Molecular evolution of antioxidant and hypoxia response in long-lived, cancer-resistant blind mole rats: The Nrf2–Keap1 pathway

Adaptation of the Spalax galili transcriptome to hypoxia may underlie the complex phenotype featuring longevity and cancer resistance

In the subterranean rodent (Nanno)spalax galili, evolutionary adaptation to hypoxia is correlated with longevity and tumor resistance. Adapted gene-regulatory networks of Spalax might pinpoint strategies to maintain health in humans. Comparing liver, kidney and spleen transcriptome data from Spalax and rat at hypoxia and normoxia, we identified differentially expressed gene pathways common to multiple organs in both species. Body-wide interspecies differences affected processes like cell death, antioxidant defense, DNA repair, energy metabolism, immune response and angiogenesis, which may play a crucial role in Spalax's adaptation to environmental hypoxia. In all organs, transcription of genes for genome stability maintenance and DNA repair was elevated in Spalax versus rat, accompanied by lower expression of aerobic energy metabolism and proinflammatory genes. These transcriptomic changes might account for the extraordinary lifespan of Spalax and its cancer resistance. The identified gene networks present candidates for further investigating the molecular basis underlying the complex Spalax phenotype.

Fructose-Driven glycolysis supports synaptic function in subterranean rodent - Gansu Zokor (Eospalax cansus)

Several studies indicate that fructose can be used as an energy source for subterranean rodents. However, how subterranean rodents utilize fructose metabolism with no apparent physiological drawbacks remains poorly understood. In the present study, we measured field excitatory postsynaptic potentials (fEPSPs) in hippocampal slices from Gansu zokor and SD rats hippocampi before and 60 min after replacement of 10 mM glucose in the artificial cerebrospinal fluid (ACSF) with 10 mM fructose (gassed with 95 % O2 and 5 % CO2). Subsequently, we performed transcriptome analysis on Gansu zokor brains incubated with ACSF containing 10 mM fructose and determined the contents of fructose, lactate, ATP, and UA. Whole brain RNA and proteins were extracted to detect the transcriptional levels of Glut5, Khk, Aldoc, and Cs and the translational levels of GLUT5, CS, NRF2, and c-FOS. The results showed that Gansu zokor brains exhibit higher levels of GLUT5 protein and Khk mRNA levels than SD rats to facilitate fructose uptake and metabolism, resulting in increased fructose, ATP, and lactate content in the brain during fructose incubation. Stable UA levels during fructose metabolism reduce the risk of oxidative stress and neuroinflammation, and activation of the Nrf2 pathway increases downstream antioxidant capacity, thereby reducing brain damage. Persistent fEPSP signaling suggests that fructose supports excitatory synaptic transmission in the CA1 region of the hippocampus of the Gansu zokor but leads to hippocampal dysfunction in SD rats. The unique insights about fructose metabolism in the brain of Gansu zokor obtained in our study will be useful for further studies on the evolution of subterranean rodents.

Ameliorative inhibition of sirtuin 6 by imidazole derivative triggers oxidative stress-mediated apoptosis associated with Nrf2/Keap1 signaling in non-small cell lung cancer cell lines

