Combining Stem Cell Rejuvenation and Senescence Targeting to Synergistically Extend Lifespan
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ABSTRACT: We combine transient stem cell rejuvenation with targeted removal of senescent cells to test the hypothesis that simultaneously targeting both cell-fate based aging mechanisms will maximize life and health span benefits.
Project description:Why biological age is a major risk factor for many of the most important human diseases remains mysterious. We know that as organisms age, stem cell pools are exhausted while senescent cells progressively accumulate. Independently, induction of pluripotency via expression of Yamanaka factors (Oct4, Klf4, Sox2, c-Myc; OKSM) and clearance of senescent cells have each been shown to ameliorate cellular and physiological aspects of aging, suggesting that both processes are drivers of organismal aging. But stem cell exhaustion and cellular senescence likely interact in the etiology and progression of age-dependent diseases because both undermine tissue and organ homeostasis in different if not complementary ways. Here, we combine transient cellular reprogramming (stem cell rejuvenation) with targeted removal of senescent cells to test the hypothesis that simultaneously targeting both cell-fate based aging mechanisms will maximize life and health span benefits. We find that OKSM extends lifespan and show that both interventions protect the intestinal stem cell pool, lower inflammation, activate pro-stem cell signaling pathways, and synergistically improve health and lifespan. Our findings suggest that a combination therapy, simultaneously replacing lost stem cells and removing senescent cells, shows synergistic potential for anti-aging treatments. Our finding that transient expression of both is the most effective suggests that drug-based treatments in non-genetically tractable organisms will likely be the most translatable.
Project description:Mitochondrial form and function are closely interlinked in homeostasis and aging. Inhibiting mitochondrial translation is known to increase lifespan in C. elegans, and is accompanied by a fragmented mitochondrial network. However, whether this link between mitochondrial translation and morphology is causal in longevity remains uncharacterized. Here, we show in C. elegans that disrupting mitochondrial network homeostasis by blocking fission or fusion synergizes with reduced mitochondrial translation to prolong lifespan and stimulate stress response such as the mitochondrial unfolded protein response, UPRMT. Conversely, immobilizing the mitochondrial network through a simultaneous disruption of fission and fusion abrogates the lifespan increase induced by mitochondrial translation inhibition. Furthermore, we find that the synergistic effect of inhibiting both mitochondrial translation and dynamics on lifespan, despite stimulating UPRMT, does not require it. Instead, this lifespan-extending synergy is exclusively dependent on the lysosome biogenesis and autophagy transcription factor HLH-30/TFEB. Altogether, our study reveals the mechanistic crosstalk between mitochondrial translation, mitochondrial dynamics, and lysosomal signaling in regulating longevity.
Project description:Proliferative and replicative senescent fibroblasts from aged human donors were reprogrammed towards pluripotency and re-differentiated in fibroblasts and then further analyzed for rejuvenation assessment. Comparison of microarrays were performed by non hierarchical clustering visualized in with Treeview software
Project description:Disruption of mitochondrial respiration in the nematode Caenorhabditis elegans can extend lifespan. We previously showed that long-lived respiratory mutants generate elevated amounts of α-ketoacids. These compounds are structurally related to α-ketoglutarate, suggesting they may be biologically relevant. Here, we show that provision of several such metabolites to wild-type worms is sufficient to extend their life. At least one mode of action is through stabilization of hypoxia-inducible factor-1 (HIF-1). We also find that an α-ketoglutarate mimetic, 2,4-pyridinedicarboxylic acid (2,4-PDA), is alone sufficient to increase the lifespan of wild-type worms and this effect is blocked by removal of HIF-1. HIF-1 is constitutively active in isp-1(qm150) Mit mutants, and accordingly, 2,4-PDA does not further increase their lifespan. Incubation of mouse 3T3-L1 fibroblasts with life-prolonging α-ketoacids also results in HIF-1α stabilization. We propose that metabolites that build up following mitochondrial respiratory dysfunction form a novel mode of cell signaling that acts to regulate lifespan.
Project description:Nearly 30% of all malignant melanomas harbor somatic mutations in NRAS. However, there are currently no effective targeted therapies for this tumor type. The bromodomain and extra terminal domain (BET) family of proteins are transcriptional regulators that serve as scaffolds to facilitate gene transcription by binding to acetylated lysine residues in the N-terminal tail of histones. BET/BRD proteins have emerged as therapeutic targets in a broad range of tumors. We found that BET proteins are overexpressed in NRAS mutant melanoma, and that high levels of BET family member BRD4 are associated with poor patient survival, suggesting that BRD4 plays a key role in melanoma. Consequently, we hypothesized that these epigenetic regulators constitute potential vulnerabilities that can be exploited for melanoma treatment. We found that genetic or pharmacological inhibition of BET/BRD proteins decreases viability and inhibits proliferation of NRAS mutant melanoma cells, as well as BRAF/MEK-inhibitor resistant melanoma cells harboring concurrent BRAF/NRAS mutations. However, BET inhibitors when used as single agents were either cytostatic (in vitro) or ineffective (in vivo). We therefore evaluated combinations that could maximize the efficacy of BET inhibitors in NRAS mutant melanoma. Here we report that co-targeting BET and MEK synergistically restrained tumor growth and significantly prolonged the survival of NRAS-mutant tumor bearing mice. RNA-sequencing and RPPA analysis revealed that co-treatment with BETi/MEKi synergistically downregulated cell cycle regulators and activated caspase-7. This study demonstrates that combined BET and MEK inhibition elicits robust synergistic therapeutic effects and supports the clinical utility of this combination therapy for NRAS mutant melanoma patients.
Project description:Antimicrobial peptides (AMPs) are important defense molecules of the innate immune system. High levels of AMPs are induced in response to infections to fight pathogens, whereas moderate levels induced by metabolic stress are thought to shape commensal microbial communities at barrier tissues. We expressed single AMPs in adult flies either ubiquitously or in the gut by using the inducible GeneSwitch system to tightly regulate AMP expression. We found that activation of single AMPs, including Drosocin, resulted in a significant extension of Drosophila lifespan. These animals showed reduced activity of immune pathways over lifetime, less intestinal regenerative processes, reduced stress response and a delayed loss of gut barrier integrity. Furthermore, intestinal Drosocin induction protected the animals against infections with the natural Drosophila pathogen Pseudomonas entomophila, whereas a germ-reduced environment prevented the lifespan extending effect of Drosocin. Our study provides new insights into the crosstalk of innate immunity, intestinal homeostasis and ageing.
Project description:Proliferative and replicative senescent fibroblasts from aged human donors were reprogrammed towards pluripotency and re-differentiated in fibroblasts and then further analyzed for rejuvenation assessment.