The transcriptional coactivator CBP/p300 is an evolutionarily conserved node that promotes longevity in response to mitochondrial stress

Mitochondria: fundamental characteristics, challenges, and impact on aging

As one of the most vital organelles within biological cells, mitochondria hold an irreplaceable status and play crucial roles in various diseases. Research and therapies targeting mitochondria have achieved significant progress in numerous conditions. Throughout an organism's lifespan, mitochondrial dynamics persist continuously, and due to their inherent characteristics and various external factors, mitochondria are highly susceptible to damage. This susceptibility is particularly evident during aging, where the decline in biological function is closely intertwined with mitochondrial dysfunction. Despite being an ancient and enigmatic organelle, much remains unknown about mitochondria. Here, we will explore the past and present knowledge of mitochondria, providing a comprehensive review of their intrinsic properties and interactions with nuclear DNA, as well as the challenges and impacts they face during the aging process.

A mitochondrial unfolded protein response-independent role of DVE-1 in longevity regulation

The special AT-rich sequence-binding (SATB) protein DVE-1 is widely recognized for its pivotal involvement in orchestrating the retrograde mitochondrial unfolded protein response (mitoUPR) in C. elegans. In our study of downstream factors contributing to lifespan extension in sensory ciliary mutants, we find that DVE-1 is crucial for this longevity effect independent of its canonical mitoUPR function. Additionally, DVE-1 also influences lifespan under conditions of dietary restriction and germline loss, again distinct from its role in mitoUPR. Mechanistically, while mitochondrial stress typically prompts nuclear accumulation of DVE-1 to initiate the transcriptional mitoUPR program, these long-lived mutants reduce DVE-1 nuclear accumulation, likely by enhancing its cytosolic translocation. This observation suggests a cytosolic role for DVE-1 in lifespan extension. Overall, our study implies that, in contrast to the more narrowly defined role of the mitoUPR-related transcription factor ATFS-1, DVE-1 may possess broader functions than previously recognized in modulating longevity and defending against stress.

A bird's eye view of mitochondrial unfolded protein response in cancer: mechanisms, progression and further applications

Mitochondria are essential organelles that play critical roles in energy metabolism, apoptosis and various cellular processes. Accumulating evidence suggests that mitochondria are also involved in cancer development and progression. The mitochondrial unfolded protein response (UPRmt) is a complex cellular process that is activated when the protein-folding capacity of the mitochondria is overwhelmed. The core machinery of UPRmt includes upstream regulatory factors, mitochondrial chaperones and proteases. These components work together to eliminate misfolded proteins, increase protein-folding capacity, and restore mitochondrial function. Recent studies have shown that UPRmt is dysregulated in various cancers and contributes to tumor initiation, growth, metastasis, and therapeutic resistance. Considering the pivotal role of the UPRmt in oncogenesis, numerous compounds and synthetic drugs targeting UPRmt-related components induce cancer cell death and suppress tumor growth. In this review, we comprehensively summarize recent studies on the molecular mechanisms of UPRmt activation in C. elegans and mammals and elucidate the conceptual framework, functional aspects, and implications of the UPRmt for cancer therapy. In summary, we paint a developmental landscape of the UPRmt in different types of cancer and offer valuable insights for the development of novel cancer treatment strategies by targeting the UPRmt.

Exercise epigenetics is fueled by cell bioenergetics: Supporting role on brain plasticity and cognition

Exercise has the unique aptitude to benefit overall health of body and brain. Evidence indicates that the effects of exercise can be saved in the epigenome for considerable time to elevate the threshold for various diseases. The action of exercise on epigenetic regulation seems central to building an "epigenetic memory" to influence long-term brain function and behavior. As an intrinsic bioenergetic process, exercise engages the function of the mitochondria and redox pathways to impinge upon molecular mechanisms that regulate synaptic plasticity and learning and memory. We discuss how the action of exercise uses mechanisms of bioenergetics to support a "epigenetic memory" with long-term implications for neural and behavioral plasticity. This information is crucial for directing the power of exercise to reduce the burden of neurological and psychiatric disorders.

Gene networks governing the response of a calcareous sponge to future ocean conditions reveal lineage-specific XBP1 regulation of the unfolded protein response

Marine sponges are predicted to be winners in the future ocean due to their exemplary adaptive capacity. However, while many sponge groups exhibit tolerance to a wide range of environmental insults, calcifying sponges may be more susceptible to thermo-acidic stress. To describe the gene regulatory networks that govern the stress response of the calcareous sponge, Leucetta chagosensis (class Calcarea, order Clathrinida), individuals were subjected to warming and acidification conditions based on the climate models for 2100. Transcriptome analysis and gene co-expression network reconstruction revealed that the unfolded protein response (UPR) was activated under thermo-acidic stress. Among the upregulated genes were two lineage-specific homologs of X-box binding protein 1 (XBP1), a transcription factor that activates the UPR. Alternative dimerization between these XBP1 gene products suggests a clathrinid-specific mechanism to reversibly sequester the transcription factor into an inactive form, enabling the rapid regulation of pathways linked to the UPR in clathrinid calcareous sponges. Our findings support the idea that transcription factor duplication events may refine evolutionarily conserved molecular pathways and contribute to ecological success.

Reproductive regulation of the mitochondrial stress response in Caenorhabditis elegans

Proteome integrity is fundamental for cellular and organismal homeostasis. The mitochondrial unfolded protein response (UPRmt), a key component of the proteostasis network, is activated in a non-cell-autonomous manner in response to mitochondrial stress in distal tissues. However, the importance of inter-tissue communication for UPRmt inducibility under physiological conditions remains elusive. Here, we show that an intact germline is essential for robust UPRmt induction in the Caenorhabditis elegans somatic tissues. A series of nematode mutants with germline defects are unable to respond to genetic or chemical UPRmt inducers. Our genetic analysis suggests that reproductive signals, rather than germline stem cells, are responsible for somatic UPRmt induction. Consistent with this observation, we show that UPRmt is sexually dimorphic, as male nematodes are inherently unresponsive to mitochondrial stress. Our findings highlight a paradigm of germline-somatic communication and suggest that reproductive cessation is a primary cause of age-related UPRmt decline.

Mitochondrial clearance and increased HSF-1 activity are coupled to promote longevity in fasted Caenorhabditis elegans

Fasting has emerged as a potent means of preserving tissue function with age in multiple model organisms. However, our understanding of the relationship between food removal and long-term health is incomplete. Here, we demonstrate that in the nematode worm Caenorhabditis elegans, a single period of early-life fasting is sufficient to selectively enhance HSF-1 activity, maintain proteostasis capacity and promote longevity without compromising fecundity. These effects persist even when food is returned, and are dependent on the mitochondrial sirtuin, SIR-2.2 and the H3K27me3 demethylase, JMJD-3.1. We find that increased HSF-1 activity upon fasting is associated with elevated SIR-2.2 levels, decreased mitochondrial copy number and reduced H3K27me3 levels at the promoters of HSF-1 target genes. Furthermore, consistent with our findings in worms, HSF-1 activity is also enhanced in muscle tissue from fasted mice, suggesting that the potentiation of HSF-1 is a conserved response to food withdrawal.

