scholarly journals Thrombospondin-1 in maladaptive aging responses: a concept whose time has come

2020 ◽  
Vol 319 (1) ◽  
pp. C45-C63
Author(s):  
Jeffrey S. Isenberg ◽  
David D. Roberts
Keyword(s):  
Molecular Mechanisms ◽  
Synapse Formation ◽  
Genotoxic Stress ◽  
Cell Types ◽  
Cellular Tissue ◽  
Therapeutic Agents ◽  
Age Related ◽  
Organ Systems ◽  
Age Dependent ◽  
Thrombospondin 1

Numerous age-dependent alterations at the molecular, cellular, tissue and organ systems levels underlie the pathophysiology of aging. Herein, the focus is upon the secreted protein thrombospondin-1 (TSP1) as a promoter of aging and age-related diseases. TSP1 has several physiological functions in youth, including promoting neural synapse formation, mediating responses to ischemic and genotoxic stress, minimizing hemorrhage, limiting angiogenesis, and supporting wound healing. These acute functions of TSP1 generally require only transient expression of the protein. However, accumulating basic and clinical data reinforce the view that chronic diseases of aging are associated with accumulation of TSP1 in the extracellular matrix, which is a significant maladaptive contributor to the aging process. Identification of the relevant cell types that chronically produce and respond to TSP1 and the molecular mechanisms that mediate the resulting maladaptive responses could direct the development of therapeutic agents to delay or revert age-associated maladies.

scholarly journals The Rise of Retinal Organoids for Vision Research

2020 ◽  
Vol 21 (22) ◽  
pp. 8484 ◽  
Author(s):  
Kritika Sharma ◽  
Tim U. Krohne ◽  
Volker Busskamp
Keyword(s):  
Molecular Mechanisms ◽  
Cell Types ◽  
Therapeutic Interventions ◽  
Retinal Cell ◽  
Retinal Diseases ◽  
Organ Systems ◽  
Cell Sources ◽  
Retinal Degenerative Diseases

Retinal degenerative diseases lead to irreversible blindness. Decades of research into the cellular and molecular mechanisms of retinal diseases, using either animal models or human cell-derived 2D systems, facilitated the development of several therapeutic interventions. Recently, human stem cell-derived 3D retinal organoids have been developed. These self-organizing 3D organ systems have shown to recapitulate the in vivo human retinogenesis resulting in morphological and functionally similar retinal cell types in vitro. In less than a decade, retinal organoids have assisted in modeling several retinal diseases that were rather difficult to mimic in rodent models. Retinal organoids are also considered as a photoreceptor source for cell transplantation therapies to counteract blindness. Here, we highlight the development and field’s improvements of retinal organoids and discuss their application aspects as human disease models, pharmaceutical testbeds, and cell sources for transplantations.

scholarly journals The islet ghrelin cell

2013 ◽  
Vol 52 (1) ◽  
pp. R35-R49 ◽  
Author(s):  
Nils Wierup ◽  
Frank Sundler ◽  
R Scott Heller
Keyword(s):  
Molecular Mechanisms ◽  
Developmental Stages ◽  
Developmental Regulation ◽  
Genetic Regulation ◽  
Cell Types ◽  
Human Islets ◽  
Histochemical Staining ◽  
Pancreatic Tumours ◽  
Age Related ◽  
Staining Methods

The islets of Langerhans are key regulators of glucose homeostasis and have been known as a structure for almost one and a half centuries. During the twentieth century several different cell types were described in the islets of different species and at different developmental stages. Six cell types with identified hormonal product have been described so far by the use of histochemical staining methods, transmission electron microscopy, and immunohistochemistry. Thus, glucagon-producing α-cells, insulin-producing β-cells, somatostatin-producing δ-cells, pancreatic polypeptide-producing PP-cells, serotonin-producing enterochromaffin-cells, and gastrin-producing G-cells have all been found in the mammalian pancreas at least at some developmental stage. Species differences are at hand and age-related differences are also to be considered. Eleven years ago a novel cell type, the ghrelin cell, was discovered in the human islets. Subsequent studies have shown the presence of islet ghrelin cells in several animals, including mouse, rat, gerbils, and fish. The developmental regulation of ghrelin cells in the islets of mice has gained a lot of interest and several studies have added important pieces to the puzzle of molecular mechanisms and the genetic regulation that lead to differentiation into mature ghrelin cells. A body of evidence has shown that ghrelin is an insulinostatic hormone, and the potential for blockade of ghrelin signalling as a therapeutic avenue for type 2 diabetes is intriguing. Furthermore, ghrelin-expressing pancreatic tumours have been reported and ghrelin needs to be taken into account when diagnosing pancreatic tumours. In this review article, we summarise the knowledge about islet ghrelin cells obtained so far.

