By exploiting an HIV protein that readily traverses cell membranes, Carnegie Mellon University scientists have developed a new way to introduce a gene-like molecule called a peptide nucleic acid (PNA) directly into live mammalian cells, including human embryonic stem (ES) cells. The work, published online December 2 in Chemical Communications, holds considerable promise in genetic engineering, diagnostics and therapeutics.
"Our results show that PNAs could be effectively delivered into mammalian cells without requiring delivery vehicles," said Danith Ly, an assistant professor of chemistry in the Mellon College of Science (MCS) at Carnegie Mellon. Ly worked with leading author and graduate student Anca Dragulescu-Andrasi on this research.
Until now, getting PNAs into living cells has been difficult. While other laboratories have developed ways to shuttle PNAs into cells, these methods remain largely ineffective and limited to small-scale experimental setups, according to Ly. "We found that our modified PNAs were not only taken up by cells, but they also were localized predominantly in the cell nucleus, a specialized compartment in the cell where messenger RNAs are made," Ly said.
Messenger RNA (mRNA), the genetic information that is translated into proteins, is the target of an emerging field called antisense therapy. "We found that we could modify PNAs so that they bind sequence-specifically to mRNA," Ly said. By binding to specific mRNAs, these agents could dampen the production of select disease-causing proteins, he added.
First reported in the early 1990s, PNAs are small synthetic molecules in which a protein-like backbone is combined with the nucleobases found in DNA and RNA. These nucleobases enable PNA to bind to DNA and RNA in a complementary, highly specific manner. Because the cell machinery cannot recognize the unnatural backbone of PNA, it fails to break down this structure, making PNAs very stable, long-lived molecules.
To enable the PNAs to enter cells, Ly modified the PNA backbone so that it contained a short sequence of chemical groups inspired by a region of the HIV-1 virus called the Tat transduction domain, which normally regulates gene expression. The modified PNAs are called GPNAs because they contain guanidinium functional groups. Ly found that GPNAs, in addition to their superior cell uptake properties, could be designed to bind sequence-specifically to RNA, with binding affinity and selectivity rivaling that of PNA. Ly and his colleagues visualized the uptake of GPNAs into living cells by attaching them to fluorescent probes.
GPNAs could gain widespread use in genetic diagnostics, therapeutics and engineering, according to Ly. For instance, scientists could use this technology to quickly identify whether specific tissues contain a cancer-causing version of a gene and are pre-cancerous. Because they enter embryonic stem cells, GPNAs potentially could be used to control gene expression and direct what kinds of tissues these malleable cells ultimately become. By infusing GPNAs to block the translation of specific RNAs, researchers also could "down-regulate" the production of disease-related proteins. Scientists could use GPNAs to temporarily inhibit production of different regulatory proteins in cells, which could prove especially helpful in modeling diseases that involve multiple genetic mistakes occurring over time. Thus, this approach could help to tease apart the sequence of molecular events that lead to diseases such as cancer or diabetes in animal models.
Ly is currently extending his research to show that GPNAs are absorbed throughout the body in mice that receive these agents.
Lauren Ward | EurekAlert!
Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel
The Nagoya Protocol Creates Disadvantages for Many Countries when Applied to Microorganisms
05.12.2016 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Earth Sciences
05.12.2016 | Physics and Astronomy
05.12.2016 | Life Sciences