Mitochondrial unfolded protein response (UPRmt): what we know thus far

Mitochondria are key organelles for the optimal function of the cell. Among their many functions, they maintain protein homeostasis through their own proteostatic machinery, which involves proteases and chaperones that regulate protein import and folding inside mitochondria. In the early 2000s, the mitochondrial unfolded protein response (UPRmt) was first described in mammalian cells. This stress response is activated by the accumulation of unfolded/misfolded proteins within the mitochondrial matrix, which results in the transmission of a signal to the nucleus to increase the expression of proteases and chaperones to address the abnormal mitochondrial protein load. After its discovery, this retrograde signaling pathway has also been described in other organisms of different complexities, suggesting that it is a conserved stress response. Although there are some specific differences among organisms, the mechanism of this stress response is mostly similar and involves the transmission of a signal from mitochondria to the nucleus that induces chromatin remodeling to allow the binding of specific transcription factors to the promoters of chaperones and proteases. In the last decade, proteins and signaling pathways that could be involved in the regulation of the UPRmt, including the Wnt signaling pathway, have been described. This minireview aims to summarize what is known about the mechanism of the UPRmt and its regulation, specifically in mammals and C. elegans.

Regulation of proteostasis and innate immunity via mitochondria-nuclear communication

Mitochondria are perhaps best known as the "powerhouse of the cell" for their role in ATP production required for numerous cellular activities. Mitochondria have emerged as an important signaling organelle. Here, we first focus on signaling pathways mediated by mitochondria-nuclear communication that promote protein homeostasis (proteostasis). We examine the mitochondrial unfolded protein response (UPRmt) in C. elegans, which is regulated by a transcription factor harboring both a mitochondrial- and nuclear-targeting sequence, the integrated stress response in mammals, as well as the regulation of chromatin by mitochondrial metabolites. In the second section, we explore the role of mitochondria-to-nuclear communication in the regulation of innate immunity and inflammation. Perhaps related to their prokaryotic origin, mitochondria harbor molecules also found in viruses and bacteria. If these molecules accumulate in the cytosol, they elicit the same innate immune responses as viral or bacterial infection.

Disease-associated astrocyte epigenetic memory promotes CNS pathology

Disease-associated astrocyte subsets contribute to the pathology of neurologic diseases, including multiple sclerosis and experimental autoimmune encephalomyelitis1-8 (EAE), an experimental model for multiple sclerosis. However, little is known about the stability of these astrocyte subsets and their ability to integrate past stimulation events. Here we report the identification of an epigenetically controlled memory astrocyte subset that exhibits exacerbated pro-inflammatory responses upon rechallenge. Specifically, using a combination of single-cell RNA sequencing, assay for transposase-accessible chromatin with sequencing, chromatin immunoprecipitation with sequencing, focused interrogation of cells by nucleic acid detection and sequencing, and cell-specific in vivo CRISPR-Cas9-based genetic perturbation studies we established that astrocyte memory is controlled by the metabolic enzyme ATP-citrate lyase (ACLY), which produces acetyl coenzyme A (acetyl-CoA) that is used by histone acetyltransferase p300 to control chromatin accessibility. The number of ACLY+p300+ memory astrocytes is increased in acute and chronic EAE models, and their genetic inactivation ameliorated EAE. We also detected the pro-inflammatory memory phenotype in human astrocytes in vitro; single-cell RNA sequencing and immunohistochemistry studies detected increased numbers of ACLY+p300+ astrocytes in chronic multiple sclerosis lesions. In summary, these studies define an epigenetically controlled memory astrocyte subset that promotes CNS pathology in EAE and, potentially, multiple sclerosis. These findings may guide novel therapeutic approaches for multiple sclerosis and other neurologic diseases.

Upregulation of p300 in paclitaxel-resistant TNBC: implications for cell proliferation via the PCK1/AMPK axis

OBJECTIVE

To explore the role of p300 in the context of paclitaxel (PTX) resistance in triple-negative breast cancer (TNBC) cells, focusing on its interaction with the phosphoenolpyruvate carboxykinase 1 (PCK1)/adenosine monophosphate-activated protein kinase (AMPK) pathway.

METHODS

The expression of p300 and PCK1 at the messenger ribonucleic acid (mRNA) level was detected using a quantitative polymerase chain reaction. The GeneCards and GEPIA databases were used to investigate the relationship between p300 and PCK1. The MDA-MB-231/PTX cell line, known for its PTX resistance, was chosen to understand the specific role of p300 in such cells. The Lipofectamine™ 3000 reagent was used to transfer the p300 small interfering RNA and the overexpression of PCK1 plasmid into MDA-MB-231/PTX. The expression levels of p300, PCK1, 5'AMPK and phosphorylated AMPK (p-AMPK) were determined using the western blot test.

RESULTS

In TNBC cancer tissue, the expression of p300 was increased compared with TNBC paracancerous tissue (P < 0.05). In the MDA-MB-231 cell line of TNBC, the expression of p300 was lower than in the PTX-resistant TNBC cells (MDA-MB-231/PTX) (P < 0.05). The PCK1 expression was decreased in the TNBC cancer tissue compared with TNBC paracancerous tissue, and the PCK1 expression was reduced in MDA-MB-231/PTX than in MDA-MB-231 (P < 0.05) indicating that PCK1 was involved in the resistance function. Additionally, p-AMPK was decreased in MDA-MB-231/PTX compared with MDA-MB-231 (P < 0.05). The adenosine triphosphate (ATP) level was also detected and was significantly lower in MDA-MB-231/PTX than in MDA-MB-231 (P < 0.05). Additionally, cell proliferation increased significantly in MDA-MB-231/PTX at 48 and 72 h (P < 0.05) suggesting that MDA-MB-231/PTX cells obtained the resistance function which was associated with AMPK and ATP level. When p300 was inhibited, p-AMPK and ATP levels elevated in MDA-MB-231/PTX (P < 0.05). When PCK1 was suppressed, the ATP consumption rate decreased, and cell proliferation increased (P < 0.05). However, there were no changes in p300.

CONCLUSIONS

In MDA-MB-231/PTX, p300 can inhibit p-AMPK and ATP levels by inhibiting PCK1 expression. Our findings suggest that targeting p300 could modulate the PCK1/AMPK axis, offering a potential therapeutic avenue for overcoming PTX resistance in TNBC.

