scholarly journals Crosstalk among DNA Damage, Mitochondrial Dysfunction, Impaired Mitophagy, Stem Cell Attrition, and Senescence in the Accelerated Ageing Disorder Werner Syndrome

2021 ◽  
Vol 161 (6-7) ◽  
pp. 297-304
Author(s):  
Ruben Gudmundsrud ◽  
Tarjei H. Skjånes ◽  
Brian C. Gilmour ◽  
Domenica Caponio ◽  
Sofie Lautrup ◽  
...  
Keyword(s):  
Dna Damage ◽  
Stem Cell ◽  
Mitochondrial Dysfunction ◽  
Clinical Features ◽  
Molecular Mechanisms ◽  
Werner Syndrome ◽  
Dna Helicase ◽  
Accelerated Ageing ◽  
Metabolic Dysfunction ◽  
Underlying Mechanisms

Werner syndrome (WS) is an accelerated ageing disease caused by multiple mutations in the gene encoding the Werner DNA helicase (WRN). The major clinical features of WS include wrinkles, grey hair, osteoporosis, and metabolic phenomena such as atherosclerosis, diabetes, and fatty liver, and resemble those seen in normal ageing, but occur earlier, in middle age. Defective DNA repair resulting from mutations in WRN explain the majority of the clinical features of WS, but the underlying mechanisms driving the larger metabolic dysfunction remain elusive. Recent studies in animal models of WS and in WS patient cells and blood samples suggest the involvement of impaired mitophagy, NAD<sup>+</sup> depletion, and accumulation of damaged mitochondria in metabolic dysfunction. This mini-review summarizes recent progress in the understanding of the molecular mechanisms of metabolic dysfunction in WS, with the involvement of DNA damage, mitochondrial dysfunction, mitophagy reduction, stem cell impairment, and senescence. Future studies on NAD<sup>+</sup> and mitophagy may shed light on potential therapeutic strategies for the WS patients.

scholarly journals NAD+ augmentation restores mitophagy and limits accelerated aging in Werner syndrome

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Evandro F. Fang ◽  
Yujun Hou ◽  
Sofie Lautrup ◽  
Martin Borch Jensen ◽  
Beimeng Yang ◽  
...  
Keyword(s):  
Werner Syndrome ◽  
Accelerated Aging ◽  
Dna Helicase ◽  
Premature Aging ◽  
Metabolic Dysfunction ◽  
Gene Encoding ◽  
Metabolic Phenotypes ◽  
Cell Dysfunction ◽  
Underlying Mechanisms ◽  
Invertebrate Models

AbstractMetabolic dysfunction is a primary feature of Werner syndrome (WS), a human premature aging disease caused by mutations in the gene encoding the Werner (WRN) DNA helicase. WS patients exhibit severe metabolic phenotypes, but the underlying mechanisms are not understood, and whether the metabolic deficit can be targeted for therapeutic intervention has not been determined. Here we report impaired mitophagy and depletion of NAD+, a fundamental ubiquitous molecule, in WS patient samples and WS invertebrate models. WRN regulates transcription of a key NAD+ biosynthetic enzyme nicotinamide nucleotide adenylyltransferase 1 (NMNAT1). NAD+ repletion restores NAD+ metabolic profiles and improves mitochondrial quality through DCT-1 and ULK-1-dependent mitophagy. At the organismal level, NAD+ repletion remarkably extends lifespan and delays accelerated aging, including stem cell dysfunction, in Caenorhabditis elegans and Drosophila melanogaster models of WS. Our findings suggest that accelerated aging in WS is mediated by impaired mitochondrial function and mitophagy, and that bolstering cellular NAD+ levels counteracts WS phenotypes.

scholarly journals Pathophysiological Molecular Mechanisms of Obesity: A Link between MAFLD and NASH with Cardiovascular Diseases

