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Category: genetics

Study based upon human skeletal muscle aging, mutagenesis, and the role of #satellite cells.

“A more comprehensive understanding of the interplay of stem cell–intrinsic and extrinsic factors will set the stage for improving cell therapies capable of restoring tissue homeostasis and enhancing muscle repair in the aged.”

Human aging has multiple effects on the human body. One of the effects of human aging is the reduction in skeletal muscle (SkM) function and a reduction in the number and activity of satellite cells (SCs), the resident stem cells. The whole genome of single SC clones of the leg muscle vastus lateralis from healthy individuals of different ages (21–78 years) was analyzed, to study the specific connection between SC aging and muscle impairment. In healthy adult muscle rapid increase of SCs is consistent with the accumulation rate of 13 somatic mutations per genome per year. Mutations typically do not happen in SkM-expressed genes because they are protected. However, as mutations in exons and promoters increase, genes involved in SC activity and muscle function are targeted which results in aging. Exons are coding sections of an RNA transcript, or the DNA encoding it, that are translated into protein. Proteins are the synthesis of molecules. A change in of a single base pair that caused the substitution of a different amino acid in the resulting protein (missense mutation) that was propagated to the muscle and detected in association with SC mutations affecting the whole tissue. #Somatic mutagenesis in SCs as a result is the driving force in the age related decline of SkM function.

Satellite Cells

Satellite cells (SCs) are a heterogeneous population of stem and progenitor cells. These cells play an important role in the growth and development of myofiber. The enlargement, regeneration, and remodeling in skeletal muscle (SkM) is the pivotal role of satellite cells. Satellite cells are dormant until they become activated through exercise or SkM injury. Upon injury skeletal muscle have a remarkable ability to recover from injury. Skeletal muscle goes through a sophisticated degeneration and regenerative process that takes place at the tissue, cellular, and molecular levels. This regenerative process relies upon the dynamic interplay between satellite cells and their environment (stem cell niche). SCs multiply further when committed to myogenic differentiation. As SCs proliferate further they begin to combine with existing SkM fibers and supply new nuclei to the growing and regenerating fibers. The declining of numbers of proliferative potential of SCs is one sign of aging in human SkMs.

A flawed SC compartment is foreseen as a major contributor for age-related deficiencies such as, skeletal muscle tissue having restricted mobility and voluntary functions. The results of such defects include a reduced capacity to respond to hypertrophic stimuli such as exercise and impaired recovery from muscle disuse and injury and the disruption of muscle tissue homeostasis. Moreover, the SCs of nonactive adult animals have been shown to contribute to differentiated fibers in non-injured muscles. Less important is the basal turnover of nuclei in adult fibers in the protection from sarcopenia. This hypothesis was tested and showed that lifelong reduction of satellite cells neither accelerated nor exacerbated sarcopenia and that satellite cells did not contribute to the maintenance of muscle size or fiber type composition during aging, but that their loss may contribute to age-related muscle fibrosis. The progressive loss of SkM mass and function known as sarcopenia affects up to 29% of the population aged 85 years. The accumulation of sarcopenia causes a highly disabling condition. It is essential, nonetheless, that the characterization of SCs in human pathology be further explored. SCs are a key factor in limiting the occurrence of fibrosis in the SkM of mice affected by sarcopenia.

The progressive loss of SkM mass and function known as sarcopenia affects up to 29% of the population aged 85 years. The accumulation of sarcopenia causes a highly disabling condition. It is essential, nonetheless, that the characterization of SCs in human pathology be further explored. Scs are key in limiting the occurrence of fibrosis in the SkM of mice affected by sarcopenia. Genome integrity is essential for the function of stem-cells. But there still must be some stability of the genome. Genetic mutations in the soma has diverse physiological roles and pathological consequences, such as the decline of stem-cell functions. Starting from the first division of the embryo, modifications in the genome extend from single-base changes (single-nucleotide variants (SNVs)) to insertions or deletions of a few bases (indels) to chromosomal rearrangements and occur during the whole life. Somatic variants are not propagated to the whole individual but to a subpopulation of cells in the body, which is strikingly different from germline variants. Adult human tissues become a mosaic of genetically different cells as a result. Furthermore, as a result of the buildup of errors taking place either during cell-division or because of environmental induced DNA damage, somatic mutation burden increases, causing age-related disease. Currently, somatic mutation burden in human SCs or SkM is unknown.