scholarly journals Liver Regeneration and Aging: A Current Perspective

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Douglas L. Schmucker ◽  
Henry Sanchez
Keyword(s):  
Liver Regeneration ◽  
Plasma Membranes ◽  
Molecular Mechanisms ◽  
Egf Receptor ◽  
Hepatic Regeneration ◽  
Remarkable Feature ◽  
Original Volume ◽  
Age Related ◽  
Current Perspective ◽  
Organ Systems

Many organ systems exhibit significant age-related deficits, but, based on studies in old rodents and elderly humans, the liver appears to be relatively protected from such changes. A remarkable feature of the liver is its capacity to regenerate its mass following partial hepatectomy. Reports suggests that aging compromises the liver's regenerative capacity, both in the rate and to the extent the organ's original volume is restored. There has been modest definitive information as to which cellular and molecular mechanisms regulating hepatic regeneration are affected by aging. Changes in hepatic sensitivity to growth factors, for example, epidermal growth factor (EGF), appear to influence regeneration in old animals. Studies have demonstrated (a) a 60% decline in EGF binding to hepatocyte plasma membranes, (b) reduced expression of the hepatic high affinity EGF receptor and (c) a block between G1 and S-phases of the cell cycle in old rats following EGF stimulation. Recent studies suggest that reduced phosphorylation and dimerization of the EGF receptor, critical steps in the activation of the extracellular signal-regulated kinase pathway and subsequent cell proliferation are responsible. Other studies have demonstrated that aging affects the upregulation of a Forkhead Box transcription factor, FoxM1B, which is essential for growth hormone-stimulated liver regeneration in hepatectomized mice. Aging appears to compromise liver regeneration by influencing several pathways, the result of which is a reduction in the rate of regeneration, but not in the capacity to restore the organ to its original volume.

scholarly journals The GH/IGF1 axis and signaling pathways in the muscle and bone: mechanisms underlying age-related skeletal muscle wasting and osteoporosis

2010 ◽  
Vol 205 (3) ◽  
pp. 201-210 ◽  
Author(s):  
Sebastio Perrini ◽  
Luigi Laviola ◽  
Marcos C Carreira ◽  
Angelo Cignarelli ◽  
Annalisa Natalicchio ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Signs And Symptoms ◽  
Well Being ◽  
Serum Levels ◽  
Normal Range ◽  
Gh Secretion ◽  
Skeletal Muscle Wasting ◽  
Age Related ◽  
Age Dependent

The widespread increase in life expectancy is accompanied by an increased prevalence of features of physical frailty. Signs and symptoms may include sarcopenia and osteopenia, reduced exercise capacity, and diminished sense of well-being. The pathogenesis of age-associated sarcopenia and osteopenia is multifactorial, and hormonal decline may be a contributing factor. Aging is associated with a progressive decrease in GH secretion, and more than 30% of elderly people have circulating IGF1 levels below the normal range found in the young. GH acts directly on target tissues, including skeletal muscle and bone among many others, but many effects are mediated indirectly by circulating (liver-derived) or locally produced IGF1. Aging is also associated with reduced insulin sensitivity which, in turn, may contribute to the impairment of IGF1 action. Recent experimental evidence suggests that besides the age-dependent decline in GH and IGF1 serum levels, the dysregulation of GH and IGF1 actions due to impairment of the post-receptor signaling machinery may contribute to the loss of muscle mass and osteopenia. This article will focus on the molecular mechanisms of impaired GH and IGF1 signaling and action in aging, and their role in the pathogenesis of sarcopenia and osteoporosis.

scholarly journals cAMP signaling in skeletal muscle adaptation: hypertrophy, metabolism, and regeneration

2012 ◽  
Vol 303 (1) ◽  
pp. E1-E17 ◽  
Author(s):  
Rebecca Berdeaux ◽  
Randi Stewart
Keyword(s):  
Skeletal Muscle ◽  
Muscular Dystrophy ◽  
Molecular Mechanisms ◽  
Muscle Development ◽  
Camp Signaling ◽  
Metabolic Phenotype ◽  
Muscle Adaptation ◽  
Age Related ◽  
Organ Systems

Among organ systems, skeletal muscle is perhaps the most structurally specialized. The remarkable subcellular architecture of this tissue allows it to empower movement with instructions from motor neurons. Despite this high degree of specialization, skeletal muscle also has intrinsic signaling mechanisms that allow adaptation to long-term changes in demand and regeneration after acute damage. The second messenger adenosine 3′,5′-monophosphate (cAMP) not only elicits acute changes within myofibers during exercise but also contributes to myofiber size and metabolic phenotype in the long term. Strikingly, sustained activation of cAMP signaling leads to pronounced hypertrophic responses in skeletal myofibers through largely elusive molecular mechanisms. These pathways can promote hypertrophy and combat atrophy in animal models of disorders including muscular dystrophy, age-related atrophy, denervation injury, disuse atrophy, cancer cachexia, and sepsis. cAMP also participates in muscle development and regeneration mediated by muscle precursor cells; thus, downstream signaling pathways may potentially be harnessed to promote muscle regeneration in patients with acute damage or muscular dystrophy. In this review, we summarize studies implicating cAMP signaling in skeletal muscle adaptation. We also highlight ligands that induce cAMP signaling and downstream effectors that are promising pharmacological targets.