Background: Redox homeostasis is the vital regulatory system with respect to antioxidative response and detoxification. The imbalance of redox homeostasis causes oxidative stress. Nuclear factor-erythroid 2 p45-related factor 2 (Nrf2, also called Nfe2l2)/Kelchlike ECH-associated protein 1 (Keap1) signaling is the major regulator of redox homeostasis. Nrf2/Keap1 signaling is reported to be involved in cancer cell growth and survival. A high level of Nrf2 in cancers is associated with poor prognosis, resistance to therapeutics, and rapid proliferation, framing Nrf2 as an interesting target in cancer biology. Sirtuins (SIRT1-7) are class III histone deacetylases with NAD + dependent deacetylase activity that have a remarkable impact on antioxidant and redox signaling (ARS) linked with Nrf2 deacetylation thereby increasing its transcription by epigenetic modifications which has been identified as a crucial event in cancer progression under the influence of oxidative stress in various transformed cells. SIRT6 plays an important role in the cytoprotective effect of multiple diseases, including cancer. This study aimed to inhibit SIRT6 using an imidazole derivative, Ethyl 2-[5-(4-chlorophenyl)-2-methyl-1-H-Imidazole-4-yl] acetate, to assess its impact on Nrf2/Keap1 signaling in A549 and NCI-H460 cell lines. Method: Half maximal inhibitory concentration (IC50) of Ethyl 2-[5-(4-chlorophenyl)-2-methyl-1-H-Imidazole-4-yl] acetate was fixed by cell viability assay. The changes in the gene expression of important regulators involved in this study were examined using quantitative real-time PCR (qRT-PCR) and protein expression changes were confirmed by Western blotting. The changes in the antioxidant molecules are determined by biochemical assays. Further, morphological studies were performed to observe the generation of reactive oxygen species, mitochondrial damage, and apoptosis. Results: We inhibited SIRT6 using Ethyl 2-[5-(4-chlorophenyl)-2-methyl-1-H-Imidazole-4-yl] acetate and demonstrated that SIRT6 inhibition impacts the modulation of antioxidant and redox signaling. The level of antioxidant enzymes and percentage of reactive oxygen species scavenging activity were depleted. The morphological studies showed ROS generation, mitochondrial damage, nuclear damage, and apoptosis. The molecular examination of apoptotic factors confirmed apoptotic cell death. Further, molecular studies confirmed the changes in Nrf2 and Keap1 expression during SIRT6 inhibition. Conclusion: The overall study suggests that SIRT6 inhibition by imidazole derivative disrupts Nrf2/Keap1 signaling leading to oxidative stress and apoptosis induction.

Regulation of CncC in insecticide-induced expression of cytochrome P450 CYP9A14 and CYP6AE11 in Helicoverpa armigera

The expression of many detoxification genes can be regulated by CncC pathway and contributes to insecticide tolerance in insects. Our previous study has demonstrated that the transcripts of CncC and cytochrome P450s (CYP9A14, CYP6AE11) were significantly up-regulated after different insecticides treatment in Helicoverpa armigera. Further study indicated that H2O2, GSH, and MDA contents and antioxidant enzyme activities of H. armigera were enhanced after chlorantraniliprole, cyantraniliprole, indoxacarb, and spinosad exposure. Silencing CncC by RNA interference significantly down-regulated the expression levels of CYP9A14 and CYP6AE11, and increased the susceptibility of dsRNA-injected larvae to λ-cyhalothrin, chlorantraniliprole, and cyantraniliprole. On the contrary, applying CncC agonist curcumin on H. armigera induced the expression of CYP9A14 and CYP6AE11, and enhanced the tolerance of H. armigera to insecticides. Treatment of ROS scavenger N-acetylcysteine on H. armigera reduced the H2O2 content and antioxidant enzyme activities, suppressed the transcripts of CncC, CYP9A14, and CYP6AE11, and decreased the larval tolerance to insecticides. These results demonstrated that the induced-expression of CYP9A14 and CYP6AE11 related with insecticides tolerance in H. armigera was regulated by CncC, which may be activated by ROS generated by insecticides. This study will help to better understand the underlying regulation mechanisms of CncC pathway in H. armigera tolerance to insecticides.

Effects of different insecticides on transcripts of key genes in CncC pathway and detoxification genes in Helicoverpa armigera