2021 ◽  
Vol 22 (21) ◽  
pp. 11629
Author(s):  
Jorge Gutiérrez-Cuevas ◽  
Arturo Santos ◽  
Juan Armendariz-Borunda
Keyword(s):  
Insulin Resistance ◽  
Metabolic Disorders ◽  
Molecular Mechanisms ◽  
Causes Of Death ◽  
Cardiovascular Prevention ◽  
Atherogenic Dyslipidemia ◽  
Metabolic Dysfunction ◽  
Systemic Insulin Resistance ◽  
Underlying Mechanisms

Obesity is now a worldwide epidemic ensuing an increase in comorbidities’ prevalence, such as insulin resistance, type 2 diabetes (T2D), metabolic dysfunction-associated fatty liver disease (MAFLD), nonalcoholic steatohepatitis (NASH), hypertension, cardiovascular disease (CVD), autoimmune diseases, and some cancers, CVD being one of the main causes of death in the world. Several studies provide evidence for an association between MAFLD and atherosclerosis and cardio-metabolic disorders, including CVDs such as coronary heart disease and stroke. Therefore, the combination of MAFLD/NASH is associated with vascular risk and CVD progression, but the underlying mechanisms linking MAFLD/NASH and CVD are still under investigation. Several underlying mechanisms may probably be involved, including hepatic/systemic insulin resistance, atherogenic dyslipidemia, hypertension, as well as pro-atherogenic, pro-coagulant, and pro-inflammatory mediators released from the steatotic/inflamed liver. MAFLD is strongly associated with insulin resistance, which is involved in its pathogenesis and progression to NASH. Insulin resistance is a major cardiovascular risk factor in subjects without diabetes. However, T2D has been considered the most common link between MAFLD/NASH and CVD. This review summarizes the evidence linking obesity with MAFLD, NASH, and CVD, considering the pathophysiological molecular mechanisms involved in these diseases. We also discuss the association of MAFLD and NASH with the development and progression of CVD, including structural and functional cardiac alterations, and pharmacological strategies to treat MAFLD/NASH and cardiovascular prevention.

scholarly journals Genetic and Epigenetic Mechanisms That Maintain Hematopoietic Stem Cell Function

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Christian Kosan ◽  
Maren Godmann
Keyword(s):  
Dna Damage ◽  
Stem Cell ◽  
Cell Fate ◽  
Molecular Mechanisms ◽  
Cell Function ◽  
Quiescent State ◽  
Ongoing Research ◽  
Hematopoietic Stem ◽  
Lineage Differentiation ◽  
Multipotent Progenitor Cells

All hematopoiesis cells develop from multipotent progenitor cells. Hematopoietic stem cells (HSC) have the ability to develop into all blood lineages but also maintain their stemness. Different molecular mechanisms have been identified that are crucial for regulating quiescence and self-renewal to maintain the stem cell pool and for inducing proliferation and lineage differentiation. The stem cell niche provides the microenvironment to keep HSC in a quiescent state. Furthermore, several transcription factors and epigenetic modifiers are involved in this process. These create modifications that regulate the cell fate in a more or less reversible and dynamic way and contribute to HSC homeostasis. In addition, HSC respond in a unique way to DNA damage. These mechanisms also contribute to the regulation of HSC function and are essential to ensure viability after DNA damage. How HSC maintain their quiescent stage during the entire life is still matter of ongoing research. Here we will focus on the molecular mechanisms that regulate HSC function.

scholarly journals The Distinct Function of p21Waf1/Cip1 With p16Ink4a in Modulating Aging Phenotypes of Werner Syndrome by Affecting Tissue Homeostasis

2021 ◽  
Vol 12 ◽  
Author(s):  
Yongjin Zhang ◽  
Chihao Shao ◽  
Haili Li ◽  
Kun Wu ◽  
Lixin Gong ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Stem Cell ◽  
Cellular Senescence ◽  
Cellular Proliferation ◽  
Werner Syndrome ◽  
Survival Curve ◽  
Cell Cycle Control ◽  
Tissue Homeostasis ◽  
Premature Aging

