DNA Methylation Plays Key Role in Stem Cell Differentiation
Northwestern Medicine scientists discovered how the process of DNA methylation regulates the development of spinal cord motor neurons, in a study published in the journal Cell Stem Cell.
DNA methylation, an epigenetic mechanism that determines whether or not a gene is expressed, guides stem cells as they transform from blank slates into specialized cells. Motor neurons are highly specialized neuronal cells that connect the central nervous system to muscle and degenerate in amyotrophic lateral sclerosis (ALS).
Caption: Neural progenitors cells differentiated from human embryonic stem cells.
Origin of Neuromodulator in the Retina Pinpointed
A single cell type in the inner retina controls the release of nitric oxide, a neuromodulator that impacts synaptic transmission and regulates blood vessel dilation, according to a study published in Neuron.
Nitric oxide’s role in blood vessel regulation means those cells, a specific kind of amacrine cell called nNOS-2, could be used to help diagnose blood vessel disorders or even as targets for future therapies
Caption: This image shows a dense gap-junction network formed between nNOS-2 amacrine cells, the main source of the neuromodulator nitric oxide in the mouse retina. Here, a single nNOS-2 amacrine cell was patched and filled with Alexa Fluor 488 to reveal this network when imaged with a multiphoton laser. The large molecule fluorescent dye Alexa Fluor 488 readily passes through nNOS-2 amacrine cell gap junctions when they are in the most open state in dark conditions.
Regenerative Bandage Accelerates Healing in Diabetic Wounds
For diabetic patients, an untreated scratch can turn into an open wound that could potentially lead to a limb amputation or even death. A Northwestern University team developed a new device, called a regenerative bandage, that quickly heals these painful, hard-to-treat sores without using drugs.
A study published in Proceedings of the National Academy of Sciences found that Northwestern’s bandage healed diabetic wounds 33 percent faster than one of the most popular bandages currently on the market.
Caption: The secret behind the regenerative bandage is laminin, a protein that sends signals to cells, encouraging them to differentiate, migrate and adhere to one another. Ameer’s team identified a segment of laminin called A5G81 that is critical for the wound-healing process. The image shows stained epidermis cells cultured on the A5G81 peptide.
Increased Cell Recycling Could Treat Aging-Related Conditions
Mice engineered to more quickly recycle their own cells lived longer than their non-engineered siblings, according to a study published in Nature.
These findings suggest that autophagy, the system of cell recycling and housekeeping, may be responsible for functional declines associated with aging, according to CongCong He, PhD, assistant professor of Cell and Molecular Biology and a co-author of the study. In fact, reinstating higher rates of autophagy may be an effective way to treat aging-related diseases.
Caption: Fasting for 24 hours induced dramatic formation of autophagic vesicles (green dots, labeled by a marker protein LC3 tagged with the green fluorescent protein) in skeletal muscle. Blue indicates stained nuclei.
Enzyme Blocker Stops Growth of Deadly Brain Tumor
Investigators were able to halt the growth of glioblastoma, an aggressive form of brain cancer, by inhibiting an enzyme called CDK5. The findings were published in Cell Reports.
The discovery of this enzyme’s regulatory influence on glioblastoma may open the door to a long-awaited improvement upon current therapy options, according to Subhas Mukherjee, PhD, research assistant professor of Pathology and first author of the study. Daniel Brat, MD, PhD, chair and Magerstadt Professor of Pathology, was senior author of the study.
Caption: Glioblastoma cells (orange) spread throughout a fly brain (normal cells in blue), used to model human cancer.
The image was also featured on the cover of the Fall 2018 issue of Northwestern Medicine magazine.
Cellular Mechanism Protects Organs During Iron Deficiency
Scientists discovered a protective cellular mechanism that kicks in during iron deficiency, keeping cells running even in the face of continued iron deprivation, according to a study published in the Proceedings of the National Academy of Sciences.
The protein, called tristetraprolin (TTP), is activated during iron deficiency, and lowers iron usage to match availability and prevents mitochondrial dysfunction. Hossein Ardehali, MD, PhD, professor of Medicine in the Division of Cardiology and of Pharmacology, was senior author of the study.
Caption: Image of mitochondria in heart cells after the levels of TTP (the master regulator of cellular iron conservation) are reduced.
Exploring the Mechanisms of Poxvirus Replication
A study published in the journal Cell uncovered how poxviruses take control of a protein complex called mTOR in order to enhance their replication and counteract a host’s immune response.
The scientists sought to understand how poxviruses exploit mTOR — a protein complex which regulates cellular metabolism and protein synthesis — and evade being sensed by host cells.
Caption: During poxvirus infection, dysregulated mTOR (orange) localizes at the host-cell golgi network resulting in degradation of the DNA sensor, cGAS (green).