctoral Fellow at the McGovern Institute who is now an assistant professor at the University of Michigan, is the lead author on the paper.

cellular history

Biological systems such as organs contain many different types of cells, each with different functions. One way to study these functions is to image proteins, RNA, or other molecules within cells that provide clues as to what the cells are doing. However, most methods for doing this only provide a glimpse at a single time point or do not work well for very large cell populations.

“Biological systems often consist of a large number of different cell types. For example, the human brain has 86 billion cells,” says Linghu. “To understand such biological systems, we need to observe physiological events over time in these large cell populations.”

To achieve this, the research team came up with the idea of ​​recording cellular events as a series of protein subunits that are continuously added to form a chain. To make their chains, the researchers used engineered protein subunits that are not normally found in living cells and can self-assemble into long filaments.

The researchers designed a genetically encoded system in which one of these subunits is continuously produced in cells, while the other is made only when a specific event occurs. Each subunit also contains a very short peptide called an epitope tag – in this case the researchers chose the HA and V5 tags. Each of these tags can bind to a different fluorescent antibody, making it easy to visualize the tags later and determine the protein subunit sequence.

For this study, the researchers made production of the V5-containing subunit dependent on activation of a gene called c-fos, which is involved in encoding new memories. HA-tagged subunits make up most of the chain, but whenever the V5 tag appears in the chain, it means c-fos was activated during that time.

“We hope to be able to use this type of protein self-organization to record the activity in each individual cell,” says Linghu. “Not only is it a snapshot, it also records the past, just like tree rings can permanently store information over time as the wood grows.”

recording of events

In this study, the researchers first used their system to record c-fos activation in neurons growing in a laboratory dish. The c-fos gene was activated by chemically induced activation of the neurons, adding the V5 subunit to the protein chain.

To see if this approach could work in animal brains, the researchers programmed mouse brain cells to generate chains of proteins that would indicate when the animals were exposed to a particular drug. Later, the researchers were able to prove this exposure by preserving the tissue and analyzing it with a light microscope.

The researchers designed their system to be modular, allowing different epitope tags to be swapped out or different types of cellular events to be detected, including in principle cell division or the activation of enzymes called protein kinases, which help control many cellular signaling pathways.

Researchers also hope to extend the record lengths they can achieve. In this study, they recorded events for several days before imaging the tissue. There is a trade-off between the time that can be recorded and the time resolution or frequency of event recording since the length of the protein chain is limited by the size of the cell.

“The total amount of information it could store is fixed, but we could in principle slow down or speed up the growth of the chain,” says Linghu. “If we want to record longer, we could slow down the synthesis so that it reaches cell size within, say, two weeks. That way we could record longer, but with lower temporal resolution.”

The researchers are also working to engineer the system so that it can record multiple types of events in the same chain by increasing the number of different sub-units that can be built in.

The research was funded by the Hock E. Tan and K. Lisa Yang Center for Autism Research, John Doerr, the National Institutes of Health, the National Science Foundation, the US Army Research Office, and the Howard Hughes Medical Institute.

Related post

Bobby Hull, Hockey Hall of Famer, dies at 84

Bobby Hull, Hockey Hall of Famer, dies at 84

CHICAGO (AP) — When Bobby Hull got the puck, he was hard to stop. He had breathtaking speed, a hard slap…
Electrify America EV Fast Chargers come in 50 mile intervals

Electrify America EV Fast Chargers come in 50 mile…

Electrify America announced Monday an agreement with TravelCenters of America (TA) to install EV fast chargers at their rest stops. TA…
CVS, Walmart and Walgreens to reduce pharmacy hours as staffing issues persist

CVS, Walmart and Walgreens to reduce pharmacy hours as…

CVS shortens and adjusts pharmacy opening hours in two-thirds of stores CVS cuts, adjust pharmacy hours in two-thirds of stores 00:37…

Leave a Reply

Your email address will not be published. Required fields are marked *