Mitochondrial stress and aging: Lessons from C. elegans

Aging is accompanied by a progressive decline in mitochondrial function, which in turn contributes to a variety of age-related diseases. Counterintuitively, a growing number of studies have found that disruption of mitochondrial function often leads to increased lifespan. This seemingly contradictory observation has inspired extensive research into genetic pathways underlying the mitochondrial basis of aging, particularly within the model organism Caenorhabditis elegans. The complex and antagonistic roles of mitochondria in the aging process have altered the view of mitochondria, which not only serve as simple bioenergetic factories but also as signaling platforms for the maintenance of cellular homeostasis and organismal health. Here, we review the contributions of C. elegans to our understanding of mitochondrial function in the aging process over the past decades. In addition, we explore how these insights may promote future research of mitochondrial-targeted strategies in higher organisms to potentially slow aging and delay age-related disease progression.

Mitochondrial recovery by the UPRmt: Insights from C. elegans

Mitochondria are multifaceted organelles, with such functions as the production of cellular energy to the regulation of cell death. However, mitochondria incur various sources of damage from the accumulation of reactive oxygen species and DNA mutations that can impact the protein folding environment and impair their function. Since mitochondrial dysfunction is often associated with reductions in organismal fitness and possibly disease, cells must have safeguards in place to protect mitochondrial function and promote recovery during times of stress. The mitochondrial unfolded protein response (UPRmt) is a transcriptional adaptation that promotes mitochondrial repair to aid in cell survival during stress. While the earlier discoveries into the regulation of the UPRmt stemmed from studies using mammalian cell culture, much of our understanding about this stress response has been bestowed to us by the model organism Caenorhabditis elegans. Indeed, the facile but powerful genetics of this relatively simple nematode has uncovered multiple regulators of the UPRmt, as well as several physiological roles of this stress response. In this review, we will summarize these major advancements originating from studies using C. elegans.

Early-life stress triggers long-lasting organismal resilience and longevity via tetraspanin

Early-life stress experiences can produce lasting impacts on organismal adaptation and fitness. How transient stress elicits memory-like physiological effects is largely unknown. Here, we show that early-life thermal stress strongly up-regulates tsp-1, a gene encoding the conserved transmembrane tetraspanin in C. elegans. TSP-1 forms prominent multimers and stable web-like structures critical for membrane barrier functions in adults and during aging. Increased TSP-1 abundance persists even after transient early-life heat stress. Such regulation requires CBP-1, a histone acetyltransferase that facilitates initial tsp-1 transcription. Tetraspanin webs form regular membrane structures and mediate resilience-promoting effects of early-life thermal stress. Gain-of-function TSP-1 confers marked C. elegans longevity extension and thermal resilience in human cells. Together, our results reveal a cellular mechanism by which early-life thermal stress produces long-lasting memory-like impact on organismal resilience and longevity.

Disease-associated astrocyte epigenetic memory promotes CNS pathology

Astrocytes play important roles in the central nervous system (CNS) physiology and pathology. Indeed, astrocyte subsets defined by specific transcriptional activation states contribute to the pathology of neurologic diseases, including multiple sclerosis (MS) and its pre-clinical model experimental autoimmune encephalomyelitis (EAE) 1-8 . However, little is known about the stability of these disease-associated astrocyte subsets, their regulation, and whether they integrate past stimulation events to respond to subsequent challenges. Here, we describe the identification of an epigenetically controlled memory astrocyte subset which exhibits exacerbated pro-inflammatory responses upon re-challenge. Specifically, using a combination of single-cell RNA sequencing (scRNA-seq), assay for transposase-accessible chromatin with sequencing (ATAC-seq), chromatin immunoprecipitation with sequencing (ChIP-seq), focused interrogation of cells by nucleic acid detection and sequencing (FIND-seq), and cell-specific in vivo CRISPR/Cas9-based genetic perturbation studies we established that astrocyte memory is controlled by the metabolic enzyme ATP citrate lyase (ACLY), which produces acetyl coenzyme A (acetyl-CoA) used by the histone acetyltransferase p300 to control chromatin accessibility. ACLY + p300 + memory astrocytes are increased in acute and chronic EAE models; the genetic targeting of ACLY + p300 + astrocytes using CRISPR/Cas9 ameliorated EAE. We also detected responses consistent with a pro-inflammatory memory phenotype in human astrocytes in vitro ; scRNA-seq and immunohistochemistry studies detected increased ACLY + p300 + astrocytes in chronic MS lesions. In summary, these studies define an epigenetically controlled memory astrocyte subset that promotes CNS pathology in EAE and, potentially, MS. These findings may guide novel therapeutic approaches for MS and other neurologic diseases.

Early-life stress triggers long-lasting organismal resilience and longevity via tetraspanin

Early-life stress experiences can produce lasting impacts on organismal adaptation and fitness. How transient stress elicits memory-like physiological effects is largely unknown. Here we show that early-life thermal stress strongly up-regulates tsp-1, a gene encoding the conserved transmembrane tetraspanin in C. elegans. TSP-1 forms prominent multimers and stable web-like structures critical for membrane barrier functions in adults and during aging. The up-regulation of TSP-1 persists even after transient early-life stress. Such regulation requires CBP-1, a histone acetyl-transferase that facilitates initial tsp-1 transcription. Tetraspanin webs form regular membrane structures and mediate resilience-promoting effects of early-life thermal stress. Gain-of-function TSP-1 confers marked C. elegans longevity extension and thermal resilience in human cells. Together, our results reveal a cellular mechanism by which early-life thermal stress produces long-lasting memory-like impact on organismal resilience and longevity.

Mitochondrial p38 Mitogen-Activated Protein Kinase: Insights into Its Regulation of and Role in LONP1-Deficient Nematodes

p38 Mitogen-Activated Protein Kinase (MAPK) cascades are central regulators of numerous physiological cellular processes, including stress response signaling. In C. elegans, mitochondrial dysfunction activates a PMK-3/p38 MAPK signaling pathway (MAPKmt), but its functional role still remains elusive. Here, we demonstrate the induction of MAPKmt in worms deficient in the lonp-1 gene, which encodes the worm ortholog of mammalian mitochondrial LonP1. This induction is subjected to negative regulation by the ATFS-1 transcription factor through the CREB-binding protein (CBP) ortholog CBP-3, indicating an interplay between both activated MAPKmt and mitochondrial Unfolded Protein Response (UPRmt) surveillance pathways. Our results also reveal a genetic interaction in lonp-1 mutants between PMK-3 kinase and the ZIP-2 transcription factor. ZIP-2 has an established role in innate immunity but can also modulate the lifespan by maintaining mitochondrial homeostasis during ageing. We show that in lonp-1 animals, ZIP-2 is activated in a PMK-3-dependent manner but does not confer increased survival to pathogenic bacteria. However, deletion of zip-2 or pmk-3 shortens the lifespan of lonp-1 mutants, suggesting a possible crosstalk under conditions of mitochondrial perturbation that influences the ageing process. Furthermore, loss of pmk-3 specifically diminished the extreme heat tolerance of lonp-1 worms, highlighting the crucial role of PMK-3 in the heat shock response upon mitochondrial LONP-1 inactivation.

