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Molecular & Cell Biology

Category: Molecular & Cell Biology

Using a multidisciplinary approach, researchers, led by those at Baylor College of Medicine, revealed in unprecedented detail the three-dimensional structure of biologically active DNA. A report on their work appears online in the journal Nature Communications.

Scientists engineered stem cells to better understand the mechanisms behind a form of leukemia caused by changes in a key gene, according to a study led by Mount Sinai researchers and published online today in the journal Cell Reports.

Cells of multicellular organisms contain identical genetic material (the genome) yet can have drastic differences in their structural arrangements and functions. This variation of the distinct cell types comes from the differential expression of genes, which is controlled by interplay between different regulators within the cells, such as transcription factors, the transcription machinery, and the "epigenetic" modifications (which do not change the underlying genetic code) that occur on the DNA and protein factors within chromatin.

New findings revealed a molecular "tug of war " that plays a key role in the proper functioning of the telomerase enzyme.
Researchers at UC Santa Cruz have determined the structure of a key part of the enzyme telomerase, which is active in most cancers and enables cancer cells to proliferate indefinitely. The new findings, published October 5 in Nature Structural & Molecular Biology, reveal how the enzyme carries out a crucial function involved in protecting the ends of chromosomes.

A single neuron in a normal adult brain likely has more than a thousand genetic mutations that are not present in the cells that surround it, according to new research from Howard Hughes Medical Institute (HHMI) scientists. The majority of these mutations appear to arise while genes are in active use, after brain development is complete.

A group of researchers, led by Prof. MATOZAKI Takashi and Associate Prof. MURATA Yoji at the Kobe University Graduate School of Medicine Division of Molecular and Cellular Signaling, were the first to demonstrate the role of stomach cancer-associated protein tyrosine phosphatase (SAP)-1 in the pathogenesis and prevention of Crohn's disease, ulcerative colitis, and other inflammatory bowel disorders. Their findings, published online ahead of print on July 20, 2015, by the Proceedings of the National Academy of Sciences of the United States of America, are expected to accelerate the development of targeted therapies for inflammatory gastrointestinal diseases.

Salk scientists have developed a new way to selectively activate brain, heart, muscle and other cells using ultrasonic waves. The new technique, dubbed sonogenetics, has some similarities to the burgeoning use of light to activate cells in order to better understand the brain.

Most people are familiar with the double-helix shape that allows genetic information to be packed into a molecule of human DNA. Less well-known is how all this information - which, if laid end-to-end, would stretch some three meters - is packed into the cellular nucleus. The secret of how this crush of genetic code avoids chaos - remaining untangled, correctly compartmentalized, and available for accurate DNA replication - has recently been revealed.

Inside the trillions of cells that make up the human body, things are rarely silent. Molecules are constantly being made, moved, and modified--and during these processes, mistakes are sometimes made. Strands of DNA, for instance, can break for any number of reasons, such as exposure to UV radiation, or mechanical stress on the chromosomes into which our genetic material is packaged.

Scientists have uncovered tens of thousands of new protein interactions, accounting for about a quarter of all estimated protein contacts in a cell.
A multinational team of scientists have sifted through cells of vastly different organisms, from amoebae to worms to mice to humans, to reveal how proteins fit together to build different cells and bodies.

This is a representation of the fluoride ion channel (center) with monobodies attached (top and bottom).
Although present almost everywhere - food, soil, toothpaste and especially tap water -, the fluoride ion is highly toxic to microorganisms and cells. To avoid death, cells must remove fluoride that has accumulated inside them, a process accomplished via ion channels - protein tunnels through the cell membrane that only allow specific substances to pass through.

In the breast, cancer stem cells and normal stem cells can arise from different cell types but tap into distinct yet related stem cell programs, according to Whitehead Institute researchers. The differences between these stem cell programs may be significant enough to be exploited by future therapeutics.

Altering the protein recycling complexes in human cells, including cancer cells, allows the cells to resist treatment with a class of drugs known as proteasome inhibitors, according to Whitehead Institute scientists.

Eliminating HK2 (shown here), which is a key enzyme for glucose metabolism, may be a way to prevent cancer cells from surviving,
A study published in The Journal of Cell Biology describes a way to force cancer cells to destroy a key metabolic enzyme they need to survive.

Olfactory signatures corresponding to specific odorants. In the background, an olfactory sensory neuroepithelium.
In animals, numerous behaviors are governed by the olfactory perception of their surrounding world. Whether originating in the nose of a mammal or the antennas of an insect, perception results from the combined activation of multiple receptors located in these organs. Identifying the full repertoire of receptors stimulated by a given odorant would represent a key step in deciphering the code that mediates these behaviors. To this end, a tool that provides a complete olfactory receptor signature corresponding to any specific smell was developed in the Faculties of Science and Medicine of the University of Geneva (UNIGE), Switzerland. Published in the journal Nature Neuroscience, this approach allows to identify thousands of chemosensory receptors, among which, potentially, those able to trigger predetermined behaviors in mammals or in insects, such as pests, disease vectors or parasites.