scholarly journals MECHANISMS OF BRAIN REJUVENATION

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S587-S587
Author(s):  
Saul Villeda
Keyword(s):  
Molecular Mechanisms ◽  
Aging Brain ◽  
Aging Effects ◽  
Effective Strategies ◽  
Mechanistic Insight ◽  
Age Related ◽  
Age Dependent ◽  
Cognitive Faculties ◽  
Insight Into ◽  
Aging Factors

Abstract A growing body of work has shown that systemic manipulations, such as heterochronic parabiosis and young blood administration, can partially reverse age-related cellular impairments and loss of cognitive faculties in the aged brain. These studies have revealed an age-dependent bi-directionality in the influence of the systemic environment indicating anti-aging factors in young blood elicit rejuvenation while pro-aging factors in old blood drive aging. It has been proposed that introducing anti-aging factors or mitigating the effect of pro-aging factors may provide effective strategies to rejuvenate aging phenotypes. Despite this potential, much is unknown as to the systemic and molecular mechanisms regulating anti-aging and pro-aging effects of blood-borne factors. I will discuss work from my research group that begins to provide mechanistic insight into the systemic and molecular drivers promoting rejuvenation in the aging brain.

scholarly journals Exosomes and Micro-RNAs in Aging Process

Biomedicines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 968
Author(s):  
Yousra Hamdan ◽  
Loubna Mazini ◽  
Gabriel Malka
Keyword(s):  
Messenger Rna ◽  
Molecular Mechanisms ◽  
Therapeutic Potential ◽  
Biological Fluids ◽  
Cell Types ◽  
Exosome Biogenesis ◽  
Age Related ◽  
Micro Rnas ◽  
Underlying Mechanisms ◽  
Almost All

Exosomes are the main actors of intercellular communications and have gained great interest in the new cell-free regenerative medicine. These nanoparticles are secreted by almost all cell types and contain lipids, cytokines, growth factors, messenger RNA, and different non-coding RNA, especially micro-RNAs (mi-RNAs). Exosomes’ cargo is released in the neighboring microenvironment but is also expected to act on distant tissues or organs. Different biological processes such as cell development, growth and repair, senescence, migration, immunomodulation, and aging, among others, are mediated by exosomes and principally exosome-derived mi-RNAs. Moreover, their therapeutic potential has been proved and reinforced by their use as biomarkers for disease diagnostics and progression. Evidence has increasingly shown that exosome-derived mi-RNAs are key regulators of age-related diseases, and their involvement in longevity is becoming a promising issue. For instance, mi-RNAs such as mi-RNA-21, mi-RNA-29, and mi-RNA-34 modulate tissue functionality and regeneration by targeting different tissues and involving different pathways but might also interfere with long life expectancy. Human mi-RNAs profiling is effectively related to the biological fluids that are reported differently between young and old individuals. However, their underlying mechanisms modulating cell senescence and aging are still not fully understood, and little was reported on the involvement of mi-RNAs in cell or tissue longevity. In this review, we summarize exosome biogenesis and mi-RNA synthesis and loading mechanism into exosomes’ cargo. Additionally, we highlight the molecular mechanisms of exosomes and exosome-derived mi-RNA regulation in the different aging processes.

scholarly journals Integrated or Independent Actions of Metformin in Target Tissues Underlying Its Current Use and New Possible Applications in the Endocrine and Metabolic Disorder Area

2021 ◽  
Vol 22 (23) ◽  
pp. 13068
Author(s):  
Giovanni Tulipano
Keyword(s):  
Molecular Mechanisms ◽  
Metabolic Diseases ◽  
Current Knowledge ◽  
Cell Types ◽  
Cellular Level ◽  
Endocrine Tumors ◽  
Age Related ◽  
Distinct Cell ◽  
First Choice ◽  
Integrated Or

