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Category: life extension – Page 4

APOE4 Increases Neurons’ Excitability Before Symptoms Appear

The pro-Alzheimer’s allele APOE4 makes hippocampal neurons in mice smaller and hyperexcitable. This effect, which resembles epilepsy and accelerated aging, can be mitigated by manipulating a neuronal protein [1].

Before symptoms arise

Alzheimer’s disease begins long before symptoms appear, building silently for decades. The single strongest genetic risk factor for the common, late-onset form of Alzheimer’s is the ε4 variant of the apolipoprotein (APOE) gene, APOE4. Carrying a single copy of this variant (being heterozygous) roughly triples your Alzheimer’s risk; having two copies increases it about 12-fold.

How an Alzheimer’s Risk Gene Disrupts Brain Circuits Long Before Memory Loss

Researchers at the Gladstone Institute have uncovered the molecular mechanism by which APOE4 — the most significant genetic risk factor for Alzheimer’s disease, present in roughly a quarter of the population — begins damaging neural circuits well before any cognitive symptoms emerge. Studying young mice carrying the APOE4 variant, the team found that the gene triggers overproduction of the protein Nell2, which causes neurons to shrink and become hyperactive. Crucially, the degree of early neuronal hyperactivity predicted the severity of memory impairment later in life, even in animals that still showed normal learning and memory at the time of measurement. Strikingly, targeting Nell2 therapeutically was able to reverse these changes even in adult animals, demonstrating that the neurodegeneration is not irreversible and that a window for intervention may exist even after the disease process has begun. The team is currently continuing preclinical testing of this therapeutic strategy.

New findings on the APOE4 gene variant point to a potential therapeutic target for Alzheimer’s disease. From left to right, Gladstone scientists Misha Zilberter, Yadong Huang, and Dennis Tabuena examine findings from their research, which is published in the journal Nature Aging.

For the millions of people who carry the gene APOE4, the strongest known genetic risk factor for Alzheimer’s disease, their brain activity may begin changing long before any memory problems appear. Now, researchers at Gladstone Institutes have uncovered a precise chain of molecular events behind those early changes and identified a potential way to reverse them.

Published in the journal Nature Aging, their new study in mouse models reveals how APOE4 triggers increased production of the protein Nell2, which makes neurons shrink and become hyperactive. The more hyperactive the neurons were in early life, the more severe were the memory problems the mice developed later in life.

T-loop dynamics: telomere structure shapes cell fate decisions

Telomere structure shapes cell fate decisions.

Telomere loops (t-loops) are dynamic DNA structures, remodelled during the cell cycle and stress, rather than static protective caps.

The three-state model defines closed, intermediate, and uncapped telomeres, linking intermediate telomeres to programmed, fusion-resistant deprotection, which activates checkpoints without genome instability.

Mitotic arrest-dependent telomere deprotection is an active pathway in which Aurora B kinase drives t-loop unwinding without telomere shortening.

Aurora B kinase phosphorylation reprograms shelterin components (TRF1 and TRF2), enabling BTR-mediated t-loop dissolution and paradoxically converting protective factors into facilitators of deprotection.

T-loop dynamics reframe telomeres as responsive signalling hubs that couple chromosome architecture to genome surveillance and cell fate control. sciencenewshighlights ScienceMission https://sciencemission.com/T-loop-dynamics

Continue reading “T-loop dynamics: telomere structure shapes cell fate decisions” | >

Cellular reprogramming beyond pluripotency

Aging, once viewed as an irreversible process, is now considered a modifiable process. Recent advances in cellular reprogramming reveal that transient expression of reprogramming factors can reverse molecular hallmarks of aging while preserving somatic cell identity. This ‘partial reprogramming’ rejuvenates tissues, restores regenerative capacity, and, in some models, extends lifespan without the tumorigenic risks of full dedifferentiation. In this review, we summarize genetic and chemical strategies for partial reprogramming, discuss their tissue-specific effects in vivo, and evaluate their implications for tissue regeneration and age-related disease. We further examine key challenges for clinical translation, including safety, delivery strategies, and temporal control of reprogramming.

