Nicotinamide adenine dinucleotide (NAD) is a ubiquitous electron carrier essential for energy metabolism and post-translational modification of numerous regulatory proteins. Dysregulations of NAD metabolism are widely regarded as detrimental to health, with NAD depletion commonly implicated in aging. However, the extent to which cellular NAD concentration can decline without adverse consequences remains unclear. To investigate this, we generated a mouse model in which nicotinamide phosphoribosyltransferase (NAMPT)-mediated NAD+ biosynthesis was disrupted in adult skeletal muscle. The intervention resulted in an 85% reduction in muscle NAD+ abundance while maintaining tissue integrity and functionality, as demonstrated by preserved muscle morphology, contractility, and exercise tolerance. This absence of functional impairments was further supported by intact mitochondrial respiratory capacity and unaltered muscle transcriptomic and proteomic profiles. Furthermore, lifelong NAD depletion did not accelerate muscle aging or impair whole-body metabolism. Collectively, these findings suggest that NAD depletion does not contribute to age-related decline in skeletal muscle function.

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NAD depletion in skeletal muscle does not impair tissue integrity and function or accelerate aging, as shown in a mouse model with an 85% decrease in muscle NAD+ levels. Muscle structure, metabolism, and mitochondrial function remain unaffected, suggesting that NAD depletion does not drive age-related muscle decline.

Ambrosi and colleagues profile human skeletal stem cells (hSSCs) across ten fetal skeletal sites and from patients throughout adulthood, identifying, mapping, and functionally testing four distinct hSSC subtypes. Skeletal aging and disease are characterized by a dominant fibrogenic hSSC variant, but targeting defined gene regulatory networks reinstates functional hSSC diversity.

Scientists at the University of East Anglia (UEA) have developed a new way of uncovering the “true age” of a heart using MRI.

Research accepted for publication European Heart Journal Open shows how an MRI scan can reveal your heart’s functional age—and how unhealthy lifestyles can dramatically accelerate this figure. The paper is titled “Cardiac MRI Markers of Ageing: A Multicentre, Cross-sectional Cohort Study.”

It is hoped that the findings could transform how heart disease is diagnosed—offering a lifeline to millions by catching problems before they become deadly.

The duplication and division of cells is critical to keeping all multicellular organisms alive. But the opposite process is equally important: cell death. Controlled death of cells, or programmed cell death, is also necessary for the proper development and function of the body. It has also been a focus of researchers developing treatments for cancer by finding ways to activate the cell death of cancer cells themselves.

Ferroptosis is a recently discovered form of programmed cell death and has been a promising target for the development of cancer treatments. It is mediated by iron molecules, with the cell dying through the degradation of the phospholipid bilayer by oxidation, a process called lipid peroxidation. However, recent studies have shown that certain cancer cells are less susceptible to ferroptosis, raising concerns that this resistance could pose a barrier to future therapeutics.

In a paper published in Nature Communications, researchers from Kyushu University, using cultured cells and mice, found that the lipid peroxidation of the lysosomes—the organelle responsible for degrading and recycling molecules in a cell—plays a critical role in the execution of ferroptosis.