RESUMEN
OBJECTIVE: Despite advances toward understanding the etiology of Alzheimer's disease (AD), it remains unclear which aspects of this disease are affected by environmental factors. Chronic life stress increases risk for aging-related diseases including AD. The impact of stress on tauopathies remains understudied. We examined the effects of stress elicited by social (chronic subordination stress, CSS) or psychological/physical (chronic restraint stress, CRS) factors - on the PS19 mouse model of tauopathy. METHODS: Male PS19 mice (average age 6.3 months) were randomized to receive CSS, CRS, or to remain as singly-housed controls. Behavioral tests were used to assess anxiety-like behaviors and cognitive functions. Immunofluorescence staining and western blotting analysis were used to measure levels of astrogliosis, microgliosis and tau burden. Immunohistochemistry was used to assess glucocorticoid receptor expression. RESULTS: PS19 mice exhibit neuroinflammation (GFAP, t-tests; p = 0.0297; Iba1, t-tests; p = 0.006) and tau hyperphosphorylation (t-test, p = 0.0446) in the hippocampus, reduced anxiety (post hoc, p = 0.046), and cognitive deficits, when compared to wild type mice. Surprisingly, CRS reduced hippocampal levels of both total tau and phospho-tauS404 (t-test, p = 0.0116), and attenuated some aspects of both astrogliosis and microgliosis in PS19 mice (t-tests, p = 0.068 to p = 0.0003); however, this was not associated with significant changes in neurodegeneration or cognitive function. Anxiety-like behaviors were increased by CRS (post hoc, p = 0.046). Conversely, CSS impaired spatial learning in Barnes Maze without impacting tau phosphorylation or neurodegeneration and having a minimal impact on gliosis. CONCLUSIONS: Our results demonstrate that social or psychological stress can differentially impact anxiety-like behavior, select cognitive functions, and some aspects of tau-dependent pathology in PS19 male mice, providing entry points for the development of experimental approaches designed to slow AD progression.
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PTEN is a multifaceted tumor suppressor that is highly sensitive to alterations in expression or function. The PTEN C-tail domain, which is rich in phosphorylation sites, has been implicated in PTEN stability, localization, catalytic activity, and protein interactions, but its role in tumorigenesis remains unclear. To address this, we utilized several mouse strains with nonlethal C-tail mutations. Mice homozygous for a deletion that includes S370, S380, T382 and T383 contain low PTEN levels and hyperactive AKT but are not tumor prone. Analysis of mice containing nonphosphorylatable or phosphomimetic versions of S380, a residue hyperphosphorylated in human gastric cancers, reveal that PTEN stability and ability to inhibit PI3K-AKT depends on dynamic phosphorylation-dephosphorylation of this residue. While phosphomimetic S380 drives neoplastic growth in prostate by promoting nuclear accumulation of ß-catenin, nonphosphorylatable S380 is not tumorigenic. These data suggest that C-tail hyperphosphorylation creates oncogenic PTEN and is a potential target for anti-cancer therapy.
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Carcinogénesis , Fosfohidrolasa PTEN , Animales , Humanos , Masculino , Ratones , Carcinogénesis/genética , Homocigoto , Mutación , Fosfatidilinositol 3-Quinasas , Proteínas Proto-Oncogénicas c-akt , Fosfohidrolasa PTEN/genética , FosforilaciónRESUMEN
In age-related neurodegenerative diseases, like Alzheimer's and Parkinson's, disease-specific proteins become aggregation-prone and form amyloid-like deposits. Depletion of SERF proteins ameliorates this toxic process in worm and human cell models for diseases. Whether SERF modifies amyloid pathology in mammalian brain, however, has remained unknown. Here, we generated conditional Serf2 knockout mice and found that full-body deletion of Serf2 delayed embryonic development, causing premature birth and perinatal lethality. Brain-specific Serf2 knockout mice, on the other hand, were viable, and showed no major behavioral or cognitive abnormalities. In a mouse model for amyloid-ß aggregation, brain depletion of Serf2 altered the binding of structure-specific amyloid dyes, previously used to distinguish amyloid polymorphisms in the human brain. These results suggest that Serf2 depletion changed the structure of amyloid deposits, which was further supported by scanning transmission electron microscopy, but further study will be required to confirm this observation. Altogether, our data reveal the pleiotropic functions of SERF2 in embryonic development and in the brain and support the existence of modifying factors of amyloid deposition in mammalian brain, which offer possibilities for polymorphism-based interventions.