Human Werner syndrome (WS) is an autosomal recessive progeria disease. A mouse model of WS manifests the disease through telomere dysfunction-induced aging phenotypes, which might result from cell cycle control and cellular senescence. Both p21Waf1/Cip1 (p21, encoded by the Cdkn1a gene) and p16Ink4a (p16, encoded by the Ink4a gene) are cell cycle inhibitors and are involved in regulating two key pathways of cellular senescence. To test the effect of p21 and p16 deficiencies in WS, we crossed WS mice (DKO) with p21–/– or p16–/– mice to construct triple knockout (p21-TKO or p16-TKO) mice. By studying the survival curve, bone density, regenerative tissue (testis), and stem cell capacity (intestine), we surprisingly found that p21-TKO mice displayed accelerated premature aging compared with DKO mice, while p16-TKO mice showed attenuation of the aging phenotypes. The incidence of apoptosis and cellular senescence were upregulated in p21-TKO mice tissue and downregulated in p16-TKO mice. Surprisingly, cellular proliferation in p21-TKO mice tissue was also upregulated, and the p21-TKO mice did not show telomere shortening compared with age-matched DKO mice, although p16-TKO mice displayed obvious enhancement of telomere lengthening. Consistent with these phenotypes, the SIRT1-PGC1 pathway was upregulated in p16-TKO but downregulated in p21-TKO compared with DKO mouse embryo fibroblasts (MEFs). However, the DNA damage response pathway was highly activated in p21-TKO, but rescued in p16-TKO, compared with DKO MEFs. These data suggest that p21 protected the stem cell reservoir by regulating cellular proliferation and turnover at a proper rate and that p21 loss in WS activated fairly severe DNA damage responses (DDR), which might cause an abnormal increase in tissue homeostasis. On the other hand, p16 promoted cellular senescence by inhibiting cellular proliferation, and p16 deficiency released this barrier signal without causing severe DDR.

scholarly journals Mitochondrial Dysfunction in Stem Cell Aging

2015 ◽  
Vol 7 (1) ◽  
pp. 15
Author(s):  
Anna Meiliana ◽  
Nurrani Mustika Dewi ◽  
Andi Wijaya
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Mitochondrial Dysfunction ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Apoptotic Cell ◽  
Tissue Homeostasis ◽  
Cell Aging ◽  
Aging Research ◽  
Age Related

BACKGROUND: Regardless of the precise underlying molecular mechanisms, the fundamental defining manifestation of aging is an overall decline in the functional capacity of various organs to maintain baseline tissue homeostasis and to respond adequately to physiological needs under stress. There is an increasingly urgent need for a more complete understanding of the molecular pathways and biological processes underlying aging and age-related disorders.CONTENT: Mitochondria constitute the most prominent source of adenosine triphosphate (ATP) and are implicated in multiple anabolic and catabolic circuitries. In addition, mitochondria coordinate cell-wide stress responses and control non-apoptotic cell death routines. The involvement of mitochondria in both vital and lethal processes is crucial for both embryonic and postembryonic development, as well as for the maintenance of adult tissue homeostasis. Age-associated telomere damage, diminution of telomere ‘capping’ function and associated p53 activation have emerged as prime instigators of a functional decline of tissue stem cells and of mitochondrial dysfunction that adversely affect renewal and bioenergetic support in diverse tissues. Constructing a model of how telomeres, stem cells and mitochondria interact with key molecules governing genome integrity, ‘stemness’ and metabolism provides a framework for how diverse factors contribute to aging and age-related disorders.SUMMARY: Cellular senescence defined as an irreversible proliferation arrest promotes age-related decline in mammalian tissue homeostasis. The aging of tissue-specific stem cell and progenitor cell compartments is believed to be central to the decline of tissue and organ integrity and function in the elderly. Taken into consideration that the overwhelming majority of intracellular reactive oxygen species (ROS) are of mitochondrial origin, it is reasonable to posit that the elevated ROS production might be caused by alteration in mitochondrial function during senescence. It is likely that mitochondria and stem cells will remain at the forefront of aging research also for the next decade.KEYWORDS: aging, stem cell, mitochondrial biogenesis, mitophagy, senescence, telomeres

scholarly journals Directly Reprogrammed Human Neurons to Understand Age-Related Energy Metabolism Impairment and Mitochondrial Dysfunction in Healthy Aging and Neurodegeneration