The CncC pathway regulates the expression of multiple detoxification genes and contributes to the detoxification and antioxidation in insects. Many studies have focused on the impacts of plant allelochemicals on the CncC pathway, whereas studies on the effects of pesticides on key genes involved in this pathway are very limited. In this study, the effects of different types of commonly used insecticides on the transcripts of CncC, Keap1, and Maf and multiple detoxification genes of Helicoverpa armigera were evaluated using real-time quantitative polymerase chain reaction. The results showed that 8 insecticides (bifenthrin, λ-cyhalothrin, chlorantraniliprole, cyantraniliprole, spinosad, indoxacarb, chlorfenapyr, tolfenpyrad, and thiacloprid) significantly induced the expression of CncC and 4 insecticides (cypermethrin, acetamiprid, thiacloprid, and indoxacarb) suppressed the expression of Keap1 both at 24 h and 48 h; meanwhile, the expression levels of Maf were induced by 5 insecticides (fenvalerate, chlorantraniliprole, cyantraniliprole, lufenuron, and tolfenpyrad) at 24 h or 48 h. Multiple detoxification genes, especially cytochrome P450s genes, showed different up-regulation after bifenthrin, λ-cyhalothrin, chlorantraniliprole, cyantraniliprole, indoxacarb, and spinosad treatment for 48 h. Our results suggest that the CncC pathway and detoxification genes can be activated by different insecticides in H. armigera. These results establish a foundation for further studies on the relationship between the CncC pathway and the detoxification genes in H. armigera.

Regulation of Cell Proliferation and Nrf2-Mediated Antioxidant Defense: Conservation of Keap1 Cysteines and Nrf2 Binding Site in the Context of the Evolution of KLHL Family

Keap1 (Kelch-like ECH-associated protein 1) is one of the major negative regulators of the transcription factor Nrf2 (nuclear factor erythroid-2-related factor 2), which induces the expression of numerous proteins defending the cell against different stress conditions. Keap1 is generally negatively regulated by post-translational modification (mostly via its cysteine residues) and interaction with other proteins that compete with Nrf2 for binding. Cysteine residues in Keap1 have different effects on protein regulation, as basic residues (Lys, Arg, and His) in close proximity to them increase cysteine modification potential. In this paper, we present an evolutionary analysis of residues involved in both mechanisms of Keap1 regulation in the broader context of the KLHL protein family in vertebrates. We identified the typical domain structure of the KLHL protein family in several proteins outside of this family (namely in KBTBD proteins 2, 3, 4, 6, 7, 8, 12 and 14). We found several cysteines that are flanked by basic residues (namely, C14, C38, C151, C226, C241, C273, C288, C297, C319, and C613) and, therefore, may be considered more susceptible to regulatory modification. The Nrf2 binding site is completely conserved in Keap1 in vertebrates but is absent or located in nonaligned DA and BC loops of the Kelch domain within the KLHL family. The development of specific substrate binding regions could be an evolutionary factor of diversification in the KLHL protein family.

Cryptic Diversity of the European Blind Mole Rat Nannospalax leucodon Species Complex: Implications for Conservation

We explored the cryptic speciation of the Nannospalax leucodon species complex, characterised by intense karyotype evolution and reduced phenotypic variability that has produced different lineages, out of which 25 are described as chromosomal forms (CFs), so many cryptic species remain unnoticed. Although some of them should be classified as threatened, they lack the official nomenclature necessary to be involved in conservation strategies. Reproductive isolation between seven CFs has previously been demonstrated. To investigate the amount and dynamics of genetic discrepancy that follows chromosomal changes, infer speciation levels, and obtain phylogenetic patterns, we analysed mitochondrial 16S rRNA and MT-CYTB nucleotide polymorphism among 17 CFs—the highest number studied so far. Phylogenetic trees delineated 11 CFs as separate clades. Evolutionary divergence values overlapped with acknowledged higher taxonomic categories, or sometimes exceeded them. The fact that CFs with higher 2n are evolutionary older corresponds to the fusion hypothesis of Nannospalax karyotype evolution. To participate in conservation strategies, N. leucodon classification should follow the biological species concept, and proposed cryptic species should be formally named, despite a lack of classical morphometric discrepancy. We draw attention towards the syrmiensis and montanosyrmiensis CFs, estimated to be endangered/critically endangered, and emphasise the need for detailed monitoring and population survey for other cryptic species.