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Encéfalo , Péptidos y Proteínas de Señalización Intracelular , Placa Amiloide , Animales , Humanos , Ratones , Péptidos beta-Amiloides/metabolismo , Encéfalo/embriología , Encéfalo/metabolismo , Desarrollo Embrionario/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones Noqueados , Placa Amiloide/metabolismoRESUMEN
Cellular senescence is a state of permanent growth arrest that plays an important role in wound healing, tissue fibrosis, and tumor suppression. Despite senescent cells' (SnCs) pathological role and therapeutic interest, their phenotype in vivo remains poorly defined. Here, we developed an in vivo-derived senescence signature (SenSig) using a foreign body response-driven fibrosis model in a p16-CreERT2;Ai14 reporter mouse. We identified pericytes and "cartilage-like" fibroblasts as senescent and defined cell type-specific senescence-associated secretory phenotypes (SASPs). Transfer learning and senescence scoring identified these two SnC populations along with endothelial and epithelial SnCs in new and publicly available murine and human data single-cell RNA sequencing (scRNAseq) datasets from diverse pathologies. Signaling analysis uncovered crosstalk between SnCs and myeloid cells via an IL34-CSF1R-TGFßR signaling axis, contributing to tissue balance of vascularization and matrix production. Overall, our study provides a senescence signature and a computational approach that may be broadly applied to identify SnC transcriptional profiles and SASP factors in wound healing, aging, and other pathologies.
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Envejecimiento , Senescencia Celular , Humanos , Ratones , Animales , Senescencia Celular/genética , Envejecimiento/genética , Fenotipo , Fibroblastos , Aprendizaje AutomáticoRESUMEN
Recent work has established associations between elevated p21, the accumulation of senescent cells, and skeletal muscle dysfunction in mice and humans. Using a mouse model of p21 overexpression (p21OE), we examined if p21 mechanistically contributes to cellular senescence and pathological features in skeletal muscle. We show that p21 induces several core properties of cellular senescence in skeletal muscle, including an altered transcriptome, DNA damage, mitochondrial dysfunction, and the senescence-associated secretory phenotype (SASP). Furthermore, p21OE mice exhibit manifestations of skeletal muscle pathology, such as atrophy, fibrosis, and impaired physical function when compared to age-matched controls. These findings suggest p21 alone is sufficient to drive a cellular senescence program and reveal a novel source of skeletal muscle loss and dysfunction.
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Senescencia Celular , Músculo Esquelético , Humanos , Senescencia Celular/fisiologíaRESUMEN
Super-enhancers regulate genes with important functions in processes that are cell type-specific or define cell identity. Mouse embryonic fibroblasts establish 40 senescence-associated super-enhancers regardless of how they become senescent, with 50 activated genes located in the vicinity of these enhancers. Here we show, through gene knockdown and analysis of three core biological properties of senescent cells that a relatively large number of senescence-associated super-enhancer-regulated genes promote survival of senescent mouse embryonic fibroblasts. Of these, Mdm2, Rnase4, and Ang act by suppressing p53-mediated apoptosis through various mechanisms that are also engaged in response to DNA damage. MDM2 and RNASE4 transcription is also elevated in human senescent fibroblasts to restrain p53 and promote survival. These insights identify key survival mechanisms of senescent cells and provide molecular entry points for the development of targeted therapeutics that eliminate senescent cells at sites of pathology.