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Camila Gudenschwager ◽  
Isadora Chavez ◽  
Cesar Cardenas ◽  
Christian Gonzalez-Billault
Keyword(s):  
Stem Cell ◽  
Mitochondrial Dysfunction ◽  
Molecular Mechanisms ◽  
Brain Aging ◽  
Dermal Fibroblasts ◽  
Cellular Reprogramming ◽  
Redox Biology ◽  
Brain Functions ◽  
Age Related ◽  
Human Neurons

Brain aging is characterized by several molecular and cellular changes grouped as the hallmarks or pillars of aging, including organelle dysfunction, metabolic and nutrition-sensor changes, stem cell attrition, and macromolecular damages. Separately and collectively, these features degrade the most critical neuronal function: transmission of information in the brain. It is widely accepted that aging is the leading risk factor contributing to the onset of the most prevalent pathological conditions that affect brain functions, such as Alzheimer’s, Parkinson’s, and Huntington’s disease. One of the limitations in understanding the molecular mechanisms involved in those diseases is the lack of an appropriate cellular model that recapitulates the “aged” context in human neurons. The advent of the cellular reprogramming of somatic cells, i.e., dermal fibroblasts, to obtain directly induced neurons (iNs) and induced pluripotent stem cell- (iPSC-) derived neurons is technical sound advances that could open the avenues to understand better the contribution of aging toward neurodegeneration. In this review, we will summarize the commonalities and singularities of these two approaches for the study of brain aging, with an emphasis on the role of mitochondrial dysfunction and redox biology. We will address the evidence showing that iNs retain age-related features in contrast to iPSC-derived neurons that lose the aging signatures during the reprogramming to pluripotency, rendering iNs a powerful strategy to deepen our knowledge of the processes driving normal cellular function decline and neurodegeneration in a human adult model. We will finally discuss the potential utilization of these novel technologies to understand the differential contribution of genetic and epigenetic factors toward neuronal aging, to identify and develop new drugs and therapeutic strategies.

scholarly journals Phytochemicals: Targeting Mitophagy to Treat Metabolic Disorders

2021 ◽  
Vol 9 ◽  
Author(s):  
Zuqing Su ◽  
Yanru Guo ◽  
Xiufang Huang ◽  
Bing Feng ◽  
Lipeng Tang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dysfunction ◽  
Metabolic Disorders ◽  
Molecular Mechanisms ◽  
Therapeutic Effects ◽  
Alcoholic Fatty Liver ◽  
Calorie Diet ◽  
Underlying Mechanisms ◽  
High Calorie

Metabolic disorders include metabolic syndrome, obesity, type 2 diabetes mellitus, non-alcoholic fatty liver disease and cardiovascular diseases. Due to unhealthy lifestyles such as high-calorie diet, sedentary and physical inactivity, the prevalence of metabolic disorders poses a huge challenge to global human health, which is the leading cause of global human death. Mitochondrion is the major site of adenosine triphosphate synthesis, fatty acid β−oxidation and ROS production. Accumulating evidence suggests that mitochondrial dysfunction-related oxidative stress and inflammation is involved in the development of metabolic disorders. Mitophagy, a catabolic process, selectively degrades damaged or superfluous mitochondria to reverse mitochondrial dysfunction and preserve mitochondrial function. It is considered to be one of the major mechanisms responsible for mitochondrial quality control. Growing evidence shows that mitophagy can prevent and treat metabolic disorders through suppressing mitochondrial dysfunction-induced oxidative stress and inflammation. In the past decade, in order to expand the range of pharmaceutical options, more and more phytochemicals have been proven to have therapeutic effects on metabolic disorders. Many of these phytochemicals have been proved to activate mitophagy to ameliorate metabolic disorders. Given the ongoing epidemic of metabolic disorders, it is of great significance to explore the contribution and underlying mechanisms of mitophagy in metabolic disorders, and to understand the effects and molecular mechanisms of phytochemicals on the treatment of metabolic disorders. Here, we investigate the mechanism of mitochondrial dysfunction in metabolic disorders and discuss the potential of targeting mitophagy with phytochemicals for the treatment of metabolic disorders, with a view to providing a direction for finding phytochemicals that target mitophagy to prevent or treat metabolic disorders.

