Unprovoked Stabilization and Nuclear Accumulation of the Naked Mole-Rat p53 Protein

Stress, epigenetics, and aging: Unraveling the intricate crosstalk

Aging, as a complex process involving multiple cellular and molecular pathways, is known to be exacerbated by various stresses. Because responses to these stresses, such as oxidative stress and genotoxic stress, are known to interplay with the epigenome and thereby contribute to the development of age-related diseases, investigations into how such epigenetic mechanisms alter gene expression and maintenance of cellular homeostasis is an active research area. In this review, we highlight recent studies investigating the intricate relationship between stress and aging, including its underlying epigenetic basis; describe different types of stresses that originate from both internal and external stimuli; and discuss potential interventions aimed at alleviating stress and restoring epigenetic patterns to combat aging or age-related diseases. Additionally, we address the challenges currently limiting advancement in this burgeoning field.

The Role of Hydrogen Sulfide in the Localization and Expression of p53 and Cell Death in the Nervous Tissue in Traumatic Brain Injury and Axotomy

Traumatic brain injury (TBI) is one of the leading causes of disability and death worldwide. It is characterized by various molecular-cellular events, with the main ones being apoptosis and damage to axons. To date, there are no clinically effective neuroprotective drugs. In this study, we examined the role of hydrogen sulfide (H2S) in the localization and expression of the key pro-apoptotic protein p53, as well as cell death in the nervous tissue in TBI and axotomy. We used a fast donor (sodium sulphide, Na2S) H2S and a classic inhibitor (aminooxyacetic acid, AOAA) of cystathionine β-synthase (CBS), which is a key enzyme in H2S synthesis. These studies were carried out on three models of neurotrauma in vertebrates and invertebrates. As a result, it was found that Na2S exhibits a pronounced neuroprotective effect that reduces the number of TUNEL-positive neurons and glial cells in TBI and apoptotic glia in axotomy. This effect could be realized through the Na2S-dependent decrease in the level of p53 in the cells of the nervous tissue of vertebrates and invertebrates, which we observed in our study. We also observed the opposite effect when using AOAA, which indicates the important role of CBS in the regulation of p53 expression and death of neurons and glial cells in TBI and axotomy.

The Naked Mole-Rat as a Model for Healthy Aging

Naked mole-rats (NMRs, Heterocephalus glaber) are the longest-lived rodents with a maximum life span exceeding 37 years. They exhibit a delayed aging phenotype and resistance to age-related functional decline/diseases. Specifically, they do not display increased mortality with age, maintain several physiological functions until nearly the end of their lifetime, and rarely develop cancer and Alzheimer's disease. NMRs live in a hypoxic environment in underground colonies in East Africa and are highly tolerant of hypoxia. These unique characteristics of NMRs have attracted considerable interest from zoological and biomedical researchers. This review summarizes previous studies of the ecology, hypoxia tolerance, longevity/delayed aging, and cancer resistance of NMRs and discusses possible mechanisms contributing to their healthy aging. In addition, we discuss current issues and future perspectives to fully elucidate the mechanisms underlying delayed aging and resistance to age-related diseases in NMRs.

Cataracts Across the Tree of Life: A Roadmap for Prevention and Biomedical Innovation

PURPOSE

Spontaneous cataracts have been identified in the lenses of animals across a phylogenetically wide range of species. This can be a source of insights and innovation for human health professionals, but many persons may lack awareness of it. By providing a phylogenetic survey and analysis of species with cataract vulnerability, this paper demonstrates how a broad comparative perspective can provide critical information about environmental hazards to human visual health and can spark potential innovations in the prevention and treatment of cataracts in humans.

DESIGN

Perspectives.

METHODS

Review and synthesis of selected literature with interpretation and perspective.

RESULTS

We found 273 recorded cases of spontaneously occurring cataracts in 113 species of birds, 83 species of mammals, 30 species of actinopterygii fish, 10 species of amphibians, 6 species of reptiles, and 1 species of cephalopod.

CONCLUSION

A phylogenetically wide range of species, including many living in and around human environments, are vulnerable to cataracts. These animals may serve as sentinels for human visual health. Variation in cataract vulnerability across species may also facilitate the identification of resistance-conferring physiologies, leading to accelerated innovation in the prevention and treatment of cataracts in humans.