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Fibroblastos , Proteína p53 Supresora de Tumor , Animales , Apoptosis/genética , Senescencia Celular/genética , Daño del ADN , Fibroblastos/fisiología , Ratones , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Senescent cells (SNCs) degenerate the fibrous cap that normally prevents atherogenic plaque rupture, a leading cause of myocardial infarction and stroke. Here we explored the underlying mechanism using pharmacological or transgenic approaches to clear SNCs in the Ldlr -/- mouse model of atherosclerosis. SNC clearance reinforced fully deteriorated fibrous caps in highly advanced lesions, as evidenced by restored vascular smooth muscle cell (VSMC) numbers, elastin content, and overall cap thickness. We found that SNCs inhibit VSMC promigratory phenotype switching in the first interfiber space of the arterial wall directly beneath atherosclerotic plaque, thereby limiting lesion entry of medial VSMCs for fibrous cap assembly or reinforcement. SNCs do so by antagonizing IGF-1 through the secretion of insulin-like growth factor-binding protein 3 (Igfbp3). These data indicate that the intermittent use of senolytic agents or IGFBP-3 inhibition in combination with lipid lowering drugs may provide therapeutic benefit in atherosclerosis.
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Aterosclerosis , Infarto del Miocardio , Placa Aterosclerótica , Ratones , Animales , Aterosclerosis/tratamiento farmacológico , Placa Aterosclerótica/genética , Infarto del Miocardio/metabolismo , Senescencia Celular , Miocitos del Músculo Liso/metabolismoRESUMEN
Immune cells identify and destroy damaged cells to prevent them from causing cancer or other pathologies by mechanisms that remain poorly understood. Here, we report that the cell-cycle inhibitor p21 places cells under immunosurveillance to establish a biological timer mechanism that controls cell fate. p21 activates retinoblastoma protein (Rb)dependent transcription at select gene promoters to generate a complex bioactive secretome, termed p21-activated secretory phenotype (PASP). The PASP includes the chemokine CXCL14, which promptly attracts macrophages. These macrophages disengage if cells normalize p21 within 4 days, but if p21 induction persists, they polarize toward an M1 phenotype and lymphocytes mount a cytotoxic T cell response to eliminate target cells, including preneoplastic cells. Thus, p21 concurrently induces proliferative arrest and immunosurveillance of cells under duress.
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Senescencia Celular , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/metabolismo , Vigilancia Inmunológica , Animales , Puntos de Control del Ciclo Celular , Línea Celular , Quimiocinas CXC/metabolismo , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/genética , Genes ras , Hepatocitos/inmunología , Hepatocitos/metabolismo , Humanos , Macrófagos/inmunología , Macrófagos/metabolismo , Ratones , Ratones Transgénicos , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Proteína de Retinoblastoma/metabolismo , Estrés Fisiológico , Linfocitos T Citotóxicos/inmunología , Transcripción GenéticaRESUMEN
Chromosome gains and losses are a frequent feature of human cancers. However, how these aberrations can outweigh the detrimental effects of aneuploidy remains unclear. An initial comparison of existing chromosomal instability (CIN) mouse models suggests that aneuploidy accumulates to low levels in these animals. We therefore developed a novel mouse model that enables unprecedented levels of chromosome missegregation in the adult animal. At the earliest stages of T-cell development, cells with random chromosome gains and/or losses are selected against, but CIN eventually results in the expansion of progenitors with clonal chromosomal imbalances. Clonal selection leads to the development of T-cell lymphomas with stereotypic karyotypes in which chromosome 15, containing the Myc oncogene, is gained with high prevalence. Expressing human MYC from chromosome 6 (MYCChr6) is sufficient to change the karyotype of these lymphomas to include universal chromosome 6 gains. Interestingly, while chromosome 15 is still gained in MYCChr6 tumors after genetic ablation of the endogenous Myc locus, this chromosome is not efficiently gained after deletion of one copy of Rad21, suggesting a synergistic effect of both MYC and RAD21 in driving chromosome 15 gains. Our results show that the initial detrimental effects of random missegregation are outbalanced by clonal selection, which is dictated by the chromosomal location and nature of certain genes and is sufficient to drive cancer with high prevalence.