The CRTC-1 transcriptional domain is required for COMPASS complex-mediated longevity in C. elegans

Loss of function during aging is accompanied by transcriptional drift, altering gene expression and contributing to a variety of age-related diseases. CREB-regulated transcriptional coactivators (CRTCs) have emerged as key regulators of gene expression that might be targeted to promote longevity. Here we define the role of the Caenorhabditis elegans CRTC-1 in the epigenetic regulation of longevity. Endogenous CRTC-1 binds chromatin factors, including components of the COMPASS complex, which trimethylates lysine 4 on histone H3 (H3K4me3). CRISPR editing of endogenous CRTC-1 reveals that the CREB-binding domain in neurons is specifically required for H3K4me3-dependent longevity. However, this effect is independent of CREB but instead acts via the transcription factor AP-1. Strikingly, CRTC-1 also mediates global histone acetylation levels, and this acetylation is essential for H3K4me3-dependent longevity. Indeed, overexpression of an acetyltransferase enzyme is sufficient to promote longevity in wild-type worms. CRTCs, therefore, link energetics to longevity by critically fine-tuning histone acetylation and methylation to promote healthy aging.

Duplications of Human Longevity-Associated Genes Across Placental Mammals

Natural selection has shaped a wide range of lifespans across mammals, with a few long-lived species showing negligible signs of ageing. Approaches used to elucidate the genetic mechanisms underlying mammalian longevity usually involve phylogenetic selection tests on candidate genes, detections of convergent amino acid changes in long-lived lineages, analyses of differential gene expression between age cohorts or species, and measurements of age-related epigenetic changes. However, the link between gene duplication and evolution of mammalian longevity has not been widely investigated. Here, we explored the association between gene duplication and mammalian lifespan by analyzing 287 human longevity-associated genes across 37 placental mammals. We estimated that the expansion rate of these genes is eight times higher than their contraction rate across these 37 species. Using phylogenetic approaches, we identified 43 genes whose duplication levels are significantly correlated with longevity quotients (False Discovery Rate (FDR) < 0.05). In particular, the strong correlation observed for four genes (CREBBP, PIK3R1, HELLS, FOXM1) appears to be driven mainly by their high duplication levels in two ageing extremists, the naked mole rat (Heterocephalus glaber) and the greater mouse-eared bat (Myotis myotis). Further sequence and expression analyses suggest that the gene PIK3R1 may have undergone a convergent duplication event, whereby the similar region of its coding sequence was independently duplicated multiple times in both of these long-lived species. Collectively, this study identified several candidate genes whose duplications may underlie the extreme longevity in mammals, and highlighted the potential role of gene duplication in the evolution of mammalian long lifespans.

Long-term exposure to polystyrene nanoparticles at environmentally relevant concentration causes suppression in heme homeostasis signal associated with transgenerational toxicity induction in Caenorhabditis elegans

Heme homeostasis related signaling participates in inducing a protective response when controlling nanopolystyrene toxic effects in parental generation. However, whether the heme homeostasis signal is involved in regulation of transgenerational toxicity of nanopolystyrene toxicity is still unclear. Herein, with the model organism of Caenorhabditis elegans, 0.1-10 μg/L nanopolystyrene particles (PS-NPs) at 20-nm treatment downregulated glb-18, and the decrease was also discovered in the offspring following PS-NPs exposure. Germline glb-18 RNAi induced susceptive property to transgenerational PS-NPs toxicity, suggesting that a decreased GLB-18 level mediated induction of transgenerational toxicity. Importantly, germline GLB-18 transgenerationally activated the function of intestinal HRG-4 in controlling transgenerational PS-NPs toxicity. In transgenerational toxicity control, HRG-1/ATFS-1/HSP-6 was recognized to be the downstream pathway of HRG-4. Briefly, germline GLB-18 in P0 generation can transgenerationally activate the downstream intestinal HRG-4/HRG-1/ATFS-1/HSP-6 pathway among offspring for controlling the transgenerational toxicity of PS-NPs. Findings in the present work strengthens the possible association of heme homeostasis signal changes with transgenerational nanoplastic toxicity within the organisms.

Temporal landscape of mitochondrial proteostasis governed by the UPRmt

Breakdown of mitochondrial proteostasis activates quality control pathways including the mitochondrial unfolded protein response (UPRmt) and PINK1/Parkin mitophagy. However, beyond the up-regulation of chaperones and proteases, we have a limited understanding of how the UPRmt remodels and restores damaged mitochondrial proteomes. Here, we have developed a functional proteomics framework, termed MitoPQ (Mitochondrial Proteostasis Quantification), to dissect the UPRmt's role in maintaining proteostasis during stress. We find essential roles for the UPRmt in both protecting and repairing proteostasis, with oxidative phosphorylation metabolism being a central target of the UPRmt. Transcriptome analyses together with MitoPQ reveal that UPRmt transcription factors drive independent signaling arms that act in concert to maintain proteostasis. Unidirectional interplay between the UPRmt and PINK1/Parkin mitophagy was found to promote oxidative phosphorylation recovery when the UPRmt failed. Collectively, this study defines the network of proteostasis mediated by the UPRmt and highlights the value of functional proteomics in decoding stressed proteomes.

Lysosomes mediate the mitochondrial UPR via mTORC1-dependent ATF4 phosphorylation

Lysosomes are central platforms for not only the degradation of macromolecules but also the integration of multiple signaling pathways. However, whether and how lysosomes mediate the mitochondrial stress response (MSR) remain largely unknown. Here, we demonstrate that lysosomal acidification via the vacuolar H+-ATPase (v-ATPase) is essential for the transcriptional activation of the mitochondrial unfolded protein response (UPRmt). Mitochondrial stress stimulates v-ATPase-mediated lysosomal activation of the mechanistic target of rapamycin complex 1 (mTORC1), which then directly phosphorylates the MSR transcription factor, activating transcription factor 4 (ATF4). Disruption of mTORC1-dependent ATF4 phosphorylation blocks the UPRmt, but not other similar stress responses, such as the UPRER. Finally, ATF4 phosphorylation downstream of the v-ATPase/mTORC1 signaling is indispensable for sustaining mitochondrial redox homeostasis and protecting cells from ROS-associated cell death upon mitochondrial stress. Thus, v-ATPase/mTORC1-mediated ATF4 phosphorylation via lysosomes links mitochondrial stress to UPRmt activation and mitochondrial function resilience.