Melatonin As a Modulator of Degenerative and Regenerative Signaling Pathways in Injured Retinal Ganglion Cells

2019 ◽  
Vol 25 (28) ◽  
pp. 3057-3073 ◽  
Author(s):  
Kobra B. Juybari ◽  
Azam Hosseinzadeh ◽  
Habib Ghaznavi ◽  
Mahboobeh Kamali ◽  
Ahad Sedaghat ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Mitochondrial Dysfunction ◽  
Signaling Pathways ◽  
Retinal Ganglion Cells ◽  
Molecular Mechanisms ◽  
Nitrosative Stress ◽  
Ganglion Cells ◽  
Axon Growth ◽  
Nerve Fibers ◽  
Retinal Ganglion

Optic neuropathies refer to the dysfunction or degeneration of optic nerve fibers caused by any reasons including ischemia, inflammation, trauma, tumor, mitochondrial dysfunction, toxins, nutritional deficiency, inheritance, etc. Post-mitotic CNS neurons, including retinal ganglion cells (RGCs) intrinsically have a limited capacity for axon growth after either trauma or disease, leading to irreversible vision loss. In recent years, an increasing number of laboratory evidence has evaluated optic nerve injuries, focusing on molecular signaling pathways involved in RGC death. Trophic factor deprivation (TFD), inflammation, oxidative stress, mitochondrial dysfunction, glutamate-induced excitotoxicity, ischemia, hypoxia, etc. have been recognized as important molecular mechanisms leading to RGC apoptosis. Understanding these obstacles provides a better view to find out new strategies against retinal cell damage. Melatonin, as a wide-spectrum antioxidant and powerful freeradical scavenger, has the ability to protect RGCs or other cells against a variety of deleterious conditions such as oxidative/nitrosative stress, hypoxia/ischemia, inflammatory processes, and apoptosis. In this review, we primarily highlight the molecular regenerative and degenerative mechanisms involved in RGC survival/death and then summarize the possible protective effects of melatonin in the process of RGC death in some ocular diseases including optic neuropathies. Based on the information provided in this review, melatonin may act as a promising agent to reduce RGC death in various retinal pathologic conditions.

Endometrial Regeneration in Asherman's Syndrome: Clinical and Translational evidence of Stem Cell Therapies

2019 ◽  
Vol 14 (6) ◽  
pp. 454-459
Author(s):  
Xuejing Hou ◽  
Ying Liu ◽  
Isabelle Streuli ◽  
Patrick Dällenbach ◽  
Jean Dubuisson ◽  
...  
Keyword(s):  
Stem Cell ◽  
Molecular Mechanisms ◽  
Uterine Cavity ◽  
Stem Cell Therapies ◽  
Intrauterine Adhesions ◽  
Asherman’S Syndrome ◽  
Cell Therapies ◽  
Fibrotic Process ◽  
Physical Barriers

Asherman’s Syndrome or Intrauterine adhesions is an acquired uterine condition where fibrous scarring forms within the uterine cavity, resulting in reduced menstrual flow, pelvic pain and infertility. Until recently, the molecular mechanisms leading to the formation of fibrosis were poorly understood, and the treatment of Asherman’s syndrome has largely focused on hysteroscopic resection of adhesions, hormonal therapy, and physical barriers. Numerous studies have begun exploring the molecular mechanisms behind the fibrotic process underlying Asherman’s Syndrome as well as the role of stem cells in the regeneration of the endometrium as a treatment modality. The present review offers a summary of available stem cell-based regeneration studies, as well as highlighting current gaps in research.

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