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Aneuploidia , Inestabilidad Cromosómica , Animales , Transformación Celular Neoplásica/genética , Inestabilidad Cromosómica/genética , Aberraciones Cromosómicas , Cariotipo , Ratones , Prevalencia , Células MadreRESUMEN
One of the greatest barriers to curative treatment of neuroblastoma is its frequent metastatic outgrowth prior to diagnosis, especially in cases driven by amplification of the MYCN oncogene. However, only a limited number of regulatory proteins that contribute to this complex MYCN-mediated process have been elucidated. Here we show that the growth arrest-specific 7 (GAS7) gene, located at chromosome band 17p13.1, is preferentially deleted in high-risk MYCN-driven neuroblastoma. GAS7 expression was also suppressed in MYCN-amplified neuroblastoma lacking 17p deletion. GAS7 deficiency led to accelerated metastasis in both zebrafish and mammalian models of neuroblastoma with overexpression or amplification of MYCN. Analysis of expression profiles and the ultrastructure of zebrafish neuroblastoma tumors with MYCN overexpression identified that GAS7 deficiency led to (i) downregulation of genes involved in cell-cell interaction, (ii) loss of contact among tumor cells as critical determinants of accelerated metastasis, and (iii) increased levels of MYCN protein. These results provide the first genetic evidence that GAS7 depletion is a critical early step in the cascade of events culminating in neuroblastoma metastasis in the context of MYCN overexpression. SIGNIFICANCE: Heterozygous deletion or MYCN-mediated repression of GAS7 in neuroblastoma releases an important brake on tumor cell dispersion and migration to distant sites, providing a novel mechanism underlying tumor metastasis in MYCN-driven neuroblastoma.See related commentary by Menard, p. 2815.
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Biomarcadores de Tumor/metabolismo , Neoplasias de la Médula Ósea/secundario , Deleción Cromosómica , Regulación Neoplásica de la Expresión Génica , Proteína Proto-Oncogénica N-Myc/metabolismo , Proteínas del Tejido Nervioso/deficiencia , Neuroblastoma/patología , Animales , Apoptosis , Biomarcadores de Tumor/genética , Neoplasias de la Médula Ósea/genética , Neoplasias de la Médula Ósea/metabolismo , Proliferación Celular , Humanos , Ratones , Ratones SCID , Proteína Proto-Oncogénica N-Myc/genética , Proteínas del Tejido Nervioso/genética , Neuroblastoma/genética , Neuroblastoma/metabolismo , Pronóstico , Tasa de Supervivencia , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de Xenoinjerto , Pez CebraRESUMEN
BACKGROUND AND AIMS: Up-regulation of the E2F-dependent transcriptional network has been identified in nearly every human malignancy and is an important driver of tumorigenesis. Two members of the E2F family, E2F7 and E2F8, are potent repressors of E2F-dependent transcription. They are atypical in that they do not bind to dimerization partner proteins and are not controlled by retinoblastoma protein. The physiological relevance of E2F7 and E2F8 remains incompletely understood, largely because tools to manipulate their activity in vivo have been lacking. APPROACH AND RESULTS: Here, we generated transgenic mice with doxycycline-controlled transcriptional activation of E2f7 and E2f8 and induced their expression during postnatal development, in adulthood, and in the context of cancer. Systemic induction of E2f7 and, to lesser extent, E2f8 transgenes in juvenile mice impaired cell proliferation, caused replication stress, DNA damage, and apoptosis, and inhibited animal growth. In adult mice, however, E2F7 and E2F8 induction was well tolerated, yet profoundly interfered with DNA replication, DNA integrity, and cell proliferation in diethylnitrosamine-induced liver tumors. CONCLUSION: Collectively, our findings demonstrate that atypical E2Fs can override cell-cycle entry and progression governed by other E2F family members and suggest that this property can be exploited to inhibit proliferation of neoplastic hepatocytes when growth and development have subsided during adulthood.