V-ATPase/TORC1-mediated ATFS-1 translation directs mitochondrial UPR activation in C. elegans

To adapt mitochondrial function to the ever-changing intra- and extracellular environment, multiple mitochondrial stress response (MSR) pathways, including the mitochondrial unfolded protein response (UPRmt), have evolved. However, how the mitochondrial stress signal is sensed and relayed to UPRmt transcription factors, such as ATFS-1 in Caenorhabditis elegans, remains largely unknown. Here, we show that a panel of vacuolar H+-ATPase (v-ATPase) subunits and the target of rapamycin complex 1 (TORC1) activity are essential for the cytosolic relay of mitochondrial stress to ATFS-1 and for the induction of the UPRmt. Mechanistically, mitochondrial stress stimulates v-ATPase/Rheb-dependent TORC1 activation, subsequently promoting ATFS-1 translation. Increased translation of ATFS-1 upon mitochondrial stress furthermore relies on a set of ribosomal components but is independent of GCN-2/PEK-1 signaling. Finally, the v-ATPase and ribosomal subunits are required for mitochondrial surveillance and mitochondrial stress-induced longevity. These results reveal a v-ATPase-TORC1-ATFS-1 signaling pathway that links mitochondrial stress to the UPRmt through intimate crosstalks between multiple organelles.

Microglial immune regulation by epigenetic reprogramming through histone H3K27 acetylation in neuroinflammation

Epigenetic reprogramming is the ability of innate immune cells to form memories of environmental stimuli (priming), allowing for heightened responses to secondary stressors. Herein, we explored microglial epigenetic marks using the known inflammagen LPS as a memory priming trigger and Parkinsonian-linked environmental neurotoxic stressor manganese (Mn) as the secondary environmental trigger. To mimic physiological responses, the memory priming trigger LPS treatment was removed by triple-washing to allow the cells' acute inflammatory response to reset back before applying the secondary insult. Our results show that after the secondary Mn insult, levels of key proinflammatory markers, including nitrite release, iNOS mRNA and protein expression, Il-6, Il-α and cytokines were exaggerated in LPS-primed microglia. Our paradigm implies primed microglia retain immune memory that can be reprogrammed to augment inflammatory response by secondary environmental stress. To ascertain the molecular underpinning of this neuroimmune memory, we further hypothesize that epigenetic reprogramming contributes to the retention of a heightened immune response. Interestingly, Mn-exposed, LPS-primed microglia showed enhanced deposition of H3K27ac and H3K4me3 along with H3K4me1. We further confirmed the results using a PD mouse model (MitoPark) and postmortem human PD brains, thereby adding clinical relevance to our findings. Co-treatment with the p300/H3K27ac inhibitor GNE-049 reduced p300 expression and H3K27ac deposition, decreased iNOS, and increased ARG1 and IRF4 levels. Lastly, since mitochondrial stress is a driver of environmentally linked Parkinson's disease (PD) progression, we examined the effects of GNE-049 on primary trigger-induced mitochondrial stress. GNE-049 reduced mitochondrial superoxide, mitochondrial circularity and stress, and mitochondrial membrane depolarization, suggesting beneficial consequences of GNE-049 on mitochondrial function. Collectively, our findings demonstrate that proinflammatory primary triggers can shape microglial memory via the epigenetic mark H3K27ac and that inhibiting H3K27ac deposition can prevent primary trigger immune memory formation and attenuate subsequent secondary inflammatory responses.

Role of primary aging hallmarks in Alzheimer´s disease

Alzheimer's disease (AD) is the most common neurodegenerative disease, which severely threatens the health of the elderly and causes significant economic and social burdens. The causes of AD are complex and include heritable but mostly aging-related factors. The primary aging hallmarks include genomic instability, telomere wear, epigenetic changes, and loss of protein stability, which play a dominant role in the aging process. Although AD is closely associated with the aging process, the underlying mechanisms involved in AD pathogenesis have not been well characterized. This review summarizes the available literature about primary aging hallmarks and their roles in AD pathogenesis. By analyzing published literature, we attempted to uncover the possible mechanisms of aberrant epigenetic markers with related enzymes, transcription factors, and loss of proteostasis in AD. In particular, the importance of oxidative stress-induced DNA methylation and DNA methylation-directed histone modifications and proteostasis are highlighted. A molecular network of gene regulatory elements that undergoes a dynamic change with age may underlie age-dependent AD pathogenesis, and can be used as a new drug target to treat AD.

The mitochondrial UPR regulator ATF5 promotes intestinal barrier function via control of the satiety response

Organisms use several strategies to mitigate mitochondrial stress, including the activation of the mitochondrial unfolded protein response (UPR^mt). The UPR^mt in Caenorhabditis elegans, regulated by the transcription factor ATFS-1, expands on this recovery program by inducing an antimicrobial response against pathogens that target mitochondrial function. Here, we show that the mammalian ortholog of ATFS-1, ATF5, protects the host during infection with enteric pathogens but, unexpectedly, by maintaining the integrity of the intestinal barrier. Intriguingly, ATF5 supports intestinal barrier function by promoting a satiety response that prevents obesity and associated hyperglycemia. This consequently averts dysregulated glucose metabolism that is detrimental to barrier function. Mechanistically, we show that intestinal ATF5 stimulates the satiety response by transcriptionally regulating the gastrointestinal peptide hormone cholecystokinin, which promotes the secretion of the hormone leptin. We propose that ATF5 protects the host from enteric pathogens by promoting intestinal barrier function through a satiety-response-mediated metabolic control mechanism.

Mitochondrial dysfunction, aging, and the mitochondrial unfolded protein response in Caenorhabditis elegans

We review the findings that establish that perturbations of various aspects of mitochondrial function, including oxidative phosphorylation, can promote lifespan extension, with different types of perturbations acting sometimes independently and additively on extending lifespan. We also review the great variety of processes and mechanisms that together form the mitochondrial unfolded protein response. We then explore the relationships between different types of mitochondrial dysfunction-dependent lifespan extension and the mitochondrial unfolded protein response. We conclude that, although several ways that induce extended lifespan through mitochondrial dysfunction require a functional mitochondrial unfolded protein response, there is no clear indication that activation of the mitochondrial unfolded protein response is sufficient to extend lifespan, despite the fact that the mitochondrial unfolded protein response impacts almost every aspect of mitochondrial function. In fact, in some contexts, mitochondrial unfolded protein response activation is deleterious. To explain this pattern, we hypothesize that, although triggered by mitochondrial dysfunction, the lifespan extension observed might not be the result of a change in mitochondrial function.

Epigenetic regulation of aging: implications for interventions of aging and diseases

Aging is accompanied by the decline of organismal functions and a series of prominent hallmarks, including genetic and epigenetic alterations. These aging-associated epigenetic changes include DNA methylation, histone modification, chromatin remodeling, non-coding RNA (ncRNA) regulation, and RNA modification, all of which participate in the regulation of the aging process, and hence contribute to aging-related diseases. Therefore, understanding the epigenetic mechanisms in aging will provide new avenues to develop strategies to delay aging. Indeed, aging interventions based on manipulating epigenetic mechanisms have led to the alleviation of aging or the extension of the lifespan in animal models. Small molecule-based therapies and reprogramming strategies that enable epigenetic rejuvenation have been developed for ameliorating or reversing aging-related conditions. In addition, adopting health-promoting activities, such as caloric restriction, exercise, and calibrating circadian rhythm, has been demonstrated to delay aging. Furthermore, various clinical trials for aging intervention are ongoing, providing more evidence of the safety and efficacy of these therapies. Here, we review recent work on the epigenetic regulation of aging and outline the advances in intervention strategies for aging and age-associated diseases. A better understanding of the critical roles of epigenetics in the aging process will lead to more clinical advances in the prevention of human aging and therapy of aging-related diseases.