The purpose of the investigation of genetic alterations that occur with aging in the genome of human adult SCs is to use the results to clearly explain mutational processes and SC replication rate occurring in vivo in adult human muscles. The prediction of global consequences on muscle aging and sarcopenia was done by evaluating the functional effects of somatic mutations on SC proliferation and differentiation.

Results

  • An accumulation of 13 mutations per genome per year that results in a 2–3-fold higher mutation load in active genes and promoters in aged SCs.
  • High mutation burden correlates with defective SC function. • The accumulation of somatic mutations as an intrinsic factor contributing to impaired muscle function with aging.
  • The accumulation of somatic mutations as an intrinsic factor contributing to impaired muscle function with aging.

Resources:

“Somatic mutagenesis in satellite cells associates with human skeletal muscle aging.”

Nature Communications volume 9, Article number: 800(2018) Full Abstract Study

“Satellite Cells and the Muscle Stem Cell Niche.”

Physiological Reviews Volume 93, No.1 (2013) Physiological Reviews

“Tissue-specific mutation accumulation in human adult stem cells during life.”

Nature International Journal of Science volume 538, pages 260–264 (13 October 2016) Abstract Study

“When stem cells grow old: phenotypes and mechanisms of stem cell aging”

Development for advances in developmental biology and stem cells Development 2016 143: 314 Abstract Study “Clock-like mutational processes in human somatic cells.”

Nature Genetics volume 47, pages 1402–1407 (2015) Abstract Study

A new class of patients could soon be treated for breast cancer, no chemotherapy required. That’s because they don’t really benefit from it, according to a study published Sunday in the New England Journal of Medicine.

Those patients: those diagnosed with early-stage, invasive, hormone-receptor-positive breast cancer who scored in a specific range of a genetic test. They benefit just as much from chemotherapy, which many don’t tolerate well and can have long-term consequences, as they do from hormone treatments, which have many fewer side effects.

But before this study came out, many people in this group were prescribed chemotherapy because doctors had, based on the best information available, assumed it would help them. For those people, the side effects of chemotherapy could have been avoided, without making the treatment any less effective.

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Today, we will be taking a look at a new study showing that an NAD+ precursor was able to improve mitochondrial function in cells and flies with a model of Parkinson’s disease.

Summary

While mitochondrial dysfunction is emerging as key in Parkinson’s disease (PD), a central question remains whether mitochondria are actual disease drivers and whether boosting mitochondrial biogenesis and function ameliorates pathology. We address these questions using patient-derived induced pluripotent stem cells and Drosophila models of GBA-related PD (GBA-PD), the most common PD genetic risk. Patient neurons display stress responses, mitochondrial demise, and changes in NAD+ metabolism. NAD+ precursors have been proposed to ameliorate agerelated metabolic decline and disease. We report that increasing NAD+ via the NAD+ precursor nicotinamide riboside (NR) significantly ameliorates mitochondrial function in patient neurons. Human neurons require nicotinamide phosphoribosyltransferase (NAMPT) to maintain the NAD+ pool and utilize NRK1 to synthesize NAD+ from NAD+ precursors. Remarkably, NR prevents the age-related dopaminergic neuronal loss and motor decline in fly models of GBA-PD.

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By Andy Coghlan

Many people with cancer die not from their original tumour, but from secondary tumours that grow elsewhere around the body. Now we’re a step closer to understanding how cancers are able to spread.

Sakari Vanharanta of the Medical Research Council Cancer Unit at the University of Cambridge and his colleagues have been studying kidney cancer cells. They found that to spread, these cells tap into the same genetic “travel” machinery normally used by healthy white blood cells to roam around the body.