Bioinspiration as a method of problem-based STEM education: A case study with a class structured around the COVID-19 crisis

Bioinspiration is a promising lens for biology instruction as it allows the instructor to focus on current issues, such as the COVID-19 pandemic. From social distancing to oxygen stress, organisms have been tackling pandemic-related problems for millions of years. What can we learn from such diverse adaptations in our own applications? This review uses a seminar course on the COVID-19 crisis to illustrate bioinspiration as an approach to teaching biology content. At the start of the class, students mind-mapped the entire problem; this range of subproblems was used to structure the biology content throughout the entire class. Students came to individual classes with a brainstormed list of biological systems that could serve as inspiration for a particular problem (e.g., absorptive leaves in response to the problem of toilet paper shortages). After exploration of relevant biology content, discussion returned to the focal problem. Students dug deeper into the literature in a group project on mask design and biological systems relevant to filtration and transparency. This class structure was an engaging way for students to learn principles from ecology, evolution, behavior, and physiology. Challenges with this course design revolved around the interdisciplinary and creative nature of the structure; for instance, the knowledge of the participants was often stretched by engineering details. While the present class was focused on the COVID-19 crisis, a course structured through a bioinspired approach can be applied to other focal problems, or subject areas, giving instructors a powerful method to deliver interdisciplinary content in an integrated and inquiry-driven way.

Antioxidant response to severe hypoxia in Brandt's vole Lasiopodomys brandtii

The antioxidant defense system is essential for animals to cope with homeostasis disruption and overcome oxidative stress caused by adverse environmental conditions such as hypoxia. However, our understanding of how this system works in subterranean rodents remains limited. In this study, Brandt's vole Lasiopodomys brandtii was exposed to normoxia (21% O₂ ) or hypoxia (mild or severe hypoxia: 10% or 5% O₂ ) for 6 h. Changes in key enzymes of the classic enzymatic antioxidant system at both mRNA and enzyme activity levels, and tissue antioxidant levels of the low-molecular-weight antioxidant system were determined in brain, liver, and kidney. Transcript levels of the upstream regulator NF-E2-related factor 2 (Nrf2) were also measured. We found that the mRNA expression of Nrf2 and its downstream antioxidant enzyme genes in L. brandtii were relatively conserved in response to hypoxia in most tissues and genes tested, except in the liver. Hepatic Nrf2, Cu/Zn SOD, GPx1, and GPx3 levels were significantly upregulated in response to mild hypoxia, whereas Mn SOD level decreased significantly in severe hypoxia. Unmatched with changes at the RNA level, constitutively high and relatively stable antioxidant enzyme activities were maintained throughout. For the low-molecular-weight antioxidant system, an abrupt increase of cerebral ascorbic acid (AA) levels in hypoxia indicated a tissue-specific antioxidant response. Although hypoxia did not cause significant oxidative damage in most tissues tested, the significant decrease in antioxidant enzyme activities (GPX and GR) and increase in lipid peroxidation in the kidney suggest that prolonged hypoxia may pose a critical threat to this species.

Antioxidant defense response during hibernation and arousal in Chinese soft-shelled turtle Pelodiscus sinensis juveniles

Antioxidant defense is essential for animals to cope with homeostasis disruption during hibernation. The present study aimed to investigate the antioxidant defense response of juvenile soft-shelled turtle Pelodiscus sinensis during hibernation and following arousal. Turtle brain, liver, and kidney samples were collected at pre-hibernation (17 °C mud temperature; MT), during hibernation (5.8 °C MT) and after arousal (20.1 °C MT) in the field. Transcript levels of NF-E2-related factor 2 (Nrf2) decreased significantly during hibernation and recovered after arousal in all tissues. Cerebral and nephric copper-zinc superoxide dismutase (Cu/Zn SOD), catalase (CAT), glutathione peroxidase 3 (GPx3) and nephric GPx4 mRNA showed similar changing patterns as Nrf2. Cerebral Mn SOD, GPx1 and nephric GPx1 up-regulated after arousal. Hepatic Cu/Zn SOD, GPx1 and GPx3 mRNA kept stable, except hepatic GPx4 increased during hibernation. Hepatic Mn SOD and CAT increased after arousal. In the GSH system, mRNA levels of glutathione synthetases (GSs) kept stable during hibernation and up-regulated after arousal in most tissues except nephric GS2 mRNA remained unchanged. Gene expressions of glutathione reductase (GR) exhibited a tissue specific changing pattern, while those of glutathione-S-Transferase (GST) shared a similar pattern among tissues: remained stable or down-regulated during hibernation then recovered in arousal. In contrast to these diverse responses in gene expressions, most of the antioxidant enzyme activities maintained high and stable. Overall, no preparation for oxidative stress (POS) strategy was found in enzymatic antioxidant system in P. sinensis juveniles during hibernation, the Chinese soft-shelled turtles were able to stay safe from potential oxidative stress during hibernation by maintaining high level activities/concentrations of the antioxidant enzymes/antioxidants.