The mitochondrial unfolded protein response: A multitasking giant in the fight against human diseases

Mitochondria, which serve as the energy factories of cells, are involved in cell differentiation, calcium homeostasis, amino acid and fatty acid metabolism and apoptosis. In response to environmental stresses, mitochondrial homeostasis is regulated at both the organelle and molecular levels to effectively maintain the number and function of mitochondria. The mitochondrial unfolded protein response (UPR^mt) is an adaptive intracellular stress mechanism that responds to stress signals by promoting the transcription of genes encoding mitochondrial chaperones and proteases. The mechanism of the UPR^mt in Caenorhabditis elegans (C. elegans) has been clarified over time, and the main regulatory factors include ATFS-1, UBL-5 and DVE-1. In mammals, the activation of the UPR^mt involves eIF2α phosphorylation and the uORF-regulated expression of CHOP, ATF4 and ATF5. Several additional factors, such as SIRT3 and HSF1, are also involved in regulating the UPR^mt. A deep and comprehensive exploration of the UPR^mt can provide new directions and strategies for the treatment of human diseases, including aging, neurodegenerative diseases, cardiovascular diseases and diabetes. In this review, we mainly discuss the function of UPR^mt, describe the regulatory mechanisms of UPR^mt in C. elegans and mammals, and summarize the relationship between UPR^mt and various human diseases.

Diets, genes, and drugs that increase lifespan and delay age-related diseases: Role of nutrient-sensing neurons and Creb-binding protein

Discovery of interventions that delay or minimize age-related diseases is arguably the major goal of aging research. Conversely discovery of interventions based on phenotypic screens have often led to further elucidation of pathophysiological mechanisms. Although most hypotheses to explain lifespan focus on cell-autonomous processes, increasing evidence suggests that in multicellular organisms, neurons, particularly nutrient-sensing neurons, play a determinative role in lifespan and age-related diseases. For example, protective effects of dietary restriction and inactivation of insulin-like signaling increase lifespan and delay age-related diseases dependent on Creb-binding protein in GABA neurons, and Nrf2/Skn1 in just 2 nutrient-sensing neurons in C. elegans. Screens for drugs that increase lifespan also indicate that such drugs are predominantly active through neuronal signaling. Our own screens also indicate that neuroactive drugs also delay pathology in an animal model of Alzheimer's Disease, as well as inhibit cytokine production implicated in driving many age-related diseases. The most likely mechanism by which nutrient-sensing neurons influence lifespan and the onset of age-related diseases is by regulating metabolic architecture, particularly the relative rate of glycolysis vs. alternative metabolic pathways such as ketone and lipid metabolism. These results suggest that neuroactive compounds are a most promising class of drugs to delay or minimize age-related diseases.

Impact of Exercise and Aging on Mitochondrial Homeostasis in Skeletal Muscle: Roles of ROS and Epigenetics

Aging causes degenerative changes such as epigenetic changes and mitochondrial dysfunction in skeletal muscle. Exercise can upregulate muscle mitochondrial homeostasis and enhance antioxidant capacity and represents an effective treatment to prevent muscle aging. Epigenetic changes such as DNA methylation, histone posttranslational modifications, and microRNA expression are involved in the regulation of exercise-induced adaptive changes in muscle mitochondria. Reactive oxygen species (ROS) play an important role in signaling molecules in exercise-induced muscle mitochondrial health benefits, and strong evidence emphasizes that exercise-induced ROS can regulate gene expression via epigenetic mechanisms. The majority of mitochondrial proteins are imported into mitochondria from the cytosol, so mitochondrial homeostasis is regulated by nuclear epigenetic mechanisms. Exercise can reverse aging-induced changes in myokine expression by modulating epigenetic mechanisms. In this review, we provide an overview of the role of exercise-generated ROS in the regulation of mitochondrial homeostasis mediated by epigenetic mechanisms. In addition, the potential epigenetic mechanisms involved in exercise-induced myokine expression are reviewed.

Protein disulfide isomerase PDI-6 regulates Wnt secretion to coordinate inter-tissue UPRmt activation and lifespan extension in C. elegans

Coordination of inter-tissue stress signaling is essential for organismal fitness. Neuronal mitochondrial perturbations activate the mitochondrial unfolded-protein response (UPR^mt) in the intestine via the mitokine Wnt signaling in Caenorhabditis elegans. Here, we found that the protein disulfide isomerase PDI-6 coordinates inter-tissue UPR^mt signaling via regulating the Wnt ligand EGL-20. PDI-6 is expressed in the endoplasmic reticulum (ER) and interacts with EGL-20 through disulfide bonds that are essential for EGL-20 stability and secretion. pdi-6 deficiency results in misfolded EGL-20, which leads to its degradation via ER-associated protein degradation (ERAD) machinery. Expression of PDI-6 declines drastically with aging, and animals with pdi-6 deficiency have decreased lifespan. Overexpression of PDI-6 is sufficient to maintain Wnt/EGL-20 protein levels during aging, activating the UPR^mt, and significantly extending lifespan in a Wnt- and UPR^mt-dependent manner. Our study reveals that protein disulfide isomerase facilitates Wnt secretion to coordinate the inter-tissue UPR^mt signaling and organismal aging.

Mechanism of Stat1 in the neuronal Ca2+ overload after intracerebral hemorrhage via the H3K27ac/Trpm7 axis

Intracerebral hemorrhage (ICH) is classified as a subtype of stroke and Calcium (Ca²⁺) overload is a catalyst for ICH. This study explored the mechanisms of Stat1 (signal transducer and activator of transcription 1) in the neuronal Ca²⁺ overload after ICH. ICH mouse models and in vitro cell models were established. Stat1 and transient receptor potential melastatin 7 (Trpm7) were detected up-regulated in ICH models. Afterwards, the mice were infected with the lentivirus containing sh-Stat1, and HT22 cells were treated with si-Stat1 and the lentivirus containing pcDNA3.1-Trpm7. The neurologic functional impairment, histopathological damage, and Nissl body in mice were all measured. HT22 cell viability and apoptosis were identified. The levels of Ca²⁺, Trpm7 mRNA, H3K27 acetylation (H3K27ac), CaMKII-α, and p-Stat1 protein in the tissues and cells were determined. We found that silencing Stat1 alleviated ICH damage and repressed the neuronal Ca²⁺ overload after ICH. H3K27ac enrichment in the Trpm7 promoter region was examined and we found that p-Stat1 accelerated Trpm7 transcription via promoting H3K27ac in the Trpm7 promoter region. Besides, Trpm7 overexpression increased Ca²⁺ overload and aggravated ICH. Overall, p-Stat1 promoted Trpm7 transcription and further aggravated the Ca²⁺ overload after ICH.