What keeps vision cells alive?

Clear patterns emerged: two kinase inhibitors consistently protected cones over extended periods.

The researchers identified inhibitors of casein kinase 1 (CK1) that protected cones, heat shock protein 90 (HSP90) inhibitors that saved cones in the short term but damaged them in the longer term, and broad histone deacetylase (HDAC) inhibition by many compounds that significantly damaged cones.

The protective effects held across different stress conditions and were further confirmed in a mouse model of retinal degeneration, supporting their broader relevance.

Beyond identifying protective pathways, the study makes a comprehensive dataset publicly available, covering the compounds tested, their molecular targets, and their effects on human cone survival. This resource will guide the development of therapies aimed at preserving central vision and enable a systematic assessment of potential retinal toxicity. ScienceMission sciencenewshighlights.

Scientists have identified genetic pathways and compounds capable of protecting cone photoreceptors from the degeneration that underlies conditions like age-related macular degeneration.

Cone photoreceptors, concentrated in the macula, are essential for reading, recognizing faces, and perceiving colors. Their death, as it happens in many inherited retinal diseases and macular degeneration, leads to the loss of central vision. Despite decades of research, no approved therapies can halt this process. This new study, conducted by researchers addresses this unmet need using a human-based experimental system.

Continue reading “What keeps vision cells alive?” | >

How stimulating the vagus nerve could protect the brain from Alzheimer’s disease

Developing tau tangles doesn’t mean a person has Alzheimer’s disease – in fact, it happens to nearly everyone to varying degrees. But because these changes start in the locus coeruleus, some brain researchers – myself included – see this area as a canary in the coal mine for developing Alzheimer’s disease.

We are exploring whether stopping or slowing down tau tangles in this brain region, or otherwise maintaining its health, may be a way to interrupt how the disease ultimately unfolds and to prevent other aspects of cognitive aging.

Emerging research from my lab and others is investigating the idea that a therapy called vagus nerve stimulation, which is already widely used for other health conditions, could be one way of keeping the locus coeruleus functioning properly.

Longevity Isn’t Equal: Why Life-Extending Treatments May Be a “Biological Lottery”

Extending life is only part of the goal in aging research. Scientists also want more people to reach old age in good health, with fewer differences in when individuals die. This ideal outcome is often described as “squaring the survival curve,” where most deaths are pushed into a narrow window late in life rather than spread out across many years.

To test how close current science comes to that goal, University of Sydney researchers revisited a large meta-analysis of studies in vertebrates. They focused on three widely studied interventions: dietary restriction, rapamycin, and metformin. While all are linked to longevity, they work in different ways.

Dietary restriction involves reducing calorie intake without causing malnutrition. It has been known for more than a century to extend lifespan in animals and is thought to act in part by dialing down a key cellular growth pathway called mTORC1, which helps regulate metabolism and aging. Because strict diets are difficult to maintain, scientists have searched for drugs that mimic these effects. Rapamycin directly blocks mTORC1 activity, while metformin, a common diabetes medication, influences the same pathway indirectly by altering how cells sense energy levels.

Molecular Markers of Blood Cell Populations Can Help Estimate Aging of the Immune System

Aging of the immune system involves functional changes in individual cell populations, in hematopoietic tissues and at the systemic level. They are mediated by factors produced by circulating cells, niche cells, and at the systemic level. Age-related alterations in the microenvironment of the bone marrow and thymus cause a decrease in the production of naive immune cells and functional immunodeficiencies. Another result of aging and reduced tissue immune surveillance is the accumulation of senescent cells. Some viral infections deplete adaptive immune cells, increasing the risk of autoimmune and immunodeficiency conditions, leading to a general degradation in the specificity and effectiveness of the immune system in old age.

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