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Proliferación Celular , Factor de Transcripción E2F7/fisiología , Hepatocitos/metabolismo , Neoplasias Hepáticas/patología , Proteínas Represoras/fisiología , Animales , Apoptosis/fisiología , Ciclo Celular/fisiología , Daño del ADN , Factor de Transcripción E2F7/deficiencia , Factor de Transcripción E2F7/genética , Células HeLa , Humanos , Neoplasias Hepáticas/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Represoras/deficiencia , Proteínas Represoras/genética , Activación TranscripcionalRESUMEN
Up to 85% of adult cancer survivors and 99% of adult survivors of childhood cancer live with an accumulation of chronic conditions, frailty, and/or cognitive impairments resulting from cancer and its treatment. Thus, survivors often show an accelerated development of multiple geriatric syndromes and need therapeutic interventions. To advance progress in this area, the National Cancer Institute convened the second of 2 think tanks under the auspices of the Cancer and Accelerated Aging: Advancing Research for Healthy Survivors initiative. Experts assembled to share evidence of promising strategies to prevent, slow, or reverse the aging consequences of cancer and its treatment. The meeting identified research and resource needs, including geroscience-guided clinical trials; comprehensive assessments of functional, cognitive, and psychosocial vulnerabilities to assess and predict age-related outcomes; preclinical and clinical research to determine the optimal dosing for behavioral (eg, diet, exercise) and pharmacologic (eg, senolytic) therapies; health-care delivery research to evaluate the efficacy of integrated cancer care delivery models; optimization of intervention implementation, delivery, and uptake; and patient and provider education on cancer and treatment-related late and long-term adverse effects. Addressing these needs will expand knowledge of aging-related consequences of cancer and cancer treatment and inform strategies to promote healthy aging of cancer survivors.
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Envejecimiento/patología , Fragilidad/epidemiología , Afecciones Crónicas Múltiples/epidemiología , Neoplasias/epidemiología , Supervivientes de Cáncer , Disfunción Cognitiva/epidemiología , Disfunción Cognitiva/etiología , Fragilidad/etiología , Humanos , National Cancer Institute (U.S.) , Neoplasias/complicaciones , Neoplasias/patología , Neoplasias/terapia , Estados Unidos/epidemiologíaRESUMEN
Decreased NAD+ levels have been shown to contribute to metabolic dysfunction during aging. NAD+ decline can be partially prevented by knockout of the enzyme CD38. However, it is not known how CD38 is regulated during aging, and how its ecto-enzymatic activity impacts NAD+ homeostasis. Here we show that an increase in CD38 in white adipose tissue (WAT) and the liver during aging is mediated by accumulation of CD38+ immune cells. Inflammation increases CD38 and decreases NAD+. In addition, senescent cells and their secreted signals promote accumulation of CD38+ cells in WAT, and ablation of senescent cells or their secretory phenotype decreases CD38, partially reversing NAD+ decline. Finally, blocking the ecto-enzymatic activity of CD38 can increase NAD+ through a nicotinamide mononucleotide (NMN)-dependent process. Our findings demonstrate that senescence-induced inflammation promotes accumulation of CD38 in immune cells that, through its ecto-enzymatic activity, decreases levels of NMN and NAD+.
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ADP-Ribosil Ciclasa 1/metabolismo , Envejecimiento/metabolismo , Glicoproteínas de Membrana/metabolismo , NAD/biosíntesis , ADP-Ribosil Ciclasa 1/genética , ADP-Ribosil Ciclasa 1/inmunología , Adipocitos Blancos/metabolismo , Tejido Adiposo Blanco/metabolismo , Envejecimiento/inmunología , Animales , Trasplante de Médula Ósea , Senescencia Celular , Células HEK293 , Humanos , Inflamación/inmunología , Hígado/crecimiento & desarrollo , Hígado/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Mononucleótido de Nicotinamida/metabolismo , FenotipoRESUMEN
Cep57 has been characterized as a component of a pericentriolar complex containing Cep63 and Cep152. Interestingly, Cep63 and Cep152 self-assemble into a pericentriolar cylindrical architecture, and this event is critical for the orderly recruitment of Plk4, a key regulator of centriole duplication. However, the way in which Cep57 interacts with the Cep63-Cep152 complex and contributes to the structure and function of Cep63-Cep152 self-assembly remains unknown. We demonstrate that Cep57 interacts with Cep63 through N-terminal motifs and associates with Cep152 via Cep63. Three-dimensional structured illumination microscopy (3D-SIM) analyses suggested that the Cep57-Cep63-Cep152 complex is concentrically arranged around a centriole in a Cep57-in and Cep152-out manner. Cep57 mutant cells defective in Cep63 binding exhibited improper Cep63 and Cep152 localization and impaired Sas6 recruitment for procentriole assembly, proving the significance of the Cep57-Cep63 interaction. Intriguingly, Cep63 fused to a microtubule (MT)-binding domain of Cep57 functioned in concert with Cep152 to assemble around stabilized MTs in vitro Thus, Cep57 plays a key role in architecting the Cep63-Cep152 assembly around centriolar MTs and promoting centriole biogenesis. This study may offer a platform to investigate how the organization and function of the pericentriolar architecture are altered by disease-associated mutations found in the Cep57-Cep63-Cep152 complex.