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Aged population is increasing worldwide due to the aging process that is inevitable. Accordingly, longevity and healthy aging have been spotlighted to promote social contribution of aged population. Many studies in the past few decades have reported the process of aging and longevity, emphasizing the importance of maintaining genomic stability in exceptionally long-lived population. Underlying reason of longevity remains unclear due to its complexity involving multiple factors. With advances in sequencing technology and human genome-associated approaches, studies based on population-based genomic studies are increasing. In this review, we summarize recent longevity and healthy aging studies of human population focusing on DNA repair as a major factor in maintaining genome integrity. To keep pace with recent growth in genomic research, aging- and longevity-associated genomic databases are also briefly introduced. To suggest novel approaches to investigate longevity-associated genetic variants related to DNA repair using genomic databases, gene set analysis was conducted, focusing on DNA repair- and longevity-associated genes. Their biological networks were additionally analyzed to grasp major factors containing genetic variants of human longevity and healthy aging in DNA repair mechanisms. In summary, this review emphasizes DNA repair activity in human longevity and suggests approach to conduct DNA repair-associated genomic study on human healthy aging.

Aging is an inevitable process in human life. Many countries are rapidly transitioning to an aging society due to increasing life expectancy and advanced medical supports [1–3]. Over the last few decades, the advent of aging society is considered a crucial issue that may cause future decline in productivity of community [1, 4]. Many researchers have recently warned that urban environmental pollutants can cause physiological weakness and increase the risk of premature aging or chronic diseases in the elderly population [5–9]. Thus, interest in antiaging and healthy longevity is constantly increasing. “Active aging” or “successful aging” has been spotlighted as a strategy to promote social contribution of the elderly [10]. The definition of successful aging remains controversial.

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http://www.thepathmag.com/can-you-actually-hack-your-dna-to-slow-down-aging/

Many technologies / interventions progressing down the development pathways in the coming years — but there are a lot of free, common sense adjustments you can make today:

https://player.fm/series/healthy-relationship-talk-radio/cellular-dna-repair-05-31-2018

It was a good week for physics as a team with members from Australia and Switzerland invented a flux capacitor able to break time-reversal symmetry. They proposed a device based on quantum tunneling of magnetic flux around a capacitor. And another team with members from across the U.S. reported on a gravitational wave event that likely signaled the creation of a black hole—the merger of two neutron stars.

In biology news, a team of engineers led by Sinisa Vukelic invented a noninvasive technique to correct vision. Like LASIK, it uses lasers but is non-surgical and has few side-effects. And an international team of researchers found what they describe as the mother of all lizards in the Italian Alps, the oldest known lizard fossil, from approximately 240 million years ago. Also, a team at the University of Sydney found that walking faster could make you live longer. People do not even need to walk more, the team reported, they just need to pick up the pace of their normal stride to see an improvement in several health factors. And a team from Cal Poly Pomona discovered how microbes survive clean rooms and contaminate spacecraft—and it involved the cleaning agents themselves.

In other news, a team of researchers from the University of California and the University of Southern Queensland announced that they had identified 121 giant planets that may have habitable moons. And a team at Stanford University found that wars and clan structure might explain a strange biological event that occurred 7,000 years ago—male genetic diversity appeared to collapse for a time. Also, a team of researchers from MIT and Harvard University report the development of a 3D printer that can print data sets as physical objects—offering far more realistic, nearly true-color renderings.

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8 Amazing CRISPR gene editing projects that could change life as we know it.

Since it burst onto the scene a decade ago, CRISPR-Cas9 has shaken the field of genetics to its core. Offering a new genomic editing tool that’s faster, cheaper and more accurate than previous approaches, it opens up an astonishing breadth of possible applications.

From saving lives to potentially rescuing coral reefs, here are eight examples of exciting CRISPR projects that showcase just why this gene-editing tech has everyone talking.

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Scientists from Purdue University and the Chinese Academy of Sciences report the use of CRISPR/Cas9 to develop a variety of rice producing 25–31% more grain than traditional breeding methods.

crispr future technology

The team, led by Jian-Kang Zhu, a distinguished professor in the Department of Horticulture and Landscape Architecture at Purdue and director of the Shanghai Center for Plant Stress Biology at the Chinese Academy of Sciences, made mutations to 13 genes associated with the plant hormone abscisic acid – known to play roles in plant stress tolerance and suppression of growth. Of several varieties created, one produced a plant that had little change in stress tolerance but produced 25% more grain in a field test in Shanghai, China, and 31% more in a field test conducted on China’s Hainan Island.

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