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Opposing protein pathways steer skin stem cells toward renewal or repair
Two proteins with opposing functions orchestrate the development and maintenance of healthy skin, Stanford Medicine researchers have found. Modulating their activity with topical drugs could reduce inflammation, aid wound healing and slow or halt the growth of skin cancer, the researchers believe. The findings are published in the journal Science.
The proteins are part of a family called ubiquitin-like proteins. Ubiquitination controls the targeted destruction and disposal of unneeded proteins in a cell. But in the skin, certain ubiquitin-like proteins instead switch on or off wide swaths of genes involved in cellular growth and development, the study found. In particular, they trigger progenitor (stem) cells in the lower layer of the skin to either mature and migrate to the skin surface or to self-renew.
“These two ubiquitin-like protein systems are remarkably dedicated and opposite in their functions,” said Paul Khavari, MD, Ph.D., chair of dermatology at the Stanford School of Medicine and senior author of the study. “One promotes the stem-cell state while the other drives differentiation. It’s like having two opposing forces that determine a cell’s fate.”
Ancient stellar flyby may still be steering long-period comets today
The Gaia mission has allowed researchers to understand the motions of stars like never before, even revealing possible interactions between our solar system and nearby stars. Planetary Science Institute Senior Scientist Nathan Kaib and collaborator Sean Raymond (Universite de Bordeaux) have found that a recent stellar passage likely triggered a huge increase in comet formation as the star’s gravity altered Oort cloud objects’ orbits, sending them cascading into the inner solar system. We may even still be feeling the effects of this passage today. This work is being presented at the American Astronomical Society Division on Dynamical Astronomy.
HD 7,977 is a nearby sun-like star in the constellation Cassiopeia whose close passage was discovered by the Gaia mission. Approximately 2.5 million years ago, the orbits of the sun and HD 7,977 brought the two stars close together, but exactly how close is still an open question. Gaia data suggest they passed within 4,000–25,000 astronomical units of one another. Now, Kaib and Raymond have shown that the orbits of long-period comets suggest HD 7,977 came within 6,000–10,000 AU of our sun, setting off a major shower of new comets into the inner solar system.
Scientists measure hidden quantum forces that could power a new generation of pharmaceutical drugs
It’s one thing to design a pharmaceutical drug. It’s another to know if and why it actually works; not on paper or in a computer model, but inside the chaotic world of living systems, where proteins twist into shape, atoms constantly pull and push each other apart, and molecular interactions are the difference between health and disease.
For decades, scientists have known that these interactions are driven by hidden quantum forces. The problem is that, like working blindfolded, they’ve never been able to measure them directly in biological systems.
Now, that era of blindfolded work may be ending.
Iron accumulation in the brain may contribute to neurodegeneration
Neurodegenerative diseases affect tens of millions of people worldwide. Among these, Alzheimer’s and Parkinson’s diseases are the most common; in the United States alone, the Alzheimer’s Disease Association and Parkinson’s Foundation report roughly 7 million people with Alzheimer’s and another million with Parkinson’s. An intriguing clue lies in the tangled mystery of neurodegeneration that scientists are working to solve: iron accumulation.
Scientists have noticed that iron can slowly build up inside neurons. Early in life, this iron accumulation appears to have little effect on neuronal function. However, later in life, it can contribute to a slow neuronal demise. Salk Institute researchers studied nerve cells to figure out whether and how this iron accumulation relates to neurodegenerative diseases. They found that the excess iron stuck in neurons lowers the cells’ defenses, making them more vulnerable to stressors and other cellular insults through a process they named chronoferroptosis.
The study, published in Cell Death Discovery on June 18, 2026, points to iron accumulation as a key target in the effort to predict, prevent and treat neurodegenerative diseases.
First 3D views of human cone opsins reveal how daylight vision reacts so fast
The retina of the human eye contains 6–7 million cone cells. These cells contain light-sensitive proteins known as cone opsins. They enable us to perceive our surroundings in detail in daylight. They allow us to see the world in thousands of colors: red strawberries, green leaves, the blue sky. They also enable us to see all the objects around us clearly. And they allow us to perceive fast movements, such as the rush of a train or the flight of a dragonfly.
Often, however, these all-rounders of daylight vision are also involved in retinal diseases. Impairment of cone receptor function, caused by genetic mutations or other degenerative processes, can lead to disorders such as color blindness and age-related macular degeneration (AMD), a disease affecting the central retina and causing progressive vision loss.
In a new study, Polina Isaikina and Sarah L. Schmidt, two researchers from the Center for Life Sciences at PSI, have succeeded for the first time in determining the three-dimensional structure of human cone opsins in their dark state and showing how their molecular architecture enables their rapid activation by light.