Carcinogenesis resistance in the longest-lived rodent, the naked mole-rat

Certain mammalian species are resistant to cancer, and a better understanding of how this cancer resistance arises could provide valuable insights for basic cancer research. Recent technological innovations in molecular biology have allowed the study of cancer-resistant mammals, despite the fact that they are not the classical model animals, which are easily studied using genetic approaches. Naked mole-rats (NMRs; Heterocephalus glaber) are the longest-lived rodent, with a maximum lifespan of more than 37 years, and almost never show spontaneous carcinogenesis. NMRs are currently attracting much attention from aging and cancer researchers, and published studies on NMR have continued to increase over the past decade. Cancer development occurs via multiple steps and involves many biological processes. Recent research on the NMR as a model for cancer resistance suggests that they possess various unique carcinogenesis-resistance mechanisms, including efficient DNA repair pathways, cell-autonomous resistance to transformation, and dampened inflammatory response. Here, we summarize the molecular mechanisms of carcinogenesis resistance in NMR, which have been uncovered over the past two decades, and discuss future perspectives.

Species-specific formation of paraspeckles in intestinal epithelium revealed by characterization of NEAT1 in naked mole-rat

Paraspeckles are mammalian-specific nuclear bodies built on the long noncoding RNA NEAT1_2 The molecular mechanisms of paraspeckle formation have been mainly studied using human or mouse cells, and it is not known if the same molecular components are involved in the formation of paraspeckles in other mammalian species. We thus investigated the expression pattern of NEAT1_2 in naked mole-rats (nNEAT1_2), which exhibit extreme longevity and lower susceptibility to cancer. In the intestine, nNEAT1_2 is widely expressed along the entire intestinal epithelium, which is different from the expression of mNeat1_2 that is restricted to the cells of the distal tip in mice. Notably, the expression of FUS, a FET family RNA binding protein, essential for the formation of paraspeckles both in humans and mice, was absent in the distal part of the intestinal epithelium in naked mole-rats. Instead, mRNAs of other FET family proteins EWSR1 and TAF15 were expressed in the distal region. Exogenous expression of these proteins in Fus-deficient murine embryonic fibroblast cells rescued the formation of paraspeckles. These observations suggest that nNEAT1_2 recruits a different set of RNA binding proteins in a cell type-specific manner during the formation of paraspeckles in different organisms.

Supermole-rat to the rescue: Does the naked mole-rat offer a panacea for all that ails us?

Over the previous several decades, many non-traditional research models have offered new avenues of exploration for biomedical research. The promise of these animals is primarily derived from adaptations to unique or challenging environments that share key factors with a disease or pathology of interest (e.g., hypoxemia or hypercarbia are clinically relevant and are also in vivo consequences of environmental hypoxia and hypercapnia, respectively). Animals adapted to such environments allow us to ask the question: how has nature solved a particular problem and what can we learn to inform novel translational research into the treatment of related diseases and pathologies? One of the most promising mammalian models that have garnered increasing attention from researchers and the public are naked mole-rats (NMRs). The NMR is a small and eusocial subterranean rodent species that live in a putatively hypoxic and hypercapnic burrow environment. Intriguingly, whereas most non-traditional biomedical models offer insight into one or only a few diseases related to a common physiological stress, NMRs in contrast have proven to be resistant to a very wide range of ailments, including aging, cancer, and hypoxia- and hypercapnia-related disorders, among many others. In the present commentary, we discuss progress made in understanding how NMRs overcome these challenges and speculate on the origins of their remarkable abilities.

Convergent evolution of a genomic rearrangement may explain cancer resistance in hystrico- and sciuromorpha rodents

The rodents of hystricomorpha and sciuromorpha suborders exhibit remarkably lower incidence of cancer. The underlying genetic basis remains obscure. We report a convergent evolutionary split of human 3p21.31, a locus hosting a large number of tumour-suppressor genes (TSGs) and frequently deleted in several tumour types, in hystrico- and sciuromorphs. Analysis of 34 vertebrate genomes revealed that the synteny of 3p21.31 cluster is functionally and evolutionarily constrained in most placental mammals, but exhibit large genomic interruptions independently in hystricomorphs and sciuromorphs, owing to relaxation of underlying constraints. Hystrico- and sciuromorphs, therefore, escape from pro-tumorigenic co-deletion of several TSGs in cis. The split 3p21.31 sub-clusters gained proximity to proto-oncogene clusters from elsewhere, which might further nullify pro-tumorigenic impact of copy number variations due to co-deletion or co-amplification of genes with opposing effects. The split of 3p21.31 locus coincided with the accelerated rate of its gene expression and the body mass evolution of ancestral hystrico- and sciuromorphs. The genes near breakpoints were associated with the traits specific to hystrico- and sciuromorphs, implying adaptive significance. We conclude that the convergently evolved chromosomal interruptions of evolutionarily constrained 3p21.31 cluster might have impacted evolution of cancer resistance, body mass variation and ecological adaptations in hystrico- and sciuromorphs.