Metformin is considered the first-choice drug for type 2 diabetes treatment. Actually, pleiotropic effects of metformin have been recognized, and there is evidence that this drug may have a favorable impact on health beyond its glucose-lowering activity. In summary, despite its long history, metformin is still an attractive research opportunity in the field of endocrine and metabolic diseases, age-related diseases, and cancer. To this end, its mode of action in distinct cell types is still in dispute. The aim of this work was to review the current knowledge and recent findings on the molecular mechanisms underlying the pharmacological effects of metformin in the field of metabolic and endocrine pathologies, including some endocrine tumors. Metformin is believed to act through multiple pathways that can be interconnected or work independently. Moreover, metformin effects on target tissues may be either direct or indirect, which means secondary to the actions on other tissues and consequent alterations at systemic level. Finally, as to the direct actions of metformin at cellular level, the intracellular milieu cooperates to cause differential responses to the drug between distinct cell types, despite the primary molecular targets may be the same within cells. Cellular bioenergetics can be regarded as the primary target of metformin action. Metformin can perturb the cytosolic and mitochondrial NAD/NADH ratio and the ATP/AMP ratio within cells, thus affecting enzymatic activities and metabolic and signaling pathways which depend on redox- and energy balance. In this context, the possible link between pyruvate metabolism and metformin actions is extensively discussed.

scholarly journals Implications of NAD+ Metabolism in the Aging Retina and Retinal Degeneration

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Ravirajsinh N. Jadeja ◽  
Menaka C. Thounaojam ◽  
Manuela Bartoli ◽  
Pamela M. Martin
Keyword(s):  
Nad Metabolism ◽  
Age Related ◽  
Promising Therapeutic Target ◽  
Organ Systems ◽  
Age Dependent ◽  
The Subject ◽  
Mitochondrial Oxidative Damage ◽  
And Function ◽  
Visual Health

Nicotinamide adenine dinucleotide (NAD+) plays an important role in various key biological processes including energy metabolism, DNA repair, and gene expression. Accumulating clinical and experimental evidence highlights an age-dependent decline in NAD+ levels and its association with the development and progression of several age-related diseases. This supports the establishment of NAD+ as a critical regulator of aging and longevity and, relatedly, a promising therapeutic target to counter adverse events associated with the normal process of aging and/or the development and progression of age-related disease. Relative to the above, the metabolism of NAD+ has been the subject of numerous investigations in various cells, tissues, and organ systems; however, interestingly, studies of NAD+ metabolism in the retina and its relevance to the regulation of visual health and function are comparatively few. This is surprising given the critical causative impact of mitochondrial oxidative damage and bioenergetic crises on the development and progression of degenerative disease of the retina. Hence, the role of NAD+ in this tissue, normally and aging and/or disease, should not be ignored. Herein, we discuss important findings in the field of NAD+ metabolism, with particular emphasis on the importance of the NAD+ biosynthesizing enzyme NAMPT, the related metabolism of NAD+ in the retina, and the consequences of NAMPT and NAD+ deficiency or depletion in this tissue in aging and disease. We discuss also the implications of potential therapeutic strategies that augment NAD+ levels on the preservation of retinal health and function in the above conditions. The overarching goal of this review is to emphasize the importance of NAD+ metabolism in normal, aging, and/or diseased retina and, by so doing, highlight the necessity of additional clinical studies dedicated to evaluating the therapeutic utility of strategies that enhance NAD+ levels in improving vision.

scholarly journals Understanding the Potential Role of Sirtuin 2 on Aging: Consequences of SIRT2.3 Overexpression in Senescence

2021 ◽  
Vol 22 (6) ◽  
pp. 3107
Author(s):  
Noemi Sola-Sevilla ◽  
Ana Ricobaraza ◽  
Ruben Hernandez-Alcoceba ◽  
Maria S. Aymerich ◽  
Rosa M. Tordera ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Potential Role ◽  
Adeno Associated Virus ◽  
Age Related ◽  
Age Dependent ◽  
Molecular Effects ◽  
Samp8 Mice ◽  
The Brain

Sirtuin 2 (SIRT2) has been associated to aging and age-related pathologies. Specifically, an age-dependent accumulation of isoform 3 of SIRT2 in the CNS has been demonstrated; however, no study has addressed the behavioral or molecular consequences that this could have on aging. In the present study, we have designed an adeno-associated virus vector (AAV-CAG-Sirt2.3-eGFP) for the overexpression of SIRT2.3 in the hippocampus of 2 month-old SAMR1 and SAMP8 mice. Our results show that the specific overexpression of this isoform does not induce significant behavioral or molecular effects at short or long term in the control strain. Only a tendency towards a worsening in the performance in acquisition phase of the Morris Water Maze was found in SAMP8 mice, together with a significant increase in the pro-inflammatory cytokine Il-1β. These results suggest that the age-related increase of SIRT2.3 found in the brain is not responsible for induction or prevention of senescence. Nevertheless, in combination with other risk factors, it could contribute to the progression of age-related processes. Understanding the specific role of SIRT2 on aging and the underlying molecular mechanisms is essential to design new and more successful therapies for the treatment of age-related diseases.

Sign in / Sign up

Export Citation Format

Share Document