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Archive - Jan 20, 2017

New Technique Enables Continuous Variation of Gene Expression; Powerful Tool for Genetic Engineering

A new technique will help biologists tinker with genes, whether the goal is to turn cells into tiny factories churning out medicines, modify crops to grow with limited water, or study the effects of a gene on human health. The technique, described online on January 20, 2017 in Nature Communications, allows scientists to precisely regulate how much protein is produced from a particular gene. The open-access article is titled “Rapid Generation of Hypomorphic Mutations.” The process is simple yet innovative and, so far, works in everything from bacteria to plants to human cells. "Basically, this is a universal toolkit for modifying gene expression," said Sergej Djuranovic (photo), Ph.D., an Assistant Professor of Cell Biology and Physiology at Washington University School of Medicine in St. Louis, and the study's senior author. "It's a tool that can be used whether you are genetically engineering cells to produce a particular organic molecule, or to study how a gene works." The ability to control the amount of protein produced from a particular gene would be a boon to biologists who design or redesign biological systems - such as the set of biochemical reactions that make up cellular metabolism - to produce a desired product. For example, some drugs - including antibiotics such as vancomycin and cancer drugs such as taxol - are produced by cells as byproducts of metabolism. By fine-tuning certain genes a biologist could maximize the quantity of medicine produced. Dr. Djuranovic himself is interested in modulating gene expression to study disease-related genes, such as ones implicated in cancer. "There are all sorts of complex diseases such as cancer and autism in which we know that expression from a particular gene is dialed down, but nobody knows how that reduction is contributing to the disease," Dr.

Cell Biologists Discover How Peroxisomes and Endoplasmic Reticulum Associate and Work Together

Scientists have made a breakthrough in understanding how different organelles of human cells interact. Organelles are the functional units of a cell. Like organs in a body, they perform specialized functions. To allow survival of the cell, organelles have to interact and cooperate. How this is mediated and regulated in the cell is an important and challenging question in cell biology. Researchers at the University of Exeter (UK) have now discovered how two cell organelles - called peroxisomes and the endoplasmic reticulum (ER) - associate with each other at the molecular level and work together. This cooperation is crucial for the production of specific lipids, which are essential for the function of nerve cells and can protect cells from oxidative damage. Loss of peroxisome function leads to a range of severe or fatal disorders associated with developmental and neurological defects. "Close contacts between peroxisomes and the ER were observed more than 50 years ago in ultrastructural studies, but the molecular mechanism remained a mystery," said lead author Dr. Michael Schrader, of the University of Exeter. "This is the first molecular tether identified in humans, which mediates the contact between these two important cell compartments." The study showed that a protein at the peroxisomes called ACBD5 directly interacts with a protein at the ER, called VAPB. This interaction links both organelles together and allows transfer of lipids between them. When the interaction between VAPB and ACBD5 is lost, the ER and peroxisomes can no longer interact and this lipid transfer appears to be prevented. The researchers are working with experts from the Academic Medical Center in Amsterdam, where a patient with an ACBD5 deficiency has been identified and linked to a peroxisomal defect.