Evaluation of the role of Nrf2/Keap1 pathway-associated novel mutations and gene expression on antioxidant status in patients with deep vein thrombosis

Deep vein thrombosis (DVT) is a type of venous thromboembolism and a clinically complex vascular disease. Oxidative stress serves a key role in the pathogenesis of numerous cardiovascular diseases, particularly in endothelial dysfunction-associated syndromes. Nuclear factor erythroid-2-like 2(Nrf2) transcription factor is the primary regulator of antioxidant responses. The levels of reactive oxygen species (ROS) are regulated by Nrf2 and its suppressor protein Kelch-like ECH-associated protein 1 (Keap1). However, to the best of our knowledge, genetic abnormalites in the Nrf2/Keap1 pathway in DVT syndrome have not been thoroughly investigated. The aim of the present study was to investigate the association between the Nrf2/Keap1 pathway and antioxidant responses in DVT. Mutations and expression levels of genes involved in the Nrf2/Keap1 pathway were measured in 27 patients with DVT via DNA sequencing analysis and reverse transcription-quantitative PCR, respectively. The Polymorphism Phenotyping v2 program was used to identify the pathogenic mutations. Total antioxidant activity levels were determined by measuring the effect of serum samples from 27 patients with DVT on oxidation of the 2,2'-azino-bis (3-ethylbenz-thiazoline-6-sulfonic acid) system. A total of 23 mutations, including seven novel mutations, were detected in the Nrf2/Keap1 pathway in 24 (89%) of the 27 patients with DVT. Keap1 mRNA expression levels were significantly higher compared with Nrf2 expression levels in patients with DVT (P=0.02). Analysis of molecular characteristics and gene expression levels demonstrated that Nrf2/Keap1-associated mutations and total antioxidant levels can be used as precursor markers in the diagnosis of DVT.

The brains of six African mole-rat species show divergent responses to hypoxia

Mole-rats are champions of self-preservation, with increased longevity compared with other rodents their size, strong antioxidant capabilities and specialized defenses against endogenous oxidative stress. However, how the brains of these subterranean mammals handle acute in vivo hypoxia is poorly understood. This study is the first to examine the molecular response to low oxygen in six different species of hypoxia-tolerant mole-rats from sub-Saharan Africa. Protein carbonylation, a known marker of DNA damage (hydroxy-2'-deoxyguanosine), and antioxidant capacity did not change following hypoxia but HIF-1 protein levels increased significantly in the brains of two species. Nearly 30 miRNAs known to play roles in hypoxia tolerance were differentially regulated in a species-specific manner. The miRNAs exhibiting the strongest response to low oxygen stress inhibit apoptosis and regulate neuroinflammation, likely providing neuroprotection. A principal component analysis (PCA) using a subset of the molecular targets assessed herein revealed differences between control and hypoxic groups for two solitary species (Georychus capensis and Bathyergus suillus), which are ecologically adapted to a normoxic environment, suggesting a heightened sensitivity to hypoxia relative to species that may experience hypoxia more regularly in nature. By contrast, all molecular data were included in the PCA to detect a difference between control and hypoxic populations of eusocial Heterocephalus glaber, indicating they may require many lower-fold changes in signaling pathways to adapt to low oxygen settings. Finally, none of the Cryptomys hottentotus subspecies showed a statistical difference between control and hypoxic groups, presumably due to hypoxia tolerance derived from environmental pressures associated with a subterranean and social lifestyle.

Oxidative stress-induced alterations in seminal plasma antioxidants: Is there any association with keap1 gene methylation in human spermatozoa?