Insights into the Molecular Basis of Genome Stability and Pristine Proteostasis in Naked Mole-Rats

The naked mole-rat (Heterocephalus glaber) is the longest-lived rodent, with a maximal reported lifespan of 37 years. In addition to its long lifespan - which is much greater than predicted based on its small body size (longevity quotient of ~4.2) - naked mole-rats are also remarkably healthy well into old age. This is reflected in a striking resistance to tumorigenesis and minimal declines in cardiovascular, neurological and reproductive function in older animals. Over the past two decades, researchers have been investigating the molecular mechanisms regulating the extended life- and health- span of this animal, and since the sequencing and assembly of the naked mole-rat genome in 2011, progress has been rapid. Here, we summarize findings from published studies exploring the unique molecular biology of the naked mole-rat, with a focus on mechanisms and pathways contributing to genome stability and maintenance of proteostasis during aging. We also present new data from our laboratory relevant to the topic and discuss our findings in the context of the published literature.

The Changes in the p53 Protein across the Animal Kingdom Point to Its Involvement in Longevity

Recently, the quest for the mythical fountain of youth has produced extensive research programs that aim to extend the healthy lifespan of humans. Despite advances in our understanding of the aging process, the surprisingly extended lifespan and cancer resistance of some animal species remain unexplained. The p53 protein plays a crucial role in tumor suppression, tissue homeostasis, and aging. Long-lived, cancer-free African elephants have 20 copies of the TP53 gene, including 19 retrogenes (38 alleles), which are partially active, whereas humans possess only one copy of TP53 and have an estimated cancer mortality rate of 11–25%. The mechanism through which p53 contributes to the resolution of the Peto’s paradox in Animalia remains vague. Thus, in this work, we took advantage of the available datasets and inspected the p53 amino acid sequence of phylogenetically related organisms that show variations in their lifespans. We discovered new correlations between specific amino acid deviations in p53 and the lifespans across different animal species. We found that species with extended lifespans have certain characteristic amino acid substitutions in the p53 DNA-binding domain that alter its function, as depicted from the Phenotypic Annotation of p53 Mutations, using the PROVEAN tool or SWISS-MODEL workflow. In addition, the loop 2 region of the human p53 DNA-binding domain was identified as the longest region that was associated with longevity. The 3D model revealed variations in the loop 2 structure in long-lived species when compared with human p53. Our findings show a direct association between specific amino acid residues in p53 protein, changes in p53 functionality, and the extended animal lifespan, and further highlight the importance of p53 protein in aging.

DNA Homeostasis and Senescence: Lessons from the Naked Mole Rat

As we age, our bodies accrue damage in the form of DNA mutations. These mutations lead to the generation of sub-optimal proteins, resulting in inadequate cellular homeostasis and senescence. The build-up of senescent cells negatively affects the local cellular micro-environment and drives ageing associated disease, including neurodegeneration. Therefore, limiting the accumulation of DNA damage is essential for healthy neuronal populations. The naked mole rats (NMR) are from eastern Africa and can live for over three decades in chronically hypoxic environments. Despite their long lifespan, NMRs show little to no biological decline, neurodegeneration, or senescence. Here, we discuss molecular pathways and adaptations that NMRs employ to maintain genome integrity and combat the physiological and pathological decline in organismal function.

A biomimetic natural sciences approach to understanding the mechanisms of ageing in burden of lifestyle diseases

The worldwide landscape of an ageing population and age-related disease brings with it huge socio-economic and public healthcare concerns across nations. Correspondingly, monumental human and financial resources have been invested in biomedical research, with a mission to decode the mechanisms of ageing and how these contribute to age-related disease. Multiple hallmarks of ageing have been identified that are common across taxa, highlighting their fundamental importance. These include dysregulated mitochondrial metabolism and telomeres biology, epigenetic modifications, cell-matrix interactions, proteostasis, dysregulated nutrient sensing, stem cell exhaustion, inflammageing and immuno-senescence. While our understanding of the molecular basis of ageing is improving, it remains a complex and multifactorial process that remains to be fully understood. A key aspect of the shortfall in our understanding of the ageing process lies in translating data from standard animal models to humans. Consequently, we suggest that a 'biomimetic' and comparative approach, integrating knowledge from species in the wild, as opposed to inbred genetically homogenous laboratory animals, can provide powerful insights into human ageing processes. Here we discuss some particularities and comparative patterns among several species from the animal kingdom, endowed with longevity or short lifespans and unique metabolic profiles that could be potentially exploited to the understanding of ageing and age-related diseases. Based upon lessons from nature, we also highlight several avenues for renewed focus in the pathophysiology of ageing and age-related disease (i.e. diet-microbiome-health axis, oxidative protein damage, adaptive homoeostasis and planetary health). We propose that a biomimetic alliance with collaborative research from different disciplines can improve our understanding of ageing and age-related diseases with long-term sustainable utility.