Rlip76: An Unexplored Player in Neurodegeneration and Alzheimer’s Disease?

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and is the most common cause of dementia in older people. AD is associated with the loss of synapses, oxidative stress, mitochondrial structural and functional abnormalities, microRNA deregulation, inflammatory responses, neuronal loss, accumulation of amyloid-beta (Aβ) and phosphorylated tau (p-tau). AD occurs in two forms: early onset, familial AD and late-onset, sporadic AD. Causal factors are still unknown for a vast majority of AD patients. Genetic polymorphisms are proposed to contribute to late-onset AD via age-dependent increases in oxidative stress and mitochondrial abnormalities. Recent research from our lab revealed that reduced levels of Rlip76 induce oxidative stress, mitochondrial dysfunction and synaptic damage, leading to molecular and behavioral phenotypes resembling late-onset AD. Rlip76 is a multifunctional 76 kDa protein encoded by the RALBP1 gene, located on chromosome 18. Rlip is a stress-protective ATPase of the mercapturic acid pathway that couples clathrin-dependent endocytosis with the efflux of glutathione–electrophile conjugates. Rlip is evolutionarily highly conserved across species and is ubiquitously expressed in all tissues, including AD-affected brain regions, the cerebral cortex and hippocampus, where highly active neuronal metabolisms render the cells highly susceptible to intracellular oxidative damage. In the current article, we summarize molecular and cellular features of Rlip and how depleted Rlip may exacerbate oxidative stress, mitochondrial dysfunction and synaptic damage in AD. We also discuss the possible role of Rlip in aspects of learning and memory via axonal growth, dendritic remodeling, and receptor regulation. We conclude with a discussion of the potential for the contribution of genetic polymorphisms in Rlip to AD progression and the potential for Rlip-based therapies.

The CBP-1/p300 Lysine Acetyltransferase Regulates the Heat Shock Response in C. elegans

The decline of proteostasis is a hallmark of aging that is, in part, affected by the dysregulation of the heat shock response (HSR), a highly conserved cellular response to proteotoxic stress in the cell. The heat shock transcription factor HSF-1 is well-studied as a key regulator of proteostasis, but mechanisms that could be used to modulate HSF-1 function to enhance proteostasis during aging are largely unknown. In this study, we examined lysine acetyltransferase regulation of the HSR and HSF-1 in C. elegans. We performed an RNA interference screen of lysine acetyltransferases and examined mRNA expression of the heat-shock inducible gene hsp-16.2, a widely used marker for HSR activation. From this screen, we identified one acetyltransferase, CBP-1, the C. elegans homolog of mammalian CREB-binding protein CBP/p300, as a negative regulator of the HSR. We found that while knockdown of CBP-1 decreases the overall lifespan of the worm, it also enhances heat shock protein production upon heat shock and increases thermotolerance of the worm in an HSF-1 dependent manner. Similarly, we examined a hallmark of HSF-1 activation, the formation of nuclear stress bodies (nSBs). In analyzing the recovery rate of nSBs, we found that knockdown of CBP-1 enhanced the recovery and resolution of nSBs after stress. Collectively, our studies demonstrate a role of CBP-1 as a negative regulator of HSF-1 activity and its physiological effects at the organismal level upon stress.

Itaconate prolongs the healthy lifespan by activating UPRmt in Caenorhabditis elegans

Itaconate (ItA), a byproduct of the Krebs cycle, has recently emerged as an anti-inflammatory metabolite for inhibiting the overactive immune response. In addition to its immunomodulatory and antimicrobial effects, ItA may have other therapeutic avenues. Herein, the effect of ItA on aging was explored in order to better establish the therapeutic potential of this promising metabolite. ItA extended the lifespan and enhanced the stress resistance of Caenorhabditis elegans (C. elegans), even at the doses of 0.01 and 0.1 μM. Moreover, the lifespan extension effect of ItA was pronounced even for the aged worms (days 7 and 9 post adult stage). Furthermore, ItA was found to extend the healthy longevity of C. elegans in a mitochondria-dependent manner. ItA protected the mitochondrial integrity, increased ATP content, and decreased the reactive oxygen species (ROS) in C. elegans. Mechanistic investigations showed that ItA specifically activated the mitochondrial unfolded protein response (UPR^mt) in worms and significantly increased the expression of activating transcription factor associated with stress-1 (ATFS-1) that senses mitochondrial stress and communicates with the nucleus during the UPR^mt. ItA extended the lifespan of C. elegans in an ATFS-1-dependent manner. In summary, this study elucidates the molecular mechanism by which ItA extends the healthy lifespan and highlights the importance of mitochondrial integrity in the intervention of aging.

Pleiotropic effects of mitochondria in aging

Aging is typified by a progressive decline in mitochondrial activity and stress resilience. Here, we review how mitochondrial stress pathways have pleiotropic effects on cellular and systemic homeostasis, which can comprise protective or detrimental responses during aging. We describe recent evidence arguing that defects in these conserved adaptive pathways contribute to aging and age-related diseases. Signaling pathways regulating the mitochondrial unfolded protein response, mitochondrial membrane dynamics, and mitophagy are discussed, emphasizing how their failure contributes to heteroplasmy and de-regulation of key metabolites. Our current understanding of how these processes are controlled and interconnected explains how mitochondria can widely impact fundamental aspects of aging.

The Unfolded Protein Responses in Health, Aging, and Neurodegeneration: Recent Advances and Future Considerations

Aging and age-related neurodegeneration are both associated with the accumulation of unfolded and abnormally folded proteins, highlighting the importance of protein homeostasis (termed proteostasis) in maintaining organismal health. To this end, two cellular compartments with essential protein folding functions, the endoplasmic reticulum (ER) and the mitochondria, are equipped with unique protein stress responses, known as the ER unfolded protein response (UPR ER ) and the mitochondrial UPR (UPR mt ), respectively. These organellar UPRs play roles in shaping the cellular responses to proteostatic stress that occurs in aging and age-related neurodegeneration. The loss of adaptive UPR ER and UPR mt signaling potency with age contributes to a feed-forward cycle of increasing protein stress and cellular dysfunction. Likewise, UPR ER and UPR mt signaling is often altered in age-related neurodegenerative diseases; however, whether these changes counteract or contribute to the disease pathology appears to be context dependent. Intriguingly, altering organellar UPR signaling in animal models can reduce the pathological consequences of aging and neurodegeneration which has prompted clinical investigations of UPR signaling modulators as therapeutics. Here, we review the physiology of both the UPR ER and the UPR mt , discuss how UPR ER and UPR mt signaling changes in the context of aging and neurodegeneration, and highlight therapeutic strategies targeting the UPR ER and UPR mt that may improve human health.