Kelch-like ECH-associated protein 1 (keap1)-nuclear factor-erythroid 2-related factor 2 (Nrf2) pathway is one of the master regulators of cellular defence against oxidative stress. Epigenetic alterations like hypermethylation of keap1 gene impair keap1-Nrf2 system in several oxidative stress-associated diseases. The objective of this study was to evaluate the epigenetic status of keap1 in sperm DNA of normozoospermic subjects, having different levels of reactive oxygen species (ROS) in seminal plasma. Semen samples were obtained from 151 apparently healthy male partners of couples who attended the Avicenna infertility clinic. Samples were categorised into four groups according to their ROS levels: group A (n = 39, ROS < 20 RLU/s per 10⁶ spermatozoa), group B (n = 38, 20 ≤ ROS < 40 RLU/s per 10⁶ spermatozoa), group C (n = 31, 40 ≤ ROS < 60 RLU/s per 10⁶ spermatozoa) and group D; (n = 43, ROS ≥ 60 RLU/s per 10⁶ spermatozoa). Keap1 methylation status was assessed using methylation-specific PCR along with seminal total antioxidant capacity. The results showed no significant alterations in keap1 methylation in any groups, whereas the total antioxidant capacity enhanced with increasing levels of ROS exposure. These results indicate that keap1 was not methylated during ROS elevation and oxidative stress, suggesting that the cells have adopted other mechanisms to elevate antioxidant level.

The double benefit of Spalax p53: surviving underground hypoxia while defying lung cancer cells in vitro via autophagy and caspase-dependent cell death

The blind subterranean mole rat, Spalax ehrenbergi, is a model organism for hypoxia tolerance. This superspecies have adapted to severe environment by altering an array of hypoxia-mediated genes, among which an alteration in the p53 DNA binding domain (corresponding to R174K in humans) that hinders its transcriptional activity towards apoptotic genes. It is well accepted that apoptosis is not the only form of programmed cell death and that mechanisms that depend on autophagy are also involved. In the current work we have extended our research and investigated the possibility that Spalax p53 can activate autophagy. Using two complementary assays, we have established that over-expression of the Spalax p53 in p53-null cells (human lung cancer cells, H1299), potently induces autophagy. As Spalax is considered highly resistant to cancer, we further studied the relative contribution of autophagy on the outcome of H1299 cells, following transfection with Spalax p53. Results indicate that Spalax p53 acts as a tumor suppressor in lung cancer cells, inducing cell death that involves autophagy and caspases and inhibiting cell number, which is exclusively caspase-dependent. To conclude, the Spalax p53 protein was evolutionary adapted to survive severe underground hypoxia while retaining the ability to defy lung cancer.

Turning natural adaptations to oncogenic factors into an ally in the war against cancer

Both field and experimental evolution studies have demonstrated that organisms naturally or artificially exposed to environmental oncogenic factors can, sometimes rapidly, evolve specific adaptations to cope with pollutants and their adverse effects on fitness. Although numerous pollutants are mutagenic and carcinogenic, little attention has been given to exploring the extent to which adaptations displayed by organisms living in oncogenic environments could inspire novel cancer treatments, through mimicking the processes allowing these organisms to prevent or limit malignant progression. Building on a substantial knowledge base from the literature, we here present and discuss this progressive and promising research direction, advocating closer collaboration between the fields of medicine, ecology, and evolution in the war against cancer.

Hypoxia tolerance, longevity and cancer-resistance in the mole rat Spalax - a liver transcriptomics approach

The blind subterranean mole rat Spalax shows a remarkable tolerance to hypoxia, cancer-resistance and longevity. Unravelling the genomic basis of these adaptations will be important for biomedical applications. RNA-Seq gene expression data were obtained from normoxic and hypoxic Spalax and rat liver tissue. Hypoxic Spalax broadly downregulates genes from major liver function pathways. This energy-saving response is likely a crucial adaptation to low oxygen levels. In contrast, the hypoxia-sensitive rat shows massive upregulation of energy metabolism genes. Candidate genes with plausible connections to the mole rat’s phenotype, such as important key genes related to hypoxia-tolerance, DNA damage repair, tumourigenesis and ageing, are substantially higher expressed in Spalax than in rat. Comparative liver transcriptomics highlights the importance of molecular adaptations at the gene regulatory level in Spalax and pinpoints a variety of starting points for subsequent functional studies.