What Animal Cancers teach us about Human Biology

Cancers in animals present a large, underutilized reservoir of biomedical information with critical implication for human oncology and medicine in general. Discussing two distinct areas of tumour biology in non-human hosts, we highlight the importance of these findings for our current understanding of cancer, before proposing a coordinated strategy to harvest biomedical information from non-human resources and translate it into a clinical setting. First, infectious cancers that can be transmitted as allografts between individual hosts, have been identified in four distinct, unrelated groups, dogs, Tasmanian devils, Syrian hamsters and, surprisingly, marine bivalves. These malignancies might hold the key to improving our understanding of the interaction between tumour cell and immune system and, thus, allow us to devise novel treatment strategies that enhance anti-cancer immunosurveillance, as well as suggesting more effective organ and stem cell transplantation strategies. The existence of these malignancies also highlights the need for increased scrutiny when considering the existence of infectious cancers in humans. Second, it has long been understood that no linear relationship exists between the number of cells within an organism and the cancer incidence rate. To resolve what is known as Peto's Paradox, additional anticancer strategies within different species have to be postulated. These naturally occurring idiosyncrasies to avoid carcinogenesis represent novel potential therapeutic strategies.

Some Exciting Future Directions for Work on Naked Mole-Rats

The naked mole-rat is a species of growing research interest. Recent focus on this species from both a biomedical and zoological perspective has led to important discoveries regarding eusociality and ecophysiological and sensory traits associated with life below ground as well as natural protection from variable oxygen availability, acid-induced pain, and the vagaries of aging. These features serve to remind us that many foundational discoveries have arisen using extremophilic organisms and elucidating the mechanisms they employ to survive the harsh environmental conditions they encounter. Investigating these evolved features also facilitates a better understanding of several human disease states that share features with this harsh subterranean milieu. Here, we provide an overview of some unanswered questions and future directions to advance this field, alongside discussion of the tools that could facilitate accelerated progression of research using this enigmatic model.

Naked Mole-Rats: Resistant to Developing Cancer or Good at Avoiding It?

It is widely accepted that cancer is driven by genetic mutations that confer uncontrolled cell proliferation and tumor formation. For tumors to take hold and grow, cancer cells evolve mechanisms to favorably shape their microenvironment and avoid being cleared by the immune system. Cancer is not unique to human, but rather affects nearly all multicellular organisms albeit to different degrees. The different degrees of cancer susceptibility across the animal kingdom could be attributed to several factors, which have been the subject of several studies in recent years. The naked mole-rat (NMR, Heterocephalus glaber), an exceptionally long-lived rodent, which, as discussed in detail in the next section, displays significant cancer resistance with only a small number of animals being reported to exhibit spontaneous neoplasms. The reason why studying cancer resistance in NMRs is of particular interest is that not only are they now an established laboratory species, but that NMRs are mammals and thus there is great potential for translating knowledge about their cancer resistance into preventing and/or treating cancer in humans and companion animals.

The use of non-traditional models in the study of cancer resistance-the case of the naked mole rat

Non-traditional model organisms are typically defined as any model the deviates from the typical laboratory animals, such as mouse, rat, and worm. These models are becoming increasingly important in human disease research, such as cancer, as they often display unusual biological features. Naked mole rats (NMRs) are currently one of the most popular non-traditional model, particularly in the longevity and cancer research fields. NMRs display an exceptionally long lifespan (~30 years), yet have been observed to display a low incidence of cancer, making them excellent candidates for understanding endogenous cancer resistance mechanisms. Over the past decade, many potential resistance mechanisms have been characterized. These include unique biological mechanisms involved in genome stability, protein stability, oxidative metabolism, and other cellular mechanisms such as cell cycle regulation and senescence. This review aims to summarize the many identified cancer resistance mechanisms to understand some of the main hypotheses that have thus far been generated. Many of these proposed mechanisms remain to be fully characterized or confirmed in vivo, giving the field a direction to grow and further understand the complex biology displayed by the NMR.