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Proteínas de Ciclo Celular/metabolismo , Centriolos/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas Nucleares/metabolismo , Proteínas de Ciclo Celular/análisis , Línea Celular Tumoral , Células HEK293 , Humanos , Proteínas Asociadas a Microtúbulos/análisis , Proteínas Nucleares/análisis , Dominios y Motivos de Interacción de Proteínas , Mapas de Interacción de ProteínasRESUMEN
Chemotherapy is important for cancer treatment, however, toxicities limit its use. While great strides have been made to ameliorate the acute toxicities induced by chemotherapy, long-term comorbidities including bone loss remain a significant problem. Chemotherapy-driven estrogen loss is postulated to drive bone loss, but significant data suggests the existence of an estrogen-independent mechanism of bone loss. Using clinically relevant mouse models, we showed that senescence and its senescence-associated secretory phenotype (SASP) contribute to chemotherapy-induced bone loss that can be rescued by depleting senescent cells. Chemotherapy-induced SASP could be limited by targeting the p38MAPK-MK2 pathway, which resulted in preservation of bone integrity in chemotherapy-treated mice. These results transform our understanding of chemotherapy-induced bone loss by identifying senescent cells as major drivers of bone loss and the p38MAPK-MK2 axis as a putative therapeutic target that can preserve bone and improve a cancer survivor's quality of life. SIGNIFICANCE: Senescence drives chemotherapy-induced bone loss that is rescued by p38MAPK or MK2 inhibitors. These findings may lead to treatments for therapy-induced bone loss, significantly increasing quality of life for cancer survivors.
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Antineoplásicos/efectos adversos , Senescencia Celular/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Neoplasias/tratamiento farmacológico , Osteoporosis/inducido químicamente , Animales , Modelos Animales de Enfermedad , Doxorrubicina/efectos adversos , Fémur/citología , Fémur/diagnóstico por imagen , Fémur/patología , Humanos , Inyecciones Intraperitoneales , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones , Ratones Transgénicos , Osteoporosis/diagnóstico , Osteoporosis/patología , Paclitaxel/efectos adversos , Proteínas Serina-Treonina Quinasas/metabolismo , Microtomografía por Rayos X , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
FoxM1 activates genes that regulate S-G2-M cell-cycle progression and, when overexpressed, is associated with poor clinical outcome in multiple cancers. Here we identify FoxM1 as a tumor suppressor in mice that, through its N-terminal domain, binds to and inhibits Ect2 to limit the activity of RhoA GTPase and its effector mDia1, a catalyst of cortical actin nucleation. FoxM1 insufficiency impedes centrosome movement through excessive cortical actin polymerization, thereby causing the formation of non-perpendicular mitotic spindles that missegregate chromosomes and drive tumorigenesis in mice. Importantly, low FOXM1 expression correlates with RhoA GTPase hyperactivity in multiple human cancer types, indicating that suppression of the newly discovered Ect2-RhoAmDia1 oncogenic axis by FoxM1 is clinically relevant. Furthermore, by dissecting the domain requirements through which FoxM1 inhibits Ect2 GEF activity, we provide mechanistic insight for the development of pharmacological approaches that target protumorigenic RhoA activity.