Exceptional Chromosomal Evolution and Cryptic Speciation of Blind Mole Rats Nannospalax leucodon (Spalacinae, Rodentia) from South-Eastern Europe

Mole rats are exclusively subterranean and highly specialized rodents. Their long lifespans, remarkable anti-cancer mechanisms, and various distinctive adaptive features make them a useful research model. Moreover, opposing convergence of morphological traits, they have developed extremely high karyotype variability. Thus, 74 chromosomal forms have been described so far and new ones are being revealed continuously. These evolved during the process of rapid radiation and occur in different biogeographical regions. During research into their reproductive biology we have already provided substantial evidence for species-level separation of these taxa. Here, we review diverse chromosomal forms of the lesser blind mole rat, Mediterranean Nannospalax leucodon, distributed in South-eastern Europe, their karyotype records, biogeography, origin, and phylogeny from our extensive research. In the light of new data from molecular genetic studies, we question some former valuations and propose a cryptospecies rank for seven reproductively isolated chromosomal forms with sympatric and parapatric distribution and clear ecogeographical discrepances in their habitats, as well as new experimental and theoretical methods for understanding the courses of speciation of these unique fossorial mammals.

Molecular signatures of longevity: Insights from cross-species comparative studies

Much of the current research on longevity focuses on the aging process within a single species. Several molecular players (e.g. IGF1 and MTOR), pharmacological compounds (e.g. rapamycin and metformin), and dietary approaches (e.g. calorie restriction and methionine restriction) have been shown to be important in regulating and modestly extending lifespan in model organisms. On the other hand, natural lifespan varies much more significantly across species. Within mammals alone, maximum lifespan differs more than 100 fold, but the underlying regulatory mechanisms remain poorly understood. Recent comparative studies are beginning to shed light on the molecular signatures associated with exceptional longevity. These include genome sequencing of microbats, naked mole rat, blind mole rat, bowhead whale and African turquoise killifish, and comparative analyses of gene expression, metabolites, lipids and ions across multiple mammalian species. Together, they point towards several putative strategies for lifespan regulation and cancer resistance, as well as the pathways and metabolites associated with longevity variation. In particular, longevity may be achieved by both lineage-specific adaptations and common mechanisms that apply across the species. Comparing the resulting cross-species molecular signatures with the within-species lifespan extension strategies will improve our understanding of mechanisms of longevity control and provide a starting point for novel and effective interventions.

AMPK and HIF signaling pathways regulate both longevity and cancer growth: the good news and the bad news about survival mechanisms

The AMP-activated protein kinase (AMPK) and hypoxia-inducible factor (HIF) signaling pathways are evolutionarily-conserved survival mechanisms responding to two fundamental stresses, energy deficiency and/or oxygen deprivation. The AMPK and HIF pathways regulate the function of a survival network with several transcription factors, e.g. FOXO, NF-κB, NRF2, and p53, as well as with protein kinases and other factors, such as mTOR, ULK1, HDAC5, and SIRT1. Given that AMPK and HIF activation can enhance not only healthspan and lifespan but also cancer growth in a context-dependent manner; it seems that cancer cells can hijack certain survival factors to maintain their growth in harsh conditions. AMPK activation improves energy metabolism, stimulates autophagy, and inhibits inflammation, whereas HIF-1α increases angiogenesis and helps cells to adapt to severe conditions. First we will review how AMPK and HIF signaling mechanisms control the function of an integrated survival network which is able not only to improve the regulation of longevity but also support the progression of tumorigenesis. We will also describe distinct crossroads between the regulation of longevity and cancer, e.g. specific regulation through the AMPKα and HIF-α isoforms, the Warburg effect, mitochondrial dynamics, and cellular senescence.