It was long believed that acquired immunity--a type of immunity mediated by T- and B-cells--had memory, meaning that it could learn from new pathogens, making subsequent reactions more effective, whereas innate immunity--which is mediated by macrophages and other types of cells that react to certain molecules typically associated with pathogens--did not. However, it gradually became clear that things were not so simple. Plants and insects, which only have innate immunity, also seem to have immunological memory. Further, it has been reported that herpes virus infection increases the resistance against bacteria in vertebrates. These phenomena suggest that innate immunity also has memory, but researchers have been reluctant to accept the hypothesis given the lack of a mechanism Now, in research published in Nature Immunology, a research team led by Keisuke Yoshida and Shunsuke Ishii of the RIKEN Molecular Genetics Laboratory has revealed that epigenomic changes induced by pathogen infections, mediated by a transcription factor called ATF7, are the underlying mechanism of the memory of innate immunity.

Every organism--from a seedling to a president--must protect its DNA at all costs, but precisely how a cell distinguishes between damage to its own DNA and the foreign DNA of an invading virus has remained a mystery.

Dr. Anita Göndör and her colleagues at Karolinska Institutet show that circadian genes 'take a nap' everyday at the periphery of the nucleus.
Mobility between different physical environments in the cell nucleus regulates the daily oscillations in the activity of genes that are controlled by the internal biological clock, according to a study that is published in the journal Molecular Cell. Eventually, these findings may lead to novel therapeutic strategies for the treatment of diseases linked with disrupted circadian rhythm.

Florida State University researchers have taken a big step forward in the fight against cancer with a discovery that could open up the door for new research and treatment options.

These are plant cells stretching within the artificial scaffold.
Miniscule artificial scaffolding units made from nano-fibre polymers and built to house plant cells have enabled scientists to see for the first time how individual plant cells behave and interact with each other in a three-dimensional environment.

UC Davis researchers show how four proteins come together to make the machine that assembles tubulin, the building block of microtubules.
When they think about how cells put together the molecules that make life work, biologists have tended to think of assembly lines: Add A to B, tack on C, and so on. But the reality might be more like a molecular version of a 3-D printer, where a single mechanism assembles the molecule in one go.

This image shows equipment used in a highly automated, robotic X-ray crystallography system at SLAC's Linac Coherent Light Source X-ray laser.
Scientists have revealed never-before-seen details of how our brain sends rapid-fire messages between its cells. They mapped the 3-D atomic structure of a two-part protein complex that controls the release of signaling chemicals, called neurotransmitters, from brain cells. Understanding how cells release those signals in less than one-thousandth of a second could help launch a new wave of research on drugs for treating brain disorders.

A ribosome (gray) creates a protein by translating the genetic code within an mRNA molecule (blue).
In what appears to be an unexpected challenge to a long-accepted fact of biology, Johns Hopkins researchers say they have found that ribosomes -- the molecular machines in all cells that build proteins -- can sometimes do so even within the so-called untranslated regions of the ribbons of genetic material known as messenger RNA (mRNA).

Until now only known for role in polyglutamine diseases, such as Huntington's.

Microtubules are hollow cylinders with walls made up of tubulin proteins -- alpha (green) and beta (blue) -- plus EB proteins (orange) that can either stabilize or destabilize the structure.
Microtubules, hollow fibers of tubulin protein only a few nanometers in diameter, form the cytoskeletons of living cells and play a crucial role in cell division (mitosis) through their ability to undergo rapid growth and shrinkage, a property called "dynamic instability." Through a combination of high-resolution cryo-electron microscopy (cryo-EM) and a unique methodology for image analysis, a team of researchers with Berkeley Lab and the University of California (UC) Berkeley has produced an atomic view of microtubules that enabled them to identify the crucial role played by a family of end-binding (EB) proteins in regulating microtubule dynamic instability.

DNA double-strand breaks (DSBs) are the worst possible form of genetic malfunction that can cause cancer and resistance to therapy. New information published this week reveals more about why this occurs and how these breaks can be repaired.

Dr. Chunhong Yan is a molecular biologist at the Georgia Regent University Cancer Center and the Department of Biochemistry and Molecular Biology at the Medical College of Georgia at GRU.
DNA damage increases the risk of cancer, and researchers have found that a protein, known to rally when cells get stressed, plays a critical, early step in its repair.

A recently discovered family of small RNA molecules, some of which have been implicated in cancer progression, has just gotten much larger thanks to a new RNA sequencing technique developed by researchers at UC Santa Cruz.

Stills from time-lapse video showing transdifferentiation of pre-B cells into yeast-eating macrophages.
All it takes is one molecule to reprogram an antibody-producing B cell into a scavenging macrophage. This transformation is possible, new evidence shows, because the molecule (C/EBPa, a transcription factor) "short-circuits" the cells so that they re-express genes reserved for embryonic development. The findings appear July 30 in Stem Cell Reports, the journal of the International Society for Stem Cell Research.

Since mice share 90 percent of our genes they play an important role in understanding human genetics. The European Mouse Disease Clinic (EUMODIC) brought together scientists from across Europe to investigate the functions of 320 genes in mice. Over half of these genes had no previously known role, and the remaining genes were poorly understood.

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