Insight into the mitochondrial unfolded protein response and cancer: opportunities and challenges

The mitochondrial unfolded protein response (UPR^mt) is an evolutionarily conserved protective transcriptional response that maintains mitochondrial proteostasis by inducing the expression of mitochondrial chaperones and proteases in response to various stresses. The UPR^mt-mediated transcriptional program requires the participation of various upstream signaling pathways and molecules. The factors regulating the UPR^mt in Caenorhabditis elegans (C. elegans) and mammals are both similar and different. Cancer cells, as malignant cells with uncontrolled proliferation, are exposed to various challenges from endogenous and exogenous stresses. Therefore, in cancer cells, the UPR^mt is hijacked and exploited for the repair of mitochondria and the promotion of tumor growth, invasion and metastasis. In this review, we systematically introduce the inducers of UPR^mt, the biological processes in which UPR^mt participates, the mechanisms regulating the UPR^mt in C. elegans and mammals, cross-tissue signal transduction of the UPR^mt and the roles of the UPR^mt in promoting cancer initiation and progression. Disrupting proteostasis in cancer cells by targeting UPR^mt constitutes a novel anticancer therapeutic strategy.

Integrative analysis of multiomics data identified acetylation as key variable of excessive energy metabolism in hyperthyroidism-induced osteoporosis rats

BACKGROUND

Results from the previous experiment have demonstrated bone loss and excess metabolism in Hyperthyroidism-induced rats. Thus, an underlying relationship between metabolism and bone loss was speculated. In addition, previous studies have shown the influence of acetylation on metabolism in tissues and diseases. The hypothesis from this case study suggests that excessive metabolism is induced by acetylation of vital metabolism enzymes.

RESULTS

In the case study, a HYP-induced osteoporosis rat model was used and the glucose metabolite was tested through the acetylation of proteins by the mass spectrometer. The results showed that pivotal enzymes of Glycolysis-Tricarboxylic acid cycle-Oxidative phosphorylation were acetylated along with upregulated metabolites. With all acetyly-lysine sites of related enzymes listed, the results in this study showed that bone loss in HYP rats was accompanied by the upregulation of CREB-binding protein (Crebbp, CBP). Furthermore, it is also indicated that CBP has a close relationship with the enhancement of LDHA which promotes glucose metabolism.

CONCLUSIONS

Acetylation is highly correlated with excessive energy metabolism in HYP-induced osteoporotic rats, where a representation relationship between CBP and LDHA is demonstrated.

SIGNIFICANCE

Hyperthyroidism may lead to osteoporosis. Our study found an interesting phenomenon of hyperthyroidism induced-osteoporosis is that osteoporosis is accompanied by excessive glucose metabolism. In this process, some molecular mechanisms are still unclear. This study indicates a high degree of acetylation of metabolic enzymes, which may be closely related to excessive glucose metabolism. The relationship between CBP and LDHA was also investigated in this study, which showed that CBP and LDHA had some extent interaction. Glucose metabolism and acetylation maybe all associated with hyperthyroidism induced-osteoporosis. This data provides new insights into the molecular mechanisms of hyperthyroidism induced-osteoporosis.

Multi-omics analysis identifies essential regulators of mitochondrial stress response in two wild-type C. elegans strains

The mitochondrial unfolded protein response (UPRmt) is a promising pharmacological target for aging and age-related diseases. However, the integrative analysis of the impact of UPRmt activation on different signaling layers in animals with different genetic backgrounds is lacking. Here, we applied systems approaches to investigate the effect of UPRmt induced by doxycycline (Dox) on transcriptome, proteome, and lipidome in two genetically divergent worm strains, named N2 and CB4856. From the integrated omics datasets, we found that Dox prolongs lifespan of both worm strains through shared and strain-specific mechanisms. Specifically, Dox strongly impacts mitochondria, upregulates defense response, and lipid metabolism, while decreasing triglycerides. We further validated that lipid genes acs-2/20 and fat-7/6 were required for Dox-induced UPRmt and longevity in N2 and CB4856 worms, respectively. Our data have translational value as they indicate that the beneficial effects of Dox-induced UPRmt on lifespan are consistent across different genetic backgrounds through different regulators.

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Dox extends lifespan of N2 and CB4856 via shared and strain-specific mechanisms

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Dox controls mitochondria, defense responses, and lipid metabolism in both strains

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Dox-mediated longevity requires acs-2/20 in N2 and fat-7/6 in CB4856 worms

Combinatorial Approach Using Caenorhabditis elegans and Mammalian Systems for Aging Research

Aging is associated with functional and structural declines in organisms over time. Organisms as diverse as the nematode Caenorhabditis elegans and mammals share signaling pathways that regulate aging and lifespan. In this review, we discuss recent combinatorial approach to aging research employing C. elegans and mammalian systems that have contributed to our understanding of evolutionarily conserved aging-regulating pathways. The topics covered here include insulin/IGF-1, mechanistic target of rapamycin (mTOR), and sirtuin signaling pathways; dietary restriction; autophagy; mitochondria; and the nervous system. A combinatorial approach employing high-throughput, rapid C. elegans systems, and human model mammalian systems is likely to continue providing mechanistic insights into aging biology and will help develop therapeutics against age-associated disorders.

Acetyl-CoA Metabolism and Histone Acetylation in the Regulation of Aging and Lifespan

Acetyl-CoA is a metabolite at the crossroads of central metabolism and the substrate of histone acetyltransferases regulating gene expression. In many tissues fasting or lifespan extending calorie restriction (CR) decreases glucose-derived metabolic flux through ATP-citrate lyase (ACLY) to reduce cytoplasmic acetyl-CoA levels to decrease activity of the p300 histone acetyltransferase (HAT) stimulating pro-longevity autophagy. Because of this, compounds that decrease cytoplasmic acetyl-CoA have been described as CR mimetics. But few authors have highlighted the potential longevity promoting roles of nuclear acetyl-CoA. For example, increasing nuclear acetyl-CoA levels increases histone acetylation and administration of class I histone deacetylase (HDAC) inhibitors increases longevity through increased histone acetylation. Therefore, increased nuclear acetyl-CoA likely plays an important role in promoting longevity. Although cytoplasmic acetyl-CoA synthetase 2 (ACSS2) promotes aging by decreasing autophagy in some peripheral tissues, increased glial AMPK activity or neuronal differentiation can stimulate ACSS2 nuclear translocation and chromatin association. ACSS2 nuclear translocation can result in increased activity of CREB binding protein (CBP), p300/CBP-associated factor (PCAF), and other HATs to increase histone acetylation on the promoter of neuroprotective genes including transcription factor EB (TFEB) target genes resulting in increased lysosomal biogenesis and autophagy. Much of what is known regarding acetyl-CoA metabolism and aging has come from pioneering studies with yeast, fruit flies, and nematodes. These studies have identified evolutionary conserved roles for histone acetylation in promoting longevity. Future studies should focus on the role of nuclear acetyl-CoA and histone acetylation in the control of hypothalamic inflammation, an important driver of organismal aging.